利用離子溶液吸收與冷凝除濕之熱質傳理論與實驗研究

Abstract

本研究利用離子溶液搭配冷凝除濕系統相較傳統冷凝系統能有效減少能耗，能減少傳統冷凝需再熱至供風需求等熱矛盾問題，除此之外利用吸收端的平行流以及交叉流理論模型來分析熱質傳效應，以方便之後設計系統時的依據。 實驗系統利用液態除濕再生端將空氣預先加濕，使空氣經過冷凝除濕端時能以更少的冷卻負載達到相變化，此外冷凝除濕後的空氣經過溶液吸收除濕端有加熱除濕效果相比傳統冷凝可減少再熱的多餘能耗。 研究變因為混風比、冰水入口溫度、溶液流量、同濕度比下外氣溫度以及外氣模擬氣候等，實驗結果顯示混風比由100%降至25%時除濕比增幅16%，於25%時有最低濕度比11.55g/kg，並且節電效率增加12%；冷凝熱交換器冰水入口溫度越低除濕量以及節電效果越好從16°C至10°C增加70%的除濕比且節電效率增加11%，；溶液流量由1.6LPM上升至2.2LPM除濕比增加37%，而節電效率則是2.0LPM時最佳為32.11%較1.6LPM成長約8%；同樣濕度比下外氣溫度24°C上升至30°C，除濕比降低12%，相反的節電效率增加8%；模擬氣候下春秋季節有最佳的出口濕度比11.46g/kg，夏季時則有更好的節電效率27.07%。 實驗系統吸收端採平行流，模擬結果與交叉流相比熱質傳系數趨勢相近，其中質傳系數平行流均略低於交叉流4%不等，將理論模型中質傳系數與傳統冷凝除濕再熱的節能量進行擬合，可用於預測及設計系統出入口參數以達到節能需求。

This study combines ionic solution with a condensation dehumidification system to effectively reduce energy consumption compared to traditional condensation systems. This approach mitigates the heat conflicts associated with traditional condensation systems that require reheating to meet the air supply demand. Additionally, a parallel flow and counter flow theoretical model is employed to analyze the heat and mass transfer effects, providing a basis for the future design of systems. In the experimental system, the air is pre-humidified at the liquid dehumidification regeneration end, allowing the air to undergo phase change with less cooling load when passing through the condensation dehumidification end. Moreover, the air after condensation dehumidification undergoes heating dehumidification when passing through the solution absorption dehumidification end, reducing the unnecessary energy consumption associated with reheating in traditional condensation systems. Various parameters were studied, including the mixing air ratio, chilled water inlet temperature, solution flow rate, outdoor air temperature at the same humidity ratio, and simulated climate conditions. The experimental results showed that reducing the mixing air ratio from 100% to 25% increased the dehumidification ratio by 16%, reaching the lowest humidity ratio of 11.55 g/kg at 25%, with a 12% increase in energy-saving efficiency. Lowering the chilled water inlet temperature of the condensation heat exchanger resulted in better dehumidification and energy-saving effects. For instance, decreasing the temperature from 16°C to 10°C increased the dehumidification ratio by 70% and the energy-saving efficiency by 11%. Increasing the solution flow rate from 1.6 LPM to 2.2 LPM led to a 37% increase in the dehumidification ratio, with the optimal rate at 2.0 LPM showing a growth of about 8% in energy-saving efficiency. Similarly, raising the outdoor air temperature from 24°C to 30°C under the same humidity ratio reduced the dehumidification ratio by 12%, but conversely increased the energy-saving efficiency by 8%. Simulating climatic conditions, the system showed the optimal exit humidity ratio of 11.46 g/kg in spring and autumn, while in summer, it exhibited better energy-saving efficiency at 27.07%. The experimental system adopts parallel flow at the absorption end. Comparative analysis between the simulation results and counter flow reveals a similar trend in heat and mass transfer coefficients, with the parallel flow coefficients slightly lower than counter flow by varying percentages, generally around 4%. The theoretical model''s coefficients and the energy-saving capacity of traditional condensation dehumidification and reheating are fitted, providing a predictive tool for designing systems to meet energy-saving requirements.