發(fā)布時(shí)間：2018-08-22 11:03

【摘要】：近年來,隨著船舶能效設(shè)計(jì)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(qiáng)化問題已越來越引起重視。本文以此作為研究背景,采用實(shí)驗(yàn)研究的方法,對(duì)脈動(dòng)流強(qiáng)化換熱問題開展了深入研究。實(shí)驗(yàn)系統(tǒng)脈動(dòng)源采用往復(fù)泵,工質(zhì)為水,流動(dòng)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(dòng)流強(qiáng)化換熱實(shí)驗(yàn)臺(tái)架,探究了不同表面結(jié)構(gòu)、不同脈動(dòng)參數(shù)變量(脈動(dòng)頻率和脈動(dòng)振幅)與換熱效果的關(guān)系。實(shí)驗(yàn)中,數(shù)據(jù)采集系統(tǒng)可對(duì)脈動(dòng)流參數(shù)的精確控制和數(shù)據(jù)的實(shí)時(shí)采集、存儲(chǔ),并且自行設(shè)計(jì)了滿足脈動(dòng)頻率和振幅要求的往復(fù)泵。熱沉室設(shè)計(jì)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(shí)驗(yàn)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(dòng)振幅條件下,隨著脈動(dòng)頻率的變化,對(duì)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(gè)最佳脈動(dòng)頻率;在實(shí)驗(yàn)工況范圍內(nèi),脈動(dòng)振幅與對(duì)流換熱強(qiáng)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(dòng)流態(tài)下,脈動(dòng)流可有效強(qiáng)化對(duì)流換熱性能。然后,針對(duì)板式換熱器,研究了脈動(dòng)流和穩(wěn)態(tài)流下的換熱性能對(duì)比,探究了脈動(dòng)振幅、脈動(dòng)頻率與其換熱特性之間的關(guān)系。實(shí)驗(yàn)結(jié)果表明,隨著雷諾數(shù)的增大,無論穩(wěn)態(tài)流動(dòng)或是脈動(dòng)流動(dòng)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(qiáng)因子呈現(xiàn)逐漸降低的態(tài)勢,這與熱沉室實(shí)驗(yàn)中得到的規(guī)律基本相同;同時(shí),在各雷諾數(shù)條件下,隨著脈動(dòng)頻率的增大,換熱增強(qiáng)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(dòng)頻率f=0.66Hz附近,換熱增強(qiáng)因子的最大值為1.598,出現(xiàn)在雷諾數(shù)Re=3774、脈動(dòng)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(hào)：2196901