| With the consumption of fossil fuels,the recoverable reserves are getting lower,and the worsening global climate is getting worse.Solar energy as a universal,clean non-polluting,huge,long-term renewable energy has been more and more attention.The absorption refrigeration technology,which takes solar energy and other renewable energy as the driving force,has become a hotspot in the research of refrigeration,which has great significance in energy saving and emission reduction.In the solar refrigeration system,the storage device solves the problem of volatility and intermittent in energy utilization,and improves the efficiency of comprehensive utilization of energy.Firstly,the physical property of ELECNRTL(electrolyte NRTL)was selected according to the thermal properties of lithium bromide aqueous solution.And then the Aspen plus software is used to model the components of the generator and condenser separately,and the simulation flow chart of the refrigeration system is established.Some basic operating parameters of 25 kw single effect lithium bromide absorption chiller are selected,and the actual value of unit heat load of the generator and simulation value are calculated and compared in the range of heat source water working temperature.This shows the credibility of the model.Based on the local meteorological conditions in Hohhot,the relationship between the inlet temperature of the heat source water,the inlet temperature of cooling water,the outlet temperature of the cooling medium and the area of the heat-collecting plate,the refrigerating capacity and the COP value of the cooling machine were analyzed.Under the condition that the refrigeration capacity and economy are satisfied,the inlet temperature range of the heat source water is 68-70 ?,the cooling water inlet temperature range is 25-30 ?,the refrigerant outlet temperature range is 14-17 ?,the maximum refrigeration capacity is about 25 kW and the optimal cop value is about 0.7.By comparing and analyzing the unit heat load of generator,the maximum error is not more than 12%,the average error is not more than 7%,which indicates that the model has high accuracyBased on the theoretical analysis of the phase change heat transfer of cylindrical isometric helical coil-tube phase change regenerator with paraffin wax as phase change material,the heat storage capacity of the heat storage unit is mainly related to the inlet temperature,inlet flow rate and heat storage time of heat transfer fluid.Therefore,under the condition of changing the inlet temperature and the inlet flow rate of the heat transfer fluid,the temperature change,the melting characteristic,the heat storage performance and the total heat transfer coefficient of the paraffin in the regenerative unit are analyzed experimentally.The results show that when the inlet flow rate of the heat transfer is certain,when the inlet temperature is increased from 70 ? to 80 ?,the phase change time of paraffin is shortened by 61.2% and 30.5% respectively,while the maximum heat storage is increased by 6% and 2.1% respectively,with each additional 5 ?.When the inlet temperature of the heat transfer is certain,the inlet flow rate is increased from 10l/h to the 20l/h,the complete phase change time of paraffin is shortened by 10.2% and 16.7% respectively,and the maximum heat storage is increased slightly with each additional 5l/h.The total heat transfer coefficient range of the device is about 5-200W/(??K),and it can be visualized that the heat transfer is the most intense in the phase change stage of paraffin,and the heat transfer is more unstable with higher temperature. |
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