The Roles Of Thermophysical Properties Of The Enclosure On The System Energy Consumption And The Object Thermal Control Effects Under Periodic Environmental Conditions

A thermal control system with active ventilation was studied, using the environmental data of typical meteorological days and years in Hefei, Nanjing, Ruoqiang and Mohe. Under periodic environmental conditions, the influences of the thermophysical properties of the enclosure on the power consumption and the thermal control effects including the temporal stability and spatial uniformity of the object surface temperature were investigated.In order to analysis the roles of the thermophysical properties of the enclosure, an entity model was built with the software I-DEAS, and the temperature field of the system was calculated through the Thermal Analysis (TMG) and Electronic System Cooling (ESC) modules. Several special materials were chosen to explore the roles of the enclosure’s thermal conductivity and volumetric heat capacity on the power consumption and the thermal control effects with various meteorological data in different areas. It was found that decreasing the thermal conductivity or increasing the volumetric heat capacity of the enclosure can both decrease the power consumption and improve the temporal stability and spatial uniformity of the surface temperature of the object.For further understanding the general roles of the thermophysical properties of the enclosure on the energy consumption and the thermal control effects, the entity model was simplified as a plate model. Under the environmental conditions of typical meteorological days and years, a traversal study was performed on the power consumption of the system and the thermal control effects of the object with enclosures of different thermal conductivity and volumetric heat capacity. It was discovered that the influence of the volumetric heat capacity depends on the value of the thermal conductivity and the difference between the inlet air temperature and the average temperature of the ambient air. When the average ambient air temperature is higher or much lower than the inlet air temperature, the thermal conductivity becomes the dominant factor in average power consumption. And the thermal control effects are both impacted by thermal conductivity and volumetric heat capacity. However, when the average ambient air temperature is close to that of the inlet air, then if the thermal conductivity is less than0.1W/(mK), the volumetric heat capacity has little effect on the average power consumption and the thermal control effects. If the thermal conductivity is higher than0.1W/(mK), a higher volumetric heat capacity could not only reduce the average power consumption but also enhance the temporal stability and spatial uniformity of the object surface temperature. Application performances of phase change materials and thermal insulation materials were discussed as two typical materials that have either a high volumetric heat capacity or a low thermal conductivity. The results shows that the enclosure material with both a low thermal conductivity and a high volumetric heat capacity has the best performance in the average power consumption, the temporal stability and spatial uniformity of the object surface temperature.