王路路張華邱金友
(1上海理工大學(xué)能源與動(dòng)力工程學(xué)院 上海 200093;2福建工程學(xué)院生態(tài)環(huán)境與城市建設(shè)學(xué)院 福州 350118)
R1234ze(E)與R32混合工質(zhì)在熱泵系統(tǒng)中替代R410A的實(shí)驗(yàn)研究
王路路1張華1邱金友2
(1上海理工大學(xué)能源與動(dòng)力工程學(xué)院 上海 200093;2福建工程學(xué)院生態(tài)環(huán)境與城市建設(shè)學(xué)院 福州 350118)
新型制冷劑R1234ze(E)因較低的GWP備受制冷行業(yè)關(guān)注,其與R32的混合工質(zhì)作為熱泵系統(tǒng)制冷劑的研究也在逐步展開,本文以R1234ze(E)/R32(質(zhì)量配比:27%/73%,命名為L(zhǎng)-41b,GWP=493)混合工質(zhì)為研究對(duì)象,在人工環(huán)境室中設(shè)計(jì)并搭建了空氣源熱泵測(cè)試系統(tǒng),對(duì)比研究了L-41b與R410A在熱泵系統(tǒng)中的性能系數(shù)COP、壓縮機(jī)功耗、制熱量、排氣溫度和循環(huán)壓比。結(jié)果表明:當(dāng)恒定冷凝溫度,蒸發(fā)溫度從5℃增加到13℃時(shí),R410A和L-41b的COP偏差從8.6%縮小到2.8%。當(dāng)恒定蒸發(fā)溫度,冷凝溫度從30℃提高到42℃時(shí),L-41b的運(yùn)行性能系數(shù)COP的降幅小于R410A,變工況實(shí)驗(yàn)表明在相對(duì)高溫區(qū)L-41b替代R410A具有較好的替代性能。
R1234ze(E)/R32;混合制冷劑;空氣源熱泵;運(yùn)行工況
在目前經(jīng)濟(jì)與技術(shù)的條件下,研究低GWP的混合替代制冷劑是當(dāng)前制冷劑的替代趨勢(shì)之一[1-4]。新型制冷劑 R1234ze(E)(trans-1,3,3,3-tetrafluoropropene)因較低的GWP備受制冷行業(yè)關(guān)注,近期的研究報(bào)告[5]表明R1234ze(E)的GWP小于1,其作為空調(diào)、熱泵的替代品已初步得到認(rèn)可[6-8]。 但R1234ze(E)單一成分的熱力學(xué)性能和傳輸特性并不理想,若直接應(yīng)用于空調(diào)和熱泵系統(tǒng),其系統(tǒng)性能系數(shù)(COP)和容積制冷量(VCC)均會(huì)低于目前常用工質(zhì)R134a和R410A。R32屬于HFCs類物質(zhì),但其GWP并不高(GWP R32=675),擁有較高的汽化潛熱和良好的傳輸性能[9-10],在R1234ze(E)中混入R32成分可以有效改善其熱力學(xué)性能和傳輸性能[11]。
目前國(guó)內(nèi)外對(duì)于環(huán)保制冷劑 R1234ze(E)和R1234ze(E)/R32混合工質(zhì)的研究近幾年才逐步展開。K.Tanaka等[12]開展對(duì)R1234ze(E)及其與R32的混合物的熱力學(xué)特性和制冷循環(huán)性能系數(shù)與其組分關(guān)系的研究,其所獲得的COP和容積制冷量VCC與R1234ze(E)的質(zhì)量分?jǐn)?shù)的依賴關(guān)系,對(duì)于指導(dǎo)正確配置R1234ze(E)與R32混合制冷劑有參考價(jià)值。S.Koyama等[13]對(duì)純R1234ze(E)及質(zhì)量比為0.5:0.5的R1234ze(E)/R32混合工質(zhì)在R410系統(tǒng)上進(jìn)行直接充灌研究,并與R410A比較。證明在R1234ze(E)中添加R32可以提高系統(tǒng)性能系數(shù)COP,且可提高系統(tǒng)制冷量。國(guó)內(nèi)張志巍等[14]對(duì)不同 R1234ze(E)/R32混合比進(jìn)行系統(tǒng)循環(huán)性能分析,指出R410A的替代方案應(yīng)從R32適合配比與減少系統(tǒng)壓力損失著手。邱金友等[15]指出需要進(jìn)行大量的實(shí)驗(yàn)室充灌與改型實(shí)驗(yàn),獲得對(duì)比性能數(shù)據(jù),找出存在的問題,并根據(jù)R1234ze(E)及其與R32混合物的特點(diǎn)對(duì)壓縮機(jī)、換熱器的傳熱面積與傳熱方式、連接管、節(jié)流裝置等方面進(jìn)行優(yōu)化設(shè)計(jì),確保其性能達(dá)到或超過原有的設(shè)計(jì)水平,為下一步產(chǎn)品的優(yōu)化設(shè)計(jì)奠定基礎(chǔ)。
