Characteristics of a series-connected two-evaporator refrigerating system

Abstract Based on the Buckingham Pi theorem, this study derives the dimensionless correlations to characterize a series-connected two-evaporator refrigerating system with propane (R-290) as the refrigerant. Experimental data are substituted into the correlations to demonstrate the most relevant factors. Simplified correlations are then obtained. The analytical results show that the mass flow rate of refrigerant ( m ˙ r ) is primarily affected by the condensing pressure, length of the high-temperature capillary tube, and the subcooling of refrigerant, while the heat transfer coefficients of refrigerant in the evaporators (hcH and hcL) are affected by the condensing pressure and the logarithmic-mean temperature difference of the specific evaporator. However, hcH and hcL are also affected by the lengths of the low- and high-temperature capillary tube, respectively. Additionally, the ratio of the cooling capacity of the high-temperature evaporator to the total capacity (α) is primarily affected by the condensing pressure and the logarithmic-mean temperature difference of both evaporators. The differences between the calculated and experimental data are between −4% and +5%, −16% and +16%, −12% and +16%, and −10% and +10% for m ˙ r , hcH, hcL, and α, respectively.

[1]  S. Wongwises,et al.  Two-phase separated flow model of refrigerants flowing through capillary tubes , 2000 .

[2]  Michael B. Pate,et al.  A Generalized Performance Prediction Method for Adiabatic Capillary Tubes , 1998 .

[3]  J. Taborek,et al.  Flow Boiling Heat Transfer in Vertical Tubes Correlated by an Asymptotic Model , 1992 .

[4]  C. Pérez-Segarra,et al.  Numerical simulation of capillary tube expansion devices behaviour with pure and mixed refrigerants considering metastable region. Part I: mathematical formulation and numerical model , 2002 .

[5]  S. Kandlikar.  A General Correlation for Saturated Two-Phase Flow Boiling Heat Transfer Inside Horizontal and Vertical Tubes , 1990 .

[6]  J. M. Gonçalves,et al.  An experimental analysis of adiabatic capillary tubes , 1999 .

[7]  J. Wattelet.  EVAPORATIVE CHARACTERISTICS OF R-12, R-134a AND A MIXTURE AT LOW MASS FLUXES , 1994 .

[8]  K. Gungor,et al.  A general correlation for flow boiling in tubes and annuli , 1986 .

[9]  Pradeep Bansal,et al.  An homogeneous model for adiabatic capillary tubes , 1998 .

[10]  Zhi-Hang Chen,et al.  Metastable flow of R12 through capillary tubes , 1990 .

[11]  N. Zuber,et al.  Dynamics of vapor bubbles and boiling heat transfer , 1955 .

[12]  Mo Se Kim,et al.  Experimental investigation of the performance of R22, R407C and R410A in several capillary tubes for air-conditioners , 2002 .

[13]  H. Wijaya.  Adiabatic Capillary Tube Test Data for HFC-134a , 1992 .

[14]  C. Su,et al.  Experimental study of a series-connected two-evaporator refrigerating system with propane (R-290) as the refrigerant , 2003 .

[15]  Carlos D. Perez-Segarra,et al.  Numerical simulation of capillary-tube expansion devices behaviour with pure and mixed refrigerants considering metastable region. Part II: experimental validation and parametric studies , 2002 .