Final Report Summary - TIFFE (Thermal Systems Integration for Fuel Economy)
Executive Summary:
The project has been devoted to the development of an innovative Integrated Vehicle Thermal System based on the integration of vehicle thermal systems to improve the on board thermal management and the energy efficiency. The major project contents are:
• Dual loop air conditioning: one loop transfers the cooling power and one rejects the heat
• Two-levels temperature heat rejection system: one temperature to reject the high temperature heat (e,g. engine waste heat) and one temperature to cool locally the vehicle auxiliary systems
• Innovative heat exchangers: new generation of compact fluid-to fluid heat exchangers and application of innovative technologies for fluid-to-air heat rejection
• Use of innovative coolants (e.g. Nanofluids): to improve the heat rejection and redesign the heat exchangers
TIFFE benefits can be summarised in a Cost Reduction (due to resize of the systems and their integration) and Fuel Economy increase of 15% on real use thanks to the:
• improvement of the aerodynamics due the new front end design
• increase of auxiliary systems efficiency thanks to the local cooling
• engine overall efficiency thanks to a fine control of heat exchange, local cooling (turbocharger, fuel, ...) and improvement of the engine intake
• the reduction of engine re-starts on Hybrid or Stop&Start vehicle due to cabin thermal comfort: the dual loop air conditioning with a designed thermal inertia guarantees thermal comfort when the thermal engine is off
• compact Refrigeration Unit compliant with Low GWP refrigerants - R-744 or flammable (R-152a, HFO-1234yf, R-290)
Two prototypes has been realised and validated:
• a diesel passenger car with Stop & Start function
• a diesel Light Commercial Vehicle
Project Context and Objectives:
The project has been focused to the development of an innovative Integrated Vehicle Thermal System to improve the overall heat rejection and vehicle efficiency thanks to the redesign of heat exchange system architecture and a more fine control of the engine and engine auxiliary subsystems working temperatures and the auxiliaries’ efficiency and as a direct consequence, the fuel economy.
Concept: the system is based on the idea to integrate the vehicle thermal systems, so to improve the on board thermal management improving the energy efficiency:
• Dual loop air conditioning: one loop to transfer the cooling power and one loop to reject the heat
• Two-levels temperature heat rejection system: one temperature to reject the high temperature heat and one temperature to cool locally the vehicle auxiliary systems
• Innovative heat exchangers: new generation of compact fluid-to fluid heat exchangers and application of innovative technologies for fluid-to-air heat rejection
• Use of innovative coolants: to improve the heat rejection and redesign the heat exchangers
The TIFFE approach will have a relevant and positive impact on the vehicle energy efficiency contributing to the reduction of fuel consumption and GHG gases emissions and its major advantages and outcomes can be summarised as follows:
Fuel consumption reduction thanks to the:
• Improvement of the aerodynamics due the new front end design and characteristics
• Increase of auxiliary systems efficiency thanks to the local cooling
• Engine overall efficiency thanks to a fine control of the heat exchange and fluids cooling (turbo charge, fuel, ...) and to the reduction of the inlet engine air line (charge air cooler integrated in on the engine)
• The reduction of engine re-start on Hybrid or Stop & Start vehicle , the minimisation of the engine–restart due to comfort or cabin thermal reasons: the dual loop air conditioning thanks to its increased thermal inertia can guarantee thermal comfort also when the thermal engine is off
The project results has been validated and demonstrated realising two vehicles prototype:
• A small passenger car with Stop & Start with an innovative engine cooling and thermal management system including the air conditioning
• A Light Commercial Vehicle with an integrated thermal system including the air conditioning
WHY A THERMAL MANAGEMENT SYSTEM?
In the next future the management on the vehicle on board thermal energy management will become a relevant issue that will be crucial to achieve the CO2 emission targets.
The conventional approach, based on the add-on concept where an heat exchanger is used per each system that needs to be cooled will represent a serious limitation that risk to affect the overall vehicle efficiency and to increase the cost.
An integrated and innovative approach is then required to make the vehicle engine and energy systems effective with limited impact on the vehicle architecture and avoiding any constraint to the design of the vehicle front end. This will contribute to the achievement the requirements of the incoming regulations on safety (pedestrian ...) and to the improvement of the air drag allowing more aerodynamic front end design (CX reduction).
CONCEPT
It is therefore easy to understand that relevant advantages and benefits arise from an integrated management of the thermal energy with a consequent optimisation of the overall energy balance of a motor vehicle and this constitutes the TIFFE Project main objective.
The project has been focused to the development of Integrated Thermal Management System that has the function to control the temperature of all the engine and vehicle auxiliaries system and to reject the heat to the ambient.
This gives an additional degree of freedom in the management of the heat exchange surface in front of the car, since now there is only one fluid exchanging with the air, simply working at two different temperature levels.
Depending of the different heat load of the two systems, heat exchange surface can therefore be managed.
If in particular conditions one temperature level needs more heat exchange surface, with this arrangement that will be possible.
The cooling power is produced by a module called Compact Refrigeration Unit that in installed in the engine compartment.
