本研究分為兩個部分，第一部分主要對H型鋼熱軋過程中之快速冷卻進行研究。H型鋼作為綠色建築的新型鋼材具有結構強度高、自重輕、工程施工快且佔地面積小等優點，但其熱軋製程極其複雜，為了增強H型鋼的機械材料性能，需對其軋後冷卻過程進行嚴格控制。本部分以數值模擬對H型鋼之快速冷卻進行最佳化分析並輔以雙噴嘴射流衝擊冷卻實驗對高溫鋼板表面之h值進行逆向求解；第二部分主要對煉鋼廠熱風爐之運作方式及其熱應力進行分析，熱風爐之功能乃供給高爐高溫熱風，是影響煉鐵產量的重要設備之一。本部分研究主要對熱風爐運作期間之熱流場進行數值模擬並與現場溫度量測值進行比對，並結合溫度場對熱風爐之熱應力進行分析。各部分之研究內容如下:
H型鋼之快速冷卻部分乃利用共軛梯度法結合三維熱力耦合模型對H型鋼均勻快速冷卻之熱傳係數進行最佳化分析，同時輔以雙噴嘴射流衝擊冷卻實驗對高溫鋼板快速冷卻之h 值分佈進行逆向求解，用以掌握H型鋼在軋後冷卻過程中多噴嘴衝擊冷卻時，由噴嘴間距、噴嘴流量、噴嘴高度及干涉效應等因素對其冷卻效果之影響。對於H型鋼均勻快速冷卻之熱傳係數最佳化分析部分，主要探討三種不同尺寸之H型鋼 ( H300×300, H250×250, 和H200×200) 在控制冷卻過程中之溫度分佈和殘餘應力分佈，研究發現在同樣的計算條件下 (初始溫度為850℃，冷卻後的平均溫度為550±10℃)，採用共軛梯度方法計算之最佳熱傳係數分佈可以產生更均勻之溫度分佈和更小之殘餘應力，不同尺寸之H型鋼最大溫差分別降低57℃，74℃和75℃，表面最大溫度差減少60〜80℃，腹板殘餘應力可以減少20〜40 MPa。對於雙噴嘴射流衝擊冷卻實驗部分，根據實驗試件建立三維數值模型，並使用共軛梯度法之逆向求解方法來計算鋼板冷卻過程中表面之傳熱係數分佈。實驗和數值結果均表明在兩個噴嘴噴射衝擊區域之間會出現干涉區域（會產生干涉效應），且干涉間距隨噴嘴流量和噴嘴高度以及噴嘴間距的變化而變化。隨著水流在鋼板表面上擴散，散熱區域逐漸從衝擊區域延伸到干涉區域和流動區域，在水流濕前沿到達處熱通量達到峰值，同時，熱通量之峰值隨著與衝擊區域之距離增加而減小。逆向計算結果顯示最大局部傳熱係數約為23000 W/(m2-K)，而平均傳熱係數在一定範圍內隨著水流速的增加而增加，但隨著噴嘴間距的增加而減小。鋼板表面之熱傳係數在衝擊區域最大，干涉區域次之，流動區域最小，干涉區域產生之干涉效應會明顯增加熱傳效果，即干涉效應的產生會增加鋼板表面之熱傳係數。
熱風爐之操作過程在一個週期內可分為燃燒期和送風期。本研究以中鋼34# KK type熱風爐之實際模型建立熱風爐之三維物理模型，蓄熱磚部分採用非平衡多孔性介質(non-equilibrium porous medium)模型進行簡化，且熱流場計算中壁磚進行等效簡化，並將模擬之溫度值與中鋼實測數據比對，結果發現Point A（拱頂），Point B（flue outlet）和Point C（hot blast outlet）最大誤差值分別為2.5%，6.4%和6.2%，均在7%以內。從模擬結果可以看出，在燃燒期和送風期流體流速隨著流道截面積和溫度的變化，其範圍分別為6 m/s～24 m/s、0.9 m/s～8 m/s。在燃燒期內，蓄熱室內流體溫度高於蓄熱磚溫度，而在送風期內，蓄熱磚溫度高於流體溫度，且在整個週期內，蓄熱室內蓄熱磚和流體之溫度均隨高度之增加而增加，蓄熱磚與流體之溫差約為10℃~35℃，熱風爐不同位置壁磚內外表面之溫差範圍為207～1100℃，拉應力(第一主軸應力)主要集中於壁磚外壁面，除了頸部外應力均在20 MPa以內，壓應力(第三主軸應力)主要集中於壁磚內壁面，除了底部外應力均在-25 MPa以內。其形變量整體表現為向上向外膨脹，最大形變量發生在燃燒室內部頂端處約為200 mm，燃燒室/蓄熱室拱頂及連接管處形變量僅與鐵殼形變量有關而與爐身之形變量之間相互獨立。熱風爐鐵殼整體形變量表現為向上向外自由膨脹，形變量最大發生在燃燒室拱頂頂部，其最大形變量約為30 mm。鐵殼主要承受拉應力，且應力主要集中於頸部、燃燒室/蓄熱室拱頂和連接管以及熱風支管與爐身交接處，壓應力主要集中於各部位連接處。

This study is divided into two parts. The first part is investigated to obtain the design requirements for maximum uniform temperature distributions and minimal residual stress after controlled cooling for the H-shape steel beams. At the meantime, in order to obtain the heat transfer coefficient distributions, a experimental of dual spray water nozzle impingement cooling are used to investigate the cooling character of the flat plate using for the spray impingement cooling process.The second part is used to calculate the temperature and stress distribution during the operating process by building a 3D thermal and thermomechanical model of a hot blast stove. The results are described as follows:
Three-dimensional thermal-mechanical models for the prediction of heat transfer coefficient distributions with different size beams are investigated. H300×300, H250×250, and H200×200 H-shape steel beams are investigated in a controlled cooling process to obtain the design requirements for maximum uniform temperature distributions and minimal residual stress after controlled cooling. An algorithm developed with the conjugated-gradient method is used to optimize the heat transfer coefficient distribution. In a comparison with the three group results, the numerical results indicate that, with the same model and under the same initial temperature (T_in = 850℃) and final temperature (T_ave= 550±10℃), the heat transfer coefficients