| In order to reduce the dependence on fossil energy,the state has proposed a strategic task of energy development,which emphasizes the need to promote the transformation of urban and rural energy use methods,and encourage the development and application of new energy sources such as photovoltaic power.However,because photovoltaic power has the characteristics of intermittent power generation,it should consider the ability of reasonable peak regulation,frequency modulation and energy storage.Technology of energy storage can save electricity during peak periods and transfer it to the peak period of power consumption,thus achieving power grid peak-shaving,alleviating the problem of abandoned energy of light and wind,and achieving the reliance of grid voltage.Based on the characteristics of distributed photovoltaic power generation system and the characteristics of phase change energy storage technology,an optoelectronic complementary phase change energy storage heating system is proposed.In this paper,the thermal properties of phase change materials are used as the basis for screening.The screening of magnesium chloride hexahydrate,potassium aluminum sulfate dodecahydrate and sodium sulfate decahydrate can be used as phase change materials for heat storage.The phase change material and the expanded graphite were mixed by pre-experiment to obtain the composite phase change material.The preliminary experimental results show that the potassium aluminum sulfate dodecahydrate and the expanded graphite cannot be uniformly adsorbed and mixed to form the shaped phase change material.The preliminary supercooling curve test was carried out on sodium sulfate decahydrate/expanded graphite and hexahydrate magnesium chloride/expanded graphite composite phase change material.The test results show that the phase transition temperature of sodium sulfate decahydrate/expanded graphite composite phase change material is lower.The subject is used as a filling material in a phase change energy storage electric heating device.The expansion ratio of the expanded graphite was determined to be 7.5% by observing the setting condition of the expanded graphite/hexahydrate magnesium chloride composite phase change material.By adding the nucleating agent calcium hydroxide to eliminate the supercooling effect of the material,it is more appropriate to determine the amount of the nucleating agent added by 1% wt according to the step cooling curve test result.The phase change energy storage electric heating device was designed by using the expanded graphite/calcium hydroxide/hexahydrate magnesium chloride composite phase change material as the filler,through three aspects: equipment structure design,thermal performance design and operation protection design.According to the characteristics of distributed photovoltaic power generation and the working characteristics of phase change energy storage electric heating device,a direct and indirect photoelectric complementary phase change energy storage heating system was designed,and two operating conditions were designed.A test bench for phase change energy storage electric heating device was built.The test results of the test bench showed that the indoor high temperature during the daytime continuous heat storage can maintain the high temperature in the room,which is the best operating condition.The performance of the optoelectronic complementary phase change energy storage heating system was evaluated in terms of economy,energy saving and emission reduction.The thermal performance of the energy storage electric heating device was evaluated by the energy storage of the equipment.With the increase of the solar energy contribution rate,the coal consumption of the photoelectric complementary phase-change energy storage heating system,the pollutant discharge is gradually reduced,and the investment recovery period is gradually shortened.The energy storage ratio of the phase change energy storage electric heating device can reach 0.76,which can achieve better heat storage effect. |
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