Exergy analysis of the effects of extreme hot conditions on cooling system efficiency: A case study of a split air conditioner

The performance of thermal systems is directly affected by the surrounding external conditions, especially those characterized by a hot climate and low relative humidity in the summer . It may enhance thermal system inefficiencies during peak daytime hours. The present work aims to study the thermal and exergonic performance of a 4-ton split air conditioning system operating under extremely hot and dry climatic conditions, such as those found in Baghdad, Iraq. The components of the air conditioner charged with 5.5 kg of R-22 refrigerant were tested at room temperature (23 °C) and in ambient temperatures (30 °C to 60 °C). Data were collected from 7:00 am to 3:00 pm in July using temperature sensors, pressure transmitters and humidity sensors. The study found that the system pressure ratio increased when the outdoor temperature rose from 30 to 60 °C, which in turn increased the energy consumption of the compressor and decreased the cooling effect of the evaporator. The compressor's volumetric and isentropic efficiencies dropped due to rising ambient temperatures. The rise in ambient temperature raised power consumption, which subsequently resulted in a reduction in the Carnot efficiency and the system's coefficient of performance (COP). The highest exergy destruction (ED) occurred in the compressor at higher ambient temperatures, while the minimum ED occurred in the expansion valve. The rising ambient temperature enhances system entropy generation and ED, resulting in reduced exergy efficiency (EE) of the air conditioner.