發泡金屬應用於熱電模組之性能分析

Abstract

本研究在固定熱側集熱器面積下，測試10種不同類型的熱交換器，包括：銅平板、發泡銅、黑體漆平板與發泡碳，其中發泡銅以不同孔數率與孔隙度進行比較。以實驗的方式探討不同熱交換器應用在熱電系統時的發電效率。 應用於實際廢熱回收中，藉由高廢熱溫度、高環溫以及距離近可增加對流熱傳量與輻射熱傳量，總熱傳量提高使熱電模組效率增加。固定10PPI改變孔隙度，熱傳量雖比同平板高，但有效距離變大，使熱傳量無法反映到熱側溫度，使效率比平板低。比較高度5mm，40PPI與50PPI發泡金屬，50PPI藉由高表面積增加對流熱量，但亦使熱側溫度下降，效率下降24.2~35.9%。 加熱器350℃黑體平板因放射率增加，增加輻射熱傳量，使效率增加1.16~3倍，而10PPI發泡金屬噴塗黑體漆後效率增加2.4~5.6倍。發泡碳效率比黑體平板較高，且加熱器350℃距離10mm有最大效率1.3%。

Thermoelectric generation has received higher attentions in recent year. This research aims to improve the Thermoelectric generation efficiency by changing operating conditions and hot side heat exchanger, including copper plate, metal foam, blackbody plate and carbon foam. The results present by high heater temperature, high ambient temperature and approaching the heater will get larger heat transfer rate. And it leads to higher efficiency. Fixed 10PPI change porosity, even though it get more heat transfer rate because of high surface area, it also caused temperature gradient. At the same high 5mm, 50PPI metal foam enhance natural convection heat transfer rate by larger surface area. But larger surface area also leads to lower hot side temperature. The efficiency decrease 24.2~35.9%. Besides, higher emissivity and carbon foam enhances more radiative heat transfer and lead to higher efficiency. After painting blackbody, the plane efficiency raise 1.16~3 times, 10PPI metal foam enhance 2.4~5.6 time. And carbon foam at heater temperature 350℃ and 10mm away from heater get the highest efficiency.