吸附制冷系统中固化吸附剂性能的实验研究
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摘要
在吸附制冷系统中,常用的吸附剂为粉末或颗粒形态,吸附剂颗粒之间的热阻和吸附剂与传热面之间的接触热阻很大,而采用固化吸附剂可以有效提高吸附剂的导热性能。本文以硫化膨胀石墨(ENG-TSA)为基质制备了固化活性炭(AC)吸附剂和固化氯化钙(Ca Cl2)吸附剂,针对固化吸附剂设计了无翅片的吸附床结构,并建立了一个低压蒸气驱动的吸附式制冷系统。通过实验对固化吸附剂的性能进行了测试,分析了吸附剂的传热性能、循环时间和蒸发/冷凝温度对吸附制冷系统性能的影响。结果表明:采用AC/ENG-TSA吸附剂,系统COP、SCP和体积制冷密度分别达到0.140,86.1 W/kg和16.11 k W/m~3;采用CaCl_2/ENGTSA吸附剂,系统COP、SCP和体积制冷密度分别达到0.279,288.6 W/kg和54.03 k W/m~3,性能较传统的吸附剂有明显的提高。
In adsorption refrigeration systems,adsorbent commonly used is in the form of powder or granular. The thermal contact resistance between adsorbent particles and the thermal contact resistance between the sorbent and heat transfer surface are large. Using consolidated adsorbent is an effective way to improve heat transfer performance. In this paper,expanded natural graphite treated with sulfuric acid( ENG-TSA) is employed as the host matrix of composite activated carbon( AC) and composite CaCl_2 adsorbents. An adsorption prototype using separate thermosyphon heat pipe technology is established. Owing to the highly thermal conductive consolidated adsorbents,no fins are needed inside the adsorbers. In the experiments,the system performance is analyzed from three aspects: heat transfer performance,cycle time and evaporation/condensation temperature. The results show that the COP,SCP and volumetric refrigeration density of the system employing AC/ENG-TSA are 0. 140,86. 1W/kg and 16. 11 k W/m~3,respectively,the COP,SCP and volumetric refrigeration density of the system employing CaCl_2/ ENG-TSA are 0. 279,288. 6 W/kg and 54. 03 k W/m~3,respectively. The refrigeration performances are improved significantly compared with conventional adsorbents.
In adsorption refrigeration systems,adsorbent commonly used is in the form of powder or granular. The thermal contact resistance between adsorbent particles and the thermal contact resistance between the sorbent and heat transfer surface are large. Using consolidated adsorbent is an effective way to improve heat transfer performance. In this paper,expanded natural graphite treated with sulfuric acid( ENG-TSA) is employed as the host matrix of composite activated carbon( AC) and composite CaCl_2 adsorbents. An adsorption prototype using separate thermosyphon heat pipe technology is established. Owing to the highly thermal conductive consolidated adsorbents,no fins are needed inside the adsorbers. In the experiments,the system performance is analyzed from three aspects: heat transfer performance,cycle time and evaporation/condensation temperature. The results show that the COP,SCP and volumetric refrigeration density of the system employing AC/ENG-TSA are 0. 140,86. 1W/kg and 16. 11 k W/m~3,respectively,the COP,SCP and volumetric refrigeration density of the system employing CaCl_2/ ENG-TSA are 0. 279,288. 6 W/kg and 54. 03 k W/m~3,respectively. The refrigeration performances are improved significantly compared with conventional adsorbents.
引文
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[10]Wang L W,Metcalf S J,Critoph R E,et al.Thermal conductivity and permeability of consolidated expanded natural graphite treated with sulphuric acid[J].Carbon,2012,49(14):4812-4819.
[11]Zhao Y J,Wang L W,Wang R Z,et al.Study on consolidated activated carbon:choice of optimal adsorbent for refrigeration application[J].International Journal of Heat and Mass Transfer,2013,67(12):867-876.
[12]Jiang L,Wang L W,Wang R Z.Investigation on thermal conductive consolidated composite CaC l2for adsorption refrigeration[J].International Journal of Thermal Science,2014,81:68-75.
[13]TamainotT elto Z,Critoph R E.Adsorption refrigerator using monolithic carbon-ammonia pair[J].International Journal of Refrigeration,1997,20(2):146-55.
