化工进展
化工進展
화공진전
CHEMICAL INDUSTRY AND ENGINEERING PROGRESS
2015年
6期
1582-1587
,共6页
自旋扭带%强化传热%摩擦因子%数值模拟%场协同%扭带选型
自鏇扭帶%彊化傳熱%摩抆因子%數值模擬%場協同%扭帶選型
자선뉴대%강화전열%마찰인자%수치모의%장협동%뉴대선형
self-rotating twisted tape%heat transfer enhancement%friction factor%numerical simulation%field synergy principle%twisted tape selection
旋转扭带是在固定式扭带基础上发展而来的，因其特殊结构所以能在管内流体作用下产生自旋效果。本文对自旋式扭带旋转特性及强化传热特性进行研究。通过理论及实验研究管内自旋扭带旋转特性后得出：扭率越小，扭带克服阻力起始旋转需要的流体速度越小；扭带转速与管内流体流速呈一次线性关系，且扭带节距不变时线性比例基本保持不变。通过实验研究后得出：自旋扭带能达到很好的强化传热性能，扭率越小其强化传热性能越明显，同时阻力特性也越明显，在雷诺数为4×103～4×104、扭率为3～8时，换热管内摩擦因子增至1.7～3.5倍，努赛尔数增幅为10%～37%。本文使用评估指标η对扭带进行综合评价，得出扭率为7的自旋扭带具有最佳的综合性能。并分别拟合出摩擦因子及努赛尔数与雷诺数、扭率之间的关联式，提出一种工程上自旋扭带选型方法。
鏇轉扭帶是在固定式扭帶基礎上髮展而來的，因其特殊結構所以能在管內流體作用下產生自鏇效果。本文對自鏇式扭帶鏇轉特性及彊化傳熱特性進行研究。通過理論及實驗研究管內自鏇扭帶鏇轉特性後得齣：扭率越小，扭帶剋服阻力起始鏇轉需要的流體速度越小；扭帶轉速與管內流體流速呈一次線性關繫，且扭帶節距不變時線性比例基本保持不變。通過實驗研究後得齣：自鏇扭帶能達到很好的彊化傳熱性能，扭率越小其彊化傳熱性能越明顯，同時阻力特性也越明顯，在雷諾數為4×103～4×104、扭率為3～8時，換熱管內摩抆因子增至1.7～3.5倍，努賽爾數增幅為10%～37%。本文使用評估指標η對扭帶進行綜閤評價，得齣扭率為7的自鏇扭帶具有最佳的綜閤性能。併分彆擬閤齣摩抆因子及努賽爾數與雷諾數、扭率之間的關聯式，提齣一種工程上自鏇扭帶選型方法。
선전뉴대시재고정식뉴대기출상발전이래적，인기특수결구소이능재관내류체작용하산생자선효과。본문대자선식뉴대선전특성급강화전열특성진행연구。통과이론급실험연구관내자선뉴대선전특성후득출：뉴솔월소，뉴대극복조력기시선전수요적류체속도월소；뉴대전속여관내류체류속정일차선성관계，차뉴대절거불변시선성비례기본보지불변。통과실험연구후득출：자선뉴대능체도흔호적강화전열성능，뉴솔월소기강화전열성능월명현，동시조력특성야월명현，재뢰낙수위4×103～4×104、뉴솔위3～8시，환열관내마찰인자증지1.7～3.5배，노새이수증폭위10%～37%。본문사용평고지표η대뉴대진행종합평개，득출뉴솔위7적자선뉴대구유최가적종합성능。병분별의합출마찰인자급노새이수여뢰낙수、뉴솔지간적관련식，제출일충공정상자선뉴대선형방법。
Because of its special structure,rotating twisted tape can rotate under the action of fluid in tube. This paper studied the rotation characteristics and heat transfer enhancement characteristics of self-rotating twisted tape. The theoretical and experimental research of rotation characteristics showed that with decreasing twist ratio,the fluid velocity tape needed to overcome resistance and starting rotation reduced;the relationship between rotating velocity and the fluid velocity was linear,and the linear ratio remained constant when the pitch of tape was unchanged. The experiment research of heat transfer and pressure drop demonstrated that Nusselt number in the tube with self-rotating twisted tape was higher than that in plain tube,and increased with the decreasing of twist ratio; when Reynolds number was in the range of 4×103—4×104,and twist ratio was at 3—8,the Nusselt number increased 10%—37% and Darcy friction factor was 1.7—3.5 times higher compared to plain tube. The comprehensive evaluation was based on evaluation indicatorη,and twisted ratio of 7 was determined to be the best comprehensive performance. The relationship of the friction factor,Nusselt number and Reynolds number with the twist ratio was also obtained.
