hi's new Phase Change Material (PCM) Evaporator will keep the cabin of start-stop vehicles cooler longer. The system is also ideal for extending the electric range of hybrid/electric vehicles.
Delphi's system is a direct replacement for the original air-conditioning evaporator yet is lower cost and less complex than an electric air conditioning compressor and is more efficient, said James Bertrand, president Delphi Thermal Systems. The new Phase Change Evaporator is an example of Delphi's ability to deliver a simple system yielding great impact.
Delphi's system integrates a reservoir of PCM within the air-conditioning evaporator. During normal operation, thermal energy is removed from the material which solidifies or freezes. When the air conditioning system is stopped, the PCM gradually liquefies or melts, drawing heat from the air to keep passengers cool and comfortable. The system can typically maintain target air temperature at the cabin vents for one to two minutes – depending on the volume of PCM specified – keeping occupants comfortable throughout periods of stop-start driving.
Several families of materials possess phase change properties, including hydrated salts, organic and inorganic eutectic mixtures, paraffins and fatty acids. Delphi selected paraffin-based PCMs for their combination of thermal properties and robust, long-term reliability.
Extensive analysis has enabled Delphi to use the PCM in current evaporators with few additional parts to create a thermosiphon effect with the refrigerant already present within the evaporator, eliminating any moving parts and simplifying the installation.
Traditional air conditioning systems account for up to 5 percent of a vehicle's average fuel usage in a hot climate and consequently a similar proportion of CO2 emissions, Bertrand said. Delphi technologies can reduce HVAC system fuel usage by 50 percent while continuing to enhance occupant comfort. For hybrid and electric vehicles, we can reduce or eliminate the compromise in cabin comfort and we can extend the zero emissions range.
The state-of-the-art technology is now moving from testing to its first vehicle development program and is expected on the road by 2015.
Our broad experience in hybrid vehicle technologies, combined with our depth of expertise in vehicle thermal systems, have allowed us to quickly develop and test this technology and vehicle integration will now be fast and efficient, said Bertrand.