Final ReportSummary - THERMALCOND (Polymeric composite materials with enhanced thermal conductivity properties for heat exchangers applications)
The main innovations claimed in THERMALCOND include the development of a new family of low cost polyolefin based components (sheets, pipes and fittings) to be used in the manufacturing of flat-plate solar thermal collectors. These components are expected to be a viable alternative to current thermal collectors' constitutive metallic components, mainly made of copper. However, due the current limitations of thermoplastics materials (low thermal conductivity and low adhesive coatings) two main advancements will be developed in this project:
- polyolefin nanocomposites by using different nanoparticles with high thermal conductive properties as additives to improve the thermal conductivity of the final components;
- a novel and specific surface treatment based on SAM technology- to provide a flexible energy absorbing coating to the different components. This coating will be based on metallic oxides (e.g. TiO2 or ZnO).
These developments will allow novel low cost and low weight components design's with enhanced thermal conductivity and high solar energy absorption to develop high efficiency thermal collector designs. The use of plastics components instead of metallic ones offer additional advantages: folding and easy assembling structures design, low energy consumption in motorised thermal collectors (follow sun light), corrosion resistance, low friction coefficient (less pump energy consume), prevent theft or vandalism (due the low cost of components in comparison with copper).
The solar thermal collector parts to be substituted by the new thermal conductive materials and flexible absorber coatings will be the extruded pipes and injected fittings of the collector heat absorption circuit and extruded sheets which will be used as absorber plate.
In this context, the polymeric materials appear as a real alternative to develop new low cost procedures in which a wide variety of component's designs could be obtained to optimise the thermal energy obtained per thermal collector surface. Due to their properties, plastics permit to produce any type of part with a free design at very competitive cost.
All the non-confidential information generated so far under the project can be found in THERMALCOND website, in the open area.
The new polyolefin nanocomposites developed in THERMALCOND project may have a significant impact on the plastic industry, providing and alternative material to the current metals used in thermal collectors or other applications where thermal conductivity is needed. Nano-particles developed can be used also with technical polymers extending the field of application. On the other hand, coating developed has provided good adherence and high solar energy absorption in plastic and metallic substrates. The low cost and easy coating application provide a real alternative to commercial coatings.
Thermal collectors components made with new nanocomposites have been scaled up successfully showing a similar behaviour in terms of mechanical properties and process ability than net polymers which it is a very important point for SMEs involved in the project.
Self-assembly, briefly, are a class of molecular assemblies that are prepared by spontaneous adsorption and organisation of molecules into stable, structurally well-defined aggregates from solution onto a solid substrate. Principles drawn from biology and have stimulated the development of new strategies and new applications.
Project context and objectives:
A flat-plate solar collector (FPC) is one of the main types of solar collectors which are key components of active solar heating systems and they are, by far, the most used type of collectors. FPCs are usually employed for low temperature applications up to 100 ºC.There are many flat-plate collector designs but generally all consist of:
(1) a transparent cover(s) that allows solar energy to pass through but reduces heat loss from the absorber;
(2) a flat-plate absorber, which intercepts and absorbs the solar energy;
(3) a heat-transport fluid (air, antifreeze or water) flowing through tubes to remove heat from the absorber; and
(4) a heat insulating backing.
The transparent cover is used to reduce convection losses from the absorber plate through the restraint of the stagnant air layer between the absorber plate and the glass. It also reduces radiation losses from the collector as the glass is transparent to the short wave radiation received by the sun but it is nearly opaque to long-wave thermal radiation emitted by the absorber plate (greenhouse effect).
The collector absorber plate absorbs as much of the irradiation as possible through the glazing cover sheet, while loosing as little heat as possible upward to the atmosphere and downward through the back of the casing. The collector plates transfer the retained heat to the transport fluid. Absorbers plates are usually made of metal-typically copper or aluminium-because the metal is a good heat conductor. Copper is more expensive, but is a better conductor and less prone to corrosion than aluminium. Absorber plates are commonly painted with selective coatings, which absorb and retain heat better than ordinary black paint. By suitable electrolytic or chemical treatments, surfaces can be produced with high values of solar radiation absorption and low values of long wave emission.
Polymers for heat thermal exchangers offer the potential advantages of:
- reduced cost of materials and manufacturing;
- resistance corrosion and mineral build-up; if mineral build-up is reduced, maintenance costs should be lower than those for metal heat exchangers;
- low friction coefficients;
- reduced weight and easy installation; and
- use of polymers may permit better integration with other components.
They are widely available low cost materials, which lend themselves to a volume production of lightweight low cost collectors tolerant to corrosion and freezing temperatures; however, their reliability, durability and long-term performance have not been fully demonstrated yet.
The thermal conductivity of polymers is substantially lower than that of ordinary metallic absorber materials, something which is very crucial for their use in solar energy applications and makes the redesign of conventional tube and metal absorber absolutely necessary.
It is in this context where the use of nanoparticles with thermal conductive properties appears like a promising solution for enhancing the thermal conductivity of the polymeric materials. Even though some works have been reported about polymeric materials used for thermal collector designs, any of them has considered the use of conductive nanoparticles to enhance the polymer heat transfer characteristics.
The objectives of this project can be quantified and measured as follows:
- Develop a new family of polyolefin composites by using different nanoparticles with high thermal conductive properties:
i. The thermal conductivity values measured in the new materials must be at least a 10 W/m.K.
ii. Increase thermal resistance of polyolefins (PP or PE) extruded and injected pieces with the use of nanoparticles. Deflection Temperature 1.8 MPa (EN-ISO 75) 60 ºC, thanks the use of nanoparticles with nucleant capacity.
iii. Competitive cost of optimised polyolefines / nanoparticles formulations. They prize of the compound must be lower than EUR 4/kg.
iv. Avoid problems of nanoparticles dispersion by their functionalisation using self-assembly molecules. This way it is possible to optimise the nanoparticles dispersion in order to use the minimal amount of nanoparticles, so that the final processability of the new compounds in extrusion and injection moulding is guaranteed since the viscosity increases will be limited to 15 %.
v. The project will broad the range of applications of conductive materials by the use of a synergy combination of conductive nanoparticles, functionalisation processes of the nanoparticles to increase the dispersion in the polymer matrix and using conventional injection and extrusion processes, whereas offering new functionalities (conductive polymers composites).
vi. Study the relation between processing parameters and part final conductivity in extruded pipes and sheets.
- Development of a flexible absorber coating (based on nanometallic oxides) by a novel cost effective and environmentally friendly surface treatment technology for extruded and injected polyolefin components:
i. Create strong bonds between the coatings and the plastic surface. This stronger adhesion of the coating to the substrate is obtained thanks to the chemical bonds created instead of the physical interaction compared to other processes.
ii. Use flexible coatings to compensate the plastic parts thermal expansion due the temperature differences during day and night and seasons and preventing the appearance of cracks or other problems in the coating.
iii. Tailor-made coating thickness from nanolayers until some microns; which is dependent on the residence time of the plastic part in the bath process. Possibilities to have a broad range of absorber coating with different properties.
iv. Low equipment investment due to the use of standard components and flexibility to scale up (the size of the plant can be adapted to the required output).
v. Flexibility to use a variety of application methods, thus making easier to integrate the coating into existing manufacturing processes.
vi. Favourable temperature and pressure conditions during manufacturing versus other methods such as chemical vapour deposition, sputtering, thermal oxidation, plasma-enhanced chemical vapour deposition, or flame hydrolysis. This process will be largely carried out at low temperature conditions using simple and economical equipment. Mild oxidation at a 50 ºC and the others two steps lower than 30 ºC.
vii. Environmentally friendly coating since the water used in the process can be easily treated, the raw materials have low vapour pressures thus minimising evaporation losses and consequently the VOC values will be close to zero.
viii. No health concerns (water based treatments and low toxicity chemicals for high scratch coating process and for waste water treatment).