初步的研究論證了環(huán)保制冷劑R1234ze(E)及其與R32的混合工質(zhì)具有與R410A相似的熱物性和傳輸性能,有望成為新一代低GWP替代制冷劑,三者基本物性如表 1所示。本文從 AHRI Low-GWP AREP項(xiàng)目[16-17]第一階段對(duì)R134a和R410A的替代候選制冷劑中選擇 L-41b(R1234ze(E)/R32(27%/73%))作為研究對(duì)象,探索其混合物在熱泵系統(tǒng)中的運(yùn)行性能。
表1 R410A、R32和R1234ze(E)的基本物性Tab.1 Physical properties of R410A,R32 and R1234ze(E)
1.1 人工環(huán)境室簡(jiǎn)介
人工環(huán)境室主要由實(shí)驗(yàn)室外圍保溫結(jié)構(gòu)、空氣處理機(jī)組、溫濕度采樣裝置、空氣流量測(cè)試裝置、系統(tǒng)控制系統(tǒng)及測(cè)量數(shù)據(jù)采集系統(tǒng)等組成。其中,空氣調(diào)節(jié)處理系統(tǒng)主要由室內(nèi)空氣處理機(jī)組、水冷壓縮冷凝機(jī)組、循環(huán)風(fēng)機(jī)、電加熱器、電加濕器及相關(guān)的控制設(shè)備組成。人工環(huán)境室的主要用途是提供測(cè)試機(jī)組性能時(shí)所需的各種工況,主要是保證室內(nèi)的空氣的溫度、濕度、空氣流動(dòng)速度等達(dá)到實(shí)驗(yàn)所需的工況條件,使測(cè)試在一個(gè)穩(wěn)定環(huán)境下進(jìn)行,以準(zhǔn)確測(cè)試空調(diào)器的性能。環(huán)境室內(nèi)的溫度和濕度參數(shù)采用兩個(gè)PID控制器調(diào)節(jié)制冷系統(tǒng)、電加熱器和加濕器來實(shí)現(xiàn),表2列舉環(huán)境室所能達(dá)到的測(cè)試工況。
表2 環(huán)境室參數(shù)控制及精度Tab.2 Working condition of environmental chamber
圖1 空氣源熱泵系統(tǒng)及測(cè)點(diǎn)布置圖Fig.1 Schematic diagram of experimental bench and measuring points
1.2 空氣源熱泵系統(tǒng)實(shí)驗(yàn)臺(tái)
圖1所示為設(shè)計(jì)搭建的空氣源熱泵實(shí)驗(yàn)系統(tǒng)流程圖及測(cè)點(diǎn)布置圖。此系統(tǒng)包括兩個(gè)循環(huán)回路:熱泵系統(tǒng)制冷劑循環(huán)回路和冷凝器側(cè)水循環(huán)回路。熱泵系統(tǒng)制冷劑循環(huán)回路主要包括壓縮機(jī)、水冷冷凝器、回?zé)崞?、電子膨脹閥和翅片管式蒸發(fā)器等;冷凝器側(cè)水循環(huán)回路主要包括恒溫水箱、循環(huán)水泵和流量計(jì)等。壓縮機(jī)采用變頻滾動(dòng)轉(zhuǎn)子式壓縮機(jī),冷凝器采用水冷套管冷凝器,膨脹閥采用電子膨脹閥;蒸發(fā)器采用翅片管的形式,回?zé)崞鲀啥诉B接旁通管路。
1.3 實(shí)驗(yàn)工況方案設(shè)定
考慮到系統(tǒng)運(yùn)行的工況未必恒定不變,同時(shí)也為了更全面的掌握新型工質(zhì)L-41b的運(yùn)行性能,研究了R410A與L-41b兩種工質(zhì)在固定蒸發(fā)溫度或冷凝溫度下運(yùn)行性能隨另一側(cè)溫度的變化情況。實(shí)驗(yàn)的方式通過改變?nèi)斯きh(huán)境室的溫度、蒸發(fā)器風(fēng)機(jī)風(fēng)量、冷凝器進(jìn)口載熱流體溫度和冷凝器載熱流體流量的參數(shù)來實(shí)現(xiàn)對(duì)工質(zhì)側(cè)的蒸發(fā)溫度和冷凝溫度的控制。為了避免冷凝溫度過高導(dǎo)致壓縮機(jī)停機(jī),設(shè)定冷凝溫度在38℃附近。同時(shí)考慮到人工環(huán)境室工況的限制,蒸發(fā)溫度設(shè)定在4℃以上,以此分別設(shè)定了三組實(shí)驗(yàn)方案,如表3所示,改變蒸發(fā)溫度,保持冷凝側(cè)參數(shù)恒定。如表4所示,改變冷凝溫度,保持蒸發(fā)側(cè)工質(zhì)參數(shù)恒定。
