Czech J. Food Sci., 2008, 26(3):199-210 | DOI: 10.17221/1590-CJFS
Prediction of the average surface heat transfer coefficient for model foodstuffs in a vertical display cabinet
- 1 Food Research Institute Prague, Prague, Czech Republic
- 2 Faculty of Mechanical Engineering, Czech Technical University Prague, Prague, Czech Republic
Calculations of transient temperatures of food products after they are transferred from a warm environment into a display cabinet, require data on the surface heat transfer coefficient (SHTC). There is no forced air flow in an ordinary display cabinet, so the energy transfer is achieved mainly by free convection, conduction to a supporting plate, and radiation. Theoretical analysis of the heat transfer to a cylindrical sample demonstrates the relative influences of these mechanisms. This work investigates the apparent surface transfer coefficients with metal models. Heated models were placed individually (bare) in containers with and without lids. Each model was surrounded by identical containers filled with water. These were initially at the same temperature as the model or at the mean cabinet temperature. There were one, two, or three layers of these water containers. From the measured time-temperature histories of the model and the air surrounding the model, the SHTCs were calculated as functions of time and transformed into the dependencies between SHTC and temperature difference. The highest SHTCs were observed when the model was placed directly on the metal shelf of the display cabinet. The models surrounded by cool water containers showed lower SHTC values. The lowest SHTC values were found with the models placed in the middle of three layers of warm water containers. Placing the model on an insulating base leads to a lower SHTC. This effect confirms that the heat conduction through the substrate increases the heat transfer from the model and thus increases the average value of the apparent SHTC.
Keywords: SHTC; vertical display cabinet; correlations; food safety
Published: June 30, 2008 Show citation
| ACS | AIP | APA | ASA | Harvard | Chicago | Chicago Notes | IEEE | ISO690 | MLA | NLM | Turabian | Vancouver |
References
- Anderson B.A., Sun S., Erdoglu F., Singh R.P. (2004): Thawing and freezing of selected meat products in household refrigerators. International Journal of Refrigeration, 27: 63-72
Go to original source... - Becker B.R., Fricke B.A. (2004): Heat transfer coefficients for forced-air cooling and freezing of selected foods. International Journal of Refrigeration, 27: 540-551. Go to original source...
- Carslaw H.S., Jaeger J.C. (1986): Conduction of Heat in Solids. 2nd Ed. Oxford University, Cary.
- Carniol N., Alvarez G., Kondjoyan A. (1998): Convective heat transfer in a tray stack of food products during cooling: influence of air velocity and packaging. In: Fikiin K. (ed.): Proceedings Conference Advances in the Refrigeration Systems, Food Technologies and Cold Chain, Sofia: 284-289.
- Hoke K., Landfeld A., Houška M. (2006): Stanovení tepelných toků při chlazení kovových modelů v obchodní vitríně. Výzkumná zpráva č. 1/360/2006. Available at www.vupp.cz - request email: m.houska@vupp.cz.
- Raznjevic K. (1984): Termodynamické tabulky. Alfa, Bratislava.
- Scott E.P, Beck J.V. (1992): Estimation of time variable heat transfer coefficients in frozen foods during storage. Journal of Food Engineering, 15: 99-121. Go to original source...
- Šesták J., Rieger F. (1974): Přenosové jevy I. Přenos hybnosti a tepla. Vydavatelství ČVUT, Praha.
This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY NC 4.0), which permits non-comercial use, distribution, and reproduction in any medium, provided the original publication is properly cited. No use, distribution or reproduction is permitted which does not comply with these terms.