Final Report Summary - WHEXPERS (Study and manufacturing of a Wasted Heat Exchanger and a hot air Piston Engine Recuperation System)
Executive Summary:
The reduction of CO2 emissions and consumption is a permanent concern of major actors in the transportation sector. Many technologies have thus been developed to improve the performance of engines. In recent years a constantly increasing number of work and patent deals with the recovery of heat losses in the exhaust. These losses represent about 30% of the energy produced by the engine.
WHEXPERS project uses an innovative WHR solution (Waste Heat Recovery), based a new thermodynamic cycle combining Ericsson Cycle and major patented improvements. The proposed thermodynamic cycle is particularly innovative since it uses a high-performance heat exchanger associated with a hot air machine that performs both compression and expansion.
This technology uses an open cycle. It means that the working fluid is air that is taken and released to the atmosphere. In fact, it is not necessary to cool it down, as it is the case for a closed cycle such as Stirling or Rankine. The exhaust gases pass through a heat exchanger to warm the fresh admission air that is compressed by the hot air machine that also carries out the expansion and generates mechanical energy. This energy is directly sent to the engine, which allows high conversion efficiency and limits the cost compared to a system of electricity generation.
The objective of the WHEXPERS project is to study and manufacture the systems and components necessary to run a proof of concept of a recovery system (composed of a hot air engine and a heat exchanger) of the energy spread in the nozzle of a small shaft turbine (helicopter engine) based on this technology. The project also includes the test of this system in order to estimate its performances.
The hot air piston engine is a mono-cylinder piston engine rotating up to 7.500 rpm fed by external air through classical admission and exhaust system, and getting its power from the artificial electric hot loop.
The heat exchanger has to respect strong environment constraints due to its integration in a turbine exhaust nozzle. It should not have a major impact on the architecture of the turbine or on the exhaust gas flow.
A new design optimization for the prototype was necessary to design parts and components that could be manufactured with a huge work of product/process study with providers at reasonable cost (material, process...).
Regarding the heat exchanger, its dimensioning and its integration in the helicopter gas turbine exhaust flow has required an adaptation of thermodynamic and mechanical sizing tooling to improve its capacity on the heat exchanger behavior simulation to obtain a real product by taking into account all the requirements and conditions of use.
Tests on some main components of the engine has made possible to optimize permeability and frictions functionality as well as product/process studies allowed to manufacture a prototype.
Nevertheless, the tests on the complete engine showed a failure of the distribution system that requires a new design with the associated costs that made impossible to achieve the objective to demonstrate the potential performances of the system.
Project Context and Objectives:
One of the existing ways of improving the efficiency of any internal combustion engine and thus its consumption and CO2 emissions is to take advantage of the energy wasted at the engine exhaust.
Depending on the type of thermodynamic cycle used, the type of fuel and of the mechanical way of running this cycle, the efficiency of an internal combustion engine ranges from 25% for a turbine to 50% for the best reciprocating engines. The rest of the energy is wasted in mechanical contacts, in heat evacuation to protect mechanical components, and for the main part, on the exhaust gases.
The goal of the topic JTI-CS-2010-3-SAGE-05-010 was to study and manufacture the systems and components necessary to run a recovery system of the energy spread in the nozzle of a small shaft turbine (helicopter engine) and then to test it. This system is a Wasted Heat Regeneration System (WHRS) which is composed of:
✓ A heat exchanger,
✓ A hot air piston engine.
In order to achieve this goal, the WHEXPERS consortium has studied and manufactured:
✓ A high mechanical efficiency engine with low friction materials and technologies, and capable of running at high temperatures and high revolution.
✓ A component test bench to validate the correct technological choices made on the engine admission components.
✓ 2 heat exchangers to recover the heat in the turbine nozzle.
✓ An engine test bench to validate the performances of the piston engines.
The heat exchanger is an air/air type directly installed in the gas turbine exhaust nozzle and in the final application, it will withdraw the heat from the exhaust gases and it will heat up the “hot loop” pressurized air flow coming from and going to the piston engine.
The air engine is an alternative monocylinder piston engine. The air admission and escape (cold loop) are realized by the same rotary valve system. The second rotary valve allows the circulation of the pressurized air (hot loop) since the cylinder towards the heat exchanger and reciprocally.
The architecture of the air engine had to be optimized in order to reduce the internal frictions and thus to maximize the work produced by the system of regeneration. The air engine uses a no conventional system of distribution (rotary valve).