表3 變蒸發(fā)溫度工況表Tab.3 Variable evaporation temperature working condition
表4 變冷凝溫度工況表Tab.4 Variable condensation temperature working condition
2.1 循環(huán)性能系數(shù)COP的對(duì)比
圖2和圖3分別給出了R410A和L-41b在固定一側(cè)溫度,循環(huán)性能系數(shù)COP隨另一側(cè)的變化規(guī)律。以圖2分析為例,在固定冷凝側(cè)溫度為38℃附近的工況下,蒸發(fā)溫度從5℃左右提高到13℃左右時(shí),R410A和L-41b的COP分別從3.52和3.30提升到3.92和3.81,R410A和L-41b的COP偏差從8.6%縮小為2.8%,說明隨蒸發(fā)溫度的升高,L-41b的COP的增幅大于R410A。在圖3中同樣可以看出L-41b的COP隨冷凝溫度升高時(shí)的降幅小于R410A,相互印證了在較高溫區(qū)間L-41b與R410A具有更相似的運(yùn)行性能,且隨著溫區(qū)的提高,L-41b表現(xiàn)出了一定的優(yōu)越性。
圖2 COP隨蒸發(fā)溫度的變化Fig.2 COP varies with evaporation temperature
圖3 COP隨冷凝溫度變化Fig.3 COP varies with condensation temperature
圖4 壓縮機(jī)功耗隨蒸發(fā)溫度的變化Fig.4 The work of compressor varies with evaporation temperature
2.2 壓縮機(jī)功耗的對(duì)比
圖4和圖5所示分別為R410A和L-41b在固定一側(cè)溫度,壓縮機(jī)功耗隨另一側(cè)的變化規(guī)律。由圖4可知,當(dāng)冷凝側(cè)溫度固定約為38℃時(shí),兩者的壓縮機(jī)功耗均隨蒸發(fā)溫度的增大而增加,這是因?yàn)楫?dāng)蒸發(fā)溫度提高時(shí),循環(huán)壓比降低,工質(zhì)流量減小,從而功率降低,但R410A的運(yùn)行功率始終大于L-41b。由圖5可知,R410A的運(yùn)行功率始終大于L-41b,而且當(dāng)冷凝溫度從30℃左右升高到42℃時(shí),R410A運(yùn)行功率的增幅大于 L-41b,表明在相對(duì)高溫區(qū) L-41b替代R410A有一定的優(yōu)越性。
圖5 壓縮機(jī)功耗隨冷凝溫度變化Fig.5 The work of compressor varies with condensation temperature
2.3 制熱量的對(duì)比
圖6和圖7所示分別為R410A和L-41b在固定一側(cè)溫度,制熱量Qh隨另一側(cè)的變化規(guī)律。其中制熱量是通過載熱流體的進(jìn)出口溫度和載熱流體回路循環(huán)流量計(jì)算得到。由兩圖可知,兩者工質(zhì)的制熱量均隨著蒸發(fā)溫度或冷凝溫度的升高而增大,總體上L-41b的制熱量小于R410A,但同時(shí)由上可知其總體功耗也比R410A小,因此L-41b的COP與R410A總體偏差不大。
圖6 制熱量隨蒸發(fā)溫度的變化Fig.6 Heating capacity varies with evaporation temperature
2.4 壓縮機(jī)排氣溫度的對(duì)比
圖8和圖9所示分別為R410A和L-41b在固定一側(cè)溫度,壓縮機(jī)排氣溫度隨另一側(cè)的變化趨勢(shì)。由兩圖可知,在整個(gè)工況溫區(qū)內(nèi),L-41b的壓縮機(jī)排氣溫度始終低于R410A。且當(dāng)固定冷凝側(cè)溫度,兩者工質(zhì)排氣溫度隨蒸發(fā)溫度的變化時(shí),L-41b的排氣溫度平均較R410A低9.6℃。壓縮機(jī)排氣溫度較低有助于延長(zhǎng)壓縮機(jī)的使用壽命,從排氣溫度角度考慮L-41b替代R410A具有較優(yōu)的性能。
