Category: Introduction to Refrigeration

The choice of a refrigerant depends upon the following factors:

With the increasing awareness of environmental degradation, the production, use and disposal of Chloro Fluoro Carbons (CFCs) and Hydro Chloro Fluoro Carbons (HCFCs) as refrigerants in mechanical refrigeration systems has become a subject of great concern. However, such systems are being developed using more eco-friendly refrigerants, such as Eco-friendly refrigerants are also known as natural…

The refrigerants and their applications are given in Table 18.1. The primary-refrigerants are further classified into the following four groups Table 18.1 Refrigerants and their applications Table 18.2 Commonly used halo carbon refrigerants Table 18.3 Azeotrope refrigerantss Table 18.4 Inorganic refrigerants Table 18.5 Hydrocarbon refrigerants Table 18.6 Ozone Depletion Potential (ODP) of Refrigerants

A good refrigerant should have the following properties:

A refrigerant may be defined as a substance which absorbs heat through expansion or vaporization and loses it through condensation in a refrigeration system.

The Bell-Coleman air refrigeration cycle was developed by Bell-Coleman and Light Foot by reversing the Joule’s or Brayton’s air cycle. The schematic diagram of such a cycle is shown in Fig. 18.8. It consists of a compressor, a cooler, an expander, and a refrigerator. The p-v and T-s diagrams are shown in Fig. 18.9. Figure 18.8 Schematic diagram of Bell-Coleman air refrigeration…

A reversed Carnot cycle, using air as working medium is shown in Fig. 18.5 on p-v and T-s diagrams. The reversed Carnot cycle is represented by four processes as described below: Heat absorbed by air (or heat extracted from cold body) per kg of air. q4−1 = are 4-1-2′-3′ =T4 (s1 − s4)=T4 (s2 − s3)=T1 (s2 − s3) Work done during the cycle per kg of air, wcycle = q2−3 − q4−1 = are 1-2-3-4 = T2 (s2 − s3)…

There are two types of air refrigeration cycles. 1 Open Air Refrigeration Cycle In an open air refrigeration cycle, the air is directly (at atmospheric pressure) led to the space to be cooled (i.e. refrigerator). The air is then allowed to circulate through the cooler and returned to the compressor to start another cycle. This…