[14]Wang S G,Wang R Z.Recent developments of refrigeration technology inshing vessels[J].Renewable Energy,2005,30(4):589-600.
[15]Lu Z S,Wang R Z,Wang L W,et al.Performance analysis of an adsorption refrigerator using activated carbon in a compound adsorbent[J].Carbon,2006,44(4):747-752.
[16]Li S L,Xia Z Z,Wu J Y,et al.Experimental study of a novel CaC l2/expanded graphite-NH3adsorption refrigerator[J].International Journal of Refrigeration,2010,33(1):61-69.
[2]Tamainot-Telto Z,Critoph R E.Monolithic carbon for sorption refrigeration and heat pump applications[J].Apply Thermal Engineering,2001,21(1):37-52.
[3]Wang L W,Wang R Z,Wu J Y,et al.Compound adsorbent for adsorption ice maker on fishing boats[J].International Journal of Refrigeration,2004,27(4):401-408.
[4]Wang K,Wu J Y,Wang R Z,et al.Composite adsorben of CaC l2and expanded graphite for adsorption ice maker on fishing boats[J].International Journal of Refrigeration,2006,29(2):199-210.
[5]Jiang L,Wang L W,Jin Z Q,et al.Permeability and thermal conductivity of compact adsorbent of salts for sorption refrigeration[J].ASME Journal of Heat Transfer,2012,134(10):644-647.
[6]张雪峰,刘长智,江龙,等.以硫化石墨为吸附剂基质的再吸附制冷性能分析[J].制冷学报,2015,36(3):41-47.(ZHANG Xuefeng,LIU Changzhi,JIANG Long,et al.Performance analysis on the resorption refrigeration based on the adsorbent with the matrix of expanded natural graphite treated with sulfuric acid[J].Journal of referigeration,2015,36(3):41-47.)
[7]江龙,金哲权,王丽伟,等.不同吸附量条件下氯化锶混合吸附剂-氨的导热系数与渗透率研究[J].制冷学报,2013,34(3):35-39.(JIANG Long,JIN Zhequan,WANG Liwei,et al.Study on the thermal conductivity and permeability of composite SrC l2-NH3working pair under the condition of different values for adsorption quantity[J].Journal of Referigeration,2013,34(3):35-39.)
[8]高佼,何燕,林艳,等.氯化钙/膨胀石墨混合吸附剂导热性能研究[J].制冷学报,2013,34(4):93-95.(GAO Jiao,HE Yan,LIN Yan,et al.Study on thermal conductivities of CaC l2/ENG composite adsorbents[J].Journal of referigeration,2013,34(4):93-95.)
[9]邱钟明,陈砺.固体吸附式制冷系统中吸附床传热强化及设计[J].制冷学报,2002,23(4):26-29.(QIUZhongming,CHEN Li.Design of adsorbent bed for solar solid adsorption refrigeration system and research on heat transfer enhancement[J].Journal of Referigeration,2002,23(4):26-29.)
[10]Wang L W,Metcalf S J,Critoph R E,et al.Thermal conductivity and permeability of consolidated expanded natural graphite treated with sulphuric acid[J].Carbon,2012,49(14):4812-4819.
[11]Zhao Y J,Wang L W,Wang R Z,et al.Study on consolidated activated carbon:choice of optimal adsorbent for refrigeration application[J].International Journal of Heat and Mass Transfer,2013,67(12):867-876.
[12]Jiang L,Wang L W,Wang R Z.Investigation on thermal conductive consolidated composite CaC l2for adsorption refrigeration[J].International Journal of Thermal Science,2014,81:68-75.
[13]TamainotT elto Z,Critoph R E.Adsorption refrigerator using monolithic carbon-ammonia pair[J].International Journal of Refrigeration,1997,20(2):146-55.
[14]Wang S G,Wang R Z.Recent developments of refrigeration technology inshing vessels[J].Renewable Energy,2005,30(4):589-600.
[15]Lu Z S,Wang R Z,Wang L W,et al.Performance analysis of an adsorption refrigerator using activated carbon in a compound adsorbent[J].Carbon,2006,44(4):747-752.
[16]Li S L,Xia Z Z,Wu J Y,et al.Experimental study of a novel CaC l2/expanded graphite-NH3adsorption refrigerator[J].International Journal of Refrigeration,2010,33(1):61-69.