圖7 制熱量隨冷凝溫度變化Fig.7 Heating capacity varies with condensation temperature
圖8 壓縮機(jī)排氣溫度隨蒸發(fā)溫度變化Fig.8 The discharge temperature of compressor varies with evaporation temperature
圖9 壓縮機(jī)排氣溫度隨冷凝溫度變化Fig.9 The discharge temperature of compressor varies with condensation temperature
2.5 循環(huán)壓比的對(duì)比
表5和表6所示為R410A和L-41b在固定一側(cè)溫度,循環(huán)性能另一側(cè)的變化趨勢(shì)。由表6可知,當(dāng)蒸發(fā)溫度恒定為5℃時(shí),兩種工質(zhì)的壓縮機(jī)吸排氣壓比均隨冷凝溫度的提高而逐漸增大,當(dāng)冷凝溫度為30℃左右時(shí),R410A的循環(huán)壓比小于R1234ze(E),偏差為8.2%。隨冷凝溫度的提升,當(dāng)冷凝溫度提高到43℃左右時(shí),R410A循環(huán)壓力大于L-41b,偏差為3.1%。其壓比的變化規(guī)律與變蒸發(fā)溫度實(shí)驗(yàn)相似,即兩工質(zhì)在較高溫度區(qū)運(yùn)行時(shí),L-41b的循環(huán)壓力小于R410A,有利于系統(tǒng)運(yùn)行性能的提高,表明在較高循環(huán)溫區(qū)中L-41b替代R410A的可行性。
表5 變蒸發(fā)溫度實(shí)驗(yàn)測(cè)試數(shù)據(jù)表Tab.5 The test results in the condition of variable evaporation temperature
表6 變冷凝溫度實(shí)驗(yàn)測(cè)試數(shù)據(jù)表Tab.6 The test results in the condition of variable condensation temperature
本文在人工環(huán)境室中設(shè)計(jì)和搭建了空氣源熱泵測(cè)試實(shí)驗(yàn)系統(tǒng),對(duì)比研究了L-41b與R410A在熱泵系統(tǒng)中的運(yùn)行性能,為L(zhǎng)-41b在熱泵系統(tǒng)中的應(yīng)用提供參考和必要的數(shù)據(jù)基礎(chǔ),得出如下結(jié)論:
1)在整個(gè)工況溫區(qū)內(nèi),兩者工質(zhì)的制熱量均隨著蒸發(fā)溫度或冷凝溫度的升高而增大,總體上L-41b的制熱量小于 R410A,但同時(shí)總體功耗也小于R410A,所以L-41b與R410A總體的COP偏差不大。而L-41b的壓縮機(jī)排氣溫度始終低于R410A,從壓縮機(jī)排氣溫度較低有助于延長(zhǎng)壓縮機(jī)使用壽命的角度,L-41b替代R410A具有較好的可行性。
2)兩工質(zhì)在較高溫度區(qū)(工況Z3和N3)運(yùn)行時(shí),L-41b與R410A的COP已較為接近,且隨著溫區(qū)的提高,L-41b的COP表現(xiàn)出了一定的優(yōu)越性。同時(shí)L-41b的循環(huán)壓比小于R410A,有利于L-41b運(yùn)行性能的提高,表明在相對(duì)高溫區(qū)L-41b替代R410A具有較優(yōu)的替代性能。
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Experimental Investigation of R1234ze(E)/R32 Replacing R410A in Heat Pump System
Wang Lulu1Zhang Hua1Qiu Jinyou2