The following tasks have been performed during the WHEXPERS project:
✓ Detailed study and manufacturing of 2 heat exchangers
✓ Study and manufacturing of the base engine components
✓ Performance test on partial cylinder head components in terms of permeability and friction-sealing compromise
✓ Partial redesign of cylinder head depending on partial tests results + process/material integration
✓ Manufacturing of one hot air piston engine
✓ Study and manufacturing of a bench for the piston engine
✓ Assembly of the piston engine.
✓ Tests
Project Results:
1 WP1 Hot Air Piston Engine Design and Manufacturing
The objectives for this WP was to design and manufacture a hot air piston engine to be tested after having optimized the original design received from the Topic leader and some of the functionalities of this engine such as permeability.
The first task to realize was the partial prototype optimization because the input data received by the consortium were not completely exploitable and not fully finished. Therefore, INTRENIA had to carry out much more design work and optimization work than forecasted, specially to design parts and components that could be manufactured with a huge work of product/process study with providers at reasonable cost (material, process...).
During this WP, the consortium has also defined the interfaces with the motor test bench not initially defined (admission, escape, cylinder head gasket) and it has realized the assembly drawings and instructions for the engine delivery.
2 WP2 Heat Exchanger Design
The WP’s objective was to demonstrate the heat exchanger feasibility from the mechanical and the thermodynamics point of view. First, ACTE activities were mainly focused on both the heat exchanger sizing and its integration in the helicopter gas turbine exhaust flow. ACTE adapted its thermodynamic and mechanical sizing tooling to improve its capacity on the heat exchanger behavior simulation:
In a parallel way, ACTE worked on the heat exchanger design and its prototyping procedure but also on the best way to deal with the heat exchanger prototype manufacturing process limitations and the integration expectation of the topic leader and to improve significantly the heat exchanger design taking into account the requirement of mass and integration.
3 WP3 Heat Exchanger Manufacturing
The objective of this WP was to demonstrate the heat exchanger feasibility from the manufacturing point of view. During this WP, the ACTE’s activities were mainly focused on the heat exchanger manufacturing but also on the optimization studies that will allow matching the initial specification regarding the performances (effectiveness and pressure drops) and the heat exchanger weight.
The heat exchangers manufacturing allowed ACTE to switch from the initial GAP heat exchanger concept to a real product by setting up the production process thanks to the test of different assembly methodologies.
In the same time, ACTE continued also its theoretical investigation on a material research that could allow the best solution for the working conditions with the thinnest heat exchanger plates and because those materials are also harder to handle, a new plate profile had to be design to take into account the future heat exchanger performances as well.
Finally, the project conclusion regarding the heat exchanger can be summarized by the heat exchanger test themselves that was realized by the topic leaders in its own facilities. Indeed, even the performances measurements have to be analyzed in detail, a preliminary comparison showed a good relationship between the theoretical performances and the measured one which is the best thing we could expect at the project beginning and this bring also very good perspective for future heat recovery development in this field.
4 WP4 Hot Air Engine System Test Rig
The objective of this work package was to design and manufacture the hot air engine system test rig in order to test the hot air engine with the artificial electrical hot source. After having analyzed the draft tests campaign the architecture of the engine test rig has been defined taking into account the requirements for the tests configurations (interfaces, software...) and the operations such as the control of the revolutions or the load of the
Based on this architecture, and the test plan, AKIRA has sourced specific components (especially electrical heater) and designed and manufactured or bought all mechanical components.
5 WP5 Hot Air Engine System Testing
The objective of this work package was first to optimize permeability and frictions tests to optimize the design of some components of the engine thanks to stereo lithography prototypes or with elements representative of parts of the engine.
Regarding to the tests on the complete engine, they showed a failure of the distribution system that requires a new design with the associated costs that made impossible to achieve the objective to demonstrate the potential performances of the system.
Potential Impact:
The project resulted in the evaluation of the performances of components necessary to run a recovery system of the energy wasted in the nozzle of a turboshaft engine, which can contribute to fuel consumption reduction.
Even if all the objectives goals of the project have not been fulfilled, significant results have been achieved to evaluate the potential of the technologies developed in the project:
• Even if the analysis is still on-going, the first trends are that the performances of heat exchanger tested at Turbomeca premises are partially compliant with the predictions. Additional work is needed to improve compactness, weight and expected life time.
• For the hot air piston engine:
✓ The detailed study performed by Turbomeca within the frame of the project showed that the performances and weight objectives needed for an application of the concept for a turboshaft engine would not be achieved.
✓ In addition, even if the complete test program could not be performed as originally planned, the project demonstrated that the implementation of the concept is very complex, and that many challenges still remain to be tackled to find an acceptable compromise between sealing (air and oil circuits) and friction.
For each partner, the project has been profitable. Intrenia has been able to acquire more experience in the design of complex aeronautics systems, AKIRA has developed new test installation and software and ACTE has developed new technologies within the heat exchanger field.