MAIN INNOVATIONS
The main innovations developed in TIFFE project are:
• An Integrated Thermal System based on two cooling loops: one at high temperature (i.e. 90 deg) devoted mainly to reject the heat of the thermal engine and one with coolant flowing at a temperature 5 deg higher the ambient and dedicated to the cooling of all the engine auxiliary system (intake air, power steering, ...) and the air conditioning (gas cooler or condenser)
• A new coolant based on innovative materials and able to improve the heat transfer to enable new heat exchangers geometries and sizing. The activity includes the evaluation of the opportunities given by the recent results in the domain of Nanoscience to design fluids with enhanced features, the so-called Nanofluids
• A Compact Refrigeration Unit, replacing the conventional air conditioning system. The CRU (patent pending) is a compact module placed in the engine bay able to maintain the temperature of a cold and hot circuit, based on a conventional vapour compression cycle. The Unit can operate, in principle, using CO2 (R-744), flammable- or conventional refrigerants
• New coolant-to-air and coolant-to-fluid heat exchangers with enhanced heat transfer features. The innovation includes also the development of flat coolant-to-air heat exchangers suitable to constitute a part of the vehicle (i.e. underbody) having also other function (i.e. aerodynamics)
• A integrated thermal control strategies allowing:
o the fine control of the temperature of the engine, engine auxiliary systems, engine intake air, electrical storage unit, control unit, ...
o smart use of the actuators (fans, compressor, pumps, ...)
These five main innovations will enable the complete re-design of the engine bay increasing the degree of freedom to enable the design more aerodynamic shapes and to make easier the complicacy with the incoming regulations on emission and safety.
TARGET PERFORMANCES
The TIFFE system aims to reduce the overall vehicle fuel consumption in real use.
For a passenger car and for a Light Commercial Vehicle, it is estimated that TIFFE can reduce the fuel consumption and CO2 emissions by around 15% in real use, following this deployment:
- 3% through the use of more efficient components such as heat exchangers, fans, ...
- 1% due the reduction of the cooling drag
- 4% thanks to the optimisation of the working temperature subsystems: charge air cooler, engine, gas cooler/condenser, alternator, ...
- 4% by means on overall and systemic thermal energy management strategy
- 3% as effect of the specific design dedicated to Stop&Start (e.g. air conditioning) and Hybrid Powertrain that will reduce the need to re-start the thermal engine
Besides the impact on vehicle fuel economy, the TIFFE system assure better thermal comfort performance due to the new approach to the air conditioning and the safe use of any low GWP refrigerants compliant with the incoming EU regulations and the worldwide scenario.
Moreover the TIFFE system assure an increase of the air conditioning efficiency of about 15% (reference baseline systems), contributing to the overall vehicle fuel economy increase in real use.
This improvement can be higher (up to 25%) in case of Stop & Start or Hybrid vehicle, because of the increased thermal inertia of the Air Conditioning system that reduces the need to activate the thermal engines to keep the thermal comfort at acceptable levels.
In addition the re-design of the engine bay will have benefit on:
- Pedestrian Impact performance, enabling more degree of freedom of the vehicle front end
- overall Vehicle Aerodynamics, thanks to less severe constraints on the frontal part of the vehicle and the use of function under-body shields
The performance has been assessed realising two demonstrator vehicles based on:
- Passenger Car with Stop & Start Function
- Light Commercial Vehicle.
Both the two vehicles has been, at first fully characterised before any change or modification following the procedure identified in the WP1, then each vehicle has been equipped with a dedicated version of the TIFFE system becoming two prototype demonstrators. The two prototypes has been, then, tuned and optimised and validated experimentally following the same testing procedure defined.
Project Results:
The project is devoted to the development of an innovative Integrated Vehicle Thermal System based on the integration of vehicle thermal systems to improve the on board thermal management and the energy efficiency.
The TIFFE consortium has been composed by CENTRO RICERCHE FIAT (with the role of project coordinator, development and validation on a demonstrator vehicle based on a diesel light commercial vehicle end the development of system control strategy), MAFLOW (with the role of development of lines and connection that are one of key component of the TIFFE system), SINTEF (with the role of evaluation of the the environmental advantage of the TIFFE system and research on innovative heat exchangers technologies), TUB, (with the role of research on fluid with enhanced heat transfer proprieties with focus on Nanofluids and support the development of the compact refrigeration unit), FORD (with the role of development and validation of a demonstrator based on a diesel passenger car with Stop & Start), DENSO (with the role of development of the innovative and enhanced coolant/to/air and coolant/to/fluids heat exchangers and development of the compact refrigeration unit).
TIFFE COMPONENTS
A complete bench test for the standard production components has been carried out by DENSO to acquire all information to develop the heat exchangers for the TIFFE vehicles both for the light commercial vehicle (IVECO Daily) and the passenger car (FORD Focus).
All new components dedicated to the TIFFE system has been bench tested and compared with the standard production components.
Within the project DENSO developed two new high-temperature radiator compliant with thermal proprieties specifications.The study produced two new engine radiator, one for the IVECO Daily commercial vehicle and one for the passenger car.
The low temperature radiators have two different coolant circuits: the major part of radiator is a U-flow path (LT) to feed Water Charge Air Cooler (WCAC) and Water Cooled Condenser (WCND), the small part of radiator is a I-flow path (ULT) to feed sub-cooling portion of WCDS. The components has been bench tested before their vehicles integration.
WCACs have been projected, developed and tested on a specific test bench, modified to operate with coolant instead of air, then results have been compared to data obtained by simulations and by standard production parts.
Bench tests on WCDS have required the construction of new test rig for coolant conditions control, coupled to standard air-cooled condenser test bench already available at DNTS for test bench on conventional condensers. In detail, air-cooled condenser test rig is used for controlling and measuring the refrigerant side conditions; the new test rig for WCDS controls and measures coolant side conditions. By controlling the speeds of an electrical water pump to manage coolant flow rate and of an axial fan for cooling the coolant from WCDS in an outside radiator, it is possible controlling the coolant temperature at WCDS inlet. The initial configuration for WCDS is of tube and shell type, made by flat multi-ports tubes (mass production part used in conventional refrigerant to air condenser) connected through end tanks and enclosed by a shell to realize coolant flow path.
Test conditions for WCDS have been derived from EUROCLIM standard by changing medium: from air to coolant.
