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制冷学报 2019
摇摆对TFE-TEGDME降膜吸收影响的可视化实验研究
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Abstract:
本文搭建以TFE-TEGDME溶液为制冷工质对的摇摆吸收式制冷实验台，对竖直管降膜吸收器进行可视化实验研究。静止状态下实验表明：当溶液质量流量为0.1~0.2 kg/min时，液膜呈层流和单色波状态；当流量为0.5 kg/min和0.8 kg/min时，液膜表面出现稳定波状流与合并波状流；当质量流量为1.2 kg/min时，液膜出现脱落现象。在不同波形下吸收器的吸收效果差别很大。摇摆状态下实验表明：随着摇摆幅度的增大或摇摆周期的减小，液膜受到的扰动越大，当摇摆幅度达到15°或摇摆周期达到4 s时将出现合并波状流和脱落现象；在同一个摇摆幅度和周期下，液膜在摆幅边缘受到扰动较大，在摆幅中间流动较为平缓；当溶液质量流量为0.28 kg/min时，在摇摆幅度为8°或摇摆周期为10 s时系统的COP最大，而当流量为0.14 kg/min时，COP峰值出现在摇摆幅度10°或摇摆周期8 s时，同时说明溶液质量流量更大时液膜受到摇摆的扰动就更大。
In this study, a swing absorption refrigeration system with 2,2,2-trifluoroethanol/tetraethylene glycol dimethyl ether (TFE-TEGDME) solution as the refrigerant pair was built to observe the vertical tube falling film absorber. Experiments in the stationary state showed that when the mass flow rate was 0.1–0.2 kg/min, the liquid film was in a laminar and monochromatic wave state; when the mass flow rate was 0.5 kg/min and 0.8 kg/min, the liquid film appeared to be a quasi-sine wave and merging wave flow, respectively; when the mass flow rate was 1.2 kg/min, the liquid film partly fell off. The absorption effect depends heavily on the surface wave type. The experimental results in the swing state showed that the perturbation on the liquid film will increase with increasing swing amplitude or a decreasing swing period. When the swing amplitude is 15° or the period is 4 s, the liquid film appears to be a merging wave or falls off from the wall of the tube. Under a fixed swing amplitude and period, the perturbation on the film is greater at the edge of the swing, whereas the flow is smoother at the middle of the swing. When the mass flow rate is 0.28 kg/min, the coefficient of performance (COP) of the system reaches the maximum at the swing amplitude of 8° or a period of 10 s. However, the COP will reach the maximum at a swing amplitude of 10° or a period of 8 s when the mass flow rate is 0.14 kg/min. The results also showed that when the flow rate is higher, the perturbation of the swing is greater
