**10. Conclusion**

This study provides access for the selection of working fluid (refrigerant), which would be appropriate for a domestic refrigerator and air-conditioning system. The effect of the working fluid contributes to the exchange rate of heat transfer in the cooling system. It also enables the computation of the system's performance characteristics (PC), which primarily predicting the system's workability and the evaporator temperature, that is, the minimum temperature required for the refrigeration system to be satisfied as efficient. The system analysis will serve as a standard measure for the procurement of any refrigeration system. Furthermore, the performance of a refrigeration system depends on the working fluid that runs through it. Therefore, based on the comparative performance of R600a and R134a refrigerants in the vapor compression refrigeration system, the working fluid dramatically impacts the overall efficiency and refrigeration effect of the cooling system, with R600a a preferable refrigerant. The use of isobutane secures the surroundings from global warming and ozone depletion and improves energy conservation.

### **11. Recommendation**

The recommendations are based on the system prototype, a specific refrigeration system suitable for Nigeria, and other areas in the perspective of the global economy.

Prototype of the refrigeration system with relevant costing based on the economy of Nigeria. The refrigeration system made from locally sourced materials was used (see **Table 3**).

Isobutane was used as a replacement for a conventional refrigerant because of its thermodynamic properties. The refrigerant has a negligible global warming potential, zero ozone depletion potential, miscible with oil, and high critical temperature, which enhance the refrigeration system's performance [72]. The price of the hydrocarbon refrigerant (isobutane) and the refrigerator's component was suitable to employ within Nigeria. The vapor compression refrigeration system is recommended for household usage because it works using non-toxic refrigerant, as in the vapor absorption system. Likewise, thermoelectric refrigeration is less


**Table 3.**

*Materials used for the construction of the refrigerator with cost in Nigeria.*

efficient compared to VCRs [73, 74]. Since most developing nations have adapted isobutane, the recommendation is made for the under-developed countries to use hydrocarbon refrigerant in their refrigeration system as it has been proved ecofriendly. The use of HCs refrigerant would reduce the overall price of the refrigerator and maintenance cost in terms of power consumption because isobutane refrigerant saves energy compared to the conventional refrigerant, but this is subject to the climate conditions of various countries [75].

The overviewed recommendation for other regions in the world from the global economy perspective was that there are approximately five different climates: temperate, dry, tropical, polar, and continental. The regions with a high degree of temperature can use conventional refrigerants if they could not meet the conditions for maintaining hydrocarbon refrigerant [21]. However, countries with cool and cloudy climates could subscribe to hydrocarbon refrigerants because their temperatures are under control. Furthermore, the cost evaluation for the prototype was 15% lower than the recent cost price of a domestic refrigerator of the same volume capacity and power rating (see **Table 3**).