Evaluation of the best coolant flow ratio between condensing and sub-cooling portions in the WCDS heat exchanger has been the goal for the first investigation by bench test.
Coolant flow ratio variations have been obtained by introducing an orifice at sub-cooler inlet.
As a first result by investigations, the higher the coolant flow through the condensing portion, the higher the overall heat rejection by WCDS. However, coolant pressure loss is increasing if coolant flow ratio is increased. Approximate method to estimate heat rejection performance when WCDS has been installed in vehicle can be obtained by the crossing of the water pump characteristic to the coolant pressure loss chart for WCDS, obtaining the actual total coolant flow rate and then compute, by using bench test results on the WCDS alone.
WCDS test results have been compared to standard production condensers, as used in the baseline A/C systems in the two demo-cars.
Although the performance achieved by the tube and shell type of WCDS seems equal or better than conventional refrigerant-to-air condensers, the needs to develop a new type of heat exchanger matrix to realize liquid cooled condenser and evaporator (with the aim to integrate them into the CRU), has driven DNTS to the conclusion to investigate the potentiality of plate type heat exchangers.
Plate technology seems suitable to realize liquid and refrigerant path to secure for the heating and pressure drop performance levels required for heat exchangers applied to automotive air conditioning systems. Moreover, plate type technologies for mass production can be derived from the current process and technologies for conventional heat exchangers manufacturing, with benefit on investment and variable cost. Securing the required level of performance for best operation of A/C system is thus the key for the success of such new products. By following such decision, a first generation of plate type liquid cooled heat exchangers have been designed and prototyped by DNTS.
The same concept about the stacking of plates for water or refrigerant passage is used to realize a WCDS or a “Chiller”. Basically, the activities on the design of plate type heat exchangers for conceiving the W-CDS and the “Chiller” contributed to the concept definition for the CRU.
Plate type heat exchangers are made up of stack of several elements which basic brick is the coolant tube made of: 2 basic plates to realize the tube and 2 dimpled plates to realize the flow guide and turbulence generator for the coolant and also to increase structural resistance.
These basic elements are then stacked up with two refrigerant fins in between to realize the refrigerant tubes. First and last elements have different basic plates to be connected with coolant inlets and with refrigerant block joints.
WCDS Refrigerant accumulator has been realized with a specific shape for the plate allowing the integration to the condenser of a tank to store liquid refrigerant during operation of the system, also providing the possibility to generating forced sub-cooling by the condenser.
The prototype has been tested as stand-alone components to verify the performance level achievable by the new design of plate and flow patterns. The performance measured in the actual prototype should be compared to the data on tube and shell WCDS .
The different amount of plates used in the plate type WCDS sample do not allow to achieve a level of heat rejection performance similar to the tube and shell one.
Based on such preliminary results and evaluation, a second generation of plate type heat exchangers has been designed and prototyping by DNTS, used for preparing updated version of stand-along components or integrated into Compact refrigeration unit.
The second generation plate lay-out does not include the integrated accumulator. Consequently, the refrigerant sub-cooling will be generated in the system by means of an Intermediate Heat Exchanger (IHX), thus simplifying the WCDS design. The “Chiller”, realized as a plate type liquid cooled evaporator, is a part of the Secondary Loop air conditioning system (SLS in the following), to be design and realized as prototype in the 2 demo vehicles of the TIFFE Project.
In SLS the conventional evaporator for refrigerant direct expansion in the cabin HVAC is replaced by a water cooled heat exchanger (“Cabin cooler” in the following), able providing the same cooling effect on cabin using cold water instead of refrigerant.
Cold water is generated by the “Chiller”, where refrigerant evaporation is used to absorb heat from coolant circulating inside cabin cooler, heated up by the cabin air.
The evaluation of the performance of the “Chiller” designed and prototyped by DNTS, required a specific test rig, integrated to the one already prepared for testing the WCDS. The resulting integration of test rigs will also allow for testing a complete Compact Refrigeration Unit.
The new test rig to allow for testing the Compact Refrigeration Unit or any type of liquid cooled heat exchanger, is made up by three separated test rigs and loops: (1) Refrigerant loop: the loop manage refrigerant conditions with an electrical compressor and a controllable expansion valve. Tests with or without Internal Heat Exchanger (IHX) can be carried out; (2) Condenser loop: an electrical pump control coolant flow rate and a radiator coupled with fan control coolant temperature by cooling the coolant at WCDS outlet; (3) Evaporator loop: an electrical pump control coolant flow rate and a heater manage coolant temperature at “Chiller” inlet. The complete test rig is controlled by a PC.
As already mentioned the assembly of WCDS to “Chiller”, TXV, pipes and, possibly, an Internal Heat Exchanger, make up the Compact Refrigeration Unit (CRU).
In SLS the conventional evaporator for refrigerant direct expansion in the cabin HVAC is replaced by a water cooled heat exchanger (“Cabin cooler” in the following), able to generate equivalent cooling effect on cabin air by using cold water instead of refrigerant.
The concept of product for “Cabin cooler” have been investigated through design, prototypes and bench tests on stand-alone parts.
As a result a basic configuration for “Cabin cooler” has been defined and applied to prepare the 2 heat exchangers to be used in the SLS for IVECO Daily and FORD Focus demo vehicles.
Starting point for the design of “Cabin cooler” has been the replacement of current refrigerant to air evaporator as installed in the mass production HVACs, both for the IVECO Daily and the FORD Focus HVAC. Both “cabin Cooler” has been tested, accordingly to DNTS standards.
Following the component specification, the designing, prototyping and testing as stand-alone components about the heat exchangers to be used in the Low Temperature Radiator Loop and the Secondary Loop Air Conditioning system, a final verification on the performance and efficiency of the integration of the systems has been done on a specific test rig.
