A comparison of transient heat pump cycle simulations with homogeneous and heterogeneous flow models

This paper compares the eects of two dierent refrigerant flow modeling assumptions on the transient performance of vapor-compression heat pump cycles. This comparison is done on a dynamic system-level model of a flash tank vapor injection cycle that includes finite volume heat exchanger models. The eect of the flow assumptions and specific slip ratio correlations on both the equilibrium operating point and the transient behavior of the cycle are demonstrated through both simulations and experiments. It is shown that equivalent simulations with dierent slip ratio correlations each have dierent equilibrium mass inventories, and that some aspects of the dynamic system behavior, such as the suction superheat or pressure transients, exhibit significant dierences both in simulations and in comparison to experimental data.

[1]  Martin Ryhl Kærn,et al.  Analysis of flow maldistribution in fin-and-tube evaporators for residential air-conditioning systems , 2011 .

[2]  M. Ishii,et al.  Thermo-Fluid Dynamics of Two-Phase Flow , 2007 .

[3]  S. Zivi.  Estimation of Steady-State Steam Void-Fraction by Means of the Principle of Minimum Entropy Production , 1964 .

[4]  Rudiger Franke,et al.  Standardization of Thermo-Fluid Modeling in Modelica.Fluid , 2009 .

[5]  M. Shah.  A general correlation for heat transfer during film condensation inside pipes , 1979 .

[6]  Xiao Li,et al.  Recent advances in dynamic modeling of HVAC equipment. Part 2: Modelica-based modeling , 2014 .

[7]  Linda R. Petzold,et al.  Numerical solution of initial-value problems in differential-algebraic equations , 1996, Classics in applied mathematics.

[8]  J. W. Ramsey,et al.  Thermal Environmental Engineering , 1970 .

[9]  François E. Cellier,et al.  Continuous System Simulation , 2006 .

[10]  Hilding Elmqvist,et al.  Object-Oriented Modeling of Thermo-Fluid Systems , 2003 .

[11]  R. Lockhart.  Proposed Correlation of Data for Isothermal Two-Phase, Two-Component Flow in Pipes , 1949 .

[12]  Nikolay Ivanov Kolev.  Multiphase Flow Dynamics 1 , 2002 .

[13]  M. O. McLinden,et al.  A Next Generation Refrigerant Properties Database , 1996 .

[14]  James E. Braun,et al.  Accurate Charge Inventory Modeling for Unitary Air Conditioners , 2003 .

[15]  S. L. Smith.  Void Fractions in Two-Phase Flow: A Correlation Based upon an Equal Velocity Head Model , 1969 .

[16]  Andrew G. Alleyne,et al.  A dynamic model of a vapor compression cycle with shut-down and start-up operations , 2010 .

[17]  Chi-Chuan Wang,et al.  Heat and momentum transfer for compact louvered fin-and-tube heat exchangers in wet conditions , 2000 .

[18]  Reinhard Radermacher,et al.  Transient modeling of a flash tank vapor injection heat pump system – Part II: Simulation results and experimental validation , 2015 .

[19]  Brian Elmegaard,et al.  Experimental comparison of the dynamic evaortor response using homogeneous and slip flow modeling , 2011 .

[20]  Michel Bernier,et al.  Transient model of a geothermal heat pump in cycling conditions – Part A: The model , 2012 .

[21]  Chi-Chuan Wang,et al.  Heat transfer and friction correlation for compact louvered fin-and-tube heat exchangers , 1999 .

[22]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[23]  Paul I. Barton,et al.  Equation-oriented dynamic simulation current status and future perspectives , 1993 .

[24]  François E. Cellier,et al.  Continuous system modeling , 1991 .

[25]  Xiao Li,et al.  Recent advances in dynamic modeling of HVAC equipment. Part 1: Equipment modeling , 2014 .

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

[27]  Hubertus Tummescheit,et al.  Modeling of Two-Phase Flows in Modelica , 2000 .

[28]  R. Radermacher,et al.  Transient modeling of a flash tank vapor injection heat pump system – Part I: Model development , 2015 .

[29]  Douglas T. Reindl,et al.  A Semi-Empirical Method for Representing Domestic Refrigerator/Freezer Compressor Calorimeter Test Data , 2000 .

[30]  S. Jain,et al.  Transient Characteristics of Split Air-Conditioning Systems Using R-22 and R-410A as Refrigerants , 2009 .

[31]  Sebastián Dormido,et al.  Chattering in dynamic mathematical two-phase flow models , 2012 .

[32]  R. Webb,et al.  Calculation of Fin Efficiency for Wet and Dry Fins , 1996 .

[33]  J. Willems.  The Behavioral Approach to Open and Interconnected Systems , 2007, IEEE Control Systems.

[34]  Denis Clodic,et al.  Dynamic modeling of an integrated air-to-air heat pump using Modelica , 2012 .

[35]  S. M. Ghiaasiaan.  TWO-PHASE FLOW, BOILING AND CONDENSATION IN CONVENTIONAL AND MINIATURE SYSTEMS , 2007 .