Experimental study of a diffusion absorption refrigeration cycle supplied by the exhaust waste heat of a sedan car at low engine speeds

Abstract

The wasted energy from a car exhaust can be considered as the heat supply for an absorption refrigeration cycle. In practice however, application of such cooling systems in automobiles has been facing a number of technical restrictions one of which is once the car engine runs idle or at low speed. To tackle this matter, the present experimental study has been carried out. A commercial diffusion absorption refrigerator with internal volume of 0.04 cubic meters (Electrolux 27A1) and the exhaust flow from a compact car engine (X100 KIA) are applied. Various engine speeds (1000–2500 rpm) have been tested. First, it was confirmed that the amount of heat transferred to the generator at low engine speeds was not adequate to obtain the low temperature required for the refrigerator compartment. A new generator was therefore designed and built. The experimental results show that by using the modified generator, the heat transfer to the generator improves by more than 19%. The evaporator and refrigerator compartment reached the desirable temperatures of −5.7 °C and 4.2 °C respectively at the engine speed of 2000 rpm. Further improvement of the results was observed at the engine speed of 1000 rpm where the temperatures at the evaporator and the refrigerator compartment were reduced by about 4 °C once the modified generator was applied.