The same system bench has been also used for testing the performance and efficiency of the CRU to be prototyped by DNTS for delivery to TIFFE Partners.
In the compact refrigeration unit the complete refrigerant loop is confined into the engine bay to avoid any cabin issue in case of refrigerant leakage. Moreover, except for compressor, all the other components can be enclosed in a box. A plate type WCDS is cooled by the LT Radiator in the low temperature loop. A chiller evaporate the refrigerant to cool down coolant in a secondary loop through an electrical water pump and a cabin cooler.
Dedicated heat exchangers have been designed and built to achieve the targets of TIFFE project.
A first proof of concept for WCDS has been designed using tubes and shell technology.
This proof of concept has been realized, bench tested at DNTS and then installed on both demo-vehicle as a first step to approach TIFFE project target.
Mass production related issues came out with this type of technology and design effort turned into plate type heat exchangers. To realize a preliminary prototype for the CRU, basic study on plate type heat exchangers have been carried out.
Plates have been designed to be used both in the WCDS and in the chiller.
Plate type heat exchangers are made up of stack of several elements which basic brick is the coolant tube made of 2 basic plates to realize the tube which and 2 dimpled plates to realize the flow guide and turbulators for the coolant also to increase structural resistance.
These basic elements are then stacked up with two refrigerant fins in between to realize the refrigerant tubes. First and last elements have different basic plates to be connected with coolant inlets and with refrigerant block joints.
WCDS Refrigerant accumulator has been realized with a specific plates shape that realize the volume of accumulator by the same stacking up to realize the exchanger.
The WCDS is realized with some modification of the basic concept: Accumulator in/out plates and baffle plates. First WCDS sizing let to an exchanger with 37 coolant tubes and 36 refrigerant tubes, with 7 plates for subcooling.
The Chiller is made up only with the basic elements because of no need to realize different flow path for refrigerant and for coolant. First Chiller sizing let to an exchanger made up of 10 coolant tubes and 9 refrigerant tubes.
The first CRU design has been based on first version of plate-type heat exchanger. CRU design aim has been to realize the most compact layout possible for the components and then to install it in both vehicles. A first non-functional mock-up has been realized according with the first design.
The new version of plate-type heat exchangers needed a new design for CRU. New design is more compact thanks to smaller plate-type heat exchangers with better performances and efficiency.
This layout has been installed into the two vehicles to perform wind tunnel tests.
Coupled with the design of CRU is the design of the cabin cooler for the two vehicles. Starting point for this design is the actual evaporator room available in the standard production HVACs.
LINES PROTOTYPES
Maflow BRS contributed to the development of hoses, fittings, connections for a low emissions integrated thermal management system including the air conditioning.
For the light commercial vehicle (IVECO Daily) an alternative rubber compound with benefit toward VMQ in terms of Process ability and costs has been chosen. Such compound belong to ACM polymer family and thanks to its thermal resistance is suitable for the use on along the charging flexible line.
ACM compound has been tested in ageing up to 190°C with Air, Engine Oils & Fuels.
The Hose lines have ID>45mm with enlarged ends, which drive the reinforcement to be knitted.
For the passenger car, a more aerodynamic vehicle and equipped with more auxiliary systems in the engine bay like the development of lines has been more difficult due to a more complex layout and an higher thermal and dynamic stress.
That is why an high performance hoses, with Polyamide inner layer has been selected. Moreover the selected hoses have a low refrigerant emissions and capable to work together with rubber compounds at very high temperature, up to 150°C.
For this kind of hoses, manufactured on thermoplastic mandrel a braided reinforcement has been used.
For the passenger car (FORD Focus) application an high performance EPDM compound with high temperature resistance and low permanent deformation has been selected
COOLANT FLUID SELECTION
An important part of the TIFFE project is the identification and validation of new coolants so to enable the redesign of heat-exchange technology. The activity within this task is focused on identifying fluids, which:
• are able to enhance the properties of the secondary loop system with regard to heat transfer or comfort aspects
• can be used in a dual loop heat rejection system
• have excellent thermal and chemical properties and are chemically inert
• are non toxic and non flammable and harmless to health
• are not too expensive and available in large quantities
In this context the Institut für Thermodynamik - as a part of the department of mechanical engineering at the University of Braunschweig, Institute of Technology, hereinafter called TUBS - evaluates the opportunities and limitations of available fluids and mixtures.
This document describes the identification and investigation of a new generation of coolant fluids with enhanced heat transfer and heat storage properties. Currently the studies concentrate on three different materials:
• Nanofluids
• Phase Change Materials (PCMs)#
• Ionic Liquids (ILs)
The first category of fluids that were investigated by TUBS belongs to the class of nanoparticle-fluid suspensions (“nanofluids”). Lots of promising results that can be found in literature seem so confirm the enhancement of the heat transfer properties of a fluid by adding nanoparticles. Aim of the subsequent investigations was to verify these measurement results.
Nanofluids are suspensions of nanometer-sized particles in heat transfer fluids like water or water-glycol mixtures (fig. 1). To utilize the benefits of nanosuspensions by definition the particle size inside the fluid has to be below 100 nm.
Numerous materials - metallic or non-metallic ones - can be used as nanoparticles.
Besides the solid component of nanosuspensions also the liquid component can be varied. Water and water-ethylene glycol mixtures are the most common fluids, but in the literature also measurements with oil, glycerin or epoxides can be found. Within the TIFFE context vehicle relevant restrictions had to have considered. Thus only water and water-glycol based nanosuspensions were and will be investigated.
In the literature a lot of promising references concerning the increase of the thermal conductivity by using nanofluids can be found. Adding nanosized particles to water or water-glycol mixtures, increases of the thermal conductivity up to 60 % were measured.
