正弦45斜度漸縮－－漸擴型波浪窄道流場與熱傳研究

Flow and Heat Transfer of Convergent-Divergent Narrow Channel with Two Opposite Skewed Sinusoidal Wavy Walls

In the attempt to develop the novel core element for plate-type heat exchanger, this study examines the flow and heat transfer phenomena in a narrow convergent-divergent wavy channel with sinusoidal wall-waves inclined at 45 degrees to the direction of main flow. Detailed heat transfer distributions over the wavy wall are measured using the steady-state infrared thermography methods. Turbulent flow phenomena in this wavy channel are analyzed using the numerical results predicted by Star-CD software. Numerical results are validated by comparing the calculated and experimental pressure-drop coefficients. Experimental heat transfer data and the calculated flow structures are cross examined to disclose the mechanism of heat transfer enhancement (HTE) in this wavy channel. Thermal performance factors for this wavy channel with turbulent flows are compared with other HET measures based on the results calculated from the empirical heat transfer and pressure drop coefficients, which enlightens the competitive advantage of this wavy channel for engineering applications. 本研究發展新型板式熱交換核心模組，研究兩相對壁面為正弦45度漸縮－－漸擴型彼浪矩形窄道之流場與熱傳現象。正弦式波浪壁面之詳細熱傳係數分佈以紅外線熱相儀穩態技術檢測。管道於紊流狀態之流場現象以數值軟體Star-CD分析；並藉由比較計算與實驗檢測之壓損係數驗證數值計算結果。藉由分析流場與熱傳結果，探討漸縮－－漸擴型波浪矩形窄道之熱傳強化機制。應用本研究推導之熱傳以及壓損係數實驗公式，計算此波浪型窄道於紊流狀態之熱性能係數；並與其它類型熱傳強化管道之熱性能係數比較，彰顯此波浪窄道於工程應用之競爭優勢。