(1.School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai,200093,China;2.College of Ecological Environment and Urban Construction,F(xiàn)ujian University of Technology,F(xiàn)uzhou,350118,China)
Nowadays,more and more attention is being paid to the new low Global Warming Potential(GWP)refrigerant R1234ze(E).Mixing this refrigerant with R32 has been studied in recent years.We focused on contrasting the actual performance of the R1234ze(E)/R32 mixture(mass ratio:27%/73%,named L-41b,with a GWP value of 493)with R410A in a heat pump system.A test system of an air source heat pump was designed and built in an environmental chamber in order to compare the differences between L-41b and R410A under a wide range of working conditions.The compressor energy consumption(COP),heating capacity,refrigeration cycle pressure ratio,and discharge temperature of the compressor were discussed and compared with R410A under similar working conditions.The results shows that,in the variable-condition experiments,the COP deviation decreased from 8.6%to 2.8%when the evaporation temperature increased from 5℃ to 13℃ at a constant condensation temperature of 38℃.The COP deviation was minimized when the condensation temperature increased from 30℃ to 42℃ at a constant evaporation temperature of 5℃.The results further demonstrate that the L-41b mixture can be used to replace R410A in a heat pump system,particularly at relatively high cycle temperatures.
R1234ze(E)/R32;mixed refrigerants;air-source heat pump;operating condition
TB61;TQ051.5;TB64
:A
0253-4339(2017)03-0030-06
10.3969/j.issn.0253-4339.2017.03.030
張華,男,教授,博士生導(dǎo)師,上海理工大學(xué)制冷與低溫工程研究所,(021)55275542,E-mail:zhanghua3000@163.com。研究方向:制冷低溫過程與系統(tǒng)。
2016年9月29日
About the corresponding author
Zhang Hua,male,professor,Ph.D.supervisor,Institute of Refrigeration and Cryogenics,University of Shanghai for Science and Technology,+86 21-55275542,E-mail:zhanghua3000@163. com.Research fields:system process of refrigeration and cryogenics.