多U型地埋管熱交換器應用於地源熱泵系統之分析

Abstract

地源熱泵系統是透過淺層溫能作為冷源或熱源，滿足室內冷負荷或熱負荷之需求，所以熱泵與淺層溫能進行熱交換之方式會大大影響地源熱泵系統之性能。本研究開發出一個以水作為回填材料之多U型地埋管熱交換器來利用淺層溫能，其與殼管式熱交換器運作模式相似，透過殼側抽取地下水進行強制對流來提升熱交換效果。本研究將此多U型地埋管熱交換器結合一淺層溫能雙效熱泵，並對此系統進行研究與分析。 本研究首先對多U型地埋管熱交換器之性能進行分析，分別以管側流量、殼側抽水量、熱交換器底部與補水孔底部距離作為參數進行實驗。實驗結果顯示，當管側流量為92LPM、殼側抽水量為73LPM、熱交換器底部與補水孔底部距離為1.6m時有最佳之熱傳性能。以此參數之多U型地埋管熱交換器應用於淺層溫能雙效熱泵，在制冷模式時，此系統之制冷性能係數(COP)為5.64，比一般冰水主機使用冷卻水塔進行散熱之性能高出約18%，在制熱模式時，此系統之平均制熱性能係數(COP)為4.99，比一般水對水熱泵熱水器之性能高出約38%，說明使用多U型地埋管熱交換器來利用淺層溫能時可提供穩定散熱源和取熱源，並有效提高熱泵主機之性能。

Ground Source Heat Pump(GSHP) System used Shallow Geothermal Energy to cool down or heat up of buildings, so the heat exchanging between Heat Pump and Shallow Geothermal Energy is important to GSHP’s performance. Here, a multi-U type borehole heat exchanger which uses groundwater as backfilled material and has similar operation mode to the shell-and-tube heat exchanger was designed. This heat exchanger has forced convection of groundwater through shell side to enhances heat exchanging. This study analyze the performance of GSHP combined with multi-U type borehole heat exchanger. This study analyzes the performance of multi-U type borehole heat exchanger with different parameters which included the water flow inside tube, ground water pumping capacity and the distance between the bottom of heat exchanger and the ground water well. The results showed that 92LPM, 73LPM and 1.6m of the water flow inside tube, ground water pumping capacity and the distance between the bottom of heat exchanger and the ground water well respectively are the best parameters for our system. At the best of our system, it showed the cooling coefficient of performance(COP) of GSHP cooling mode is 5.64 and a better cooling performance with 18% higher than conventional water chilling packages, the average heating coefficient of performance(COP) of GSHP heating mode is 4.99 and a better heating performance with 38% higher than conventional heat pump water heaters.This study showed using multi-U type borehole heat exchanger can provide a stable cooling and heating way of GSHP systems, and it can improve Heat Pump’s performance.