【摘要】：近年來,隨著船舶能效設(shè)計指數(shù)的推廣,船用設(shè)備的節(jié)能日益受到關(guān)注,換熱設(shè)備的傳熱強化問題已越來越引起重視。本文以此作為研究背景,采用實驗研究的方法,對脈動流強化換熱問題開展了深入研究。實驗系統(tǒng)脈動源采用往復(fù)泵,工質(zhì)為水,流動狀態(tài)是層流或過渡流工況,雷諾數(shù)范圍在2000≤Re≤9000范圍。首先,搭建了的脈動流強化換熱實驗臺架,探究了不同表面結(jié)構(gòu)、不同脈動參數(shù)變量(脈動頻率和脈動振幅)與換熱效果的關(guān)系。實驗中,數(shù)據(jù)采集系統(tǒng)可對脈動流參數(shù)的精確控制和數(shù)據(jù)的實時采集、存儲,并且自行設(shè)計了滿足脈動頻率和振幅要求的往復(fù)泵。熱沉室設(shè)計采用三層結(jié)構(gòu),包括加熱銅塊、熱沉室蓋板和熱沉室底座,加熱銅塊表面分別加工為平板流道和周期性矩形凹槽流道。實驗研究發(fā)現(xiàn):1.在矩形平板通道中,Re=2406、A=0.12Mpa、f=1.08Hz工況下,換熱效果比穩(wěn)態(tài)流下提高了160%;在周期性變化的矩形凹槽通道中,Re=2406、A=0.12Mpa、f=1.08Hz工況下,換熱效果比穩(wěn)態(tài)流下提高了200%;2.在相同雷諾數(shù)和脈動振幅條件下,隨著脈動頻率的變化,對流換熱性能呈現(xiàn)逐漸減小或者先增大后減小的態(tài)勢,存在一個最佳脈動頻率;在實驗工況范圍內(nèi),脈動振幅與對流換熱強化效果正相關(guān);3.周期性凹槽通道的整體換熱性能要優(yōu)于平板通道。上述結(jié)果表明:在層流和脈動流態(tài)下,脈動流可有效強化對流換熱性能。然后,針對板式換熱器,研究了脈動流和穩(wěn)態(tài)流下的換熱性能對比,探究了脈動振幅、脈動頻率與其換熱特性之間的關(guān)系。實驗結(jié)果表明,隨著雷諾數(shù)的增大,無論穩(wěn)態(tài)流動或是脈動流動下板式換熱器的總傳熱系數(shù)呈現(xiàn)增大的現(xiàn)象,換熱增強因子呈現(xiàn)逐漸降低的態(tài)勢,這與熱沉室實驗中得到的規(guī)律基本相同;同時,在各雷諾數(shù)條件下,隨著脈動頻率的增大,換熱增強因子出現(xiàn)了先減小后增大的現(xiàn)象,最低值出現(xiàn)在脈動頻率f=0.66Hz附近,換熱增強因子的最大值為1.598,出現(xiàn)在雷諾數(shù)Re=3774、脈動頻率f=0.55Hz附近。
[Abstract]:In recent years, with the promotion of ship energy efficiency design index, the energy saving of marine equipment has been paid more and more attention, and the heat transfer enhancement of heat transfer equipment has been paid more and more attention. In this paper, the pulse flow enhancement heat transfer problem is studied in detail by using the experimental method. The pulsating source of the experimental system is the reciprocating pump, the working fluid is water, the flow state is laminar flow or transient flow condition, and the Reynolds number is in the range of 2000 鈮，

本文編號：2196901