**Abstract**

The effect of heat transfer medium (HTM) on the environment is associated with ozone layer depletion and global warming. The role of HTM (working fluid) in the heating and air conditioning industries is paramount, which cannot be underestimated. The conventional refrigerant has been predominantly used over decades due to their thermodynamic properties. However, hydrocarbon refrigerants such as isobutane are considered substitutes because they have negligible global warming potential and zero ozone depletion. That makes it eco-friendly among other existing refrigerants. The investigation of the refrigeration system's performance characteristics required consideration for the coefficient of performance, refrigerating effect, and the compressor work; this enables the determination of the system's efficiency without any assumption. Another factor that suggests a better absorption of refrigerant (working fluid) into a refrigeration system is an increase in the coefficient of performance (COP). The effect will cause a reduction in the rate of energy consumption by the compressor. The result shows that the system's coefficient of performance when using R600a was 27.1% higher than when working with R134a, with an energy reduction of 23.3%.

**Keywords:** coefficient of performance, refrigerating effect, global warming potential, working fluid, ozone depletion potential

### **1. Introduction**

At the beginning of the eighteenth century, natural ice was exploited for domestic and commercial purposes, such as food preservation. Also, in the 1800s, there was a discovery of volatile liquids that could condense by applying compression and cooling [1]. The combination of these two inventions results in the fabrication of the household refrigeration system, which has worldwide applications. Since the nineteen centuries that vapor compression system (VCS) has been invented, its practical implementation has cut across various fields, including preservation of food and vaccine, heat ventilation and air-conditioning for human comfort, and storage of farm produce, and industrial processing. Preservation became essential to expand the product's shelf life, which enables the quality in terms of physical properties that include color, texture, and flavor. More so, the refrigeration process, among other food storage methods, has been proved to be

most effective, dependable, desirable, and applicable worldwide [2–5]. Over two decades ago, thermal systems have found increased application in the tropical region, and they consumed a massive amount of electrical energy. Furthermore, contrary to the excessive energy consumption rate exhibited by the refrigeration system (RS), the refrigerant plays a vital role in the overall performance of a vapor compression system [6].

The heat gained by the refrigerant in VCS flows in the direction of decreasing temperature, from the high-temperature region to the low-temperature region. Also, there are assumptions required for an ideal vapor compression system to occur. These include:


More so, there are four processes involved in establishing low temperature in a refrigeration system was explained and represented by a pressure-enthalpy (p-h) diagram, as shown in **Figure 1**.
