Research On Phase Change Radiant Floor Heating System Of Low Temperature Water Produced By Multi-source Water Heater

Both of energy-saving and environmental protection are important topics in the field ofenergy use. At present, it is recognized that the low-temperature radiant heating technology isan effective way to solve the problem of energy and environment of the world. Because phasethermal storage has advantages of small temperature change and high storage density, the useof phase change materials in construction can increase the regenerator performance of thebuilding envelope.thereby,it can reduce the indoor temperature fluctuations, increase comfortand improve the building thermal performance. In the view of the problem of energy andenvironment in our country, on the basis of low-temperature water floor radiant heatingsystem of the hot-resource produced by the multiple source water heater which is optimized,an advanced idea was put forward that phase change radiant floor heating system of lowtemperature water produced by multi-source water heater combining the chatacteristics ofphase-change heat storage.A kind of organic/inorganic composite phase change materials(PCM) with polyethyleneglycol(PEG) as phase change materials and a porous silicon dioxide as skeleton materials wasprepared in this paper. Some primary instruments, such as differential scanning calorimeter(DSC), scanning electron microscope (SEM) and FTIR transmittance, were used tocharacterize the materials. The heat transfer performance of the composite cement block wasthen investigated by the Hot Disk thermal analysis and the heat storage/release experiment.The results show that the PEG/SiO2composite thermal storage PCMs have many excellentperformances, such as high thermal storage capacity, appropriate phase change temperature,steady structure, and so on. For effectively improving the thermal properties of constructioncomponents, it can be designed to store energy in buildings, especially for radiant floorheating system.PEG/SiO2composite thermal storage PCMs and concrete were mixed to prepare phasechange thermal storage concrete bricks and concrete walls. Some important performances ofthe concrete bricks with different amounts of PCMs, such as apparent density, thermalconductivity and compressive strength, were tested in this paper. According to the comprehensive analysis of the performances of concrete bricks, the optimum amount ofPCMs in the concrete walls was determined as 6%. The apparent density, thermalconductivities, compressive strength of this concrete brick are 2.009g·cm-3, 1.545W·m-1·K-1and 22.519MPa respectively.The heating room with sizes of 480cm×415cm×290cm was measured. The resultsshowed that the heat pump units need about 7 hours to preheat, which can make the supplyand return water temperature upto the stable state, so the temperature of water pump for theasymptotic rising influence the floor heating ability and the ability to quickly preheating to acertain extent; the indoor temperature is stable and the phase change materials can reduce thetemperature fluctuation. We can feel comfortable inside which the steady change oftemperature in 23～27℃and the maximum temperature difference is 1.0℃in the verticaldirection while the outside in 27～32℃; The solar energy water heater combined with otherscan reduce the operating costs.