- High efficiency designs of flat-plate solar thermal collectors using different plastics components with enhanced properties:
i. Polyolefin pipes, fitting and absorber extruded sheets will substitute high cost and difficult to process metallic parts (Cu or Al), and so they will reduce the energy to produce them, the weight and the final costs. With the new technology these parts could be made with PP or PE, maintaining almost the same requirements, and increasing the processability, high design flexibility and large potential for part and multi-functional integration.
ii. The thermal conductivity of polymers is three orders of magnitude lower compared to metals, which are widely in use for common absorbers. Nevertheless with an appropriate design of the material this disadvantage can be compensated. The collector containing plastic components must have an efficiency not lower than 70 % (current metallic thermal collector have an efficiency of 87 %).
iii. Cost of the collector plastics component less than 50 % of current metallic ones.
Expected final results:
All expected final results foreseen initially were achieved under the scope of the project, demonstrating the capability of the new nano-composites and coating developed.
In order to improve the design of the solar collector and industrialise it, SMEs have submitted a demo project, 'Polymeric thermal collector demonstration (POLYTHERMALCOLL) (reference No. FP7-SME-2013).
Project results:
Technical information have been provided in the corresponding task reports of those work packages and their deliverables (confidential information sent only to EC).
WP1: Requirements definition and selection of adequate nanoparticles (D1.1 D1.2)
Leader: Resenergie (SME)
WP2: Compounding studies of selected materials (D2.1 D2.2)
Leader: Aimplas (RTD)
WP3: Pipe and sheet extrusion, injected parts and characterisation (D3.1 D3.2)
Leader: RAPRA (RTD).
WP4: Develop an absorption coating in plastics components (D4.1 D4.2)
Leader: Avanzare (RTD)
WP5: Thermal collector prototype and characterisation studies (D5.1 D5.2)
Leader: RAPRA (RTD)
WP6: Industrial scale-up and case-studies validation (D6.1)
Leader: ABN (SME)
WP7: Economic, regulatory and environmental studies (D7.1 D7.2 D7.3 D7.4)
Leader: Archimedes (SME)
WP8: Dissemination, exploitation and training (D8.1 D8.2 D8.3 D8.4 D8.5)
Leader: Colorex (SME)
WP9: Project management (D9.1 D9.2 D9.3 D9.4 D9.5)
Leader: Aimplas (RTD).
WP1: Requirements definition and selection of adequate nanoparticles
Contractors involved:
Resenergie, Colorex, ABN, Archnimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 1.1 Material requirements for the plastic components
Task 1.2 Selection of the nanoparticles, coupling agents and reactives for nanoparticles functionalisation and for absorption flexible coating
Work performed:
Selection of nanoparticles and polymers taking into account SMEs requirements and project objectives. The standard UNE EN-12975-2 has been taking into account along the project to fulfil thermal collector requirements:
-pressure work: 2 bar (test: 2x1.5/Time: 1h/radiation: 1000 W/m2), stagnation temperature will determine the test temperature;
-UV polymer resistance;
-low temperature: no failure up to -10 ºC;
-weld ability: depends on geometry;
-thermal stress: in normal use: range of 60 - 70 ºC. In extremely conditions has to resist around 140 ºC;
Polymers selection has been carried out taking into account their:
- thermal stability of polymer, particularly in air;
- softening behaviour of the polymer;
- polymer cost.
- Nanoparticles selection was a key factor in THERMALCOND project in order to obtain a competitive product. This task was divided depending on application:
-nanoparticles to increase thermal conductivity;
- nanoparticles to improve light absorption.
In all cases, regardless of the nanomaterials used as fillers, there were two issues taken into account:
-size and shape of the filler nanoparticle; in this case, the synthesis of the nanoparticle could be modulated in order to obtain the desired nano-particle characteristics.
- the dispersion and homogenous spatial distribution within the matrix.
Within the possible fillers to improve thermal conductivity, carbon materials were proposed, such as graphene, nanographene and carbon nanotubes. With materials and nano-particles selected, a compounding experimental design was carried out.
Conclusions (WP1):
Materials selected are suitable for THERMALCOND application and have demonstrated their resistance in hot and cold water systems where similar pressures have to be supported.
On the other hand, nano-particles selected for thermal conductivity have the highest values (W/mK) of particles studied and reasonable cost.
The use of nanostructures can certainly increase the transmission and absorption properties of many components of solar cells and could possibly provide low cost production processes.
Completion degree: 100 %
WP2: Compounding studies of selected materials
Contractors involved:
Colorex, Archimedes, Proform, Aimplas, Avanzare
Objectives:
Task 2.1 Thermal conductive nanoparticles modification
Task 2.4 Thermal conductive compounds optimisation
Task 2.3 Production of Tests specimens and their characterisation
Task 2.2 Development of thermal conductive compounds
Work performed:
Once established the optimal materials to be develop in the THERMALCOND project (WP1), it was necessary to mix physically and bind chemically the nanoparticles selected with plastic matrices in order to enhance polyolefins properties. Thus, the main goal of this work package was the proper dispersion and distribution of the fillers in the polymer. This step is crucial to obtain composites with the desired characteristics which have been measured.
Two ways were studied to embed graphene sheets in a polymer matrix:
- The first one exploits the interaction forces between polymer and graphene, by simple mixing (non-covalent functionalisation).
- The second one, by covalent bonding between the graphene and polymer matrix, either by polymerisation or by chemical modification reactions (covalent functionalisation).
In order to mix nanoparticles selected with polymers, several trials were developed both at laboratory and pilot plant level.
Compounds obtained were characterised in terms of:
-themal conductivity
- rheology
- thermal stability
- melt flow index (MFI)
- mechanical properties.
The objective was to select the best compounds, taking into account properties and process ability, and to test the coating developed in terms of adherence and absorption capability.
Conclusions (WP2):
Compounding characterisation confirms a considerable increase in thermal conductivity (increase of 4,5 times) maintaining melt flow index and main mechanical properties, which indicate their suitability to obtain injected and extruded parts without problems.
Trials developed to test coating adherence to the collector parts gave optimal results (impact testing and thermal shock were overcome). First coating evaluation in terms of absorption provided good behaviour compared net polymer and copper pipe.
Completion degree: 100 %
WP3: Pipe and sheet extrusion, injected parts and characterisation
Contractors involved: ABN, Proform, Aimplas, RAPRA
Objectives:
Task 3.1 Optimisation of processing protocols in the production of thermal conductive extruded pipes and sheets
Task 3.2 Injection processing protocols in the injection of thermal conductive fittings
Task 3.3 Material characterisation, analysis and post processing testing
Work performed:
The key process elements for polyolefin-based pipes are the extruder, the forming die, calibration sleeve, vacuum cooling bath and haul-off. Taking into account rheology data obtained from previous compounds characterisation process element were selected. On the other hand, processing conditions to obtain pipe and sheets with materials selected were adjusted. Pipes and sheets obtained were used to develop coating testing and also for material adjustments.
Selected compounds and collector parts were tested following standards:
- UNE-EN ISO 180
- UNE-EN ISO 527-2
- UNE-EN ISO 1183-1 (September 2004).
- UNE-EN ISO 75-2 (January 2005).
- UNE-EN ISO 306 (February 2005).
In terms of the comparison between filled and unfilled materials, there are no drastic changes in the properties that would cause concern as possible causes of component failure. Specifically, both materials show a significant increase in the modulus values. This is expected from most filler types, and particularly from nanofillers, due to their large surface area. For the PP grades, there is a small increase in tensile strength.
In case of oxidation induction time, formulation developed show better resistance to oxidation induction time than typical HDPE materials employed for hot water pipes (typical value 20 minutes). Values for THERMALCOND materials are around 60 minutes.
Also, pipes made with materials selected were tested under standard UNE EN ISO 1167: 2006 ('Determination of resistance to internal pressure') resist 165 hours at 95 ºC and under an internal pressure of 15 bar.
Two different exposure tests were developed: xenon light testing and halide light exposure test.
Conclusions (WP3):
Rheological, physical and thermal characterisation of candidate's materials have demonstrated their appropriateness for extrusion and injection processing and in their suitability for thermal collector applications taking into account requirements defined in WP1.
Optimisation of pipe / sheet production process for candidate materials selected in WP2 has carry out. Also, one step process has studied to reduce processing cost and to avoid material degradation.
