36C-3 |
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G. BINGOL1, M. O. Balaban2, and Y. O. Devres1. (1) Food Engineering Dept., Istanbul Technical Univ., 34469 Maslak, Istanbul, Turkey, (2) Dept. of Food Science and Human Nutrition, Univ. of Florida, 126-A Aquatic Foods Pilot Plant, PO Box 110370, Gainesville, FL 32611-0370 The psychrometric chart is an essential tool in drying and HVAC calculations. However, its concepts are difficult to teach and, due to its graphical nature, determination of various properties are not precise. Also, most charts are available at 1 atm. It is desirable to have a graphical representation of the chart in a computerized fashion to help teaching, and to have the flexibility to work at different total pressures. Our objectives were to develop a computer model of the psychrometric chart including the use of different total pressures, and the ability to redraw the chart at these pressures. Also, all properties (dry bulb and wet bulb temperatures, dew point, enthalpy, specific volume, total pressure, absolute and relative humidities) were calculated starting from any three properties, with a few exceptions. The program was written in Visual Basic, Version 6. The Pinnacle graphics server was used for graphical representations. The possible combinations of 3 properties out of a total of 8 resulted in 56 different combinations. The combinations that were not possible to calculate will be presented, as well as the reasons. The program also aids in teaching because methods of reading properties knowing a point can be shown on the chart. Also, once the total pressure is known, the method of finding the location of the point using two properties is also demonstrated on the chart. The chart can be drawn at any given total pressure and saved or printed. The ranges of properties within which calculations can be made will also be presented. This program is a tool that will significantly facilitate the teaching of the psychrometric chart concepts. Within its domain of validity, it can also be used in the industry to predict properties at different total pressures.
Session 36C, Education: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |