Thermal Design Optimization Of The Building Envelope Of Quasi-Low Temperature Warehouse In Henan Based On Multi-Objective Optimization

Food security is an important foundation of national security,and solving the problem of food supply is a top priority in governance.The optimal temperature for storing grain is below20℃,which can inhibit the growth and reproduction of microorganisms,ensure the quality of grain,and reduce chemical contamination from fumigation.However,creating a storage environment below 20℃ requires a large amount of energy consumption from refrigeration and air conditioning systems,which not only increases the cost of grain storage but also adds to environmental burdens.The thermal design of grain bin enclosure structures is an important means of reducing energy consumption,and therefore,the study of thermal design methods for grain bin enclosures is of great significance for reducing storage costs and ensuring environmental sustainability.This paper proposes a thermal design method for grain bin enclosures that optimizes for refrigeration energy consumption and cost,and demonstrates the effectiveness and implementation steps of this method using examples from Henan province.The paper presents the optimal thermal design solution for low-temperature grain bin enclosures in Henan province,and outlines the following research steps:First,basic grain bin cases in Henan province were obtained through literature surveys,questionnaire surveys,and field investigations.Second,an Energyplus numerical model was used to establish a grain bin model,and the accuracy of the modeling method was verified using data from field tests.Third,two different sensitivity analysis methods were used to determine the important thermal design parameters that affect the refrigeration load of low-temperature grain bins in Henan province.The two sensitivity analysis results were significantly different,and ultimately,18 important parameters were selected as important parameters for later multiobjective optimization considerations.These parameters include the heat transfer coefficient and thermal inertia of the outer walls and roof(insulation material thickness,structural layer material density),the heat transfer coefficient of doors and windows,and the solar radiation absorption rate of the outer surface of the roof and walls.Fourth,multi-objective optimization algorithms were used to optimize the main thermal design parameters determined by sensitivity analysis for the purpose of reducing the refrigeration load and initial investment cost of low-temperature grain bins.The optimization results showed that low-temperature grain bins in Henan province have great potential for reducing refrigeration loads and initial investment costs.The distribution ranges of refrigeration load and initial investment cost were 3212.7k Wh～34161.99 k Wh and 475552.08yuan～762748.92 yuan,respectively.Fifth,the TOPSIS multi-criteria decision-making method was used to determine the final optimal solution for thermal design of grain bin enclosures in Henan province from the Pareto non-dominated solutions obtained from the multi-objective optimization.Compared with the basic grain bin case,the optimized thermal design solution for the enclosure structure reduced the refrigeration load by 88.4% and the initial investment cost by 22.72%.Finally,a life cycle cost analysis was conducted for the optimal solution(different from the refrigeration load and initial investment cost optimization in the fourth step).The results showed that the life cycle cost of grain bins was reduced by 41.75% when the thermal design of the enclosure structure was optimized from the basic grain bin case.The optimal thermal design solution for low-temperature grain bin enclosures in Henan province is easy for architects to understand and implement in practice.Furthermore,the proposed method provides a clear path for the design of grain bin buildings in other regions of China,which is helpful for environmental sustainability and grain storage safety.