Results obtained have been used in the rest of work packages.
Completion degree: 100%
WP4: Develop an absorption coating in plastics components.
Contractors involved:
Archimedes, Aimplas, Avanzare
Objectives:
Task 4.1 Development of mild oxidation process
Task 4.2 Absorptive nanoparticles modification
Task 4.3 Nanoparticles deposition over the selected plastic components.
Task 4.4 Coating characterisation
Task 4.5 Industrial evaluation of the new coating process
Task 4.6 Study of the best technologies for water treatment
Work performed:
Plastic components manufactured in WP3 were subjected to a mild oxidation. Also, nanoparticles surface were modified with the objective to obtain functional groups suitable for the formation of thin layers by self-assembly. To develop appropriate self-assembly process, selected molecules on WP1 were studied on different conditions: reagents, solvent, concentration of the reagents, temperature of the mixture, etc. Particles with best functionalisation performance and thermal absorption were selected.
The modified nanoparticles were deposited over the plastic components treated. The full process parameters, such as application mode, time of application and temperature of drying was optimised.
In order to test the coatings developed, several trials of grip impact resistance and extreme temperatures in samples of 10 cm tubes were carry out rejecting coatings with bad adherence.
To study the effect of the sun during the day, the development of an experimental device was carried out. The main idea was to evaluate the influence of solar radiation and temperature variations in samples of polyolefin tubes. To do this, we establish that the difference of temperature measured in treated and untreated pipes will be enough to determinate the efficiency of the heat absorber coating.
Different experimental devices were developed. All of them have in common that the tubes were placed on a surface with adjustable inclination. Water was flowed through the tubes using pumps with a constant water flow. In addition, thermo flasks with a temperature sensor inside were available.
During the project, protocols in bath water treatment were fixed in order o remove nanoparticles from water.
Conclusions (WP4):
Through experiments the combinations of materials and treatments were established taking into account best results obtained (graphene GR29 and coating TC90 were selected as best candidates)
In addition, indicative data on the necessary areas and energy levels achieved have been managed. These data are important to consider in the design of the prototype.
On the other hand, the water treatment studied, taking into account methods employed to obtain the coating, fixed protocols steps needed to remove any kind on nanoparticle from it.
The coatings developed based on nanomaterials are able to increase the effectiveness of different polyolefin materials. The simplicity in obtaining and apply these treatments involves a reduction in costs required for industrial implementation.
Completion degree: 100%
WP5: Thermal collector prototype and characterisation studies
Contractors involved:
Resenergie, ABN, Proform, Aimplas, RAPRA
Objectives:
Task 5.2 Solar thermal collector validation
Task 5.1 Solar thermal collector prototype assembling. In order to assemble a thermal collector prototype, several pieces need to be manufactured using the best compound developed in WP2
Work performed:
To assembly and test prototypes agree by the consortium, parts obtained during the scaling up process were needed (WP6). For a starting point, commercial solar panels were dismantled. This allowed the existing metallic components to be used as controls for direct comparison against the newly manufactured pipes, sheets and fittings.
Different methods of joining the new THERMALCOND pipes for the prototype designs, ranging from standard plastic pipe fittings with grab ring (e.g. Wavin Hep2O, Uponor), welded fittings and metal fabricated fittings (e.g. Emmeti) were taken into account:
- standard plastic pipe fitting cheapest;
- welded fitting most expensive initially due to high equipment cost to set-up, but cheapest for production;
- metal fittings more versatile and re-useable.
It has been decided to use metal fittings for prototype construction and for testing small networks of pipes.
Construction of several collector prototypes was compared to commercial ones. For this purpose, extruded parts were coated with novel coating developed in WP4.
The comparison in efficiency between the commercial panel and the prototype by square meter was carried out. To validate THERMALCOND collector, the standard EN12975 was followed which includes a range of tests concerning the reliability and performance of the installed collector panels cases, rather than the absorber assembly. Specifically, these are:
- exposure test (the characterisation tests carried out for WP3 are more demanding than the tests specified in EN12975);
- external thermal shock;
- rain penetration;
- freeze resistance;
- mechanical load;
- impact resistance.
Since the technical annex for WP5 specifies that tests will be carried out to compare the newly developed plastic absorber materials against commercial copper based collectors, it has been agreed that a standard commercial panel be disassembled , and rebuilt containing the plastic components.
Halide light exposure testing of materials
A series of tensile and impact bars were prepared from four different materials, both PP and PB-1 pipe grades, and the THERMALCOND nanocomposite materials based on each resin type. Half of each batch of bars was coated, via paintbrush application, with two coats of the coating selected. Half of each sub-batch was then exposed to a halide light with a constant irradiance of 1000 W.m-2 with a chamber temperature of 65 ºC for 250 hours.
The yield strength results show no particular trend apart from a marked reduction in the strength of the unfilled and uncoated PP samples after exposure. The elongation at yield results showed no noticeable trends.
The tensile strength results showed no noticeable trends with respect to the coating and exposure, but it is interesting to note that the compounding of the nanoparticles gives a significant boost to the tensile strength of the PP, but not so for the PB samples. Conversely, the elongation at break results show a significant decrease for the PP, but not for the PB.
The graphs for Izod impact strength show that the decrease in the impact strength for the clear PP after the light exposure is not present for the coated samples, demonstrating that the coating gives additional UV protection. It is also notable that the light exposure actually increases the impact strength of the PB samples.
Overall, it can be said that for the filled and coated grades, good long term resistance has been shown to the possible effects of UV degradation.
Internal thermal shock test
This test is designed to establish the capability of the collector design to withstand a severe internal thermal shock, such as may occur when the collector is brought into operation when already at its stagnation temperature. An eight riser absorber is constructed using each of the THERMALCOND candidate materials, and exposed to the solar light array for one hour before starting the water flow to the collector at less than 25 ºC. This is repeated twice for each absorber, and since the stagnation temperature is well within the operating temperature range of the materials, as expected, there is no discernible impact on the absorber assembly
Optimisation of plastic absorber design
It was decided, based on the results of the 'stagnation' tests, to have into account Reynolds number to optimise plastic absorber design. Reynolds number is the ratio of intertial versus viscous forces within a flowing fluid. In a pipe, the equation is simplified to Re=(?*u(D)/µ where Re is the Reynolds number, ? is the fluid density (approximately 1000 for water), u is the fluid velocity and µ is the fluid viscosity (varies with temperature).
Nusseldt number is the ratio of convective to conductive heat across the boundary between pipe and fluid: Nu=(h*D)/k where Re is the Reynolds number, ? is the fluid density (approximately 1000 for water), u is the fluid velocity, µ is the fluid viscosity (varies with temperature).
The Reynolds number, Re, is the determining factor of the flow regime in a pipework system. For Re > 2000, laminar flow is present, which means that water flows in annular layers within the pipe, and there is little interchange of fluid between the layers. For Re > 10000, fully turbulent flow exists - there are no layers, and the fluid can be considered fully mixed at all points within the flow. For 2000 < Re < 10000, the fluid is in transition between these two states.
Conclusions (WP5):
From the data produced close to ambient temperature, the commercial copper collector has a measured efficiency of 78.6 %, which is only 6.7 % higher than the THERMALCOND collector prototype.
The absorber pipes for the THERMALCOND single loop design (50 m of PB pipe) weighs 6.88 kg, compared with the copper absorber weight of 12.5 kg.
The absorber design has the benefit that no pipe joints are present within the collector body, and the PB pipes are frost proof which means that the collector does not need to be drained during the colder months of winter.
Completion degree: 100 %
WP6: Industrial scale-up and case-studies validation
Contractors involved:
Resergie, Colorex, ABN, Archimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 6.1 Scaling up and optimisation of compounding process
Task 6.2 Extrusion and Injection Processing at industrial level
Task 6.3 End user prototype validation
Task .6.4 Study of new designs of high efficiency thermal solar
Work performed:
SMEs scaled up each process in order to study differences between THERNMALCOND compounds developed and commercial polymers.
