TTD - Transports Terrestres Durables

High energy efficiency heat pumps for relectrified vehicles and trains – ELEC-HP

Generic development of electric heat pumps for electric vehicles and trains

Design of innovative heat exchangers aiming at the limitation of frost formation<br />Integration system design for froting and defrosting management<br />System design for recovery and upgrading available heat<br />Pilot demonstration

Electric -vehicle heating and divide by three the heating energy consumption

The ELEC-HP project aims at developing a family of automotive heat pumps to be sustituted to heating by electric resistances. Barriers to overcome are as follows: <br />- use a refrigerant with a GWP < 150, which presents good energy efficiency in heating for -20 °C outdoor temperature and in cooling for + 40 °C outdoor temperature<br />- design fully-brazed aluminum heat exchangers, with new fin design, optimized for improved management of frosting/defrosting cycles, <br />- design new defrosting strategies that do not reverse the cycle and do not impact the cabin comfort,<br />- develop, for road vehicles, strategies of pre-conditioning including energy storage,<br />- design systems diffusing heat and coldness as near as possible of passengers in order to improve the ratio useful energy/produced energy,<br />For electric vehicles, stakes are to reduce of more than 50% the annual energy consumption of thermal comfort and to obtain autonomy savings of more than 50% on cold periods with high occurence (-5°C / +5°C) compared to heating with resistance.<br />For rail cars, stages are to limit by at least a factor 3 the energy consumption currently ensured by electric resistances and to improve the comfort felt by passengers via improved heat diffusion.

The first innovative path is in the design, simulation, and definition of vortex generators allowing the amplification of heat exchanges and the frost growth management. This management is dual, either by the management of the heat-exchanger rows or by limitation of the solid deposit.
The second innovative path is associated to the systemdesign at several scales: hte heat-exchanger scale for the management of the frost deposit and defrosting, the heat-exchanger scale for the minimization of exergy losses due to defrosting, the vehicle scale for the minimization of needs and the energy recovery of the extracted air, the user scale for the supply of the adequate energy quantity.

Majors results:
- low energy impact defrosting strategies
- evaporator-condenser design with low frost deposit (under development)
- system development af a reversible heat pump operating from -20°C to +40°C (in the near future)

Development of new heat-pump systems using the same type of heat exchangers and the same type of concept of frosting/defrosting management for electric vehicles and railway vehicles.


The aim of this project is to develop a family of generic heat pumps for on-board reversible air conditioning systems to replace heating systems using electrical resistance. In that perspective, it is necessary to design and/or adapt architectures and components allowing the realization of on-board reversible heat pumps (providing heating and cooling), with high energy efficiency, and using an electrical compressor. Barriers to be overcome are as follows:
• To use a refrigerant with GWP lower than 150 and presenting high energy efficiency in heating mode for outdoor temperature of -30°C as well as in cooling mode for outdoor temperature of +40°C
• To design fully-brazed aluminum heat-exchangers with new optimized fin designs, so as to achieve improved management of frosting/defrosting cycles, which is a major stake for robust and durable use of heat pumps in transports
• To design new defrosting strategies that do not reverse the cycle and do not impact the cabin comfort
• To develop systems diffusing heating and cooling as close as possible of passengers in order to improve the ratio of useful energy to produced energy.
Once those barriers will be overcome and technical solutions will be proven at the laboratory level, two demonstrators will be designed, realized, and tested; one pre-existing demonstrator of heat pump for electric vehicle will be modified to integrate the new heat exchangers, modify the defrosting mode, and modify the overall system control. It will be necessary to perform dynamic simulation of heating and cooling needs as well as the associated overall energy management, which is specific to plug-in hybrid vehicles, electric vehicles, trains, and tramways. Pre-conditioning strategies will be designed and implemented. The two plus one demonstrators of reversible heat pumps will be designed in parallel and require dedicated developments for:
• Plug-in hybrid vehicles
• Electric vehicles
• Car tramway
The three prototypes will be realized during this project and will be tested during one year integrating the four seasons. This will allow tests in heating and cooling modes. Prototypes will operate as of the beginning of the third year of the program and measurements will be carried out over one year.

Project coordination


The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.



Help of the ANR 893,706 euros
Beginning and duration of the scientific project: September 2011 - 36 Months

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