平板太阳集热器热性能模拟分析

SIMULATION OF THERMAL PERFORMANCE OF FLAT-PLATE SOLAR COLLETORS

为对平板太阳集热器进行热性能分析及优化设计,建立平板太阳集热器的稳态性能数学模型,编制热性能模拟程序,分析环境参数、运行参数及结构参数对集热器瞬时效率的影响特性。模拟结果表明,环境温度升高、工质入口温度降低均可显著提高集热器瞬时效率;降低盖板发射率和吸热板表面发射率有利于提高集热器瞬时效率;减小工质质量流量和增大集热管间距会使集热器瞬时效率减小;环境风速变化对集热器瞬时效率影响较小;夹层间距变化对集热器瞬时效率的影响随工质入口温度的增大而增大;太阳辐射强度对集热器瞬时效率的影响跟集热器与环境间的热交换有关。

In order to analyze and optimize the thermal performance of flat-plate solar collectors, the simulation program of the thermal performance was coded based on the steady-state model of flat-plate solar collectors. The effect of various parameters including environmental, operational and structural parameters on instantaneous efficiency was investigated. The simulation results show that instantaneous efficiency increases significantly with increases of environmental temperature and decreases of the inlet temperature of working fluid; instantaneous efficiency also increases moderately with decreases of the emissivity of cover and absorber-plate. However, instantaneous efficiency decreases with decreases of the mass flow rate of working fluid and increases of distance between collector tubes; instantaneous efficiency has little variation with increases of wind velocity. The impact of the air-gap spacing on the instantaneous efficiency becomes more significant as the inlet temperature of working fluid increases. The influence of the solar radiation intensity on instantaneous efficiency is related with the heat exchange between collector and environment.