DETERMINING CONVECTIVE HEAT TRANSFER COEFFICIENT (h) FOR HEATING AND COOLING OF BOTTLES IN WATER IMMERSION

作者：Augusto Pedro E D^*; Pinheiro Talita Ferramola; Cristianini Marcelo

来源：Journal of Food Process Engineering, 2012, 35(1): 54-75.

DOI：10.1111/j.1745-4530.2009.00571.x

Thermal process, specially the in-package process, is one of the safest and most frequently used methods for food preservation. Mathematical models for heat transfer have been widely used as a powerful tool in safety and high-quality food process design. The convective heat transfer coefficient (h) is essential for heat flux calculation in model boundary conditions, and its determination must be done by the actual heat transfer system. The present study has determined the h-values for two commercial bottles (G1 and G2) in two water immersion systems, one for heating and one for cooling. It was calculated by an inverse heat transfer problem, using computational fluid dynamics. Two methodologies for h determination were compared, using either a conductive material or a convective material inside the packages. The methodology that uses a conductive material showed simpler and faster computational simulation, but presented a limitation related with the Biot number of the process. Results indicated a limitation in the most used methodology for h determination, and suggest that the convective material methodology can be an alternative for this analysis. For the same systems, the hheating value for G1 was almost 50% higher than for G2, and hcooling values for G1 were almost 70% higher than for G2. Differences obtained between bottles highlight the need to determine h for the exact heat transfer system. Moreover, these results indicate that there is a potential for process optimization only by varying its package format, as it can influence the heat flux for the packaging.

• 出版日期2012-2