Search

The demand for environmentally friendly refrigerants arises to anticipate two global environmental issues: global warming and climate change. The use of environmentally friendly refrigerants is one of the efforts to address these issues. This study aims to investigate the possibility of the use of dimethyl ether (DME) for substituting R134a that has been widely used worldwide. The simulation reveals that both subcool and superheat affect the performance of both refrigerants. The cooling capacity of R134a system increases with the increase of subcool and superheat. Meanwhile, even though the cooling capacity of DME increases with the increase of subcool, it decreases with the increase of superheat. For subcool 0C, DME has a coefficient of performance (COP) 4.8% higher than that of R134a although the cooling capacity is 4.5% lower. When the subcool is set at 8C, the cooling capacity of DME is 6.5% lower than R134a but the COP is 2.6% higher. Another important finding in this study is that the best performance of DME over R134a is obtained at low subcool and low superheat.

Energy demand for the air conditioning sector is increasing due to increasing population, increasing living standards, and global warming. This increase in demand must be accompanied by efforts to increase energy efficiency. Evaporative cooling is one effort that can be chosen to increase the energy efficiency of the air conditioning system. The use of evaporative cooling by utilizing condensate water from the evaporator has been experimentally investigated. This research was conducted directly on an air conditioner unit that had already been installed in a room. Specifically, experiments were carried out by flowing and dripping condensate water into the compressor body of an air conditioner and examining its effect on the performance of the air conditioner. The research results show that the use of condensate water can reduce suction temperature, discharge temperature and condensation temperature by 0.7°C, 3.2°C, and 1.2°C, respectively. As a result, cooling capacity increases by 2.8%, energy consumption decreases by 3.5%, and energy efficiency ratio increases by 7.6%. Overall, the use of condensate water for compressor cooling can improve air conditioner performance. [ABSTRACT FROM AUTHOR]

Cooling Seasonal Performance Factor (CSPF) is one of methods for measuring the performance of a room air conditioner to assess its energy efficiency and, therefore, its effect on climate change and environmental impact. A set of bin temperatures from a certain region was used in this method to compare the performance of an air conditioner. Due to the variety of hourly local ambient temperature distribution, the performance of an air conditioner could be different in various cities in Indonesia. In this paper, a room air conditioner was tested on the basis of ISO 5151 and analyzed by using ISO 16358-1. The CSPF calculation is then modified based on the ambient local temperature distribution for Jakarta and Bandung. The CSPF for Jakarta City is 1.45% lower and the CSPF for Bandung is 1.49% higher than that of ISO 16358-1-based calculation. It means that for more realistic performance of an air conditioner, the modification of measurement standard could be applied based of local temperature distribution.

Refrigeration system evacuation is one of the most important steps in achieving refrigeration or air conditioning system quality. This procedure is used to remove water vapor and non-condensable gas from the pipeline and the heat exchangers that can be dangerous for a vapor compression refrigeration system. In this paper, the performance of an air conditioner (AC) was experimentally tested under varied duration of system evacuation from 0 to 60 minutes with an increment of 15 minutes. Cooling capacity, power consumption, and coefficient of performance were tested in accordance with ISO 5151 and ISO 16358-1. Generally, the ISO 16358-1 gives the lower power consumption and higher cooling capacity and coefficient of performance. ISO 16358-1 test results in 12.8% lower power consumption than that of ISO 5151. On the contrary, ISO 16358-1 test gives higher cooling capacity and coefficient of performance by 11.5% and 6.2%, respectively. It is also observed from this study that the longest evacuation period results in the most efficient operation, thus providing less effect on climate change and less environmental impact. However, it should be observed in a longer period of operation.

This paper presents a numerical approach on exergy loss in an air conditioner (A/C) using ejector asexpansion device with R290 (propane) as working fluid. R290 is a natural refrigerant and environmental friendly, recommended by many researchers as a substitute for R22. In the numerical approach, exergy analysis was carried out on an A/C with cooling capacity of 2.4 kW, and the room and the ambient temperatures were varied from 18 °C to 26 °C and 30 °C to 34 °C respectively. The results show that the total exergy loss in an air conditioner using ejector as an expansion device is lower than that of using conventional as an expansion device. In addition, exergy analysis shows that thegradients of increment of total exergy loss due to increase in the ambient temperature are constant, that is 0.003 for the five different room temperatures, namely 18 °C, 20 °C, 22 °C, 24 °C and 26 °C.

The experimental investigation of subcooling effects on system COP was carried out on a residential air conditioning using R410A as working fluid, with a compressor capacity of about 0.75 kW. In the experiment, the indoor and outdoor temperatures were controlled at 24°C and 32°C. The results showed that the use of condensate water lowers the refrigerant temperature in the condenser outlet by 2.7°C. By lowering the refrigerant temperature, the cooling capacity of the air conditioning can be enhanced. The decrease in of refrigerant temperature results in COP improvement 16.4%. Besides increasing the COP, the condensate water also decreases the discharge compressor temperature by 7.6°C. The decrease in of the discharge compressor temperature resulted in the decrease in power consumption of the air conditioning system by 5.9%.