Determination of optimum high-side pressure of R744 automotive heat pump using Fibonacci search method

This paper deals with maximizing coefficient of performance (COP) of R744 automotive heat pump. A high-side pressure variation is possible during transcritical operation employing low pressure receiver and electronic expansion valve (EXV). The optimal high-side pressure is then determined using Fibonacci search method. This approach is one of possible methods of online high-side pressure control and it has significant advantages over the offline methods. Employing this innovative method of R744 heat pump optimization a disadvantage of low COP during transcritical operation can be eliminated. Thus further usage of R744 refrigerant in automotive applications will be possible without any negative impact on energy consumption. As a result, this work can help with development of more environmental friendly vehicles.