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本文在分析水在真空状态下蒸发特性的基础上,提出了一种用于小型无泵溴化锂吸收式空调器的新的蒸发器设计方案。对于所设计蒸发器的管内换热机理首先进行了理论分析,然后用单管模拟的方法对四种不同结构的水平蒸发管进行了实验研究。根据实验数据,得到了针对四种结构的水平管内水的蒸发换热系数的经验公式。实验结果表明,第三种结构的蒸发管(管内径10mm,出口截掉1/4d_i)是一种有效的强化传热管,它的蒸发换热系数是200～300W/m~2·℃。本文最后还提出了对强化管内换热的进一步的改进措施。
In this paper, based on the analysis of the evaporation characteristics of water under vacuum, a new evaporator design scheme for a small pump-free lithium bromide absorption air conditioner is proposed. The theoretical analysis of the heat transfer mechanism inside the tube of the designed evaporator was first carried out, and then four kinds of different horizontal evaporation tubes were experimentally studied by the single tube simulation method. Based on the experimental data, empirical formulas for evaporation heat transfer coefficients of water in horizontal tubes for four structures were obtained. The experimental results show that the third structure of the evaporation tube (tube diameter 10mm, exit cut off 1/4d_i) is an effective heat transfer tube, and its evaporation heat transfer coefficient is 200 ~ 300W/m ~ 2 · °C. Finally, this article also proposes further measures to improve the heat transfer in the tube.