地鐵列車空調(diào)機(jī)組中橢圓管換熱器的應(yīng)用

李 劍 蔣 奎 張子楊 張春路

(1.中車青島四方機(jī)車車輛股份有限公司,266111,青島; 2.河北軌道運(yùn)輸職業(yè)技術(shù)學(xué)院，050021，石家莊；3.同濟(jì)大學(xué)機(jī)械與能源工程學(xué)院制冷與低溫工程研究所,201804,上?！蔚谝蛔髡?，高級(jí)工程師)

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地鐵列車空調(diào)機(jī)組中橢圓管換熱器的應(yīng)用

李 劍1蔣 奎2張子楊3張春路3

(1.中車青島四方機(jī)車車輛股份有限公司,266111,青島; 2.河北軌道運(yùn)輸職業(yè)技術(shù)學(xué)院，050021，石家莊；3.同濟(jì)大學(xué)機(jī)械與能源工程學(xué)院制冷與低溫工程研究所,201804,上?！蔚谝蛔髡撸呒?jí)工程師)

地鐵列車空調(diào)機(jī)組功耗約占列車牽引動(dòng)力的40%,合理有效提高列車空調(diào)機(jī)組能效比(COP)是降低地鐵能耗的重要課題。提出了將橢圓管換熱器應(yīng)用于地鐵列車空調(diào)的設(shè)想,通過(guò)建立仿真模型,對(duì)原設(shè)計(jì)采用圓管換熱器的制冷系統(tǒng)與采用橢圓管換熱器的制冷系統(tǒng)進(jìn)行了對(duì)比。結(jié)果表明：將冷凝器和蒸發(fā)器都用橢圓管優(yōu)化后,制冷系統(tǒng)COP提升了12.4%,制冷量提升了12.6%,可以選擇小號(hào)的壓縮機(jī)來(lái)進(jìn)一步降低成本。此外，對(duì)φ7 mm強(qiáng)化管蒸發(fā)器優(yōu)化的制冷系統(tǒng)進(jìn)行了分析,結(jié)果表明，采用強(qiáng)化管蒸發(fā)器的制冷系統(tǒng)性能也有改善,略次于采用橢圓管蒸發(fā)器的制冷系統(tǒng)。因此，橢圓管換熱器應(yīng)用于地鐵列車空調(diào)機(jī)組中,對(duì)制冷系統(tǒng)性能改善顯著,對(duì)降低地鐵列車能耗有重要意義。

地鐵列車; 空調(diào)機(jī)組; 橢圓管換熱器

First-author′s address CRRC Qingdao Sifang Co.,Ltd.,266111,Qingdao,China

為保證車廂適宜的溫度與濕度,地鐵列車空調(diào)機(jī)組的配備必不可少,其消耗功率約占地鐵列車牽引動(dòng)力的40%。然而，地鐵列車空調(diào)機(jī)組的COP(能效比)只有2.2～2.3,遠(yuǎn)低于同類住宅空調(diào)機(jī)組的COP[1]。在大力倡導(dǎo)節(jié)能減排的今天,如何通過(guò)合理有效的設(shè)計(jì)改進(jìn)來(lái)優(yōu)化地鐵列車空調(diào)系統(tǒng)至關(guān)重要。本文從換熱器層面入手,考慮將原設(shè)計(jì)的圓管換熱器替換為橢圓管換熱器。橢圓管換熱器對(duì)管外繞流而言將脫體繞流點(diǎn)延遲,可減小管外壓降;對(duì)管內(nèi)流動(dòng)而言,管道當(dāng)量直徑減小,對(duì)換熱是有利的[2];同時(shí)，橢圓管管間距減小使得同樣的空間可以布置更多的換熱管。已有試驗(yàn)證明,橢圓管換熱器的風(fēng)側(cè)阻力、導(dǎo)熱系數(shù)、換熱效率等各項(xiàng)性能均優(yōu)于圓管換熱器[3]。橢圓管應(yīng)用于制冷劑-空氣換熱器,可使管外空氣側(cè)壓降減小,換熱器換熱能力加強(qiáng)[4-6],使蒸發(fā)溫度升高、冷凝溫度降低,可提高空調(diào)系統(tǒng)COP。因此，本文提出將橢圓管換熱器應(yīng)用于地鐵列車空調(diào)機(jī)組中,通過(guò)在制冷空調(diào)系統(tǒng)通用仿真平臺(tái)GREATLAB[7]中進(jìn)行系統(tǒng)仿真,比較原設(shè)計(jì)的圓管換熱器與橢圓管換熱器的性能參數(shù),驗(yàn)證該方案的可行性。