LIGHT COMMERCIAL VEHICLE PROTOTYPE
The IVECO Daily is one of the vehicles where the TIFFE system has been integrated and fully tested at bench and on road.
According to Denso activities the engine cooling loop is unchanged and a loop is used to liquid cool the condenser and the charge air cooler where the coolant is flown with an e-pump. A section of the system is devoted to the refrigerant sub-cooling. The front end module has been redesigned in order to substitute the original one (composed by HT radiator, Condenser and Charge Air Cooler) with a new one composed only by an HT radiator and a LT radiator divide in two part internally to provide the sub-cooling function for the A/C system.
The Denso components has been integrated on vehicle and testes in Denso facilities.
Moreover a complete study on flat heat exchanger has been done and a prototype version of aerodynamic underbody with heat exchangers function has been integrated on the vehicle and fully characterized.
The flat heat exchangers concept developed has been focused on integration in the engine hood, in the front mudguards (low temperature) and in the aerodynamic Underbody (high temperature)
Specific study for moodguards realization has been carried out. Several assembly technologies has been evaluated, laser soldering, brazing and glueing.
Based on Roll-Bond Technology a new heat exchangers for IVECO Daily aerodynamic underbody has been projected and realized. The main advantage of the component is the integration of the aerodynamic and the heat exchangers functions.
The IVECO Daily equipped with TIFFE system has been bench validated according to the test procedure defined during the first part of the project, in particular a cool-down test, an ATD test and a fuel consumption test has been done.
The tests has been performed following different step of vehicle integration (TIFFE system, TIFFE System with flat heat exchangers and TIFFE System with compact refrigeration Unit), but first of all the base line vehicle has been characterized to compare it with the new system.
During the Cool-down test the TIFFE System shown the same performance of the base line system, while the TIFFE system with the flat heat exchangers presented a lower performance but the target has been achieved. The TIFFE system equipped with the Compact Refrigeration Unit shown very high performance in term of A/C high pressure reduction. These reduction give back more efficiency to the A/C System contributing to the fuel consumption reduction.
The procedure on fuel consumption test is based on a NEDC cycle performed in a climatic chamber at 28 ºC and 50% R.H. with the A/C system set point of 20 ºC in fresh air mode.
The fuel consumption test shown the high performance of the TIFFE system achieved a total fuel consumption reduction of about 3% and, considering only the A/C fuel over consumption, the reduction is about 25 %.
LIGHT COMMERCIAL VEHICLE PROTOTYPE - CONCLUSION
Main result achieved:
Fuel consumption results
• Fuel consumption reduction with A/C ON: 3%
• A/C Fuel over consumption reduction: 30%
ATD Index
• Increase of ATD index:
• IVECO TARGET: > 40 °C
• Standard Production: 44 °C
• TIFFE: 49 °C
Flat heat exchangers ATD test performance:
• Aerodynamic underbody (power reject): 10 kW
CRU Cool down test performance:
• A/C HP reduction:
• Driving 4 bar
• Idling 8 bar
PASSENGER CAR
Ford Focus 1.6 D Econetic was selected as a baseline / reference vehicle for the TIFFE project. The Ford Focus is a C-segment vehicle, approximately 4.5 m long.The vehicle is available in three basic body styles: 3/5 door (hatchback), 4 door, and estate. For the TIFFE project, the 5 door version was selected, which is the volume model.
The passenger compartment represents a compact size / C-segment vehicle.The interior volume of the 5-door body style is 2.7 m3, the glass surface area of all windows is 3.4 m2. The Ford Focus Econetic baseline vehicle has a 1.6 l 4-cylinder turbocharged Diesel Engine with start/stop system.
The engine is transversally mounted and drives the front wheels. The vehicle has a 5-speed manual transmission. The final drive ratio is adapted for reduced fuel consumption of the Econetic version. This engine speed reduction also results in slightly lower performance of the air conditioning system compared to the normal version because of lower A/C compressor speeds.
The start/stop system is optimised for fuel consumption, so that the operation of the air conditioning system is to some extent compromised during engine stops.
The vehicle has a conventional engine cooling circuit with the main radiator in parallel to the heater loop. Additionally, an engine bypass is connected also in parallel. Both, main radiator and bypass flow are controlled by a double-acting thermostat.
Both the heater loop and the main radiator are connected to the degas bottle via degas lines. The oil cooler is mounted directly on the engine.
The main characteristics of the HVAC/ air distribution unit are:
• Centre-mounted
• Dual zone temperature control
• Air-side (blend doors) temperature control
• Automatic or manual controls
The main characteristics of the refrigerant loop are:
• Orifice tube / accumulator system
• Internally variable 160cc piston compressor (swash plate)
• microchannel condenser
• plate/fin evaporator
• Pressure transducer for high pressure sensing, evaporator ice protection via low pressure switch
• 600g R134a refrigerant charge
The cooling module consists of the charge air cooler, the A/C condenser, and the main radiator. These heat exchangers are ventilated by a single electric cooling fan.
The Ford Focus Econetic vehicle has blanking plates in the lower front-end opening to improve the exterior aerodynamics, which reduces the size of this opening compared to the normal version.
The engine cooling performance has been tested in two different conditions: Maximum speed test and Grade Load 40 test.
To assess the engine cooling performance at top speed, the test consists of a pre-conditioning phase at 145 km/h and the actual maximum speed phase. This can be followed by an idle and/ or a soak phase. This is tested at 35°C ambient temperature The primary test result is the radiator top water inlet temperature.
The aim of grade load 40 test is to assess the engine cooling performance during hill climb operation. The test conditions simulate climbing a 12% grade at a vehicle speed of 40 km/h.
During the preconditioning phase, the vehicle speed is 80 km/h. This can also be followed by an idle and/ or a soak phase. The test is conducted at 27°C ambient temperature. The primary test result is also the radiator top water inlet temperature.