First step was the compounding scale up trials developed by COLOREX in order to obtain enough materials to use in subsequent steps (extrusion and injection parts). In order to obtain formulations selected, a co-rotative twin screw extruder is needed, preferably with a side feeder port to feed correctly powders into the process.
Personal protective equipment: full face mask (special filters for nanoparticles, gloves and clothing (i.e.Tyvex).
To ensure a quality control of compounds obtained, the twin screw extruder resulting process factors (The machine answer after setting some adjustable parameters) have to be taking into account:
- torque
- die pressure
- residence time
- dispersion quality
- melt temperature
- specific mechanical energy (SME).
Also, it is important to test the thermal conductivity of materials obtained. No difficult was found during compounding scale up.
Pipe extrusion scales up was performed by ABN. Materials obtained in compounding step gave similar melt flow index and rheology compared with base net polymer. For this reason, pipe extrusion did not find any processing problem.
Sheet extrusion and injection scale up were perfomed by Proform. As in case of pipe extrusion, compounds developed need very similar parameters than net polymers to be extruded and to obtain sheets for thermal collectors.
Conclusions (WP6):
Compounded PP/PB materials are suitable for PP pipe / sheet extrusion and fitting injection moulding. Only slight changes were done to adjust the processing conditions to new materials. No investments were necessary to use new materials with traditional equipments.
All partners worked actively in the study of the possible designs of the collector. Efficiency, assembly steps and cost were key factors in design steps.
Completion degree: 100 %
WP7: Economic, regulatory and environmental studies
Contractors involved:
Resenergie, Colorex, ABN, Archimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 7.1 Economic analysis
Task 7.2 Product life-cycle-analysis (LCA)
Task 7.3 Regulatory analysis
Task 7.4 Safety issues.
Work performed:
In order to calculate material cost developed and final panel price, all partners involved in the project provided data required. Also, all data was used to develop life cycle assessment (LCA) which is a process of identification and evaluation of the environmental impacts associated with a product, process or service, throughout its entire life cycle. The life cycle concept implies that the inputs to the cycle i.e. materials and energy and outputs i.e. products and co- / by-products, waste materials and energy, are evaluated for each step of product or process life. The cycle begins at process or product conception and ends with the recycle / disposal of the product and its constituents; hence, LCA takes a 'cradle to grave' approach in the analysis of environmental impacts, from materials acquisition, manufacturing, distribution, use and end of life. The assessment involves look at waste generation, emissions to air, water and soil as well as energy consumption. A cradle to gate approach can also been taken, whereby the assessment is done form the raw material acquisition to the product.
Two methods were employed during analysis: eco-indicator 99 (H) V2.09 and CLM 2 baseline 2000 V2.05.
The whole process was described in a best practice guideline developed in WP8 and completed in present WP with installation, materials, process issues, personal protective equipment and handling requirements, to contribute to the technology transfer and dissemination of the project.
In case of regulatory assessment, information provided was focused in selected coating and nanoparticles. REACH, the European Community Regulation on chemicals and their safe use is a regulation of the European Union, adopted to improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry. It also promotes alternative methods for the hazard assessment of substances in order to reduce the number of tests on animals. REACH must be taken into consideration in every country of the European Community, so all of the compounds of this project must fulfill this regulation.
With this new legislation, manufacturers and importers are required to gather information on the properties of their chemical substances, which will allow their safe handling, and to register the information in a central database run by the European Chemicals Agency (ECHA). Depending on the risks of the chemical, the agency classifies them and decides if it is necessary to substitute those dangerous products.
REACH regulation also binds to register all substances to study them to know their properties and hazards, so all industries must ensure that safety data regarding their uses is available. All substances used on THERMALCOND project has been registered or pre-registered in the central database run by the ECHA.
Conclusions (WP7):
The THERMALCOND panels compare favourably with the equivalent sised copper panels in terms of environmental loadings and also in terms of costs.
All substances used on this project has been registered or pre-registered in the central database run by the ECHA.
Completion degree: 100 %
Potential impact:
Dissemination activities
It is essential to highlight that a considerable number of dissemination activities have been completed during the development of the THERMALCOND project (i.e. more than 30 general dissemination activities and 1 scientific poster). The project information has been disseminated via three channels:
a) by partners within their organisations (e.g. internal newsletters, meetings, workshops, seminars, training courses, etc.);
b) by partners during external events (e.g. fairs, conferences, networking events, etc.);
c) by partners using media across Europe (e.g. press release, Internet, specialised magazines, etc.).
The use of various channels (internal and external) and methods (mainly written and online) assured an optimal contribution of coverage, visibility and most important setting up the scene for better market acceptance in the near future.
The activities in the dissemination plan covers different audiences and channels depending on the type of information to be disseminated, in order to assure the success of the project from a strategic, environmental, technologic and economic direction based on THERMALCOND approach.
Dissemination tools and activities could be divided in two main groups:
a) Industrial level:
For the SMEs, the principal objectives have been to obtain results that will increase their competitiveness and market opportunities and to show these results to any potential client, in order to have a wider commercial activity and increase the company benefits. Activities such as participation in fairs, seminars, press releases are aiming these results.
b) Non-commercial level, mainly scientific level:
The RTD participants of the project are more focussed in non-commercial promotion and scientific aspects of the work. Only non-confidential project results are susceptible of publication or dissemination in journals, web-sites, congresses, workshops, fairs and seminars.
Therefore, it is clear that the dissemination actions for THERMALCOND project is continuing after the end of the project, focused on the commercial and scientific audience, aiming the successful exploitation of the project results. Different Dissemination tools have been prepared, such as:
- maintenance of the online portal: http://www.thermalcond.eu
- THERMALCOND logo
- postcard
- general presentation of the project
- press release.
All these resources are available at the public part of the website and will be displayed in fairs and meetings.
Potential impact and exploitation
The new plastic-based product developed in the THERMALCOND project may have a significant impact on the solar collector industry, but also on the construction industry among others; providing an environmentally friendly, cheaper and lighter alternatives to the current metal-based on conventional collectors. True industrial impact will require further investment, mainly aimed to optimise the actual scale-up of the different parts manufacturing at scale-up level and the pattern assessment (manufacturing of the whole collector system), making them suitable for a continuous fabrication stage, profitable for the SMEs involved in the production chain.
Although the project development is aimed at solar collector (according to the end-user business field and what was agreed under Annex I of the project), the compound developed (trade secret according to the PUDF) plus the industrial procedure for manufacturing pipes, sheets and fittings will be able to be applied to other type of pipes (such as in construction related sectors) and even in other applications where concern about the environment, weight and price is increasing (such as automotive or aeronautic sectors), provided that the specific requirements of each final product can be fulfilled / adjusted from the starting characteristics of the new material developed.
All the above mentioned sectors could be additional business for the SMEs involved in the value chain (compounder, pipe / sheet / fittings manufacturers, end-users / distributors). The owners of the different results defined in the final version of the PUEDF will take into account these new niche market sectors.
Therefore, the protection plan of the project results has been initiated after the final meeting among the SMEs. For two results, the patentability is being studied by one of the SME on behalf of the other owners. As a general basis, the scheme in accordance with the Grant Agreement (article II 33 and II.34) and the THERMALCOND consortium agreement (article 9.3 and 9.4) will be applied.
Finally, it is important to highlight that an EU funded demonstration project has been applied for with SME Resenergie acting as coordinator. This is intended over a two year time period (if successful from mid 2013). All of the SME partners have transferred their rights 'nem con' to the application which has a new partner, a Spanish supplier Prosolia. Rapra who carried out the THERMALCOND research test program work on behalf of the THERMALCOND consortium have also joined because of the needs for test and validation and certification work to be carried out.
List of websites:
The updated THERMALCOND website domain (see http://www.thermalcond.eu online) was established at the end of the project under the Project Officer requirement of having an URL friendly, accessible, with its own domain, and with additional improvements, such as a content more structured and accessible to all users, without installing any additional technology, a redesign of the website, and an improved search engine optimisation (SEO).
Deliverable 9.1 'Project website' gives an overview of the main functionalities and structure of the website. The main structural difference is based on the intended audience: the public at large (industry stakeholders, academia, EU and national officials, etc.) and the beneficiaries involved in the project, the consortium.