1 圓管換熱器系統(tǒng)仿真與標(biāo)定

本文研究的軌道車輛空調(diào)為雙制冷劑回路,每個(gè)制冷劑回路的設(shè)計(jì)相同。單回路制冷系統(tǒng)流程如圖1所示。

注：數(shù)字表示建模時(shí)的部件/流路順序

蒸發(fā)器和冷凝器均為翅片管換熱器仿真模型,采用分布參數(shù)模型[8]可以更好地反應(yīng)換熱器內(nèi)制冷劑和空氣不均勻流動(dòng)對(duì)于換熱器及系統(tǒng)性能的影響。該模型在求解中將翅片管換熱器模型按換熱器結(jié)構(gòu)分解為以下四個(gè)層次:換熱器模型、流路模型、換熱管模型和微元模型。計(jì)算時(shí),由微元模型開始,根據(jù)控制體內(nèi)制冷劑和空氣的狀態(tài),選取相應(yīng)的換熱關(guān)聯(lián)式,自下而上完成換熱器仿真。

基于上述分布參數(shù)模型,可以快速便捷地完成實(shí)際換熱器模型的仿真。先按照實(shí)際設(shè)計(jì)完成流路連接(見圖2),再輸入換熱器結(jié)構(gòu)參數(shù)及制冷劑側(cè)空氣側(cè)工況參數(shù),就可完成換熱器模型仿真,求解制冷劑和空氣的出口狀態(tài)、壓降和換熱量。

圖2 圓管系統(tǒng)換熱器流路連接

壓縮機(jī)模型采用壓縮機(jī)廠商廣泛采用的AHRI 10系數(shù)模型：

式中：

y——壓縮機(jī)的冷量、能效比、功耗、質(zhì)量流量等性能參數(shù);

c1～c10——常數(shù)項(xiàng)；

Te——蒸發(fā)溫度；

Tc——冷凝溫度。

蒸發(fā)器、冷凝器兩側(cè)風(fēng)機(jī)采用效率模型,輸入風(fēng)量及功耗;膨脹閥采用控制模型,即壓縮機(jī)吸氣過(guò)熱度為定值(換熱器、壓縮機(jī)、膨脹閥等部件模型詳見文獻(xiàn)[8])。名義工況下機(jī)組性能仿真結(jié)果與試驗(yàn)結(jié)果的對(duì)比如表1所示。

在此基礎(chǔ)上,根據(jù)試驗(yàn)結(jié)果對(duì)仿真模型進(jìn)行標(biāo)定,使得在名義工況下模型主要性能參數(shù)與試驗(yàn)結(jié)果一致,從而保證后續(xù)優(yōu)化結(jié)果的精度。模型標(biāo)定結(jié)果如表2所示。

表2 模型標(biāo)定

2 橢圓管冷凝器

2.1 橢圓管冷凝器設(shè)計(jì)

原有的圓管冷凝器設(shè)計(jì)參數(shù)與橢圓管冷凝器設(shè)計(jì)參數(shù)(管的類型皆為螺旋槽強(qiáng)化管)分別如表 3、表 4[7]所示。由表3、表4可知,橢圓管冷凝器管間距減小,在保持冷凝器高度不變的情況下,每排管數(shù)可以增加至22；橢圓管冷凝器排間距變化較小,排數(shù)不變。對(duì)橢圓管冷凝器流路進(jìn)行重新優(yōu)化設(shè)計(jì),各流路數(shù)下?lián)Q熱量對(duì)比如圖3所示?？梢?，11流路下?lián)Q熱量最大，故選取11流路連接形式。

表3 原有的圓管冷凝器設(shè)計(jì)參數(shù)

表4 橢圓管冷凝器設(shè)計(jì)參數(shù)

原設(shè)計(jì)與新設(shè)計(jì)對(duì)比如表5所示。顯然,橢圓管冷凝器換熱量有明顯提高(+53%),空氣側(cè)壓降也有下降(-24%)?？梢愿鶕?jù)風(fēng)機(jī)曲線模型對(duì)冷凝器側(cè)風(fēng)機(jī)的風(fēng)量、功耗重新匹配(風(fēng)量將會(huì)增大)。

表5 原設(shè)計(jì)和新設(shè)計(jì)的冷凝器性能參數(shù)對(duì)比

2.2 采用橢圓管冷凝器的制冷系統(tǒng)

