The Role of Heat Transfer in Refrigeration

Refrigeration plays a key role in today’s society, providing human comfort and food preservation. From ice and large foodpacking plants to oil refineries and chemical manufacturing, industrial processes rely heavily on refrigeration. According to the International Institute of Refrigeration [1], approximately 15% of the world’s electricity consumption goes to refrigerating and air conditioning systems. The importance of refrigeration is also reflected in the ever-growing number of specialized literature and conferences held worldwide. No doubt, there is much room for improvement, especially by reducing the impact of refrigeration on the environment and improving equipment design (thereby improving energy utilization). The systematic application of the science of heat transfer to refrigeration engineering will certainly contribute to achieve these ends. The efficiency of a heat pump cycle is primarily dictated by the temperature levels at which the cycle operates. In the vapor compression cycle, this means that the pressure levels that affect compressor behavior are ultimately determined by the performance of the heat exchangers that establish the interaction between the working fluid and the heat source and heat sink. In the vapor compression refrigeration cycle, poor heat exchanger efficiency will result in greater temperature differences across both the condenser and evaporator, given heat sink (ambient) and source (refrigerated medium) temperatures. Thus, the thermodynamic cycle would operate under increasingly separated temperature levels. Because the heat extraction (evaporator) and heat rejection (condenser) occur with phase change,