Performance simulation of refrigerated display cabinets operating with refrigerants R22 and R404A

This paper describes the analysis and performance comparison of a display cabinet system using refrigerant R404A and its substitute refrigerant R22. The model of the display cabinet is developed at steady state and integrated from three main component sub-models, air-cooling finned-tube evaporator, air curtain and display cabinet body. The evaporator model is built up based on the distributed method, which can simulate the heat exchangers with different circuit structures. The frost effect on the performance of the evaporator is included in the model. The correlations for the heat transfer and pressure drop calculations of both air and refrigerant sides are purposely selected in the evaporator model. In addition, the evaporator model has been validated with experimental results at steady states from published literature. Several correlated functions from the detailed numerical solution are used for the model of the air curtain. Some simplifications are also utilized for the model of display cabinet body. The performance simulation and comparison of the display cabinet using refrigerants R404A and R22 are carried out at different indoor ambient conditions especially at varied ambient air humidity to mimic the actual indoor space conditions in super stores. Some significant results such as the comparison of cooling load requirement for different refrigerant display cases have been obtained from the simulation, which can significantly contribute to the optimal cabinet design and operating analysis.

[1]  John R. Thome,et al.  Prediction of Two-Phase Pressure Gradients of Refrigerants in Horizontal Tubes , 2002 .

[2]  T. W. Davies,et al.  A low carbon, low TEWI refrigeration system design , 2004 .

[3]  H. Müller-Steinhagen,et al.  A simple friction pressure drop correlation for two-phase flow in pipes , 1986 .

[4]  Savvas A. Tassou,et al.  Mathematical modelling of supermarket refrigeration systems for design, energy prediction and control , 2000 .

[5]  J. Thome,et al.  Flow Boiling in Horizontal Tubes: Part 3—Development of a New Heat Transfer Model Based on Flow Pattern , 1998 .

[6]  Savvas A. Tassou,et al.  Simulation of the performance of single jet air curtains for vertical refrigerated display cabinets , 2001 .

[7]  Carolus Theodorus Sanders,et al.  The influence of frost formation and defrosting on the performance of air coolers , 1974 .

[8]  Omer Comakli,et al.  Determination of optimum working conditions R22 and R404A refrigerant mixtures in heat-pumps using Taguchi method , 2009 .

[9]  Clark W. Bullard,et al.  Development of a design tool for display case evaporators , 2006 .

[10]  Alvin C.K. Lai,et al.  Dynamic behavior of a direct expansion evaporator under frosting condition. Part I. Distributed model , 2006 .

[11]  Ramin Faramarzi.  Efficient Display Case Refrigeration , 1999 .

[12]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[13]  S. Rouhani,et al.  CALCULATION OF VOID VOLUME FRACTION IN THE SUBCOOLED AND QUALITY BOILING REGIONS , 1970 .

[14]  Chi-Chuan Wang,et al.  Technical Note A heat transfer and friction correlation for wavy fin-and-tube heat exchangers , 1999 .

[15]  J. Thome,et al.  Flow Boiling in Horizontal Tubes. Part 1; Development of a Diabatic Two–Phase Flow Pattern Map , 1998 .

[16]  Chi-Chuan Wang,et al.  A comparative study of compact enhanced fin-and-tube heat exchangers , 2001 .

[17]  Piotr A. Domanski,et al.  Properties and Cycle Performance of Refrigerant Blends Operating Near and Above the Refrigerant Critical Point, Task 2: Air Conditioner System Study , 2002 .

[18]  J. Thome,et al.  Flow Boiling in Horizontal Tubes: Part 2—New Heat Transfer Data for Five Refrigerants , 1998 .

[19]  S. Klein,et al.  NIST Standard Reference Database 23: NIST Thermodynamic and Transport Properties of Refrigerants and Refrigerant Mixtures-REFPROP, Version 6.0 | NIST , 1998 .