Narrow Results

Electrical energy consumption in air conditioning systems reaches 60% to 70% of the total electric energy consumption in buildings. Therefore, saving electrical energy consumption in air conditioning systems would have a significant impact on the national electrical energy consumption. Currently, the air conditioning sectors were having a dilemma on finding the alternative substitutes for CFC and HCFC refrigerants which are proven to cause destruction of the ozone layer and contribute to the effects of global warming. This paper will discuss the problems faced by an Article 5 country similar to Indonesia in phasing-out HCFC especially in air conditioning and refrigeration sectors. This paper will also discuss the possibility to use hydrocarbon-based refrigerants, which have zero ozone depletion potential (ODP) and low global warming potential (GWP), in air conditioning sectors. Some results of field applications of this refrigerant will be reported, and in general it can be concluded that the air conditioning retrofitted with hydrocarbon refrigerant consumes 10%–20% less electrical energy. Mixture of R-290 and R-134a was also investigated. R-134a is used to reduce the flammability of R-290 and to make the saturation pressure close to R-22. The results show that at composition of 0.6 R-290/0.4 R-134a mole fractions, the mixture behave as an azeotrope refrigerant mixture and can be used for R-22 replacement. At this composition, lower flammability limit (LEL) is 3693%, which is higher than pure R-290. Hence, the refrigerant mixture can be classified as less flammable A2 class refrigerant. The performance test shows that the refrigerant mixture can be used as a drop-in refrigerant in the R-22 machine. The measurement of refrigeration capacity and compressor input work at the same chilled water temperature shows that the calculated COP of the refrigerant mixture is better than R-22's but lower than R-290's.

The existing artificial and chemical refrigerants have been phased out due to environmental concerns, and they have been replaced with environmentally friendly refrigerants. Among them, carbon dioxide, ammonia, and hydrocarbons are paid attention as next generation refrigerants, and their application has been widely expanded. Therefore, in this paper, the latest studies of flow boiling and condensation heat transfer characteristics of carbon dioxide, ammonia, and hydrocarbon are reviewed. The heat transfer characteristics of ammonia and hydrocarbon show the relatively similar trends with the conventional refrigerants compared to those of carbon dioxide. The general trends and recommendable models of flow boiling and condensation heat transfer with carbon dioxide, ammonia, and hydrocarbons are summarized.

In this paper, the window air conditioner performance with commercial LPG as a replacement of HFC134a is assessed with modified capillary lengths for charge optimization. Global Warming Potential (GWP) of commercial LPG is only three, which is neglected compared to HFC134a (1300). Flammability issues will also be reduced in charge optimization and adopting safety standards. Initially, baseline tests are conducted with HFC134a and commercial LPG in the existing system, and optimum refrigerant charge is determined. The simulation study is conducted with modified capillary lengths for charge reduction of commercial LPG. Experimental assessment is conducted for the charge optimization as per IS 1349 (Part 1) for low ambient test conditions (Domestic Test-DT and Export Test A-ETA) and high ambient test conditions (Export Test B-ETB). With the optimized capillary length and optimum charge quantity, 0.4–2.03% higher cooling capacity, 0.62–8.9% lesser power consumption, and 10.49–16.4% higher COP are achieved with commercial LPG than that of HFC134a baseline at low and high ambient test conditions, respectively.