現今有需多ＬＮＧ蒸發器已被應用於工業上，例如開放式蒸發器、自然空氣蒸 發器、沉浸式蒸發器及中間流體式蒸發器。由於ＬＮＧ在運送目的地時需要透 過再汽化過程能於管線中運輸，因此改善再汽化過程式重要的課題。由於目前 較常用於再汽化過程之蒸發器為殼管蒸發器，其再汽化過程需要大量的熱傳面 積，導致蒸發器體積需求很大，成本造價昂貴。中間流體式蒸發器由於其密集 式的設計及有較高的性能，因此能應用於改善成本昂貴的問題。 本研究透過改善中間流體式蒸發器（本文為板式熱交換器）來取代原本的殼管 式蒸發器以提高其熱傳性能。本實驗分析六種不同冷媒於不同飽和溫度之熱傳 性能影響。實驗結果顯示，隨著飽和溫度的提高，蒸發器所需要的熱傳面積會 增加，冷凝器上的熱傳面積會縮小，兩者相加達到最小面積在飽和溫度為２４ ７Ｋ。此外，在不同冷媒實驗中以二甲醚之熱傳性能為最佳。 實驗還針對上述兩種不同蒸發器之應用進行分析與比較。結果顯示相比殼管式 蒸發器，板式熱交換器的熱傳面積可以減少４００％，而熱傳性能也比殼管式 蒸發器多了４倍。此外，實驗也針對不同地點蒸發器設置進行比較與討論。由 於海水的平均溫度會影響中間流體式蒸發器的設置地點，在海水平均溫度較高 的國家，適合安裝中間流體式蒸發器。然而在海水平均溫度較低的國家，中間 流體式蒸發器與殼管式蒸發器所需要的熱傳面積差異小於２５％，因此相較於 前者，兩者差異沒有很大。 ;The required regasification terminal of LNG remains researchers to develop a new model for LNG vaporizer to decreasing the cost. Various LNG vaporizer has been developed, such as open rack vaporizer, ambient air vaporizer, submerged combustion vaporizer, and intermediate fluid vaporizer. Intermediate fluid vaporizer remains the lowest cost due to its compact design and high thermal performance. However, the existing model was employing shell and tube as a thermolator to reheating natural gas to become superheated natural gas. It contributes more than 50% of the total required heat transfer area of the system, as found by the previous study. Furthermore, this study has been conducted by modified the IFV in replacing the shell and tube heat exchanger of thermolator to plate heat exchanger to enhance the heat transfer performance. The effect of six intermediate fluids on the heat transfer performance is compared in a wide saturation temperature range. Dimethyl ether has the best performance compared to the rest of the intermediate fluids. The required heat transfer area on the evaporator increased and on the condenser decreased with an increasing intermediate fluid saturation temperature. The minimum required heat transfer area for both condenser and evaporator is at 247 K. The pressure drop in the evaporator increased with saturation temperature. Moreover, The replacing shell and tube to the plate heat exchanger on the thermolator of IFV were compared and analyzed. Employing plate heat exchanger in thermolator can reduce 400% of the required heat transfer area and result in four times higher heat transfer coefficient by replacing shell and tube. In addition. The location of the installation modified IFV due to its average seawater temperature was discussed. The countries with higher average seawater temperatures, the most economically suitable for installing the modified IFV. Although it is installed in the lower average seawater temperature, the heat transfer area contributions from the plate heat exchanger thermolator are not as lower as 25% of the heat transfer area of the rest of the system. It is much lower than the heat transfer area contributions of the shell and tube thermolator to the entire system that have been done by the previous work.
