Experimental study on the impact of indoor unit airflow velocity on the performance of an automotive heat pump system with a suction line heat exchanger
Özet
This study aimed to investigate the effect of changing the indoor unit air flow rate on the performance of an automobile heat pump with a suction line heat exchanger. Using a four-way valve,
the automotive heat pump system was developed by reversing the refrigerant direction in the
automobile air conditioning system, excluding the compressor. A suction line heat exchanger was
added to the test system to enhance heat transfer between the liquid and suction lines of the
automotive heat pump system. Performance comparisons were first performed for R134a and
R1234yf by disabling the suction line heat exchanger. Then, the suction line heat exchanger was
activated for R1234yf, and the tests were repeated. Performance comparisons were made for two
different compressor speeds and three different indoor unit airflow speeds. It was found that using
the heat exchanger in R1234yf operations improved the heating capacity, compressor discharge
temperature and coefficient of performance by approximately 1.8 %, 5.1 % and 5.9 %, respectively. The heating capacity of the heat pump system using R134a, R1234yf, and R1234yf with
the suction line heat exchanger was determined to be in the range of 2.46–3.29 kW, 2.35–3.04
kW, and 2.39–3.11 kW, respectively. An increase in the airflow speed of the indoor unit from 1.4
m s
− 1 to 3.2 m s
− 1 resulted in an average decrease of approximately 12.3 % in the compressor
discharge temperature. In contrast, the heating capacity and coefficient of performance increased
by approximately 11.8 % and 14.4 % on average, respectively, for R1234yf operations with the
heat exchanger. This study revealed that by optimizing the air flow rate in the R1234yf heat pump
system with a suction line heat exchanger, improvements in the heating capacity and coefficient
of performance can be achieved, thus providing better thermal comfort in the passenger
compartment.