Basic Research Of Phase Change Materials Applied In Greenhouses

Abundant solar energy resources in northern China, agricultural greenhouses are widely used. Greenhouse heat during the day using solar radiation for improving the greenhouse temperature is to provide a good environment for the growth of crops. Traditional greenhouse structures poor insulation performance, the proper temperature during the day to protect the greenhouse, Traditional greenhouse structures poor thermal insulation properties, in the daytime, solar can makes the greenhouse temperature good. But by night, the heat loss seriously, greenhouse temperature is too low and not suitable for crop growth, need for additional heating. Wherein people often using coal, oil and other heating methods, Because power consumption, high cost, environmental pollution and other shortcomings, so a variety of new greenhouses emerging, building envelope insulation performance continuously strengthened. Therefore, the study of a "smart" type greenhouse, storage of excess solar energy during the day and at night this part of the energy is released, instead of coal and other ways to greenhouse heating, which is more meaningful with the times.In recent years, the phase change energy storage technology continues to be applied to building energy, industrial waste heat utilization and other fields. Phase change energy storage technology has a latent heat storage, energy saving and environmental protection features, applied to agriculture in greenhouses, has great scientific value.The purpose of this study was the composite phase change material storage can be combined with solar water heaters complement. Applications greenhouse, reduce energy consumption, save costs and increase revenue greenhouses. Based on the northern greenhouse climate, choose a suitable phase change material, the use of binary phase diagram of the principle by melt mixing method, step cooling curve, DSC thermal analysis prepared composite phase change materials, Based on both inside and outside the northern greenhouse greenhouse climate, select the appropriate range of phase transition temperature, by melt mixing method, step cooling curve, DSC thermal analysis test thermal properties of composite phase change material properties, drawn binary phase diagram?Choose red perlite particles phase change material through the experiment, phase change temperature range of 19-27? range, the phase change peak temperature 24.28?, latent heat 114.2J/g, as a phase change material applications greenhouse model.obtained experimentally 20#,30# paraffin with ratio 4:6 phase change material, phase change temperature range 20.03?-29.08?, latent heat is 84.04J/g, more suitable for applications conservatory.Because paraffin phase change material of poor thermal conductivity, low efficiency of energy storage, so the phase change material thermal conductivity to be improved. Therefore, this use of high thermal conductivity iron filings, copper scrap, aluminum scrap as a phase change material heat transfer mediumusing mixing method the metal reinforced composite material with phase change material by DSC thermal properties of phase change materials to analyze the performance curve research to strengthen thermal conductivity. The better thermal conductivity of metal, thermal resistance is smaller, enhanced thermal capacity, improve thermal conductivity of the phase change material enhancement; wherein the strengthening effect preferably to add particle size 0.15mm?R<0.16mm iron filings 11.9%,relative to blank sample ahead of 34.44%.Finally, build the greenhouse model with phase change materials and solar water heaters combined application greenhouse, research and analysis phase change materials greenhouse and ordinary greenhouse temperature change and environmental temperature changes.Experimental greenhouse model, the phase change materials greenhouse in the daytime indoor temperature is lower than normal greenhouse greenhouse, maximum temperature difference about 9?,the average temperature about 6?.Solar hot water heating greenhouses complement 2 times, each time heat complement Q??=211.68KJ, at night to meet the growing demand of crops.After mixing iron enhanced greenhouse, the maximum temperature increased of 5?, at noon heat storage capacity increased by 1.97×105J, release heat at night increases the 8.13×104J, improve the greenhouse heat storage capacity and reduce the greenhouse temperature fluctuations.Greenhouse planted peppers, pepper growth of in 1# phase change materials greenhouse is significantly better than 2# ordinary greenhouse peppers.1# phase change materials greenhouse 10 seeds emergence 7, average height 17mm; 2# ordinary greenhouse 10 seeds emergence 4, the average height of 6mm.1# phase transition greenhouse peppers growing conditions better than 2# ordinary greenhouse peppers.Through experimental studies, the phase change material storage technology applications greenhouses, greenhouse regenerative performance improvement, regenerative heat combined with the complement to create a more suitable for growing crops of the "micro-climate" environment, to achieve agricultural greenhouse project saving, environmental protection and sustainable development. Phase change materials research and development of greenhouse laid the foundation.