Contact details:
Aimplas (coordinator)
Tel: +34-961-366040
Fax: +34-961-366041
proyectos@aimplas.es
- polyolefin nanocomposites by using different nanoparticles with high thermal conductive properties as additives to improve the thermal conductivity of the final components;
- a novel and specific surface treatment based on SAM technology- to provide a flexible energy absorbing coating to the different components. This coating will be based on metallic oxides (e.g. TiO2 or ZnO).
These developments will allow novel low cost and low weight components design's with enhanced thermal conductivity and high solar energy absorption to develop high efficiency thermal collector designs. The use of plastics components instead of metallic ones offer additional advantages: folding and easy assembling structures design, low energy consumption in motorised thermal collectors (follow sun light), corrosion resistance, low friction coefficient (less pump energy consume), prevent theft or vandalism (due the low cost of components in comparison with copper).
The solar thermal collector parts to be substituted by the new thermal conductive materials and flexible absorber coatings will be the extruded pipes and injected fittings of the collector heat absorption circuit and extruded sheets which will be used as absorber plate.
In this context, the polymeric materials appear as a real alternative to develop new low cost procedures in which a wide variety of component's designs could be obtained to optimise the thermal energy obtained per thermal collector surface. Due to their properties, plastics permit to produce any type of part with a free design at very competitive cost.
All the non-confidential information generated so far under the project can be found in THERMALCOND website, in the open area.
The new polyolefin nanocomposites developed in THERMALCOND project may have a significant impact on the plastic industry, providing and alternative material to the current metals used in thermal collectors or other applications where thermal conductivity is needed. Nano-particles developed can be used also with technical polymers extending the field of application. On the other hand, coating developed has provided good adherence and high solar energy absorption in plastic and metallic substrates. The low cost and easy coating application provide a real alternative to commercial coatings.
Thermal collectors components made with new nanocomposites have been scaled up successfully showing a similar behaviour in terms of mechanical properties and process ability than net polymers which it is a very important point for SMEs involved in the project.
Self-assembly, briefly, are a class of molecular assemblies that are prepared by spontaneous adsorption and organisation of molecules into stable, structurally well-defined aggregates from solution onto a solid substrate. Principles drawn from biology and have stimulated the development of new strategies and new applications.
Project context and objectives:
A flat-plate solar collector (FPC) is one of the main types of solar collectors which are key components of active solar heating systems and they are, by far, the most used type of collectors. FPCs are usually employed for low temperature applications up to 100 ºC.There are many flat-plate collector designs but generally all consist of:
(1) a transparent cover(s) that allows solar energy to pass through but reduces heat loss from the absorber;
(2) a flat-plate absorber, which intercepts and absorbs the solar energy;
(3) a heat-transport fluid (air, antifreeze or water) flowing through tubes to remove heat from the absorber; and
(4) a heat insulating backing.
The transparent cover is used to reduce convection losses from the absorber plate through the restraint of the stagnant air layer between the absorber plate and the glass. It also reduces radiation losses from the collector as the glass is transparent to the short wave radiation received by the sun but it is nearly opaque to long-wave thermal radiation emitted by the absorber plate (greenhouse effect).
The collector absorber plate absorbs as much of the irradiation as possible through the glazing cover sheet, while loosing as little heat as possible upward to the atmosphere and downward through the back of the casing. The collector plates transfer the retained heat to the transport fluid. Absorbers plates are usually made of metal-typically copper or aluminium-because the metal is a good heat conductor. Copper is more expensive, but is a better conductor and less prone to corrosion than aluminium. Absorber plates are commonly painted with selective coatings, which absorb and retain heat better than ordinary black paint. By suitable electrolytic or chemical treatments, surfaces can be produced with high values of solar radiation absorption and low values of long wave emission.
Polymers for heat thermal exchangers offer the potential advantages of:
- reduced cost of materials and manufacturing;
- resistance corrosion and mineral build-up; if mineral build-up is reduced, maintenance costs should be lower than those for metal heat exchangers;
- low friction coefficients;
- reduced weight and easy installation; and
- use of polymers may permit better integration with other components.
They are widely available low cost materials, which lend themselves to a volume production of lightweight low cost collectors tolerant to corrosion and freezing temperatures; however, their reliability, durability and long-term performance have not been fully demonstrated yet.
The thermal conductivity of polymers is substantially lower than that of ordinary metallic absorber materials, something which is very crucial for their use in solar energy applications and makes the redesign of conventional tube and metal absorber absolutely necessary.
It is in this context where the use of nanoparticles with thermal conductive properties appears like a promising solution for enhancing the thermal conductivity of the polymeric materials. Even though some works have been reported about polymeric materials used for thermal collector designs, any of them has considered the use of conductive nanoparticles to enhance the polymer heat transfer characteristics.
The objectives of this project can be quantified and measured as follows:
- Develop a new family of polyolefin composites by using different nanoparticles with high thermal conductive properties:
i. The thermal conductivity values measured in the new materials must be at least a 10 W/m.K.
ii. Increase thermal resistance of polyolefins (PP or PE) extruded and injected pieces with the use of nanoparticles. Deflection Temperature 1.8 MPa (EN-ISO 75) 60 ºC, thanks the use of nanoparticles with nucleant capacity.
iii. Competitive cost of optimised polyolefines / nanoparticles formulations. They prize of the compound must be lower than EUR 4/kg.
iv. Avoid problems of nanoparticles dispersion by their functionalisation using self-assembly molecules. This way it is possible to optimise the nanoparticles dispersion in order to use the minimal amount of nanoparticles, so that the final processability of the new compounds in extrusion and injection moulding is guaranteed since the viscosity increases will be limited to 15 %.
v. The project will broad the range of applications of conductive materials by the use of a synergy combination of conductive nanoparticles, functionalisation processes of the nanoparticles to increase the dispersion in the polymer matrix and using conventional injection and extrusion processes, whereas offering new functionalities (conductive polymers composites).
vi. Study the relation between processing parameters and part final conductivity in extruded pipes and sheets.
- Development of a flexible absorber coating (based on nanometallic oxides) by a novel cost effective and environmentally friendly surface treatment technology for extruded and injected polyolefin components:
i. Create strong bonds between the coatings and the plastic surface. This stronger adhesion of the coating to the substrate is obtained thanks to the chemical bonds created instead of the physical interaction compared to other processes.
ii. Use flexible coatings to compensate the plastic parts thermal expansion due the temperature differences during day and night and seasons and preventing the appearance of cracks or other problems in the coating.
iii. Tailor-made coating thickness from nanolayers until some microns; which is dependent on the residence time of the plastic part in the bath process. Possibilities to have a broad range of absorber coating with different properties.
iv. Low equipment investment due to the use of standard components and flexibility to scale up (the size of the plant can be adapted to the required output).
v. Flexibility to use a variety of application methods, thus making easier to integrate the coating into existing manufacturing processes.
vi. Favourable temperature and pressure conditions during manufacturing versus other methods such as chemical vapour deposition, sputtering, thermal oxidation, plasma-enhanced chemical vapour deposition, or flame hydrolysis. This process will be largely carried out at low temperature conditions using simple and economical equipment. Mild oxidation at a 50 ºC and the others two steps lower than 30 ºC.
vii. Environmentally friendly coating since the water used in the process can be easily treated, the raw materials have low vapour pressures thus minimising evaporation losses and consequently the VOC values will be close to zero.
viii. No health concerns (water based treatments and low toxicity chemicals for high scratch coating process and for waste water treatment).
- High efficiency designs of flat-plate solar thermal collectors using different plastics components with enhanced properties:
i. Polyolefin pipes, fitting and absorber extruded sheets will substitute high cost and difficult to process metallic parts (Cu or Al), and so they will reduce the energy to produce them, the weight and the final costs. With the new technology these parts could be made with PP or PE, maintaining almost the same requirements, and increasing the processability, high design flexibility and large potential for part and multi-functional integration.
ii. The thermal conductivity of polymers is three orders of magnitude lower compared to metals, which are widely in use for common absorbers. Nevertheless with an appropriate design of the material this disadvantage can be compensated. The collector containing plastic components must have an efficiency not lower than 70 % (current metallic thermal collector have an efficiency of 87 %).
iii. Cost of the collector plastics component less than 50 % of current metallic ones.
