At the end of this module, you will be able to:
In this module, you will learn the general principles underlying a vapor compression refrigeration system. These systems are widely used in cooling applications such as in automobiles, buildings, cold storages for fresh and frozen foods, and food display counters in retail shops. In the following video, you will learn the underlying mechanism of heat transfer in a vapor compression refrigeration system using a refrigerant. We will consider some key refrigerants and their characteristics. The physical and chemical properties of a refrigerant determine its suitability for application in a vapor compression refrigeration system. In the next video, you will learn the important characteristics of refrigerants that should be considered for their selection.
Next, we will examine a vapor compression refrigeration system and its four components, namely, evaporator, compressor, condenser, and an expansion valve. As the refrigerant flows through each of these components cyclically, its state changes to a vapor as it absorbs heat from the surrounding atmosphere of an evaporator, to later discharge it in the atmosphere surrounding a condenser, where its state changes back to a liquid. In the next video, you will view the components of the refrigeration system, including their role in transferring heat from one location to another.
Now that we have gained a qualitative understanding of the vapor compression refrigeration system, let us look at a Pressure-Enthalpy diagram of a refrigerant. This diagram is useful in determining the enthalpy or heat content of the refrigerant as it flows through the various components of the refrigeration system. In the next video, we will examine how a Pressure-Enthalpy diagram is constructed.
In this module, you learned the key purpose of a vapor compression refrigeration system, namely, to transfer heat from one location to another. The transfer of heat is accomplished using a chemical substance called a refrigerant whose state changes as it flows through the refrigeration cycle. The physical and chemical characteristics of a refrigerant must be carefully evaluated for its suitability. You also learned that there are only four components in a typical vapor compression refrigeration system. In the following modules on this topic, we will use Pressure-Enthalpy diagrams of different refrigerants to design refrigeration systems.