Regarding the air conditioning, the vehicle is tested in a climatic windtunnel at 43°C ambient temperature with 40% relative humidity in max. AC mode. Interior temperatures in the cabin are recorded vs. time, from the start condition 60°C average cabin soak temperature. Sunload is simulated by 1 kW/m2 radiation intensity. The test includes 3 phases of different driving conditions: 50 km/h, 100 km/h, and idle – 30 min duration each.
The comfort-consumption test is conducted according to the procedure defined in the EU project B-COOL.
The concept of the TIFFE cooling system as established by DNTS includes a low-temperature (LT) cooling loop with a water-cooled charge air cooler (WCAC) and a water-cooled A/C condenser/ sub-cooler (WCDS). The LT loop is cooled by an integrated LT/ sub-cool (SC) radiator, mounted upstream of the main engine cooling (high temperature/ HT) radiator.
In order to gain additional efficiency of the air conditioning (A/C) system, the orifice tube set-up used in the reference vehicle was replaced by a thermal expansion valve (TXV) installation, together with a sub-cooled WCDS. Thereby, accumulator used in the reference vehicle was replaced by the receiver integrated in the WCDS, which freed up some additional package space.
The WCAC assembly could be packaged in the front rhs corner of the vehicle, behind the front bumper. The WCDS was packaged behind the engine near the firewall and attached to a cross-member of the body structure. The electrical coolant pump was packaged behind the WCAC
The LT expansion tank was packaged near the WCDS next to the suspension strut.
The LT and HT coolant radiators were replacing the original radiator and condenser of the baseline vehicle. The AC lines, coolant hoses and charge air hoses were routed accordingly.
The Step 2 TIFFE system installation in Ford Focus included the compact refrigeration unit (CRU), integrated with a secondary loop air conditioning system. With the compact refrigeration unit (CRU), an additional coolant circuit was designed for the air conditioning secondary loop, to circulate cold coolant between chiller (evaporator) and cabin cooler. The added components are highlighted in the table below.
The packaging of the CRU proved to be a difficult issue, as the component is compact, but still relatively large, especially for a passenger car engine compartment.
The CRU was installed between engine and dash panel, in the cowl area. The cowl was reworked to make space available, where cowl sealing was an issue.
Changes to the low temperature cooling loop included the deletion of the subcooled section of the water cooled condenser (WCDS) and the separate degas line. The degas bottle was converted to a simple overflow bottle and the subcooling part of the low temperature radiator was not used anymore.
To verify the engine cooling, air conditioning, and comfort-consumption performance, the baseline was characterised and the demonstrator vehicle was tested according to the defined procedures.
The measured temperatures for TIFFE step 1 and step 2 systems are very similar to the baseline system in the vmax case.
In the GL40 case, higher temperatures were seen with the TIFFE step 2 system, which is related with the installation of the CRU in the cowl area of the vehicle. As a result of the CRU installation, the cowl sealing could not be realised as leak-tight as in the baseline vehicle. Therefore, there was significant heat pick-up of the ventilation air in the cowl area. This caused higher load on the air conditioning system, which is running in outside air mode in this test. The higher A/C heat rejection in the LT cooling loop caused higher temperatures.
In the vmax case, the A/C system is running in recirculation mode.
As the higher temperatures with step 2 in the GL40 test are explained by the cowl heat pick-up and cannot be attributed to the CRU or the TIFFE system, the cooling performance of the TIFFE systems was deemed to be on the same level as the baseline.
During the A/C pull-down the observed performance with the step 1 TIFFE system is slightly lower than the baseline, but on the same level, considering the tolerance band (approximately 1K) related with this kind of measurements in the climatic windtunnel.
With the TIFFE step 2 system, the observed performance is lower than the baseline and the step 1 TIFFE system. A major part of this deterioration is probably due to the thermal inertia of the coolant in the secondary loop, which also needs to cool down during the test. However, also the 2-step heat transfer refrigerant-coolant-air (chiller – cabin cooler) has a contribution. The air discharge/ vent temperatures are higher than the baseline.
Further details for performance optimisation could be the system set-up with regards to the tuning the control elements TXV and compressor control valve, the coolant volume in the secondary loop, and the integration of the cabin cooler into the HVAC unit.
However, the step 2 system can maintain thermal comfort during idle better than the baseline system. At the end of the idle phase of the test, the average interior temperature is again very similar to the baseline. The interior temperature in the passenger compartment increases less during the idle phase than it does with the baseline system. This is also due to the thermal inertia of the secondary loop.
Also, comparing the A/C pressures, the TIFFE step 2 system also has 1 bar less compressor discharge pressure in idle than the baseline system.
Regarding the comfort-consumption tests the vehicle equipped with the TIFFE step 1 system showed a similar incremental consumption as the baseline at 15°C.
At 28°C and 35°C however, the incremental consumption with the TIFFE step 1 system was initially higher than the baseline. This was then improved to slightly below the baseline be shutting off the degas line in the LT loop. Table below shows the results of the step 1 system in relative values. The 100% value is the incremental consumption of the baseline at 28°C.
With the TIFFE step 2 system, the total consumption with A/C on could be reduced by approximately 4% compared to the baseline. With the start/stop system active during the test, a fuel consumption reduction of 6% could be achieved with the TIFFE step 2 system.
PASSENGER CAR VEHICLE PROTOTYPE - CONCLUSION
The engine cooling performance of the TIFFE step 1 and step 2 systems is comparable to the baseline.
The A/C performance of the TIFFE step 1 system is on the same level as the baseline. The initial pull-down of the TIFFE step 2 system is not as good as the baseline or the TIFFE step 1 system.
