抗凝水抗結冰低溫廢冷回收裝置之設計與測試研究

Abstract

本論文是研究一個利用低溫氮氣進行廢冷回收的熱電發電裝置。藉由實驗驗證此裝置克服了凝水以及結冰之問題，成功發出電能，研究並探討熱電晶片的層數與分布方式對發電效率之影響。從實驗結果發現，在同一種晶片設置下，輸出功率會隨流量增加而增加；當晶片的層數相同時，每側只在熱擴散塊中間黏貼晶片時的輸出功率會較每側貼滿晶片時高；而當熱擴散塊每側黏貼晶片的情形相同時，黏貼三層時的輸出功率會比只黏貼一層時高。 接著藉由理論模型輔以實驗數據進行探討。黏貼一層時，晶片冷端溫度隨著氮氣流量增加而增加，而黏貼三層晶片時，晶片冷端溫度有著相反的變化趨勢。而晶片熱電參數的部分，從四種晶片排列中得到的賽貝克係數大部分都小於廠商提供的數據。晶片內電阻則隨著溫度上升而增加，且與熱端溫度呈現線性關係。所有實驗中，最大發電功率以及最大實驗發電效率分別為0.93W和2.67%，且均發生在每側只在熱擴散塊中間黏貼三層晶片、氮氣流量達到245SLPM時。

In this thesis, a waste-cold-recovery system which can extract cold energy from cryogenic nitrogen and generates electricity in use of thermoelectric power generators (TEGs) is investigated experimentally. The system is proved to be anti-icing and anti-condensing; effects of the number of the layer of the TE chips and the distribution of the TE chips are explored. The experimental results show the output power increases with the flow rate for a given layout of the TE chips; when the number of the layer of the TE chips is fixed, the output power is larger when the thermal spreader is only middle covered by TE chips than when it is fully covered. When the distribution over the thermal spreader of the TE chips is fixed, the output power in the three-layer layout is larger than that in the one-layer layout. A theoretical analysis and experimental data are further studied to explore the system. The cold-side temperature of the one-layer layouts increases with the flow rate; an opposite trend is observed however from the measurements associated with the three-layer cases. For the properties of the TE chips, most of the Seebeck coefficients obtained are smaller than the value provided by the manufacturer. The internal resistances increase with the temperature and a linear dependence on the hot-side temperature is found. Among all tests, the largest output power and the largest efficiency are 0.93W and 2.67% when the thermal spreader is middle covered by three layers of TE chips and the flow rate of the nitrogen is 245SLPM.