A stationary test bench has been developed for the investigation of steady state and dynamic performance of an
automotive air conditioning system. The test facility replicates the hardware arrangement of the actual automobile as
far as practicable and uses the components used in the actual system. As the engine is absent in the facility the
variation of the compressor speed is achieved through a variable frequency motor which engages with the
compressor through a magnetic clutch. Additionally, an indigenously designed controller has been used in the test
facility. It actuates the magnetic clutch following the protocols for safety and drive sequence of the fan (condenser)
and blower (evaporator) motors exactly as it is done in the car. The facility also contains a large number of sensors
in excess to those few present in the actual system. The steady state performance of the system has been investigated
for three independent variables, namely the refrigerant charge level, the compressor speed and the speed of the
evaporator fan as they are the only variable parameters for a running car. The following trends have been observed.
• The suction and discharge pressure increases with the increase of refrigerant charge whereas, the suction
and discharge temperature decreases with the charge amount.
• The discharge pressure and temperature increases with the increase of compressor speed.
• Suction pressure and temperature increases with the increase of blower speed accompanied by a decrease in
discharge pressure and temperature.
• A distribution rating parameter has been calculated to quantify the temperature non-uniformity in the
condenser as well as the effective use of the available heat transfer area through the use of infrared
thermography.
• With the increase of compressor speed, cooling load and compression work increases Cooling Performance Characteristics on Mobile
Air-Conditioning System for Hybrid Electric Vehicles