The idle A/C performance of the TIFFE step 2 system is better than step 1 system and better than the baseline. The A/C compressor discharge pressure in idle is reduced by 1 bar relative to baseline with the step 2 system.
With the TIFFE step 2 system, the overall fuel consumption with A/C on is improved by 4% relative to the baseline, or by 6% with the start/stop system active respectively.
The packaging of the CRU can be an issue in a tight engine compartment.
ENVIRONMENTAL IMPACT TOOL
While cars mainly use fuel to get from A to B, a part of the fuel is also needed for the air conditioning (AC) of the passenger compartment. This consumption and the corresponding emissions depend a lot on the ambient conditions and thus vary throughout a year. They also depend on the car usage, e.g. driving frequency, distance and on the car's location. The TIFFE Environmental Impact Tool (EIT) was developed to calculate the annual fuel consumption for air conditioning including all these factors.
The EIT is a Microsoft Excel-based calculation tool, which is fed with data from Meteonorm and Dymola.
The EIT is an advanced set of spreadsheets that runs without Visual Basic macros. It was decided to leave out macros to make the calculations more traceable and transparent.
In the EIT's user interface, the user can select the city, air conditioning system and weekly driving routine. In this case, the car is used to drive to work and lunch (and back) every weekday. On the weekends, it is used for a shopping trip on Saturday and a family tour on Sunday. This adds up to a total of 15 630 km/year.
The input from Meteonorm and Dymola is needed for the calculation of the environmental impact. Since the EIT calculates every hour of the year separately, the input data from Meteonorm and Dymola is on an hourly basis.
PROJECT WEBSITE
Within the TIFFE project the site has two major functions:
• Promote and disseminate the project aim and results.
• Exchange of information between the partners of the consortium.
To enter the TIFFE website, please go to www.tiffe.eu.
The TIFFE website has two main purposes: On the one hand it would like to offer a public platform to inform an interested audience about the project´s aim, contents and results. It can be seen the members of the consortium and their role within the project are presented on the site, too.
On the other hand the website provides an easy way for data exchange between the TIFFE partners. For this purpose, the site includes a download section divided in two areas: One freely accessible “public” area and one confidential “intern” area for the consortium members. This second area will be used to exchange information among the TIFFE partners and to create a virtual archive of the project reports. To enter the confidential area the members have to log in with their personalized username and password.
The contents of the public part of the site has been updated periodically according the project advances. This part has been addressed mainly to non-specialists so to enlarge the potential visitors’ number contributing to increase the public sensitiveness to the environmental issue.
Potential Impact:
STRATEGIC IMPACT
The project targets activity “The greening of surface transport” in the work programme, specifically area “The greening of products and operations” where the stated objective is to ensure environmental friendly surface transport activities through the greening of transport products and operations.
In particular a stated requirement of the work programme is that “For road transport research will aim by 2020 at a 40% CO2 reduction for new passenger cars and light-duty vehicles and 10% for new heavy-duty vehicles (both based on 2003 figures)”.
The TIFFE project addresses more then one the work item SST.2008.1.1.1 Clean and energy efficient gasoline & diesel powertrains technologies and innovative solutions for clean and highly energy-efficient gasoline and diesel power trains. The proposal covers the two following topics:
- Innovative components and auxiliary systems: a new generation thermal system will be realised including the re-design of the engine auxiliaries (e.g. water pump, compressor, turbocharger and air intake, ...) so to increase the controllability of the heat rejection increasing the efficiency of all the subsystems.
- Overall power-train optimisation: the opportunity given by TIFFE approach to fine control the working temperature of the powertrain subsystems allows a overall increase of the powertrain efficiency and performance.
SST.2008.1.1.2 Electric-hybrid power trains Technologies and integration for improved hybrid electric power-trains, ranging form low and mild hybrid solutions to full hybridisation and including"plug-in" solutions. This because the two demonstrator vehicles will be:
- a Passenger Car with a Stop&Start function
- a Light Commercial Vehicle
The TIFFE system has been design so to manage in a more rational way the on board thermal energy, this includes the temperature control of the generator, the power electronics and of the batteries pack.
The TIFFE project therefore specifically addresses many of the items listed in the work programme that can have a significant impact on CO2 generation by road vehicles.
The benefit of the EC contribution to this project is that none of the participants is able by working alone to deliver the required innovation to achieve the Europe-wide improvement needed in energy efficiency and hence CO2 reductions for road vehicles. By receiving this support, the participants are enabled to create new partnerships to deliver the required improvements and to create benefit to European industry and the European economy.
DIRECT APPLICATIONS AND MARKET PROSPECTS
Development of the concepts developed in TIFFE provides many opportunities for European industry to remain competitive and to gain market share in the area of technologies for energy efficiency in road vehicles.
European vehicle manufacturers will be able to produce vehicles that meet exacting standards for energy efficiency whilst retaining the attributes of safety, comfort and performance that make European vehicles attractive to purchasers worldwide.
Furthermore, the concept of an integrated thermal system and the use of the thermal energy in rational way based on patent and patentable components and sophisticated algorithms provides many global business opportunities for the European component supply industry thus further contributingto European competitiveness.
BENEFITS AND COMPETITIVE ADVANTAGES
The TIFFE project has direct benefits and competitive advantages for the partners:
For the Fiat Group, represented in the project by CRF, and for and for Ford there are significant benefits for commercial vehicles as well as passenger cars. The rational use of the on board energy reduces the fuel consumption, which is very important for commercial vehicles since it directly affects the operational cost for a fleet owner. CO2 reductions are also very important for future competitiveness since legal requirements and taxes on CO2 will be important parameters for vehicle owners.
