Study On Thermal Comfort And Solar Air Source Heat Pump System Based On PCM Wall

Under the severe energy situation,the 13 th Five-Year Plan of China has put forward new goals for building energy conservation and new requirements for building envelope energy conservation.Most of the domestic envelope structures are lightweight structures with small specific heat,easily to permeate heat and increase building load.In order to reduce infiltration,thermal insulation layer is added to the outer envelope of the envelope structure.However,the stability and thermal storage capacity of the thermal insulation layer are poor.Phase change materials(PCM)can solve the problem of poor thermal storage capacity of traditional thermal insulation materials due to their isothermal phase change and high latent heat per unit volume.The urea-formaldehyde resin microcapsule-coated paraffin was selected as phase change material.After consulting its relevant physical parameters,the dynamic model was built.The simulation results were compared with the literature to verify the reliability of the model.The gypsum layer model is established as referential wall model.The temperature,thermal load and indoor thermal comfort of phase change wall and referential wall are compared and analyzed.Indoor thermal comfort takes PMV-PPD as index.The thermal comfort improvement ratio is defined to quantify the degree of thermal comfort improvement.Considering heating system provided in winter,the solar assisted air source heat pump system is established with the building model.The heating system has four modes,when setting up the control strategy,outdoor air is taken as a referential factor.At the same time,the influence of adding heating system on indoor thermal comfort of buildings is explored,and the phase change wall heating system and referential wall heating system are compared and analyzed.The results show that the simulated phase change wall has thermal inertia,which can delay 2 hours heating/cooling compared with the reference wall,and the indoor thermal load is reduced,the peak load reduction rate can reach 29%.In the late heating period,the PMV of the phase change wall mostly concentrates between-0.2 and 0.4,and the PPD mostly concentrates between 5% and 9%,meaning that the thermal comfort of the referential wall is mostly in the first grade,while the PMV of the reference wall is mostly in the first grade.Most of the PPD is between 0.6 and 0.8,and most of the PPD is between 10% and 20% which means that the thermal comfort of PCM wall can be improved by 13%.After adding heating system,the average reduction rate of heat load is about 25%,and the PMV improvement ratio of phase change wall heating system is 7%.With the development of economy,people’s demand for comfort is getting higher and higher.Phase change wall has important practical significance for energy saving and improving indoor air quality.