Date of Award


Publication Type

Master Thesis

Degree Name



Mechanical, Automotive, and Materials Engineering


Applied sciences, Air conditioning, Amesim, Internal heat exchanger, Power consumption, R134a


Zheng, Ming




This thesis investigates the change in power consumption for a mobile air conditioning (MAC) system from the introduction of an internal heat exchanger (IHX). The internal heat exchanger is so named since it is a simple heat exchanger that is placed internally into the AC system. It serves to transfer heat from the high to low pressure refrigerant to maximize the system cooling capacity. The work investigates how other performance parameters such as the pressure drops, IHX capacity, evaporator capacity, coefficient of performance and the absolute efficiency ratio change from the introduction of the IHX. The steady-state simulation results are compared to data available in the literature and transient experimental tests including the cabin cool-down, and the simulation results from the New European Driving Cycle. The results from the simulations show a reduction in power consumption of up to 2% in high ambient temperatures but an increase in power consumption of up to 1.5% for low ambient temperatures. The power consumed by the MAC system is largely by the compressor. Placing the thermal sensing bulb (TSB) of the thermal expansion valve downstream of the internal heat exchanger yielded higher MAC coefficient of performance, lower suction line pressure drops and compressor power consumption compared to placing the TSB upstream of the internal heat exchanger.