Heat Transfer in Vacuum Drying Oven: A Simulation Study

The flow field,in a vacuum drying oven of bio-products,was mathematically formulated with surface-to-surface radiation model in Boussinesq assumption,theoretically analyzed and numerically simulated with CFD Fluent software.The influence of the pressure on the heat transfer and uniformity of temperature distribution was investigated to verify the applicability of JJF 1101-2003 in vacuum clrying oven calibration. The simulated results show that the pressure significantly affects the uniformity of temperature distribution.As the pressure decreases,the uniformity of the temperature distribution worsens because of an increased fraction of radiation heat,accompanied by a decreased fraction of convention heat.We concluded that at an atmospheric pressure and/or at a pressure approaching to the specified drying-pressure of 1013 Pa,the uniformity of temperature field,in the vacuum drying oven,does not satisfy the requirement of JJF 1101-2003 Calibration Specification.