Improving Energy Efficiency in Supermarkets by Retrofitting Low-E Glass Doors for Open Refrigeration Systems with Digital Semi Hermetic Compressor

Abstract

This research will be presenting energy efficiency improvement options by retrofitting doors for open refrigeration systems in Central Thailand supermarkets that open during the daytime (06:00 am – 06:00 pm), and are closed during the night-time (00:00 am – 6:00 am). The materials and methods used consisted of 15 open refrigeration cabinets with 82 retrofitted doors supported by 41 frames, with the temperature set at medium. The power consumption was indicated in kW, kWh through a power meter data logger for analysis and summarization. The investment required was €21,694 /store, while the payback period of this research was determined to be at 14 months. The cost of energy savings was found to be within a period of 1.1 years, at the rate of 192,220 kWh/year or €18,503 annually. The retrofitted doors is expected to reduce the cooling load and over-burdening of the compressor. The research found that the most viable solution was to use a digital semi-hermetic compressor that can operate in unload and full load status, that was being controlled by the evaporator temperature (TEV) which was set at -10 degree, the condenser temperature (TCD) set at 38 degrees, and the superheat temperature (TSH) at 10 degrees. In the unload status, the power consumption of the digital semi hermetic compressor will decrease by 50%, which has a significant impact for energy savings and is important for night-time when low cooling load is required whereby the compressor’s multiple start–stop cycles are not required. The investment for a digital semi-hermetic compressor was determined to be €7,800/store, and is able to yield energy savings of up to 26,890 kWh/year, or €2,589 annually, with a payback period of 2.9 years.

Residual energy use and energy efficiency improvement of European supermarket facilities during the post-COVID and energy crisis period

“… The use of refrigerated cabinets that are closed with glass doors results in significant energy savings. According to sources [ 38 , 61 ], in Mediterranean climate areas and high temperatures, the energy consumption of the refrigeration system compressors can decrease by 25–50 % in the unloaded state. Additionally, this measure can help keep the temperature of the supermarket more stable in winter by avoiding cold areas with open furniture, which can increase the energy consumption of the air conditioning system.…”

Low GWP Refrigerant R1234yf, R1234ze(z), R13I1 as an Alternative to New Zeotropic Refrigerant

“…R13I1 is a halocarbon agent used in fire extinguishing agents same as R227ea [9]. R13I1 has a GWP of 1, a boiling point of -21.9°C, a critical temperature of 123.3°C and a critical pressure of 3950kPa [10]. It can be seen that it is a refrigerant with properties similar to R134a.…”

Energy Efficiency Improvement Solutions for Supermarkets by Low-E Glass Door and Digital Semi-Hermetic Compressor

“…As for the air conditioner, it can be adjusted according to room temperature. For air conditioners, the cycle can be adjusted according to room temperature by calculating from room temperature and suction pressure, as well as other parameters [53,54]. For refrigeration systems, the cycle can also be adjusted according to room temperature by calculating from room temperature and suction pressure or other parameters [55,56].…”