Optimization Of Thermal Performance Of Enclosures Of Industrial Buildings Based On Operative Temperature Control

There are different intensity heat sources in industrial building.Convection heat dissipation and radiation heat dissipation of heat sources are the main reasons affecting the indoor thermal environment.At the same time,radiation heat dissipation of heat sources also affects the temperature of the inner wall surface of the envelope structure.The thermal design of the building envelope structure of an industrial building is not only affected by outdoor weather conditions,but also affected by the strength of the indoor heat source.Therefore,the thermal design of industrial buildings must consider thermal insulation and consider indoor heat dissipation at the same time.Therefore,the thermal performance optimization of the industrial building enclosure should consider both heat insulation and indoor heat dissipation,and the optimization method of thermal performance of civil buildings cannot be directly applied to optimizing of thermal performance of industrial buildings.The study on the optimization of the thermal performance of the enclosure structure under the ventilation of industrial buildings will contribute to guide the optimization of the thermal performance of the enclosure structure,improve the indoor thermal environment and save the energy consumption of the ventilation.In this paper,the distribution characteristics of the thermal parameters of 74 existing industrial buildings were investigated and analyzed.It was found that the shape coefficient of industrial buildings and the area ratio of window wall area are smaller than those of civil buildings,and the shape coefficient and window wall area ratio of most buildings are concentrated in the small enclosure.The thermal performance requirements of industrial building envelope are generally lower than that of civilian buildings.According to the characteristics of the thermal performance of the industrial building enclosure,indoor operative temperature was adopted as the optimization control parameter of thermal performance of the building envelope,taking " unsatisfied total hours" as the optimal control target of thermal performance,when " unsatisfied total hours" is the minimum,the envelope structure of the corresponding has the best thermal performance effect.Since the thermal protection of the building envelope must consider the heat insulation and the heat dissipation,so the heat transfer coefficient obtained in this paper is recommended,the heat transfer coefficient is too large or too small will affect the overall effect of thermal performance.The thermal parameters of industrial building envelopes under different thermal strengths,different ventilation times and different climatic conditions were optimized by the optimization method for thermal performance proposed in the paper.When the number of ventilation is certain,the recommended value of heat transfer coefficient of the envelope structure in the same area will increase with the increase of heat intensity.When the indoor heat intensity is certain,the recommended value of the heat transfer coefficient of the envelope structure in the same area will increase with the increase of ventilation times.When the indoor heat intensity and the number of ventilation changes are constant,the heat transfer coefficient of the envelope structure in Guangzhou,Wuhan and Xi’an shows a decreasing trend.When the heat intensity is 15W/m3 and the number of ventilation changes is 8 times per hour,the recommended values of the heat transfer coefficient of the exterior wall and roof in Guangzhou area are 6.67 W/(m2·K)and 7.27 W/(m2·K)respectively;the recommended values of heat transfer coefficient for the external walls and roofs of Wuhan area are 6.67 W/(m2·K)and 0.85 W/(m2·K)respectively;the recommended values for the heat transfer coefficient of external walls and roofs in Xi’an area are 1.47 W/(m2·K)and 1.52 W/(m2·K)respectively.By solving the heat conduction differential equation of the enclosure structure,taking Xi’an and Wuhan as examples,the thermal performance of the internal and external wall surface temperature,heat flux density and attenuation delay of different structures under the same heat transfer coefficient are compared and analyzed.The structural form and its thermal parameters of the Xi’an and Wuhan areas with relatively better thermal protection performance under natural ventilation conditions are obtained.Taking the Xi’an area as an example,when the external wall heat transfer coefficient is 0.3 W/(m2·K),the thermal inertia of the structure is 3.5,and the corresponding structure is 20 mm cement mortar +200mm reinforced concrete +105mm polyurethane rigid foam +25mm cement mortar.When the heat transfer coefficient of the roof is 1.2 W/(m2·K),its thermal inertia is 2.5,and the corresponding structure is 25 mm cement mortar,+120mm reinforced concrete +20mm cement mortar +90mm hydrophobicity perlite board +20mm cement mortar.