利用熱電晶片除濕與熱回收技術應用於家用烘乾機之節能效益研究

Abstract

本研究利用熱電冷凝冷回收式除濕和熱交換器除濕與熱回收的方法，分別對於家用高耗電量的電器設備進行節能效益研究。 對於熱電冷凝冷回收除濕實驗，首先探討除濕系統於自然對流式除濕系統與強制進氣式冷回收除濕系統進行性能比較，透過本研究冷回收通道的設計，以強制進風的方式，將通過冷端鰭片之低溫空氣回收利用，並透過風扇將低溫空氣全部導入熱端鰭片對其進行輔助散熱，此方法不但能提高熱端的散熱能力，使冷端鰭片冷凝能力提升，亦能降低除濕機出口排放溫度，減少室內因需長期除濕而使空間溫度升高，又得開啟空調降溫至人體舒適溫度所額外消耗過量的電力。而針對冷凝面下方的滴狀冷凝研究，本研究提出冷凝面傾斜特殊的角度與除濕效率之間的相關性，實驗當中分別透過非垂直的四種不同的鰭片傾斜角度(〖38〗^o 、〖52〗^o 〖、66〗^o 〖、80〗^o)進行冷凝液滴形成現象進行分析與其除濕量之比較。最後為熱回收技術實驗，本研究使用熱交換器與熱回收裝置，針對高耗能與排放廢熱量高的烘乾機進行實驗，實驗方法為將烘乾機排出的高溫高濕氣體，利用熱交換器將排出的氣體進行除濕，同時引進外氣進行預熱，最後將兩種氣體搭配熱回收控制系統進行混合與最佳比例的調配，並利用國際對於烘乾機認證的性能指標-單位能耗除濕量(Specific Moisture Extraction Rate)進行計算，進行性能比較。 由實驗結果可知，強制進風冷回收式除濕系統，比自然對流無冷回收式系統提升48.8%的除濕量。而傾斜式冷凝方面，在冷端鰭片傾斜角度在〖52〗^o時有最佳的除濕量，又與強制進風垂直式除濕系統相比，能更提升7.5% 的除濕量與減少11%的出風口溫度，且一天總耗電量僅為1.3度，非常具有節能特色。而對於熱回收除濕技術方面，加裝熱交換器的烘乾性能SMER值比未加裝前還低19%。實驗再將其結合熱回收裝置進行實驗，結果顯示，當除濕後的排氣與預熱後的外氣回收混合比例為6:4的時候，系統呈現出最佳及最低的烘乾性能指標SMER值 (1.086)，其節約電量百分比亦高達最佳的18%。

This study investigated the energy efficiency of high energy-consuming appliances by examining thermoelectric cooling, cold-recovery condensation dehumidification as well as a heat exchanger’s dehumidification and heat recovery. To conduct an experiment for the thermoelectric, cold-recovery condensation dehumidification, this study first compared the performance of a dehumidifier based on natural convection and a cold-recovery dehumidifier based on forced air intake. In the study’s cold-recovery channel, forced air intake was employed to recover and reuse the low-temperature air passing the evaporator; then, a fan was used to transfer the low-temperature air into the condenser to remove the heat in the condenser. This method improved the heat removal, enhanced the condensation by the evaporator, and reduced the temperature of outlet air from the dehumidifier, thereby eliminating the problem of excessive electricity used by air-conditioning system. This mitigate the problem of additional electricity used by air-conditioning systems for reducing the increased indoor temperature, which is caused by continuous dehumidification for a long time, to a comfortable range for human body. Investigating on the condensed drips below the evaporator, this study proposed a correlation between the tilt angle of the evaporator and the dehumidification efficiency. An experiment was conducted by analyzing the drip condensation and comparing the dehumidification performance of the dehumidifier when its evaporator was positioned in four different angles, namely 38°, 52°, 66°, and 80°. In terms of heat recovery, this study used a heat exchanger and heat-recovery device in an experiment on appliances exhibiting high energy consumption and waste heat. In the experiment, a heat exchanger was used to dehumidify the high-temperature and humid air exhausted from a dryer; concurrently, ambient air was drawn to the heat exchanger and preheated. Then, the two types of air were mixed in various ratios by using a heat-recovery device to identify the optimal amount of heat recovery. The specific moisture extraction rate (SMER), an international performance indicator for dryers, of the dryer was calculated to analyze its performance. According to the experimental results, the forced-air-intake cold-recovery dehumidifier achieved a higher amount of dehumidification than the natural-convection dehumidifier without cold recovery by 48.8%. Regarding the tilt angle of evaporator, the dehumidifier with an evaporator tilt angle of 52° achieved optimal dehumidification efficiency and, compared with the forced-air-intake dehumidifier whose evaporator was positioned vertically, exhibited a higher amount of dehumidification and a lower temperature of outlet air by 7.5% and 11%, respectively. Additionally, the dehumidifier with an evaporator tilt angle of 52° was highly capable of energy saving, consuming only 1.3 kWh a day. With regards to the heat recovery method, the dryer’s SMER was reduced by 19% after it was installed with a heat exchanger. The experimental results also revealed that, in the dryer installed with a heat-recovery device, the optimal SMER (1.086) and percentage of electricity saved (18%) were achieved when the mixing ratio of the dehumidified air exhausted by the dryer to the preheated air collected from the ambient air was 6:4.