Heating and cooling vehicle seat via air conditioner coils

Abstract

A real vehicle seat was modified in order to locate evaporator coils extended from a vehicle air conditioner system just beneath the back and cushion surfaces. The seat back and cushion surface temperatures were measured by several thermocouples. Air conditioner system was operated in heat pump and cooling modes for different compressor speeds. After steady operation of the air conditioner was attained, a live manikin sat to the seat and remained in sitting position for five minutes. The temperatures were recorded during the existence of the manikin and they were recorded for an additional five minutes after the manikin left the seat. The coils embedded under the seat surfaces were made of flexible hoses for the sake of usage due to the shape changing seat surfaces under the load of the manikin weight. Coils were in parallel configuration by the help of a distributer and collector. The temperatures of the seat surfaces were evaluated in respect of the thermal comfort and feasibility of the application. Air conditioner system was also monitored in respect of the COP and energy consumption values. At the instance of sitting, the transient response of the system is very significant due to the weight of the live manikin. However it settles quickly. Cooling was observed to be more realizable while heating seat surfaces had problems due to flow blockage. There were no significant discomfort issues due to the seat surface temperatures and the existence of the coils. The surface temperatures of the seat back exhibited differences from the seat cushion although the formations were same. The orientation of the coils and the weight of the passenger were concluded to be the reason for that. COP was found to be changing between 3 and 3.56 for cooling mode while the highest amount was found for 600 rev/min compressor speed in cooling operation. Heat pump operation had relatively higher COP values ranging between 3.31-3.64. 700 rev/min compressor speed gave the 3.64 COP value for heat pump operation. The difference between COP values of the working modes was concluded to be due to the seat coils and their effect on the additional pumping work. The potential of the application and possible field of studies were evaluated according to the conducted tests and the survey about the topic.