List of Websites:
Not applicable
The reduction of CO2 emissions and consumption is a permanent concern of major actors in the transportation sector. Many technologies have thus been developed to improve the performance of engines. In recent years a constantly increasing number of work and patent deals with the recovery of heat losses in the exhaust. These losses represent about 30% of the energy produced by the engine.
WHEXPERS project uses an innovative WHR solution (Waste Heat Recovery), based a new thermodynamic cycle combining Ericsson Cycle and major patented improvements. The proposed thermodynamic cycle is particularly innovative since it uses a high-performance heat exchanger associated with a hot air machine that performs both compression and expansion.
This technology uses an open cycle. It means that the working fluid is air that is taken and released to the atmosphere. In fact, it is not necessary to cool it down, as it is the case for a closed cycle such as Stirling or Rankine. The exhaust gases pass through a heat exchanger to warm the fresh admission air that is compressed by the hot air machine that also carries out the expansion and generates mechanical energy. This energy is directly sent to the engine, which allows high conversion efficiency and limits the cost compared to a system of electricity generation.
The objective of the WHEXPERS project is to study and manufacture the systems and components necessary to run a proof of concept of a recovery system (composed of a hot air engine and a heat exchanger) of the energy spread in the nozzle of a small shaft turbine (helicopter engine) based on this technology. The project also includes the test of this system in order to estimate its performances.
The hot air piston engine is a mono-cylinder piston engine rotating up to 7.500 rpm fed by external air through classical admission and exhaust system, and getting its power from the artificial electric hot loop.
The heat exchanger has to respect strong environment constraints due to its integration in a turbine exhaust nozzle. It should not have a major impact on the architecture of the turbine or on the exhaust gas flow.
A new design optimization for the prototype was necessary to design parts and components that could be manufactured with a huge work of product/process study with providers at reasonable cost (material, process...).
Regarding the heat exchanger, its dimensioning and its integration in the helicopter gas turbine exhaust flow has required an adaptation of thermodynamic and mechanical sizing tooling to improve its capacity on the heat exchanger behavior simulation to obtain a real product by taking into account all the requirements and conditions of use.
Tests on some main components of the engine has made possible to optimize permeability and frictions functionality as well as product/process studies allowed to manufacture a prototype.
Nevertheless, the tests on the complete engine showed a failure of the distribution system that requires a new design with the associated costs that made impossible to achieve the objective to demonstrate the potential performances of the system.
Project Context and Objectives:
One of the existing ways of improving the efficiency of any internal combustion engine and thus its consumption and CO2 emissions is to take advantage of the energy wasted at the engine exhaust.
Depending on the type of thermodynamic cycle used, the type of fuel and of the mechanical way of running this cycle, the efficiency of an internal combustion engine ranges from 25% for a turbine to 50% for the best reciprocating engines. The rest of the energy is wasted in mechanical contacts, in heat evacuation to protect mechanical components, and for the main part, on the exhaust gases.
The goal of the topic JTI-CS-2010-3-SAGE-05-010 was to study and manufacture the systems and components necessary to run a recovery system of the energy spread in the nozzle of a small shaft turbine (helicopter engine) and then to test it. This system is a Wasted Heat Regeneration System (WHRS) which is composed of:
✓ A heat exchanger,
✓ A hot air piston engine.
In order to achieve this goal, the WHEXPERS consortium has studied and manufactured:
✓ A high mechanical efficiency engine with low friction materials and technologies, and capable of running at high temperatures and high revolution.
✓ A component test bench to validate the correct technological choices made on the engine admission components.
✓ 2 heat exchangers to recover the heat in the turbine nozzle.
✓ An engine test bench to validate the performances of the piston engines.
The heat exchanger is an air/air type directly installed in the gas turbine exhaust nozzle and in the final application, it will withdraw the heat from the exhaust gases and it will heat up the “hot loop” pressurized air flow coming from and going to the piston engine.
The air engine is an alternative monocylinder piston engine. The air admission and escape (cold loop) are realized by the same rotary valve system. The second rotary valve allows the circulation of the pressurized air (hot loop) since the cylinder towards the heat exchanger and reciprocally.
The architecture of the air engine had to be optimized in order to reduce the internal frictions and thus to maximize the work produced by the system of regeneration. The air engine uses a no conventional system of distribution (rotary valve).
The following tasks have been performed during the WHEXPERS project:
✓ Detailed study and manufacturing of 2 heat exchangers
✓ Study and manufacturing of the base engine components
✓ Performance test on partial cylinder head components in terms of permeability and friction-sealing compromise
✓ Partial redesign of cylinder head depending on partial tests results + process/material integration
✓ Manufacturing of one hot air piston engine
✓ Study and manufacturing of a bench for the piston engine
✓ Assembly of the piston engine.
