Visualization and measurement of adsorption and desorption process in activated carbon/ethanol pair adsorber.

Estimation of refrigerant distribution in adsorbent bed is important to design an adsorber of an adsorption refrigerating system, because the adsorption and desorption process is complex phenomena with heat and mass transfer, and strongly effects on the cycle performance. The adsorbed refrigerant distribution in a rectangular adsorber was visualized and measured by a neutron radiography method for activated carbon and ethanol pair. Quantitative measurement of adsorbed refrigerant amount was realized by applying the umbra method to compensate neutron scattering effect. It was confirmed from the visualization of adsorbent in equilibrium that the measured results from the radiographs were agreed well with the previous data measured by a weight method. In the experiments of adsorption and desorption process with heat transfer, transient behaviors of adsorbed refrigerant distribution could be clearly visualized. It was clarified from the results that the refrigerant adsorption was dominated by heat diffusion in the adsorbent bed, and adsorbed amount became higher around the heat-transfer surface including fins.

吸附床（adsorbent bed）内制冷剂分布的估算对于吸附式制冷系统（adsorption refrigerating system）吸附器的设计具有重要意义，因吸附与脱附过程属于伴随热质传递的复杂现象，且对循环性能影响显著。本研究针对活性炭-乙醇工质对（activated carbon and ethanol pair），采用中子射线照相法（neutron radiography）对矩形吸附床内的吸附态制冷剂分布进行了可视化观测与定量测量。通过应用本影法（umbra method）补偿中子散射效应（neutron scattering effect），成功实现了吸附态制冷剂含量的定量检测。通过平衡状态下吸附剂的可视化结果验证，本次中子射线照相法的测量结果与此前采用重量法（weight method）获得的实验数据吻合良好。在伴随传热过程的吸附与脱附实验中，研究清晰观测到了吸附态制冷剂分布的瞬态演化行为。实验结果表明，制冷剂吸附过程受吸附床内的热扩散（heat diffusion）主导，且在包含翅片的传热表面（heat-transfer surface）附近，吸附量相对更高。