Radiation Heat Transfer of In-line Infrared Halogen Lamp Tube of Vacuum Freeze-drying

In recent years, the vacuum freeze-drying technology has been widely applied in material science, but it still has the disadvantage of long drying time. Among various vacuum freeze-drying heating technologies, the thermal radiant heating is the cleanest, safest and quickest. Therefore, this study employed the CFD software CFD-ACE TM + to simulate the thermal radiation phenomenon of three-dimensional in-line halogen lamp tube heating. The model was a cylindrical vacuum chamber with a diameter of 0.355m and a length of 0.5m, with 2 pieces of drying materials placed between heating lamp tubes. This study considered natural convection occurred inside the vacuum chamber to explore the influence of setting density of 9 halogen lamp tubes and 2 kinds of distance between lamps and drying materials upon heating uniformity, where the total heating power of the lamp tubes is 10 and 100W. It aimed to improve the heating uniformity of drying materials while conforming to energy efficiency and providing dried materials with better appearance. The results showed that the denser setting density of halogen lamp could enhance the uniformity of heating temperature distribution of materials. Furthermore, under fixed setting density of lamp tubes, although increasing the distance between halogen lamps and drying materials would decrease the average heating temperature of materials, the heating temperature of materials would be more uniform. The results can serve as a reference to the designer of heating lamps for vacuum freeze-drying equipment of thermal radiation.