Numerical Investigation of Heat and Mass Transport and Surface Condensation due to Food Respıratıon and Transpıratıon in a Refrıgerated Space with Forced Convection

Abstract

Food load and air-flow area within a refrigerated space having one air inlet and one air outlet have been taken as two separate control volumes interacting with each other at their boundaries. In the lower control volume, stored vegetable products have been located and heat and mass transfer due to respiration and transpiration of these products have been modeled for determining boundary conditions of the upper control volume, in which heat and mass transport within the air circulation above the products have been modeled and numerically investigated. Upper surface temperature of the said upper control volume has been compared with the dew point temperature, and condensation heat and mass fluxes through the surface have been taken as upper boundary condition. Time-dependent heat and mass transport equations of each control volume for forced convection case have been simultaneously solved together. An implicit finite difference approach has been applied for the numerical solution of transport equations. Fortran programming language has been used to develop the numerical model. As a result; temperature and humidity ratio distribution, the amount of vapor transpiration from food products, and the amount of condensation on the underside of the upper surface due to heat-and-mass transport and transpiration characteristics of the products have been time-dependently calculated.

Keywords

• Surface condensation; food respiration; transpiration; humidity; moisture loss; water vapor; mass concentration; finite difference

References

1. Anderson, J. D. (1995). Computational Fluid Dynamics: The Basics with Applications. New York: McGraw-Hill.
2. ASHRAE Handbook (2006). Refrigeration, ASHRAE – American Society of Heating, Refrigerating and AirConditioning Engineers, Atlanta
3. Becker, B. R., Misra, A. ve Fricke, B. A. (1996). Bulk Refrigeration of Fruits and Vegetables Part 1: Theoritical Considerations of Heat and Mass Transfer, HVAC&R Research, Vol.2, No.2, p.122-134.
4. Becker, B. R., Misra, A. ve Fricke, B. A. (1996). Bulk Refrigeration of Fruits and Vegetables Part 2: Computer Algorithm for Heat Loads and Moisture Loss, HVAC&R Research, Vol.2, No.3, p.215-230.
5. Çengel, Y., and Boles, M, 2000, Mühendislik Yaklaşımıyla Termodinamik, Literatür Yayınevi, İstanbul
6. Incropera, F. P. ve DeWitt, D. P., trans. Derbentli et al. (2007). Isı ve Kütle Geçişinin Temelleri. İstanbul: Literatür Yayınları.
7. Mills, A. F. (2001). Mass Transfer. Upper Saddle River, NJ: Prentice Hall.
8. Olivieri, J., Singh, T. et al. (1996). Psychrometrics: Theory and Practice, ASHRAE – American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, ABD.

9. Taner, D. J., Cleland, A. C., Opara, L. U. ve Robertson, T. R. (2002). A generalised mathematical modelling methodology for design of horticultural food packages exposed to refrigerated conditions Part 1: Formulation, Int. J. Refrigeration, Vol.25, p.33-42.
10. Taner, D. J., Cleland, A. C., Opara, L. U. ve Robertson, T. R. (2002). A generalised mathematical modelling methodology for design of horticultural food packages exposed to refrigerated conditions Part 2: Heat transfer modelling and testing, Int. J. Refrigeration, Vol.25, p.43Taner, D. J., Cleland, A. C., Opara, L. U. ve Robertson, T. R. (2002). A generalised mathematical modelling methodology for design of horticultural food packages exposed to refrigerated conditions Part 3: Mass transfer modelling and testing, Int. J. Refrigeration, Vol.25, p.54Terrell, W., Newell, T. A. (2007). Experimental techniques for determining heat and mass transfer due to condensation of humid air in cooled, open cavities, Applied Thermal Engineering, Vol.27, p.1574-1584.
11. Volchlov, E. P., Terekhov, V. V. ve Terekhov, V.I. (2004). A numerical study of boundary-layer heat and mass transfer in a forced flow of humid air with surface steam condensation, Int. J. Heat and Mass Transfer, Vol.47, p.1473-1481.
12. Wang, S., Chen, C. ve Yang, Y. (2006). Steady filmwise condensation with suction on a finite-size horizontal flat plate embedded in a porous medium based on Brinkman and Darcy models, I. J. Thermal Sciences, Vol.45, p.367-377.
13. White, A. J. (2000). Numerical investigation of condensing steam flow in boundary layers, Int. J. Heat Fluid Flow, Vol.21, p.727-734.
14. White, F. M. (1991). Viscous Fluid Flow. New York: McGraw-Hill.
15. Yang, Y., Chen, C. ve Hsu, P. (1997). Laminar film condensation on a finite-size horizontal wavy disk, Applied Mathematical Modelling, Vol.21, p.139-144.