Category: Air Conditioning and Refrigeration

Psychrometry is the study of air–water vapour mixtures. It is also sometimes referred to as hygrometry. Many mechanical engineering devices exploit psychrometric processes, such as air conditioning systems and cooling towers. Two important principles upon which psychrometric relationships are based are the perfect gas equation and Dalton’s law regarding the mixture. The perfect gas equation, PV = RT,…

A refrigerator maintains the temperature slightly higher than the freezing point of the water. There is a freezer which maintains the temperature below the freezing point of water. As far as the classification of refrigerators is concerned, it can be widely classified into four classes. They are top-mount freezer refrigerator, side-by-side refrigerators, freezer on bottom,…

roadly, the refrigeration systems can be categorized as 8.4.1  Air-refrigeration System Reversed Carnot cycle Reversed Carnot cycle is shown in Figure 8.2. It consists of the following processes. Figure 8.2 P−V and T−S Diagrams for Reversed Carnot Cycle Process a–b: Absorption of heat by the working fluid from refrigerator at constant low temperature TL during isothermal expansion. Process b–c: Isentropic compression of the working fluid with…

The five basic components of a refrigeration system are as follows: 8.3.1  Evaporator The purpose of the evaporator is to remove unwanted heat from the product via the liquid refrigerant. The liquid refrigerant contained within the evaporator is boiling at a low pressure. The level of this pressure is determined by two factors: 8.3.2  Compressor The purpose…

Clausius statement of the Second Law of Thermodynamics: It is impossible to construct a device that, operating in a cycle, has no effect other than the transfer of heat from a cooler to a hotter body. Thus, the Clausius statement tells us that heat will not flow from cold to hot regions without assistance of outside…

Initially, the main purpose of refrigeration was to conserve foods. The Chinese were the first to find out that ice increased the life and improved the taste of drinks and for centuries Eskimos have conserved food by freezing it. At the beginning of the 19th century, it had been observed that the growth of microorganisms…