Expected final results:
All expected final results foreseen initially were achieved under the scope of the project, demonstrating the capability of the new nano-composites and coating developed.
In order to improve the design of the solar collector and industrialise it, SMEs have submitted a demo project, 'Polymeric thermal collector demonstration (POLYTHERMALCOLL) (reference No. FP7-SME-2013).
Project results:
Technical information have been provided in the corresponding task reports of those work packages and their deliverables (confidential information sent only to EC).
WP1: Requirements definition and selection of adequate nanoparticles (D1.1 D1.2)
Leader: Resenergie (SME)
WP2: Compounding studies of selected materials (D2.1 D2.2)
Leader: Aimplas (RTD)
WP3: Pipe and sheet extrusion, injected parts and characterisation (D3.1 D3.2)
Leader: RAPRA (RTD).
WP4: Develop an absorption coating in plastics components (D4.1 D4.2)
Leader: Avanzare (RTD)
WP5: Thermal collector prototype and characterisation studies (D5.1 D5.2)
Leader: RAPRA (RTD)
WP6: Industrial scale-up and case-studies validation (D6.1)
Leader: ABN (SME)
WP7: Economic, regulatory and environmental studies (D7.1 D7.2 D7.3 D7.4)
Leader: Archimedes (SME)
WP8: Dissemination, exploitation and training (D8.1 D8.2 D8.3 D8.4 D8.5)
Leader: Colorex (SME)
WP9: Project management (D9.1 D9.2 D9.3 D9.4 D9.5)
Leader: Aimplas (RTD).
WP1: Requirements definition and selection of adequate nanoparticles
Contractors involved:
Resenergie, Colorex, ABN, Archnimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 1.1 Material requirements for the plastic components
Task 1.2 Selection of the nanoparticles, coupling agents and reactives for nanoparticles functionalisation and for absorption flexible coating
Work performed:
Selection of nanoparticles and polymers taking into account SMEs requirements and project objectives. The standard UNE EN-12975-2 has been taking into account along the project to fulfil thermal collector requirements:
-pressure work: 2 bar (test: 2x1.5/Time: 1h/radiation: 1000 W/m2), stagnation temperature will determine the test temperature;
-UV polymer resistance;
-low temperature: no failure up to -10 ºC;
-weld ability: depends on geometry;
-thermal stress: in normal use: range of 60 - 70 ºC. In extremely conditions has to resist around 140 ºC;
Polymers selection has been carried out taking into account their:
- thermal stability of polymer, particularly in air;
- softening behaviour of the polymer;
- polymer cost.
- Nanoparticles selection was a key factor in THERMALCOND project in order to obtain a competitive product. This task was divided depending on application:
-nanoparticles to increase thermal conductivity;
- nanoparticles to improve light absorption.
In all cases, regardless of the nanomaterials used as fillers, there were two issues taken into account:
-size and shape of the filler nanoparticle; in this case, the synthesis of the nanoparticle could be modulated in order to obtain the desired nano-particle characteristics.
- the dispersion and homogenous spatial distribution within the matrix.
Within the possible fillers to improve thermal conductivity, carbon materials were proposed, such as graphene, nanographene and carbon nanotubes. With materials and nano-particles selected, a compounding experimental design was carried out.
Conclusions (WP1):
Materials selected are suitable for THERMALCOND application and have demonstrated their resistance in hot and cold water systems where similar pressures have to be supported.
On the other hand, nano-particles selected for thermal conductivity have the highest values (W/mK) of particles studied and reasonable cost.
The use of nanostructures can certainly increase the transmission and absorption properties of many components of solar cells and could possibly provide low cost production processes.
Completion degree: 100 %
WP2: Compounding studies of selected materials
Contractors involved:
Colorex, Archimedes, Proform, Aimplas, Avanzare
Objectives:
Task 2.1 Thermal conductive nanoparticles modification
Task 2.4 Thermal conductive compounds optimisation
Task 2.3 Production of Tests specimens and their characterisation
Task 2.2 Development of thermal conductive compounds
Work performed:
Once established the optimal materials to be develop in the THERMALCOND project (WP1), it was necessary to mix physically and bind chemically the nanoparticles selected with plastic matrices in order to enhance polyolefins properties. Thus, the main goal of this work package was the proper dispersion and distribution of the fillers in the polymer. This step is crucial to obtain composites with the desired characteristics which have been measured.
Two ways were studied to embed graphene sheets in a polymer matrix:
- The first one exploits the interaction forces between polymer and graphene, by simple mixing (non-covalent functionalisation).
- The second one, by covalent bonding between the graphene and polymer matrix, either by polymerisation or by chemical modification reactions (covalent functionalisation).
In order to mix nanoparticles selected with polymers, several trials were developed both at laboratory and pilot plant level.
Compounds obtained were characterised in terms of:
-themal conductivity
- rheology
- thermal stability
- melt flow index (MFI)
- mechanical properties.
The objective was to select the best compounds, taking into account properties and process ability, and to test the coating developed in terms of adherence and absorption capability.
Conclusions (WP2):
Compounding characterisation confirms a considerable increase in thermal conductivity (increase of 4,5 times) maintaining melt flow index and main mechanical properties, which indicate their suitability to obtain injected and extruded parts without problems.
Trials developed to test coating adherence to the collector parts gave optimal results (impact testing and thermal shock were overcome). First coating evaluation in terms of absorption provided good behaviour compared net polymer and copper pipe.
Completion degree: 100 %
WP3: Pipe and sheet extrusion, injected parts and characterisation
Contractors involved: ABN, Proform, Aimplas, RAPRA
Objectives:
Task 3.1 Optimisation of processing protocols in the production of thermal conductive extruded pipes and sheets
Task 3.2 Injection processing protocols in the injection of thermal conductive fittings
Task 3.3 Material characterisation, analysis and post processing testing
Work performed:
The key process elements for polyolefin-based pipes are the extruder, the forming die, calibration sleeve, vacuum cooling bath and haul-off. Taking into account rheology data obtained from previous compounds characterisation process element were selected. On the other hand, processing conditions to obtain pipe and sheets with materials selected were adjusted. Pipes and sheets obtained were used to develop coating testing and also for material adjustments.
Selected compounds and collector parts were tested following standards:
- UNE-EN ISO 180
- UNE-EN ISO 527-2
- UNE-EN ISO 1183-1 (September 2004).
- UNE-EN ISO 75-2 (January 2005).
- UNE-EN ISO 306 (February 2005).
In terms of the comparison between filled and unfilled materials, there are no drastic changes in the properties that would cause concern as possible causes of component failure. Specifically, both materials show a significant increase in the modulus values. This is expected from most filler types, and particularly from nanofillers, due to their large surface area. For the PP grades, there is a small increase in tensile strength.
In case of oxidation induction time, formulation developed show better resistance to oxidation induction time than typical HDPE materials employed for hot water pipes (typical value 20 minutes). Values for THERMALCOND materials are around 60 minutes.
Also, pipes made with materials selected were tested under standard UNE EN ISO 1167: 2006 ('Determination of resistance to internal pressure') resist 165 hours at 95 ºC and under an internal pressure of 15 bar.
Two different exposure tests were developed: xenon light testing and halide light exposure test.
Conclusions (WP3):
Rheological, physical and thermal characterisation of candidate's materials have demonstrated their appropriateness for extrusion and injection processing and in their suitability for thermal collector applications taking into account requirements defined in WP1.
Optimisation of pipe / sheet production process for candidate materials selected in WP2 has carry out. Also, one step process has studied to reduce processing cost and to avoid material degradation.
Results obtained have been used in the rest of work packages.
Completion degree: 100%
WP4: Develop an absorption coating in plastics components.
Contractors involved:
Archimedes, Aimplas, Avanzare
Objectives:
Task 4.1 Development of mild oxidation process
Task 4.2 Absorptive nanoparticles modification
Task 4.3 Nanoparticles deposition over the selected plastic components.
