【摘要】 采用真空集热管收集太阳能是利用这一新型洁净能源有效技术方法之一,如何提高真空管热转换效率依然是该技术领域一个重要的问题。本文在真空集热管工作原理简要分析的基础上,建立了一个集热管热在平衡状态下的稳态传导模型。通过数值计算,给出了不同温差下的热损失量,获得了给定太阳能真空集热管热转换效率的理论分析计算结果。并与试验测试结果的对比分析表明,理论方法具有良好预测能力,其最大相对误差在3%以下。随着传导工质与环境温差的增大,热转换效率持续下降。当温差超过250!C时,热转换效率小于65%。文中的理论模型和计算结果对太阳能真空集热管设计及其应用具有一定的参考价值。更多还原

【Abstract】 Heat collection of solar energy by evacuated solar collector tubes is one of the classical technical approaches to efficiently employ solar energy as a new type of energy,in which how to increase heat collecting performance of the collector tubes is still an important basic problem in this technical field.This work presents a theoretical model of the steady heat transfer in thermal equilibrium state,after a brief analysis of working principle of the evacuated solar collector tube under consideration.The heat losses at various differences in temperature are calculated through numerical analysis,and the theoretical results of heat collecting efficiency are obtained for the given collector tube.Comparison of the theoretical heat losses with experimental results shows that the presented model has a good ability for predicting the heat collecting efficiency,with a maximum relative error less than 3%.As the difference in temperature increases between the working medium of heat exchange and the circumstance,the heat collecting efficiency continues to decrease.Beyond 250 !C of the difference in temperature,it is lower than 65%.The presented theoretical model and calculation results may provide a useful reference for the design of evacuated solar collector tubes and their applications.更多还原