15D-1 |
An interactive graphical tool for vapor-compression refrigeration cycle calculations |
N. A. MILLS, Food Sci. and Human Nutrition Dept., University of Florida, 359 FSHN Newell Drive P.O. Box 110370, Gainesville, FL 32611 and M. O. Balaban. New regulations in the use of refrigerants forced out old refrigerants and modified processes. Therefore, prior refrigeration computer programs are becoming outdated. With the availability of fast computers, complex calculations that could not be made “instantaneous” now can be displayed in real time. There is a need for such software for teaching and demonstration of refrigeration calculations. The objective was to create a user-friendly, graphical computer program to display actual refrigeration cycles, and easily calculate thermodynamic and process variables. This could be used as a teaching tool. The program was written in Visual Basic 6.0 with Graphics Server 5.0. The thermodynamic equations relating pressure, temperature, phase, enthalpy, entropy, specific volume, and heat of evaporation were simultaneously solved. The Pressure-Enthalpy (P-H) diagram was displayed, together with the two-phase region of the refrigerant. Graphical user interface allowed simple user interaction. Properties of a point can be calculated with one click. Also, complete refrigeration cycles can be displayed, and COP calculated. The program is easy to understand and follow with only little knowledge of refrigeration. It can be easily modified to adapt to new refrigerants and ideas. All calculations can be completed within 1.5 % of actual experimental values for temperatures and pressures between –30C and 93C, with the exception of liquid enthalpy having a range of –15C to 61C. This program is a great tool for teaching thermodynamic and refrigeration courses. This package is an excellent teaching tool for students studying the effect of fluid and process parameters on the overall performance of the refrigeration cycle.
Session 15D, Food Engineering: Processing Technologies
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