將原設(shè)計(jì)中的冷凝器替換為新的橢圓管冷凝器,并匹配相應(yīng)的風(fēng)機(jī),對(duì)制冷系統(tǒng)進(jìn)行仿真。原設(shè)計(jì)與新設(shè)計(jì)性能對(duì)比如表6所示。可見,用橢圓管冷凝器代替圓管冷凝器后,制冷量幾乎不變的情況下,COP提升了6%左右。

表6 原設(shè)計(jì)和新設(shè)計(jì)的制冷系統(tǒng)性能比較一

3 橢圓管蒸發(fā)器

3.1 橢圓管蒸發(fā)器設(shè)計(jì)

原有的圓管蒸發(fā)器設(shè)計(jì)參數(shù)與橢圓管蒸發(fā)器設(shè)計(jì)參數(shù)分別如表7、表8所示。

表7 圓管蒸發(fā)器設(shè)計(jì)參數(shù)

由表8計(jì)算可得,在保持蒸發(fā)器高度、寬度不變的情況下,采用橢圓管蒸發(fā)器，排數(shù)可由原來(lái)的8排變?yōu)?排,每排管數(shù)由19增加至26。重新設(shè)計(jì)換熱器流路,橢圓管蒸發(fā)器各流路數(shù)的換熱量如圖4所示?？梢?，26流路時(shí)換熱量最大。因此，選擇26流路下的橢圓管蒸發(fā)器。

表8 橢圓管蒸發(fā)器設(shè)計(jì)參數(shù)

圖4 橢圓管蒸發(fā)器各流路數(shù)的換熱量

表9為原設(shè)計(jì)與新設(shè)計(jì)的比較。顯然,橢圓管蒸發(fā)器換熱量有明顯提高(+37%),空氣側(cè)壓降也有下降(-25%)。因此，可根據(jù)風(fēng)機(jī)曲線模型對(duì)蒸發(fā)器側(cè)風(fēng)機(jī)的風(fēng)量、功耗重新匹配(風(fēng)量將會(huì)增大)。新設(shè)計(jì)將光管改為強(qiáng)化管,雖然每一流路只走6根管,少于原設(shè)計(jì)的8根管,但制冷劑側(cè)壓降仍為26.6 kPa,高于原設(shè)計(jì)的12.8 kPa。由于原設(shè)計(jì)的制冷劑側(cè)壓降不大,所以制冷劑壓降升高對(duì)制冷系統(tǒng)的影響比較小。

3.2 采用橢圓管蒸發(fā)器的制冷系統(tǒng)

將原設(shè)計(jì)中的蒸發(fā)器替換為新的橢圓管蒸發(fā)器,并匹配相應(yīng)的風(fēng)機(jī),對(duì)制冷系統(tǒng)進(jìn)行仿真。原設(shè)計(jì)與新設(shè)計(jì)的制冷系統(tǒng)性能對(duì)比如表10所示?？梢?用橢圓管蒸發(fā)器代替圓管蒸發(fā)器后,制冷系統(tǒng)性能改善顯著,制冷量增加了10.3%,COP提升了7.3%。

表9 原設(shè)計(jì)和新設(shè)計(jì)的蒸發(fā)器性能參數(shù)對(duì)比

表10 原設(shè)計(jì)和新設(shè)計(jì)的制冷系統(tǒng)性能比較二

4 壓縮機(jī)重新選型

將冷凝器和蒸發(fā)器都替換為橢圓管后，對(duì)橢圓管換熱器與原設(shè)計(jì)的圓管換熱器相比較,如表11所示。

表11 橢圓管換熱器與圓管換熱器比較

由于冷凝器和蒸發(fā)器優(yōu)化后,制冷量提升了12.6%,因此可以選擇小號(hào)的壓縮機(jī)來(lái)降低成本。同時(shí)，由于壓縮機(jī)流量減少,換熱器的相對(duì)換熱面積增大,換熱溫差減小,COP可進(jìn)一步提升。原設(shè)計(jì)中壓縮機(jī)型號(hào)為ZR 94 KCE-TFD,現(xiàn)選擇小兩號(hào)的ZR 84 KCE-TFD型壓縮機(jī),其性能見表12。

表12 重新選型的橢圓管換熱器的壓縮機(jī)性能表

表12中,小兩號(hào)壓縮機(jī)系統(tǒng)COP下降是因?yàn)樵谲壗豢照{(diào)的工況下，ZR 84 KCE-TFD的效率只有ZR 94 KCE-TFD的90%。

5 φ7 mm強(qiáng)化管蒸發(fā)器

5.1 強(qiáng)化管蒸發(fā)器設(shè)計(jì)

