Refrigeration Systems

This chapter covers refrigeration systems, which enable the maintenance of cool temperatures in spaces by transferring heat from the cooled space to warmer surroundings. After a brief introduction in Sect. 7.1, Reversed Carnot Cycle is covered in detail in Sect. 7.2, including coefficient of performance (COP) measures for both cooling and heating purposes. Section 7.3 covers absorption refrigeration systems including calculations for maximum coefficient of performance and actual coefficient of performance. Vapor Compression Refrigeration Cycle, the most widely used refrigeration cycle in practice, is covered in Sect. 7.4 including the use of P–h diagrams for determining enthalpies at different state points in the cycle. Section 7.4 also illustrates various types of calculations related to the vapor compression cycle. Terms such as Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER) are also explained in Sect. 7.4. Refrigeration and freezing of foods is covered in Sect. 7.5 including calculations of sensible and latent cooling required. Section 7.5 also discusses and presents the thermal properties of selected food items. Section 7.6 covers refrigerants in detail. Included in this section are definitions of terms related to refrigerants including types of refrigerants (CFCs, HFCs, etc.) and important refrigerant characteristics such as Ozone Depletion Potential (ODP) and Global Warming Potential (GWP). Refrigerant safety designations (as per ASHRAE Standard – 34) are also explained in Sect. 7.6.