Refrigerant R134a (tetrafluoroethane) is widely used in automotive air conditioners and has a good performance. However, since refrigerant R134a still has a high global warming potential (GWP), this refrigerant must be replaced with environmentally friendly refrigerants such as R600a (isobutane), which is a natural fluid, no effect on the climate, inexpensive and readily available. In this study, thermodynamic analysis of a bus air conditioner working with refrigerant R600a was performed. Adana province of Turkey was chosen as the study region. Firstly, a bus used for inter-city passenger transportation with a passenger capacity of 56 persons was selected. Cooling Load Hourly Analysis Program (HAP) was used to determine the hourly cooling load capacity of the selected inter-city bus model. Useful and reversible works of compressor, coefficient of performance (COP), exergy efficiency and exergy destructions of the bus air conditioning system were obtained and evaluated in detail.

The purpose of this study is to perform thermodynamic analysis of an intercity bus airconditioning (ICBAC) system working with hydrochlorofluorocarbon (HCFC), hydrofluorocarbon (HFC), chlorofluorocarbon (CFC) and hydrocarbon (HC) refrigerants. For this aim, an intercity bus with a busload of 56 passengers, which is thought to motion in the Adana province of Turkey, was selected. R404A, R410A, R502, R507, R22, R290, R134a, R500 and R600a were selected as different HCFC/HFC/CFC/HC refrigerant types in the ICBAC system. Useful and reversible works of compressor, coefficient of performance (COP), exergy efficiency and exergy destructions of the entire ICBAC system and its each sub-unit were obtained. The results showed that the performance of the ICBAC system was significantly influenced by changing the refrigerants. However, R600a refrigerant based on hydrocarbon was found as a refrigerant to have minimum total exergy destruction, maximum exergy efficiency and maximum COP compared to other refrigerants used in the ICBAC system with the same amount of cooling load and the same climatic condition.