Task 4.4 Coating characterisation
Task 4.5 Industrial evaluation of the new coating process
Task 4.6 Study of the best technologies for water treatment
Work performed:
Plastic components manufactured in WP3 were subjected to a mild oxidation. Also, nanoparticles surface were modified with the objective to obtain functional groups suitable for the formation of thin layers by self-assembly. To develop appropriate self-assembly process, selected molecules on WP1 were studied on different conditions: reagents, solvent, concentration of the reagents, temperature of the mixture, etc. Particles with best functionalisation performance and thermal absorption were selected.
The modified nanoparticles were deposited over the plastic components treated. The full process parameters, such as application mode, time of application and temperature of drying was optimised.
In order to test the coatings developed, several trials of grip impact resistance and extreme temperatures in samples of 10 cm tubes were carry out rejecting coatings with bad adherence.
To study the effect of the sun during the day, the development of an experimental device was carried out. The main idea was to evaluate the influence of solar radiation and temperature variations in samples of polyolefin tubes. To do this, we establish that the difference of temperature measured in treated and untreated pipes will be enough to determinate the efficiency of the heat absorber coating.
Different experimental devices were developed. All of them have in common that the tubes were placed on a surface with adjustable inclination. Water was flowed through the tubes using pumps with a constant water flow. In addition, thermo flasks with a temperature sensor inside were available.
During the project, protocols in bath water treatment were fixed in order o remove nanoparticles from water.
Conclusions (WP4):
Through experiments the combinations of materials and treatments were established taking into account best results obtained (graphene GR29 and coating TC90 were selected as best candidates)
In addition, indicative data on the necessary areas and energy levels achieved have been managed. These data are important to consider in the design of the prototype.
On the other hand, the water treatment studied, taking into account methods employed to obtain the coating, fixed protocols steps needed to remove any kind on nanoparticle from it.
The coatings developed based on nanomaterials are able to increase the effectiveness of different polyolefin materials. The simplicity in obtaining and apply these treatments involves a reduction in costs required for industrial implementation.
Completion degree: 100%
WP5: Thermal collector prototype and characterisation studies
Contractors involved:
Resenergie, ABN, Proform, Aimplas, RAPRA
Objectives:
Task 5.2 Solar thermal collector validation
Task 5.1 Solar thermal collector prototype assembling. In order to assemble a thermal collector prototype, several pieces need to be manufactured using the best compound developed in WP2
Work performed:
To assembly and test prototypes agree by the consortium, parts obtained during the scaling up process were needed (WP6). For a starting point, commercial solar panels were dismantled. This allowed the existing metallic components to be used as controls for direct comparison against the newly manufactured pipes, sheets and fittings.
Different methods of joining the new THERMALCOND pipes for the prototype designs, ranging from standard plastic pipe fittings with grab ring (e.g. Wavin Hep2O, Uponor), welded fittings and metal fabricated fittings (e.g. Emmeti) were taken into account:
- standard plastic pipe fitting cheapest;
- welded fitting most expensive initially due to high equipment cost to set-up, but cheapest for production;
- metal fittings more versatile and re-useable.
It has been decided to use metal fittings for prototype construction and for testing small networks of pipes.
Construction of several collector prototypes was compared to commercial ones. For this purpose, extruded parts were coated with novel coating developed in WP4.
The comparison in efficiency between the commercial panel and the prototype by square meter was carried out. To validate THERMALCOND collector, the standard EN12975 was followed which includes a range of tests concerning the reliability and performance of the installed collector panels cases, rather than the absorber assembly. Specifically, these are:
- exposure test (the characterisation tests carried out for WP3 are more demanding than the tests specified in EN12975);
- external thermal shock;
- rain penetration;
- freeze resistance;
- mechanical load;
- impact resistance.
Since the technical annex for WP5 specifies that tests will be carried out to compare the newly developed plastic absorber materials against commercial copper based collectors, it has been agreed that a standard commercial panel be disassembled , and rebuilt containing the plastic components.
Halide light exposure testing of materials
A series of tensile and impact bars were prepared from four different materials, both PP and PB-1 pipe grades, and the THERMALCOND nanocomposite materials based on each resin type. Half of each batch of bars was coated, via paintbrush application, with two coats of the coating selected. Half of each sub-batch was then exposed to a halide light with a constant irradiance of 1000 W.m-2 with a chamber temperature of 65 ºC for 250 hours.
The yield strength results show no particular trend apart from a marked reduction in the strength of the unfilled and uncoated PP samples after exposure. The elongation at yield results showed no noticeable trends.
The tensile strength results showed no noticeable trends with respect to the coating and exposure, but it is interesting to note that the compounding of the nanoparticles gives a significant boost to the tensile strength of the PP, but not so for the PB samples. Conversely, the elongation at break results show a significant decrease for the PP, but not for the PB.
The graphs for Izod impact strength show that the decrease in the impact strength for the clear PP after the light exposure is not present for the coated samples, demonstrating that the coating gives additional UV protection. It is also notable that the light exposure actually increases the impact strength of the PB samples.
Overall, it can be said that for the filled and coated grades, good long term resistance has been shown to the possible effects of UV degradation.
Internal thermal shock test
This test is designed to establish the capability of the collector design to withstand a severe internal thermal shock, such as may occur when the collector is brought into operation when already at its stagnation temperature. An eight riser absorber is constructed using each of the THERMALCOND candidate materials, and exposed to the solar light array for one hour before starting the water flow to the collector at less than 25 ºC. This is repeated twice for each absorber, and since the stagnation temperature is well within the operating temperature range of the materials, as expected, there is no discernible impact on the absorber assembly
Optimisation of plastic absorber design
It was decided, based on the results of the 'stagnation' tests, to have into account Reynolds number to optimise plastic absorber design. Reynolds number is the ratio of intertial versus viscous forces within a flowing fluid. In a pipe, the equation is simplified to Re=(?*u(D)/µ where Re is the Reynolds number, ? is the fluid density (approximately 1000 for water), u is the fluid velocity and µ is the fluid viscosity (varies with temperature).
Nusseldt number is the ratio of convective to conductive heat across the boundary between pipe and fluid: Nu=(h*D)/k where Re is the Reynolds number, ? is the fluid density (approximately 1000 for water), u is the fluid velocity, µ is the fluid viscosity (varies with temperature).
The Reynolds number, Re, is the determining factor of the flow regime in a pipework system. For Re > 2000, laminar flow is present, which means that water flows in annular layers within the pipe, and there is little interchange of fluid between the layers. For Re > 10000, fully turbulent flow exists - there are no layers, and the fluid can be considered fully mixed at all points within the flow. For 2000 < Re < 10000, the fluid is in transition between these two states.
Conclusions (WP5):
From the data produced close to ambient temperature, the commercial copper collector has a measured efficiency of 78.6 %, which is only 6.7 % higher than the THERMALCOND collector prototype.
The absorber pipes for the THERMALCOND single loop design (50 m of PB pipe) weighs 6.88 kg, compared with the copper absorber weight of 12.5 kg.
The absorber design has the benefit that no pipe joints are present within the collector body, and the PB pipes are frost proof which means that the collector does not need to be drained during the colder months of winter.
Completion degree: 100 %
WP6: Industrial scale-up and case-studies validation
Contractors involved:
Resergie, Colorex, ABN, Archimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 6.1 Scaling up and optimisation of compounding process
Task 6.2 Extrusion and Injection Processing at industrial level
Task 6.3 End user prototype validation
Task .6.4 Study of new designs of high efficiency thermal solar
Work performed:
SMEs scaled up each process in order to study differences between THERNMALCOND compounds developed and commercial polymers.
First step was the compounding scale up trials developed by COLOREX in order to obtain enough materials to use in subsequent steps (extrusion and injection parts). In order to obtain formulations selected, a co-rotative twin screw extruder is needed, preferably with a side feeder port to feed correctly powders into the process.
Personal protective equipment: full face mask (special filters for nanoparticles, gloves and clothing (i.e.Tyvex).
