| With the continuous development of the national economy, the demand for electric power becomes bigger and bigger. To meet the customers’requirements, on the one hand, more power stations must be built to increase the power network capacity, on the other hand, in order to adapt to the user’s huge gap between peak and valley, effect measures must be taken to improve the peak regulation ability of power network. But both of the two methods have several faults, for example, bigger investment, environment pollution, waste of resource, weaker security of unit operation and so on. So management in the demand side are proposed. Energy consumption of air conditioning is more than40%of the total building energy consumption; cool storage air conditioning technique is the main means of management in the demand side. At present, the research of cool storage media becomes focus in cool storage technology; cool storage phase change materials mainly include ice, inorganic and organic phase change materials. Ice storage systems are used widely, but the system evaporation temperature is low which cause COP and refrigerating capacity lower. In the process of inorganic salt phase change exist subcooling and after many times circulation exist phase separation phenomenon. Organic phase change materials don’t exist subcooling, good stability after many times circulation, but its thermal conductivity is relatively poor.This paper mainly studies phase change materials used in conventional air conditioning. Based on the problems between ice storage and inorganic salt cool storage, organic phase change materials whose phase change temperature is5～8℃are developed. By adding nanoparticles into the organic PCM improve thermal conductivity. The mainly study work and result are presented as follows:(1) Through inquiring chemical reagent manual, several PCM whose phase change temperature is5～8℃are chosen, a groups of organic PCM are prepared with different mixing ratio, phase change temperature and subcooling of mixed materials are determined initially by cold curve method. Finally, an organic PCM whose phase change temperature is about7℃, no subcooling, and phase change process stable, is chosen.(2) A new type of organic phase change cool storage media HS-10used in conventional air-conditioning is developed. Aim at the problem of the low thermal conductivity of organic phase change cool storage media. Two step approach is adopted to prepara uniformity and stable nanocomposite organic phase change cool storage media. Through analysis the stress of nano particle in the fluid and the stable mechanism of nano fluid, choose span80to be the dispersant. The standard curve of TiO2concentration is obtained by application of uv-vis absorption spectrum measurement method. Experiment verification is carried for accuracy of the standard curve, both the relative errors are within5%, and have good accuracy. The influence of the density of the surfactant to stable, the time of ultrasound to stable and the bath temperature of ultrasound to stble. Through orthogonal experiment verify and optimize the process conditions, finally stable nano PCM HS-14are prepared.(3) Phase change latent heat of nano PCM is measured by differential scanning calorimetry (DSC). The potential heat value of the nano PCM HS-14is170.46kJ/kg; and the base fluid HS-10is174.08kJ/kg; the thermal conductivity of TiO2nano organic PCM is measured by transient hotline method. Experiments show that the thermal conductivity of organic PCM containing TiO2nanoparticles HS-14is higher than original liquid HS-10with13.24%, and the phase change latent heat is lower with2.1%. |
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