考慮到橢圓管換熱器在生產(chǎn)工藝上的復(fù)雜性,本文對(duì)地鐵列車空調(diào)機(jī)組蒸發(fā)器的優(yōu)化提出另一種方案：將原有的圓管蒸發(fā)器的光管替換為φ7 mm螺旋槽強(qiáng)化管。其具體結(jié)構(gòu)參數(shù)如表13所示。

根據(jù)表13參數(shù),在保持蒸發(fā)器尺寸不變的情況下,每排管數(shù)可以由原來(lái)的18增加至24，排間距不變,排數(shù)不變。重新設(shè)計(jì)換熱器流路,各流路數(shù)所對(duì)應(yīng)的換熱量如圖5所示。由圖5可見，24流路時(shí)換熱量最大，故選擇24流路下的強(qiáng)化管蒸發(fā)器。

表13 φ7 m強(qiáng)化管蒸發(fā)器設(shè)計(jì)參數(shù)

圖5 強(qiáng)化管蒸發(fā)器各流路數(shù)的換熱量

將橢圓管蒸發(fā)器與φ7 mm強(qiáng)化管蒸發(fā)器進(jìn)行比較,如表14所示?？梢钥闯?φ7 mm強(qiáng)化管蒸發(fā)器換熱性能與橢圓管蒸發(fā)器換熱性能接近,但是空氣側(cè)壓降比橢圓管蒸發(fā)器大,與原設(shè)計(jì)接近,風(fēng)機(jī)風(fēng)量功耗與原設(shè)計(jì)保持一致。

5.2 采用強(qiáng)化管蒸發(fā)器的制冷系統(tǒng)

將原設(shè)計(jì)中的蒸發(fā)器替換為φ7 mm強(qiáng)化管蒸發(fā)器,對(duì)制冷系統(tǒng)進(jìn)行仿真。兩種蒸發(fā)器優(yōu)化設(shè)計(jì)方案比較如表15所示。

表14 蒸發(fā)器優(yōu)化設(shè)計(jì)比較

表15 蒸發(fā)器優(yōu)化的制冷系統(tǒng)性能比較

在制冷系統(tǒng)中將冷凝器替換為橢圓管冷凝器,兩種方案的性能對(duì)比如表16所示。

表16 兩種換熱器優(yōu)化方案系統(tǒng)性能比較

由表16可知,蒸發(fā)器和冷凝器都換為橢圓管是最佳組合；采用橢圓管冷凝器與φ7 mm強(qiáng)化管蒸發(fā)器的制冷系統(tǒng)的COP提升也較為顯著；制冷量有增長(zhǎng),但不足以換小一號(hào)的壓縮機(jī)(若壓縮機(jī)換為小一號(hào)的ZR 90 K3E-TWD,制冷量將降為19.42 kW)。

6 結(jié)語(yǔ)

本文提出了將橢圓管換熱器用于地鐵列車空調(diào)的設(shè)想,通過(guò)建立仿真模型,對(duì)原設(shè)計(jì)的采用圓管換熱器的制冷系統(tǒng)與采用橢圓管冷凝器和橢圓管蒸發(fā)器后的制冷系統(tǒng)進(jìn)行對(duì)比。結(jié)果表明,采用橢圓管冷凝器,COP提升了6%左右;橢圓管蒸發(fā)器代替圓管蒸發(fā)器后,制冷量增加了10.3%,COP提升了7.3%;將冷凝器和蒸發(fā)器都用橢圓管后,COP提升了12.4%,制冷量提升了12.6%,可以選擇小號(hào)的壓縮機(jī)來(lái)進(jìn)一步降低成本。考慮到橢圓管換熱器在生產(chǎn)工藝上的復(fù)雜性,本文對(duì)φ7 mm強(qiáng)化管蒸發(fā)器的制冷系統(tǒng)也作了分析,結(jié)果表明，采用強(qiáng)化管蒸發(fā)器的制冷系統(tǒng)性能也有提高,制冷量提升4.4%,COP提升3.4%,但整體性能不如采用橢圓管蒸發(fā)器。綜合以上分析,橢圓管換熱器應(yīng)用于地鐵列車空調(diào)機(jī)組中,對(duì)制冷系統(tǒng)性能改善顯著,對(duì)降低地鐵列車能耗有重要意義。

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[5] KIM Nae-Hyun,LEE Kang-Jong,JEONG Yeong-Bin. Airside performance of oval tube heat exchangers having sine wave fins under wet condition[J].Applied Thermal Engineering,2014,66(1-2):580.

