Regenerative Air-conditioner

Two-thirds of the energy of an engine is lost as heat to the environment. While significant steps have been made in improving engine efficiency, the opportunities are becoming marginal. Recovering waste energy provides the next step in efficiency improvements. First generation energy recovery in vehicles is now already reality, in the form of regenerative braking. The next generation is heat recovery. Currently, these systems are large, expensive and bulky, suitable for stationary applications but not in vehicles.

This invention provides a heat recovery system that improves the fuel efficiency of a vehicle with minimal on-cost. In order to recover energy, the installed air conditioning system is operated in reverse in Organic Rankine Cycle mode.


This invention is intended for reducing the fuel consumption of road vehicles.

Technical Summary

Most vehicles are fitted with air conditioning systems. These systems are idle for much of the time. This invention utilises waste engine heat to drive the A/C compressor, converting the heat into either drive power or electricity, reducing fuel consumption by reducing engine load. The system is especially suited to hybrid vehicles fitted with an electric A/C system. Using the existing A/C system results in a significant reduction in the number of required parts and associated costs. An additional advantage is the ability to recover low quality heat, due to the nature of the refrigerant.

License - Intellectual Property

WO 2008/075958
Regenerative Air-conditioner

License - Stage of Development


License - Proposal

licensing opportunity and research collaboration

License - TNO reference number

Licensing opportunities


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