To ensure a quality control of compounds obtained, the twin screw extruder resulting process factors (The machine answer after setting some adjustable parameters) have to be taking into account:
- torque
- die pressure
- residence time
- dispersion quality
- melt temperature
- specific mechanical energy (SME).
Also, it is important to test the thermal conductivity of materials obtained. No difficult was found during compounding scale up.
Pipe extrusion scales up was performed by ABN. Materials obtained in compounding step gave similar melt flow index and rheology compared with base net polymer. For this reason, pipe extrusion did not find any processing problem.
Sheet extrusion and injection scale up were perfomed by Proform. As in case of pipe extrusion, compounds developed need very similar parameters than net polymers to be extruded and to obtain sheets for thermal collectors.
Conclusions (WP6):
Compounded PP/PB materials are suitable for PP pipe / sheet extrusion and fitting injection moulding. Only slight changes were done to adjust the processing conditions to new materials. No investments were necessary to use new materials with traditional equipments.
All partners worked actively in the study of the possible designs of the collector. Efficiency, assembly steps and cost were key factors in design steps.
Completion degree: 100 %
WP7: Economic, regulatory and environmental studies
Contractors involved:
Resenergie, Colorex, ABN, Archimedes, Proform, Aimplas, RAPRA, Avanzare
Objectives:
Task 7.1 Economic analysis
Task 7.2 Product life-cycle-analysis (LCA)
Task 7.3 Regulatory analysis
Task 7.4 Safety issues.
Work performed:
In order to calculate material cost developed and final panel price, all partners involved in the project provided data required. Also, all data was used to develop life cycle assessment (LCA) which is a process of identification and evaluation of the environmental impacts associated with a product, process or service, throughout its entire life cycle. The life cycle concept implies that the inputs to the cycle i.e. materials and energy and outputs i.e. products and co- / by-products, waste materials and energy, are evaluated for each step of product or process life. The cycle begins at process or product conception and ends with the recycle / disposal of the product and its constituents; hence, LCA takes a 'cradle to grave' approach in the analysis of environmental impacts, from materials acquisition, manufacturing, distribution, use and end of life. The assessment involves look at waste generation, emissions to air, water and soil as well as energy consumption. A cradle to gate approach can also been taken, whereby the assessment is done form the raw material acquisition to the product.
Two methods were employed during analysis: eco-indicator 99 (H) V2.09 and CLM 2 baseline 2000 V2.05.
The whole process was described in a best practice guideline developed in WP8 and completed in present WP with installation, materials, process issues, personal protective equipment and handling requirements, to contribute to the technology transfer and dissemination of the project.
In case of regulatory assessment, information provided was focused in selected coating and nanoparticles. REACH, the European Community Regulation on chemicals and their safe use is a regulation of the European Union, adopted to improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry. It also promotes alternative methods for the hazard assessment of substances in order to reduce the number of tests on animals. REACH must be taken into consideration in every country of the European Community, so all of the compounds of this project must fulfill this regulation.
With this new legislation, manufacturers and importers are required to gather information on the properties of their chemical substances, which will allow their safe handling, and to register the information in a central database run by the European Chemicals Agency (ECHA). Depending on the risks of the chemical, the agency classifies them and decides if it is necessary to substitute those dangerous products.
REACH regulation also binds to register all substances to study them to know their properties and hazards, so all industries must ensure that safety data regarding their uses is available. All substances used on THERMALCOND project has been registered or pre-registered in the central database run by the ECHA.
Conclusions (WP7):
The THERMALCOND panels compare favourably with the equivalent sised copper panels in terms of environmental loadings and also in terms of costs.
All substances used on this project has been registered or pre-registered in the central database run by the ECHA.
Completion degree: 100 %
Potential impact:
Dissemination activities
It is essential to highlight that a considerable number of dissemination activities have been completed during the development of the THERMALCOND project (i.e. more than 30 general dissemination activities and 1 scientific poster). The project information has been disseminated via three channels:
a) by partners within their organisations (e.g. internal newsletters, meetings, workshops, seminars, training courses, etc.);
b) by partners during external events (e.g. fairs, conferences, networking events, etc.);
c) by partners using media across Europe (e.g. press release, Internet, specialised magazines, etc.).
The use of various channels (internal and external) and methods (mainly written and online) assured an optimal contribution of coverage, visibility and most important setting up the scene for better market acceptance in the near future.
The activities in the dissemination plan covers different audiences and channels depending on the type of information to be disseminated, in order to assure the success of the project from a strategic, environmental, technologic and economic direction based on THERMALCOND approach.
Dissemination tools and activities could be divided in two main groups:
a) Industrial level:
For the SMEs, the principal objectives have been to obtain results that will increase their competitiveness and market opportunities and to show these results to any potential client, in order to have a wider commercial activity and increase the company benefits. Activities such as participation in fairs, seminars, press releases are aiming these results.
b) Non-commercial level, mainly scientific level:
The RTD participants of the project are more focussed in non-commercial promotion and scientific aspects of the work. Only non-confidential project results are susceptible of publication or dissemination in journals, web-sites, congresses, workshops, fairs and seminars.
Therefore, it is clear that the dissemination actions for THERMALCOND project is continuing after the end of the project, focused on the commercial and scientific audience, aiming the successful exploitation of the project results. Different Dissemination tools have been prepared, such as:
- maintenance of the online portal: http://www.thermalcond.eu
- THERMALCOND logo
- postcard
- general presentation of the project
- press release.
All these resources are available at the public part of the website and will be displayed in fairs and meetings.
Potential impact and exploitation
The new plastic-based product developed in the THERMALCOND project may have a significant impact on the solar collector industry, but also on the construction industry among others; providing an environmentally friendly, cheaper and lighter alternatives to the current metal-based on conventional collectors. True industrial impact will require further investment, mainly aimed to optimise the actual scale-up of the different parts manufacturing at scale-up level and the pattern assessment (manufacturing of the whole collector system), making them suitable for a continuous fabrication stage, profitable for the SMEs involved in the production chain.
Although the project development is aimed at solar collector (according to the end-user business field and what was agreed under Annex I of the project), the compound developed (trade secret according to the PUDF) plus the industrial procedure for manufacturing pipes, sheets and fittings will be able to be applied to other type of pipes (such as in construction related sectors) and even in other applications where concern about the environment, weight and price is increasing (such as automotive or aeronautic sectors), provided that the specific requirements of each final product can be fulfilled / adjusted from the starting characteristics of the new material developed.
All the above mentioned sectors could be additional business for the SMEs involved in the value chain (compounder, pipe / sheet / fittings manufacturers, end-users / distributors). The owners of the different results defined in the final version of the PUEDF will take into account these new niche market sectors.
Therefore, the protection plan of the project results has been initiated after the final meeting among the SMEs. For two results, the patentability is being studied by one of the SME on behalf of the other owners. As a general basis, the scheme in accordance with the Grant Agreement (article II 33 and II.34) and the THERMALCOND consortium agreement (article 9.3 and 9.4) will be applied.
Finally, it is important to highlight that an EU funded demonstration project has been applied for with SME Resenergie acting as coordinator. This is intended over a two year time period (if successful from mid 2013). All of the SME partners have transferred their rights 'nem con' to the application which has a new partner, a Spanish supplier Prosolia. Rapra who carried out the THERMALCOND research test program work on behalf of the THERMALCOND consortium have also joined because of the needs for test and validation and certification work to be carried out.
List of websites:
The updated THERMALCOND website domain (see http://www.thermalcond.eu online) was established at the end of the project under the Project Officer requirement of having an URL friendly, accessible, with its own domain, and with additional improvements, such as a content more structured and accessible to all users, without installing any additional technology, a redesign of the website, and an improved search engine optimisation (SEO).
Deliverable 9.1 'Project website' gives an overview of the main functionalities and structure of the website. The main structural difference is based on the intended audience: the public at large (industry stakeholders, academia, EU and national officials, etc.) and the beneficiaries involved in the project, the consortium.
Contact details:
Aimplas (coordinator)
Tel: +34-961-366040
Fax: +34-961-366041
proyectos@aimplas.es