Study On The Application Of Phase Change Thermal Storage Electric Floor Heating

Under the urgent need to improve the uneven consumption time of the current power grid and the macro-policy of clean heating policy,the integration of composite phase change material(CPCM)into the thermal floor heating storage system can not only effectively alleviate the mismatch between the user side and the power generation side in time and space,but also play the role of peak shifting and valley filling for power,indoor temperature control and improve the thermal comfort of human body.However,due to the low thermal conductivity of phase change materials(PCM),heat cannot be stored and released in time,and the delay is too high for active heating equipment,and the reliability of the fusion of PCM and building matrix is difficult to ensure.Therefore,the preparation and application of a phase-change thermal storage electric floor heating is proposed in this study.Its heat storage and release characteristics and safety reliability are studied by experiments,and thermal comfort in buildings is studied by numerical simulation.Specific research contents are as follows:1.According to the relevant requirements of human thermal comfort and energy saving specifications,paraffin wax with phase change temperature of 27.5℃-32.5℃ is selected as the phase change heat storage material,and expanded graphite(EG)of different sizes is selected as the heat conduction strengthening material.It was observed by electron microscope that the smaller the particle size of EG,the smaller the aperture.According to the leakage test of maximum tolerance,the smaller EG particle size is,the more paraffin can be accommodated.The composite phase change material(CPCM)prepared with 100 mesh,200 mesh and 800 mesh EG as matrix can accommodate 75%,85% and 95% of paraffin wax,respectively.The latent heat of phase transition decreases with increasing EG.However,the excessive porosity of the 800 purpose EG reduced its thermal reliability,so it was abandoned as a reinforcing material.The results show that the thermal conductivity of CPCM is up to 5times higher than that of pure paraffin wax,the degree of supercooling is reduced by 3.53%,and the phase change temperature is more suitable to be added into the phase change thermal storage floor heating.2.CPCM1 and CPCM2 with EG size of 100 mesh and 200 mesh were selected as additives when preparing phase change concrete(BPCM).The heat storage and release characteristics,thermal reliability and compressive strength of BPCM were tested by experiments.The results show that BPCM can store heat rapidly before reaching the phase transition point,and the heat release rate is slow.The heat storage and release characteristics of BPCM are better than that of ordinary concrete,and the holding time of BPCM is 1h52 min longer than that of ordinary concrete.In addition,after 50 times of heating and cooling,BPCM’s heat storage and release characteristics are still good,which proves its thermal reliability.The compressive strength of BPCM is lower than that of pure concrete.With the increase of CPCM,the strength of BPCM gradually decreases,showing a negative correlation between the two,reaching the lowest of 25.56 MPa,decreasing by 31.58%.But it still meets the specifications.3.Using COMSOL software,numerical simulation is carried out on the application of phase change thermal storage electric floor heating in buildings.Different phase change floor thickness D and heating cable power P were studied as variables.The results show that different types of rooms have inconsistent temperatures.The master bedroom with two external walls is lower than the second bedroom and the living room under the same heating condition due to the large heat load,and the temperature uniformity is low and the vertical temperature difference is large.The higher the power of the heating cable,the higher the indoor thermal comfort.Heat storage and rate are closely related to floor thickness.In the application of CPCM latent heat,the floor is too thick to make full use of it,and the floor is too thin to reflect the advantages of CPCM.Different heating power matches different optimal thickness.P80D70,P90D80 and P100D90 are the optimal heating selection.