**6. Environmental effect and economic impact of hydrocarbon refrigerants**

Hydrocarbon refrigerants (HCs) such as carbon dioxide, water, ammonia, butane, propane, isobutene, and propylene are commonly used in residential and commercial buildings to attain a cooling effect. However, the HCs refrigerants have found their heating, ventilation, and air conditioning system applications due to their advantages over conventional refrigerants in terms of global warming, ozone depletion, and energy reduction in energy consumption. HC refrigerants do not have any halogen elements in their compound formulation, which enable a safe environment and prevent climate change [59]. Most developed nations have used HCs refrigerant in their refrigeration systems, such as domestic refrigerators, cars, heat pumps, and industrial air cooling systems, etcetera.

The economic implication of hydrocarbon refrigerants is obvious, the price of the compressor that uses HCs is less compared to a compressor that uses HFC, and the mass charge of HC refrigerant is lower compared to HFC refrigerant, which is ratio 1:2 respectively [65]. The reduction in mass charge of isobutane (HC600a) was due its higher value of latent heat or high volumetric capacity [25]. Also, HC refrigerant, when in use, saves more energy compare to HFC refrigerant (see **Figure 6**), and that leads to cost reduction. Moreover, the cooling capacity of a

**Figure 6.** *Correlation between power input for R600a and R134a with time.*


**Table 2.**

*Economic analysis of emissions for compressor HC600a and HCF134a [66].*

refrigeration system can be enhanced using the cryogenic refrigeration approach. According to [66], the economic analysis of emissions for compressor that uses HC600a and HFC134a refrigerants for 15 years lifecycle evaluation (LCE) was taken, despite of wear coefficients of the lubricant and lower friction rate the energy reduction rate was 6.54% lower when using HCF134a. The evaluation of environmental cost was based on key environmental indicators, GWP (Carbon dioxide/CO2), SO2, NO2 and PM10. See **Table 2** for details.
