- 期刊
A Comparative Study of Heat Transfer in Reciprocating Smooth-walled and Rib-roughened Helical Pipes
摘要
本文描述應用於活塞冷卻系統中，內設突起物與平滑面之往復螺旋管熱傳實驗研究結果。文中選用之熱傳檢測數據說明、比較往復力與浮力間交互作用，對內設突起物與平滑面之往復螺旋管內、外緣熱傳物理現象所產生之影響。於內設突起物與平滑面之往復螺旋管內，浮力效應增強其熱傳。於低往復力時，Nusselt數會降至低於靜態管之熱傳係數；但於高往復力時，往復Nusselt數逐漸隨著往復力增加而提高。雖然往復運動對兩螺旋管熱傳之影響趨勢相同，但其影響程度隨著往復管表面特徵改變。本研究焦點比較於內設突起物及平滑面之往復螺旋管內，往復力及往復浮力效應對其熱傳產生之單獨與偶合效應；並彰顯使用週期式凸起物於往復螺旋管中產生之熱傳強化作用。
關鍵字
往復螺旋管熱傳並列摘要
This paper describes a detailed experimental investigation of heat transfer in reciprocating smooth-walled and rib-roughened helical pipes with particular reference to the piston cooling application. A selection of heat transfer measurements with which the physics of pulsating and buoyancy forces interactively affect the heat transfer along the inner and outer edges of the reciprocating smooth-walled and rib-roughened helical tubes is illustrated and compared. In both smooth-walled and rib-roughened helical pipes, the increase of buoyancy level improves heat transfer; while the local Nusselt number is initially impaired from the static value with weak reciprocation; but recovered at the higher level of pulsating force. Although the general reciprocating effects on heat transfer are similar, the degrees of heat transfer modifications caused by the reciprocating forces vary with the wall geometry. This study focuses on the comparison of the individual and interactive effects of pulsating and reciprocating buoyancy effects on heat transfer in the smooth-walled and rib-roughened helical pipes with the attempt to reveal the heat transfer augmentation generated by the attached periodical ribs in the reciprocating helical pipe.