obtained with the conjugated gradient method can produce more uniform temperature distribution and smaller residual web stress, with objective functions of the final average temperature (T_ave±ΔT) and maximum temperature difference to minimum min{ΔTmax (x, y)}. The maximum temperature difference is decreased by 57℃, 74℃, and 75℃ for Case 1, Case 2, and Case 3, respectively, the surface maximum temperature difference is decreased by 60 ~ 80℃ for three cases, and the residual stress at the web can be reduced by 20 ~ 40 MPa for three cases. For the experimental part, dual nozzles are used to investigate the cooling character of the flat plate using for the spray impingement cooling process. Based on an experimental temperature measurement, a three-dimensional numerical model is set up to calculate the transient heat transfer coefficient of the cooling plate by solving the inverse heat conduction problem with the conjugate gradient method. Both the experimental and numerical results indicated that an interference region appeared between the two jet spray impingement regions. The interference pitch varied with the flow rates, the height from the plane to the jet outlet, and the distance between the two jets. As water spread over the plate, the heat dissipation region gradually stretched from the impingement region to the interference and flow regions. A peak in the heat flux curve was observed when the water arrived at the wet front of the flow. Meanwhile, the peak in the heat flux decreased as the distance from the impingement region increased. A maximum local heat transfer coefficient 23000 W/(m2K) was observed in this experiment. The global average heat transfer coefficient increased with increases in the water flow rate, but it decreased with increases in the pitch.
Hot blast stoves are important equipment used in the iron-making process, the structure of which is composed of five parts: (1) checker chamber, (2) combustion chamber, (3) checker dome, (4) combustion dome, and (5) cross-over. The cyclic operating process consists of an on-gas period and an on-blast period. In this study, a 3D thermal and thermomechanical model of a hot blast stove were used to calculate the temperature and stress distribution during the operating process.The thermal analysis simulation results are compared with the in-situ data, and the maximum error was found to be lower than 7%. The results indicated that the flue gas or the cold/hot blast temperature is higher than that in the checker in the checker chamber during the on-gas period but lower than that in the checker during the on-blast period, and the range of the temperature difference is 10~35℃. The maximum principal stress mainly occurred outside of the refractory linings, and the minimum principal stress mainly occurred inside of the refractory linings. The maximum strain occurred inside of the refractory linings in the combustion chamber. The shell is mainly subjected to the maximum principal stress, where the minimum principal stress only occurred at the junction. The maximum strain of the shell occurred at the top of the combustion dome.

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