✓ Tests
Project Results:
1 WP1 Hot Air Piston Engine Design and Manufacturing
The objectives for this WP was to design and manufacture a hot air piston engine to be tested after having optimized the original design received from the Topic leader and some of the functionalities of this engine such as permeability.
The first task to realize was the partial prototype optimization because the input data received by the consortium were not completely exploitable and not fully finished. Therefore, INTRENIA had to carry out much more design work and optimization work than forecasted, specially to design parts and components that could be manufactured with a huge work of product/process study with providers at reasonable cost (material, process...).
During this WP, the consortium has also defined the interfaces with the motor test bench not initially defined (admission, escape, cylinder head gasket) and it has realized the assembly drawings and instructions for the engine delivery.
2 WP2 Heat Exchanger Design
The WP’s objective was to demonstrate the heat exchanger feasibility from the mechanical and the thermodynamics point of view. First, ACTE activities were mainly focused on both the heat exchanger sizing and its integration in the helicopter gas turbine exhaust flow. ACTE adapted its thermodynamic and mechanical sizing tooling to improve its capacity on the heat exchanger behavior simulation:
In a parallel way, ACTE worked on the heat exchanger design and its prototyping procedure but also on the best way to deal with the heat exchanger prototype manufacturing process limitations and the integration expectation of the topic leader and to improve significantly the heat exchanger design taking into account the requirement of mass and integration.
3 WP3 Heat Exchanger Manufacturing
The objective of this WP was to demonstrate the heat exchanger feasibility from the manufacturing point of view. During this WP, the ACTE’s activities were mainly focused on the heat exchanger manufacturing but also on the optimization studies that will allow matching the initial specification regarding the performances (effectiveness and pressure drops) and the heat exchanger weight.
The heat exchangers manufacturing allowed ACTE to switch from the initial GAP heat exchanger concept to a real product by setting up the production process thanks to the test of different assembly methodologies.
In the same time, ACTE continued also its theoretical investigation on a material research that could allow the best solution for the working conditions with the thinnest heat exchanger plates and because those materials are also harder to handle, a new plate profile had to be design to take into account the future heat exchanger performances as well.
Finally, the project conclusion regarding the heat exchanger can be summarized by the heat exchanger test themselves that was realized by the topic leaders in its own facilities. Indeed, even the performances measurements have to be analyzed in detail, a preliminary comparison showed a good relationship between the theoretical performances and the measured one which is the best thing we could expect at the project beginning and this bring also very good perspective for future heat recovery development in this field.
4 WP4 Hot Air Engine System Test Rig
The objective of this work package was to design and manufacture the hot air engine system test rig in order to test the hot air engine with the artificial electrical hot source. After having analyzed the draft tests campaign the architecture of the engine test rig has been defined taking into account the requirements for the tests configurations (interfaces, software...) and the operations such as the control of the revolutions or the load of the
Based on this architecture, and the test plan, AKIRA has sourced specific components (especially electrical heater) and designed and manufactured or bought all mechanical components.
5 WP5 Hot Air Engine System Testing
The objective of this work package was first to optimize permeability and frictions tests to optimize the design of some components of the engine thanks to stereo lithography prototypes or with elements representative of parts of the engine.
Regarding to the tests on the complete engine, they showed a failure of the distribution system that requires a new design with the associated costs that made impossible to achieve the objective to demonstrate the potential performances of the system.
Potential Impact:
The project resulted in the evaluation of the performances of components necessary to run a recovery system of the energy wasted in the nozzle of a turboshaft engine, which can contribute to fuel consumption reduction.
Even if all the objectives goals of the project have not been fulfilled, significant results have been achieved to evaluate the potential of the technologies developed in the project:
• Even if the analysis is still on-going, the first trends are that the performances of heat exchanger tested at Turbomeca premises are partially compliant with the predictions. Additional work is needed to improve compactness, weight and expected life time.
• For the hot air piston engine:
✓ The detailed study performed by Turbomeca within the frame of the project showed that the performances and weight objectives needed for an application of the concept for a turboshaft engine would not be achieved.
✓ In addition, even if the complete test program could not be performed as originally planned, the project demonstrated that the implementation of the concept is very complex, and that many challenges still remain to be tackled to find an acceptable compromise between sealing (air and oil circuits) and friction.
For each partner, the project has been profitable. Intrenia has been able to acquire more experience in the design of complex aeronautics systems, AKIRA has developed new test installation and software and ACTE has developed new technologies within the heat exchanger field.
List of Websites:
Not applicable
