Development of a dynamic model for a DX VAV air conditioning system

Abstract A direct expansion (DX) variable air volume (VAV) air conditioning (A/C) system consists of a VAV air distribution subsystem and a DX refrigeration plant. This paper reports on the development of a representative and complete dynamic mathematical model for the DX VAV A/C system having a variable speed compressor and pressure independent VAV terminals. The model is component based and takes into account the dynamic behaviors of both the DX refrigeration plant and the VAV air distribution subsystem simultaneously. The dynamic model has been developed based on the principles of mass and energy conservation and using correlations describing the operational performance of some of the system’s components, which are either field tested or available from manufacturers. An experimental rig has been set up for the DX VAV A/C system, and experimental work has been conducted to obtain the system’s responses to the step change of compressor speed. The dynamic model developed was then validated using the experimental data obtained. Steady state and transient responses for five major operating parameters obtained from both the model and the experiment were compared and found to be in good agreement.

[1]  D. Didion,et al.  A simulation model of the transient performance of a heat pump , 1982 .

[2]  J. Vargas,et al.  Simulation in transient regime of a heat pump with closed-loop and on-off control , 1995 .

[3]  Comparison of three steady-state heat pump computer models , 1990 .

[4]  Deng Shiming.  A dynamic mathematical model of a direct expansion (DX) water-cooled air-conditioning plant , 2000 .

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

[6]  J. MacArthur.  Transient heat pump behaviour: a theoretical investigation , 1984 .

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

[8]  Piotr A. Domanski,et al.  A Simplified Cycle Simulation Model for the Performance Rating of Refrigerants and Refrigerant Mixtures , 1992 .

[9]  P. G. Jolly,et al.  Simulation and measurement on the full-load performance of a refrigeration system in a shipping container , 2000 .

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

[11]  Piotr A. Domanski,et al.  Simulation of an Evaporator with Nonuniform One-Dimensional Air Distribution | NIST , 1991 .

[12]  Chris Underwood.  Robust control of HVAC plant I: modelling , 2000 .

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

[14]  Shane Clements,et al.  Heat pump assisted continuous drying part 1: Simulation model , 1990 .

[15]  H. N. Lam,et al.  Dynamic Performance of an Electronic Zone Air Temperature Control Loop in a Typical Variable-Air-Volume Air Conditioning System , 1999 .

[16]  S. G. Talbert,et al.  Status of corrosion research for condensing heat exchangers , 1985 .

[17]  A. C Cleland,et al.  Computer subroutines for rapid evaluation of refrigerant thermodynamic properties , 1986 .

[18]  J. A. Fox,et al.  An introduction to engineering fluid mechanics , 1974 .

[19]  R. C. Legg,et al.  Characteristics of single and multi-blade dampers for ducted air systems , 1986 .

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

[21]  S. Borg,et al.  CYRANO: a computational model for the detailed design of plate-fin-and-tube heat exchangers using pure and mixed refrigerants , 1997 .

[22]  A. London,et al.  Compact heat exchangers , 1960 .