Exergetic performance assessment of a variable-speed R404a refrigeration system

Abstract

SUMMARYThe goal of this study is to carry out exergy analyses for an experimental variable-speed refrigeration system working with R404a in order to determine irreversibility rates and exergetic efficiencies of system components and the overall system. For this aim, an experimental refrigeration system was designed with a frequency inverter mounted on compressor electric motor. Controlling the rotational speed of the compressor with a frequency inverter is one of the best methods to vary the capacity of the refrigeration system. The experiments were made for different compressor electric motor frequencies. The results showed that at low-frequency values, irreversibility rates of the system decreased and exergetic efficiencies were increased. In addition, the major irreversibility occurs in the compressor by 61.47-61.83% followed by condenser by 17.00-16.52%, evaporator by 12.39-13.73% and expansion valve by 6.24-6.76% for different compressor frequencies.

Rational efficiency in agro-industrial process with cold chain: Thermodynamic and exergoeconomic measurement

“…These rates exceed by more than 15 % those reported by the manufacturers of the equipment and components; furthermore, they differ from those reported in the literature because the parameters that affected the exergy were, in order, evaporation temperature, condensation temperature, sub-cooling temperature, and compressor pressure [13]. Kizilkan [14] analyzed the exergy in a refrigeration system designed with different freezing rates and R404A refrigerant, and found that the highest inefficiency rates were in the compressor, condenser, evaporator, and expansion valve.…”

“…Based on Table 4 and equations (11)(12), we calculated the amount of resources, products, residues, irreversibilities, exergetic efficiencies, operating exergetic costs, and operating exergoeconomic costs for each equipment and current (flow) of the refrigeration system determined in the production structure. In addition, we obtained the exergetic efficiency of each equipment and current by applying the balance equations (13)(14)(15)(16)(17)(18)(19) and the 2 nd law.…”

A review on recent developments in new refrigerant mixtures for vapour compression-based refrigeration, air-conditioning and heat pump units

“…They also suggested that the COP and exergy efficiency of the system can be improved by sub-cooling the condensed liquid refrigerant. Kizilkan et al [44] studied the exergitic performance of a variable-speed R404A refrigeration system. It has been reported that the major irreversibility occurs in the compressor (62%) followed by condenser by (17%), evaporator (13%) and expansion valve (6%) for different compressor frequencies.…”

Investigation on Liquid Density Data at the Bubble Point and Equations for the Refrigerant HFC-404A over a Wide Temperature Range

“…Therefore, research on the thermophysical properties of HFC-404A was further developed for the energy saving and the global environment protection to some extent. Some research on HFC-404A was done. − But it is hard to obtain available liquid density data for refrigerant HFC-404A in the existing literatures. To date, some literature − gave the some relative results about the density of HFC-404A, for example, Lemmon gave the Pseudo Pure-Fluid Equations of State for calculating the liquid densities of R404A; Kleemiss mainly gave the liquid densities of HFC-404A in the subcooled area; Fujiwara et al gave the density data of HFC-404A from the superheat state to the subcooled area, and the density data referred to the whole density data of HFC-404A (they did not be specified for the saturated liquid densities of HFC-404A at the bubble point); Bouchot measured the lots of density data of HFC-404A, including the density data in the superheat area, the density data in the subcooled area, the saturated liquid density data of HFC-404A at the bubble point and the saturated vapor density data of HFC-404A at the dew point in two phase area.…”