複合除濕材料結合熱泵應用於空調系統之性能研究

Performance investigation of composite desiccant combined with heat pump for air-conditioning systems

陳志豪(Chih-Hao Chen)

指導教授 ： 陳希立

國立臺灣大學/工學院/機械工程學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.11179

摘要

本研究之目的為開發一除濕空調設備，期望以節能的方式引進室外新鮮空氣，營造一「室內空氣品質優化」及「綠色環保」之生活空間。本文藉由實驗方式進行除濕材料的性能研究、複合材料除濕轉輪結合熱泵系統性能測試，與循環流體化床結合熱泵系統模擬測試之研究探討。
在除濕材料性能研究方面，本文首先藉由實驗研究針對矽膠顆粒、氧化鋁顆粒、高分子顆粒、矽藻土顆粒及分子篩顆粒等除濕材料，進行基礎性能測試及週期運轉性能測試，藉由改變再生溫度及測試週期時間，分析探討各除濕材料之吸附與再生性能，由研究結果顯示，矽膠填充床轉輪具有較高除濕性能與較低的出口溫升量，為最適用應用於除濕轉輪結合熱泵系統。為了有效的降低壓降與提高相對濕度下的除濕性能，使用矽膠顆粒與高分子製作出具有空氣流道的複合材料，在風速為2.5m/s時可以使壓降比填充床系統降低40％。在相對濕度90％的操作情況下，矽膠、聚丙烯酸與聚丙烯酸鈉以10：1：1比例製成之低壓降複合材料具有最佳的除濕性能與硬度，因此做為後續研究的主要材料應用於除濕轉輪結合熱泵系統。除溼轉輪結合熱泵系統是利用熱泵的熱源再生除溼轉輪，而冷源則用來進行冷凝除溼，外氣先經過蒸發器被冷凝除濕，使空氣變為低溫高濕的狀態，高濕的空氣狀態可使除濕轉輪的性能發揮到最大值，因此可以有效地進行第二階段的吸附除濕，熱泵的冷凝器使空氣溫度保持在40-50℃，利用此低溫熱源對轉輪進行再生達到連續操作的目的。
複合材料除濕轉輪結合熱泵系統性能測試部份，複合材料除濕轉輪因為較低的壓降，可以提高熱泵的性能並降低風機的耗能，複合材料在高相對濕度狀態下的除濕性能也優於矽膠填充床，因此系統總除濕性能在夏天可以達到7 g/kg，能源因素可以達到2.3 kg/kW·hr。循環流體化床結合熱泵系統測試方面，利用循環流體化床自然流動的特性，配合特殊流道設計，使除濕材料顆粒可以在流體化飛舞的過程中以一定機率落入漏斗做成的收集器中，並透過流道進入再生床體，再生完成後再以同樣的方式回到吸附床體中，與傳統除濕轉輪系統相比，此系統不需使用馬達帶動轉輪循環操作，加上流體化床的壓降更低，可以進一步降低耗能，流體化床系統相對於填充床系統，依造不同特性的除濕材料平均可以提升除溼能力10％-15％、降低壓降30％-60％與降低出口溫昇25-35％，利用高分子顆粒與矽膠顆粒以3：7的方式混和後，可以有效的降低流體化床造成的粉層問題，最後，循環流體化床結合熱泵系統的測試結果顯示系統的能源因素E.F.值可以達到2.8 kg/kW·hr。對於推廣於民生商場、辦公大樓等公共場合具有更高之優勢。

關鍵字

除濕材料 ； 複合材料 ； 熱泵 ； 循環流體化床 ； 低壓降 ； 高分子除濕材料

並列摘要

The purpose of this study is to develop a desiccant air conditioning equipment introducing fresh outdoor air with an energy-efficient way, and creating an " Excellent indoor air quality" and " Green" living space. This article experimentally studied the dehumidification performance of different desiccant materials, composite desiccant wheel combined with heat pump system, and circulating fluidized bed combined with heat pump system.
In the desiccant basic tests, we tested four types of isotherms of desiccants to find a suitable desiccant material for the desiccant wheel/heat pump system. The main materials used are silica gel, polyacrylic acid, activated alumina, a molecular sieve, and diatomite. By changing the regeneration temperature and test cycle, the adsorption and regeneration performance of each desiccant material are analyzed and discussed. The results showed that silica gel packed bed has higher performance and lower outlet temperature, as the most suitable desiccant for desiccant wheel combined with heat pump system. In order to effectively reduce the pressure drop and to enhance the dehumidification performance in a high relative humidity condition, silica gel and polymer are used to produce a composite desiccant wheel with air flow channels. When the wind speed is 2.5 m/s, pressure drop of composite desiccant system can be reduced by 40% compared to the packed bed system. At a relative humidity of 90% operating conditions, composite desiccant producing by silica gel, polyacrylic acid and sodium polyacrylate with a ratio of 10: 1: 1 has the best dehumidification performance and hardness, and then as an main material to the follow-up study. The desiccant wheel combined with a heat pump system uses the released heat from a heat pump as the heat source to regenerate a silica gel/polymer composite desiccant wheel and also uses the adsorb heat of the heat pump to dehumidify the processed air by condensing it and creating a high relative humidity condition, which helped to improve the performance of the composite desiccant wheel. The desiccant wheel was placed behind the evaporator to handle the second stage of dehumidification.
In the composite desiccant wheel combined with a heat pump system performance testing, the heat pump can improve it’s performance and the fan can reduce the energy consumption by the lower pressure drop of composite desiccant wheel. The dehumidification performance of the composite desiccant is also excellent at a high relative humidity state. Comparing with silica gel basic system, the dehumidification performance of the composite desiccant basic system in the summer can reach 7 g / kg and the energy factor can reach 2.3 kg / kW • hr. In the Circulating fluidized bed combined with heat pump system test, the fans drive desiccant particles upward to form fluidized beds; as the particles descend, funnels inside the beds allow particles to move between absorption and desorption beds through connecting pipes. The particles circulate between beds to create a continuous operating dehumidification air conditioning system, compared with desiccant wheel systems, this system does not need to use a motor to drive the desiccant wheel, and has a lower pressure drop that energy consumption can be further reduced. The fluidized bed system relativing to the packed bed system can increase the dehumidification performance by 10% -15%, reducing the pressure drop by 30% -60% and reducing the outlet temperature by 25-35% according to the different desiccant materials. Polymer and silica gel with a ratio of 3: 7 effectively reduce the dust pollution caused by the fluidized bed. Finally, circulating fluidized bed combined with heat pump system showed that the energy factor can reach 2.8 kg / kW • hr. These aspects collectively make the system desirable for use as a residential air conditioning system.

並列關鍵字

desiccant ； composite material ； heat pump ； circulating fluidized beds ； low pressure drop ； polymer desiccant material

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