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(Continued from Special Commentary)

“The 13thFive-Year Plan” works out a more ambitious blueprint for China′s economic and social developments. It points to comprehensively building a moderately prosperous society, achieves the first Centenary Goal, and fully reflects the five development concepts of “innovation, harmonization, green, openness and sharing”. Its main line is the structural reform of the supply front.

In the 25 special columns of “The 13thFive-Year Plan Outline”, the five aspects of technological innovation, structure upgrading, infrastructural facilities, ecological environment and improving people′s livelihood, etc. are involved. Among them, the objective set for rail transit is that within five years, China will improve and perfect the modern integrated transportation system. The main key projects constructions in the rail transport field are described as follows. The high-speed railway mileage in service will reach 30 000 km, linking more than 80% major cities. The intercity railway networks of the urban agglomerations of Beijing-Tianjin-Hebei, the Yangtze River Delta, the Pearl River Delta, the middle reaches of the Yangtze River, the Central Plains, the Chengdu-Chongqing, and the Shandong peninsula will be basically completed. The main skeleton of intercity rail networks of other urban agglomerations will be constructed. The demonstration project of urban areas (suburbs) railways will be implemented. The rail transit networks of super cities and mega cities will be perfected and optimized. The urban rail transit networks of those cities with more than 3 million populations will be sped up to be formed. The additional urban rail transit mileage in service will reach about 3 000 km. “Four ‘Along’s (along coasts/rivers/borders/the Belt and Road) Channels”— The high-speed railways along coasts and along rivers will be basically run-through. The railways along borders, such as the railway from Hetian to Ruoqiang, the railway along the border in Northeast China and the Sichuan-Tibet railway, etc., will be constructed. Push on the constructions of cross-border passageways linking with neighboring countries around China and the passages along “The Belt and Road”. Build the logistics platform of international trains of important node cities, such as Urumqi and Lanzhou. Construct the Shenzhen-Zhongshan Channel (the dual-channel of highway and railway from Shenzhen to Zhongshan, its subject engineering′s being the dual-purpose bridge of highway and railway with more cost-effective). “The 13thFive-Year Plan Outline” also points out that in urbanization areas, intercity railways and urban areas (suburbs) railways should be greatly developed, and using existing railways to run intercity trains should be encouraged, so as to form backbone networks of multi-level rail transit and high-efficiently connect large- medium-small cities and towns. Thus, during the period of “the 13thFive-Year Plan”, the topic words of rail transport development are “perfection and optimization”.

The intercity rail transit constructions are of great significance for advancing the new type of urbanization, the industrial structure adjustment and the technology development of the railway industry itself. The development of the high-speed rail and railway freight will not only greatly promote “the Belt and Road Initiative” constructions, but also improve the capability of independent innovation of China′s railways. Perfecting and optimizing the rail transit networks of mega cities, and speeding up to make the urban rail transit of those cities with more than 3 million people form networks are vitally interrelated with building a harmonious and livable cities and improving the people′s livelihood. “The 13thFive-Year Plan Outline” has indicated the direction and the road for our rail transit field. Our mission is both glorious and arduous. Let us work together to produce a satisfactory answer to the motherland and the people.

(Translated by SUN Zheng)

Application of Oval Tube Heat Exchanger in Air-conditioning Units of Metro Vehicles

LI Jian, JIANG Kui, ZHANG Ziyang, ZHANG Chunlu

The power consumption of air-conditioning units installed in metro vehicles accounts for about 40% of the total traction power, it is important to improve effectively the COP (coefficient of performance) of AC (air-conditioning) units installed in metro vehicles. The application of an oval tube heat exchanger in the AC units of metro vehicles is proposed, and a simulation model is built to compare the system optimized by the oval tube exchanger with the original system. The results show that system COP will be increased by 12.4% and cooling capacity be increased by 12.6% if the oval tube is applied in both evaporator and condenser. Meanwhile, a smaller compressor can be chosen to further reduce the cost. If it maintains the same efficiency, the system COP will be about 2.80, promoted by 19.7%. The system optimized by enhanced heat exchanger tube (7 mm) is analyzed, thus the system COP will also be promoted only one step short of the system with oval tube. The application of oval tube heat exchanger in AC units of metro vehicles results in significant promotion of the system COP and plays a critical role in reducing energy consumption.

metro vehicle; air-conditioning system; oval tube heat exchanger

U 270.38+3

10.16037/j.1007-869x.2016.04.024

2015-11-19)