Study on Compact Absorber and Evaporator using finned wall

提出了一种紧凑型吸收器-蒸发器组合式吸收式热泵。吸收器和蒸发器均为竖直板，液膜沿竖直板沿着下落，通过将蒸发器板和吸收器板依次交替布置，将吸收器和蒸发器集成为一个单元。为了提高溴化锂溶液沿着垂直板降膜吸收水蒸气的能力，研究了壁面偏置翅片的影响.测量了不同液体流速下的吸收速率，并与光滑壁的吸收速率进行了比较。实验发现，在小液流条件下，翅片管壁的吸收速率特别大，约为光滑管壁吸收速率的3倍。虽然实验的吸收率比数值结果大，但数值分析也预测了这种增强。本文还研究了在垂直平板上焊接网栅的壁面对蒸发的强化作用，结果表明，由于毛细效应和翅片效应，壁面网栅具有很高的蒸发性能，并通过实验确定了最佳网栅尺寸。

A compact absorber combined with evaporator was proposed for absorption heat pumps. Both the absorber and evaporator are vertical plates, along which liquid films fall down, and they are integrated into one unit by arranging the evaporator plate and absorber plate one by one alternatively. In order to enhance the absorption of water vapor into a falling liquid film of LiBr/water solution along the vertical plate, the effect of offset fins on the wall was investigated. The absorption rate was measured for various liquid flow rates and compared with that for a smooth wall. It was experimentally found that the absorption rate for the finned wall is especially large under the condition of small liquid flow rate and is about three times larger than that for a smooth wall. The enhancement is also predicted by a numerical analysis although the experimental absorption rate is larger than the numerical results. The enhancement of evaporation on a vertical plate was also investigated by using a wall with mesh screen soldered on it. It was shown that the wall mesh has a high evaporation performance due to the capillary and fin effects, and an optimum mesh size was determined experimentally.