Future vehicles which have an increasing demand of thermal management due to the incoming new engine and engine system generation will take benefit form high efficiency technologies such as the ones developed in the TIFFE project are the enabler for the ability to achieve the future severe emission and fuel economy targets at a sustainable cost.
DNTS will use the know how from TIFFE project for new product developments with the overall goals to reduce CO2 emissions and fuel consumption and to increase vehicle safety. The results from TIFFE flow directly into new innovative products. Environment-friendly, safe and innovative components and systems are important to strengthen the position for DNTS as the world’s leading automotive supplier for components and thermal systems. Simultaneously the project enables to strengthen the DNTS position in Europe promoting the increase of the investment in Europe and the consolidation of the present production facilities.
For MAFLOW, as a leading supplier of connections, lines and tubiing the TIFFE project represented a great opportunity to reinforce its capabilities and to extend its product portfolio. The TIFFE results will origin a new category of products for Maflow that will contribute to increase the company competitiveness and enable a strong supplier-position with a fast, strong and effective penetration of the automotive. The TIFFE outcomes will be reinforcing the Maflow development strategy focused to develop best-in-class components and to the extension of the perimeter to subsystem so to increase the product added value.
For TUBS and SINTEF, the project will allow continuing and tightening the research activity and know how regarding novel energy saving and low environmental impact technologies for vehicles and will contribute to the formation of new young engineers and researcher in the field of environmental friendly technologies.
STRATEGY FOR IMPACT ACHIEVEMENT
The TIFFE dissemination and exploitation activities in WP7 are designed to ensure that the project results are communicated outside the project to appropriate stakeholders and within the project to relevant industries and universities etc. By achieving a high level of awareness of the project and its results, industry will be encouraged to develop commercial applications of the technology following the end of the project.
EUROPEAN DIMENSION
The principal European dimension to this project is the reduction of CO2 emissions and the related reduced fuel consumption related to surface transport. The Commission Communication COM/2007/0019 “Results of the review of the Community Strategy to reduce CO2 emissions from passenger cars and light-commercial vehicles” makes the following key points:
- Road transport is the second largest sector in the EU for emissions of greenhouse gases.
- Although overall greenhouse gas emissions in the EU fell by 5% over the period 1990–2004, the emissions of CO2 from road transport rose by 26%.
- Improvements in vehicle technology have led to reductions in CO2 emissions, for example the average CO2 emissions in new vehicles was 186 g/km in 1995 but 163 g/km in 2004. However increases in traffic volumes and congestion have been responsible for the net growth in CO2 emissions.
- Continued growth in CO2 emissions from road transport means that improvements in other sectors to the overall carbon emissions in Europe are reduced or even negated.
- Targets have therefore been set for the average CO2 emissions of new vehicles to be 140 g/km in 2008/9 and 120 g/km by 2012, with further reductions anticipated beyond that date.
Technologies such as those proposed for development in TIFFE are a key part of achieving these improvements. In particular, the significant improvements delivered are needed in order to make road transport and the vehicles used in road transport a net contributor to decreasing overall levels ofCO2 generation in Europe. As the volumes of road vehicles in service and the CO2 they produce are significantly greater than other surface transport means, EE-VERT presents an opportunity to make a substantial impact at the European level.
For a passenger car and for a Light Commercial Vehicle, it is estimated that TIFFE can reduce the fuel consumption and CO2 emissions by around 15% in real use, following this deployment:
- 3% through the use of more efficient components such as heat exchangers, fans, ...
- 1% due the reduction of the cooling drag
- 4% thanks to the optimisation of the working temperature subsystems: charge air cooler, engine, gas cooler/condenser, alternator, ...
- 4% by means on overall and systemic thermal energy management strategy
- 3% as effect of the specific design dedicated to Stop&Start (e.g. air conditioning) and Hybrid Powertrain that will reduce the need to re-start the thermal engine Moreover the TIFFE system will assure an increase of the air conditioning efficiency of about 15% (reference baseline systems) and of about 25% in case of Stop & Start or Hybrid vehicle), contributing to the overall vehicle fuel economy increase in real use.
CONTRIBUTION TO COMMUNITY SOCIETAL OBJECTIVES
The TIFFE outcomes project will contribute to the Community’s societal objectives to address climate change. The principal contribution is in reducing the level of CO2 emissions from road transport. However, as fuel consumption is also reduced the results of the project will help to reduce the dependence of the European area on imported fuel. Furthermore, improvements in air quality can be expected to result from the implementation of the technologies to be developed in this project, therefore contributing to improved health of European citizens.
PLAN FOR THE USE AND DISSEMINATION OF FOREGROUND
Overall the benefits to society of this project will only to be realised if many, if not all, manufacturers use this technology, consequently the dissemination activities are crucial in obtaining the widest possible benefit from the project.
EXPLOITATION AND DISSEMINATION PLAN FOR USE OF PROJECT RESULTS
Dissemination activities take place at three main levels:
- Ensure that the developed technology matches the requirements of the European automotive industry on the long term as part of the project exploitation.
- Make engineering departments from the project main stakeholders plus the supply chain aware of new technologies that should be used in future products.
- Publish scientific and technical papers in conferences, journals, web sites, etc.
The dissemination objectives was:
- Create a common roadmap for technology adoption with the different stakeholders to be able to produce vehicles incorporating the developed technologies through future development activities.
- Prepare the European automotive industry and its supply chain for integration of TIFFE technologies in products.
- Strengthen academic partners in their R&D efforts to support the automotive sector in future programs.
These objectives has been achieved through the following dissemination actions:
- Public website: A public website will be set up to present the main benefits and outcomes.
- Internal dissemination by the participants to their own customers and suppliers.
Technology transfer actions has been carried out for the engineering and manufacturing departments of the European vehicle manufacturers and for their supply chain.
List of Websites:
www.tiffe.eu