本研究針對使用螺旋板式熱交換器應用在固態氧化物燃料電池系統中前端空氣預熱，並分別探討在不同燃燒尾氣組成比例、不同入口雷諾數情況下的熱傳分析。由於螺旋板式熱交換器具有高密集度、能自清潔、理論熱損失極小的優點，同時固態氧化物燃料電池系統中為了提升系統的整體效率，通常會將反應完或燃燒後的氣體回收並且應用於前端燃料及氣體進行預熱，因此本文將討論螺旋板式熱交換器應用於固態氧化物燃料電池系統前端空氣預熱的熱傳現象。
根據上述目的，在本研究中考慮二維螺旋板式熱交換器模型，其軌跡可以由阿基米德螺旋線表示，並探討在氣體比例效應與流速效應下，螺旋板式熱交換器中的溫度、對流熱傳係數、紐塞數、換熱效能等差異。從數值模擬結果得知水蒸氣的比例是影響熱交換器效能的重要參數。其中，當雷諾數等於1000，水蒸氣含量最多的Case1換熱效能會比含量最少的Case3高出約4%，同時隨著入口雷諾數的增加，水蒸氣含量較高的Case1與含量較少的Case3間空氣出口溫度差也會逐漸提升，當入口雷諾數從250提升至1000時，空氣出口溫差也從7K提升至37K。
另一方面，當流體雷諾數增加，熱交換器的溫度及熱傳分布也會隨之改變。從結果可知，熱交換器冷流中間區域與內外半圈的熱傳現象會隨著雷諾數增加而差距會越來越大，由本文中Case1結果可知，在低雷諾數時中間溫差約330K，但在高雷諾數時中間溫差會提升至702K。而隨著雷諾數的增加，入口附近的對流熱傳係數反而會降低，出口附近的對流熱傳系數會先提升後降低，但對冷流總體而言仍然是提升的，雷諾數250與雷諾數1000相比，局部對流熱傳係數最大提升約36.5%，局部紐賽數最大提升約56.7%。在熱流中，隨著雷諾數的增加，因為質量流率的增加出口溫度反而會提升，在低雷諾數時出口溫度為1100K，但在高雷諾數時的出口溫度為1131K。隨著雷諾數的增加，局部對流熱傳係數與局部紐賽數皆會增加，雷諾數250與雷諾數1000相比，局部對流熱傳係數增加的最大幅度約為26.6%，局部紐賽數增加約為10.9%。
根據本研究的分析結果可以發現，水蒸氣比例與流體雷諾數會影響熱交換器的溫度與熱傳能力，此結果能夠提供未來固態氧化物燃料電池系統設計過程中作為參考數據，並且減少產業進行系統設計與實驗之成本。

This research investigates the heat transfer of a Spiral Plate Heat Exchanger (SPHE) applied to air preheating process for Solid Oxide Fuel Cells (SOFC) system by numerical simulation, and discusses the analysis under different compositions of afterburner exhaust and different inlet Reynold number. Owing to the advantages of SPHE such as high density, self-cleaning capability, and minimal theoretical heat loss compared to other types of heat exchangers, it has the potential to reduce waste heat generation and improve overall heat transfer efficiency. At the same time, to enhance the overall efficiency in SOFC systems, it is common practice to recycle the reacted or afterburned gases back to the front end for preheating. Therefore, this research discusses the application of a SPHE for air preheating in SOFC systems.
To achieve the above objectives, a two-dimensional SPHE model is considered in the research, with its trajectory can be represented by an Archimedean spiral. Numerical analysis of computational fluid dynamics (CFD) are applied to discretize the governing equations by using the Finite Volume Method (FVM), and the influence of different compositions exhaust and different inlet Reynolds numbers on air preheating is investigated, such as temperature distribution, convective heat transfer. In order to get accuracy simulation, using the condition of air preheating for SOFC system and investigating the temperature, convective heat transfer coefficient, Nusselt number and effectiveness of SPHE. When the inlet Reynolds number is equal to 1000, the heat transfer efficiency of Case1 with the most water vapor content is about 4% higher than that of Case3 with the least water vapor content. The air outlet temperature difference between Case3 will also gradually increase. When the inlet Reynolds number increases from 250 to 1000, the air outlet temperature difference also increases from 7K to 37K.
On the other hand, as the inlet Reynolds number of the fluid increases, the temperature and heat transfer distribution of the heat exchanger will also change accordingly. It also can be observed that the difference of the heat transfer between the middle area of the cold flow of the heat exchanger and the inner and outer half circles will increase as the inlet Reynolds number increases. From the results of Case1 in this research, the temperature difference is about 330K at low inlet Reynolds numbers. But at high inlet Reynolds number, the temperature difference will increase to 702K. As the inlet Reynolds number increases, the convective heat transfer coefficient near the inlet will decrease, but it will still increase for the cold flow overall. Compared with the inlet Reynolds number 1000, the convective heat transfer coefficient increases by about 33%. The Nusselt number increased by about 45%. In hot flow, as the inlet Reynolds number increases, the outlet temperature will increase due to the increase in mass flow rate. The outlet temperature is 1100K at low inlet Reynolds number, but 1131K at high inlet Reynolds number. As the inlet Reynolds number increases, both the convective heat transfer coefficient and the Nusselt number will increase. Compared with the inlet Reynolds number 250 and the inlet Reynolds number 1000, the convective heat transfer coefficient increases by about 19%, and the Newey number increases by about 20%.
According to the analysis results of this research, it can be concluded that the steam ratio and fluid inlet Reynolds number affect the temperature and heat transfer capability of the heat exchanger. The result can provide reference data for future design processes of solid oxide fuel cell systems, and help reduce industrial cost of system design and experimentation.

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