風機盤管加新風系統(tǒng)變水溫節(jié)能研究

1、風機盤管加新風系統(tǒng)變水溫節(jié)能研究許遠超,李蘇瀧(南京理工大學,江蘇南京210094摘要:研究了在風機盤管加新風系統(tǒng)中冷水溫度變化對末端空氣處理設備換熱能力、除濕能力以及冷水機組性能的影響;給出風機盤管加新風系統(tǒng)中室內(nèi)熱濕平衡方程,編制計算程序,通過計算實例表明,對于一般舒適性空調(diào)系統(tǒng),質(zhì)調(diào)節(jié)能夠滿足室內(nèi)溫濕度要求,節(jié)能效果明顯。關鍵詞:部分負荷;風機盤管;變水溫;節(jié)能中圖分類號:T U83113+6文獻標識碼:B 文章編號:1004-7948(200510-0014-031引言在中央空調(diào)系統(tǒng)的實際運行過程中,空調(diào)負荷隨著室外氣象條件等因素變化,多數(shù)時間遠小于設計負荷。如果在空調(diào)負荷減少時,適當

2、提高冷水供水溫度,則可以提高冷水機組的運行效率,降低運行能耗。然而,目前實際運行中,冷水機組的變水溫調(diào)節(jié)帶有很大的隨意性,關于這方面的定量研究也較少,文獻1通過對全空氣系統(tǒng)中空調(diào)機組的表冷器變水溫性能進行分析,給出了某大型機場空調(diào)系統(tǒng)分階段變水溫節(jié)能運行方案;文獻2對冷水溫度變化對末端空氣處理設備除濕能力的影響進行了分析,但所用樣本數(shù)據(jù)較老。兩者均沒有涉及到風機盤管機組,對于風機盤管加新風系統(tǒng),其變水溫運行必須考慮回風和新風處理的協(xié)調(diào)問題,以保證總的效果滿足舒適性要求,本文對此進行研究。2空調(diào)系統(tǒng)變水溫性能211風機盤管變水溫性能在進行空調(diào)系統(tǒng)變水溫節(jié)能運行時必須考慮到末端空氣處理設備的性能。

3、文獻3對風機盤管性能參數(shù)進行了整理和分析,假定風機盤管的風量和水流量不變,運用多元回歸的數(shù)學方法得出風機盤管冷量Q 的回歸方程:Q t Q t0=t s1-t w1t s10-t w10(1Q s Q s0=t 1-t w1t 10-t w10t s1t s10-017(2Q l Q l0=Q t -Q sQ t0-Q s0(3式中下標t ,s ,l 分別表示風機盤管的全熱、顯熱和潛熱;下標“0”在標準工況條件下,沒有下標表示在實際工況條件下;t 1、t s1空氣進口干、濕球溫度;t w1冷水出口溫度?，F(xiàn)取某FP -613型風機盤管為例進行研究,標況下風機盤管進風干球溫度27,濕球溫度1915

4、,冷水供水溫度7,溫差為5。此型號盤管標況下的全熱冷量和顯熱冷量分別為4141kW 和2198kW 。圖1是根據(jù)以上公式得到風機盤管的顯熱、潛熱和全熱冷量隨冷水溫度變化的曲線。由圖1可見,冷水溫度的升高將導致冷量下降,冷量與溫度間基本呈線性變化,但冷凍水溫度提高 對全熱冷量、顯熱冷量和潛熱冷量的影響程度是不同的,其中對潛熱冷量的影響最大,顯熱冷量影響最小,全熱冷量介于其間。當冷水溫度由7改變?yōu)?時,風機盤管的全熱冷量下降了16%;變?yōu)?2時,全熱冷量下降為原來的60%。圖1風機盤管冷量隨冷水溫度變化曲線212新風機組變水溫性能對于風機盤管加新風系統(tǒng),既要考慮變水溫對于風機盤管熱濕處理能力的影響

5、,同時也要考慮在相同冷水溫度下,新風機組處理能力的變化。表冷器的熱工性能主要受到以下幾個因素的影響:進口空氣參數(shù)、風量、冷水溫度和流量。為便于說明問題41節(jié)能E NERGY C ONSERVATI ON 2005年第10期(總第279期起見,現(xiàn)以JW30-4型6排通用型表冷器為例,其處理風量為16000kg/h ,水流量23500kg/h ,迎面風速215m/s ,水流速116m/s 。本文采用全熱交換效率計算法,假設風量和水量不變,通過改變冷水溫度和進出口空氣參數(shù)來具體分析表冷器熱工性能的變化。計算中,假設在統(tǒng)計意義上空調(diào)負荷率與室外空氣干球溫度呈線性關系,負荷率與室外干濕球溫度間的對應關系

6、采用ARI 標準4,見表1。表1部分負荷時新風機組的熱工性能負荷率/%10090807060冷水溫度/781291410161118室外新風干球溫度/353218301528132611室外新風濕球溫度/292612723153201818107新風送風干球溫度/151715141511151419從表1可以看到,由于室外氣象條件變化,在空調(diào)負荷減少時,新風機組采取提高冷水溫度做法,室外參數(shù)對新風機組的影響超過了冷水溫度提高對新 風機組的影響,處理后的新風送風干球溫度略有下降,但變化不大,說明在室外氣象條件變化時,冷水溫度提高對新風機組處理新風終狀態(tài)影響不大,部分負荷時,相應提高冷水溫度是可行

7、的。213冷水機組變水溫性能圖2是某空調(diào)公司特定型號的三種類型(活塞式、螺桿式、離心式冷水機組C OP 和冷水溫度的關系,可以看出當冷卻水供回水溫度不變(32/37,冷水溫度提高時,C OP 值變大,效率提高,冷水溫度由7提高到10時,活塞式C OP 值提高了817%,螺桿式C OP 值提高了912%,離心式C OP 值提高了515%,通過提高水溫的節(jié)能效果很明顯。圖2冷水出口溫度對機組C OP 的影響3變水溫對室內(nèi)溫濕度的影響根據(jù)以上分析,當室外氣象條件變化,空調(diào)系統(tǒng)處于部分負荷時,可以通過提高冷凍水供水溫度,在滿足室內(nèi)負荷的同時,提高冷水機組的運行效率,以節(jié)約能耗。但變水溫運行,冷水溫度提

8、高不僅會對風機盤管的熱濕處理能力產(chǎn)生影響,還會影響到新風機組的處理能力,最終還會對室內(nèi)參數(shù)以及舒適度產(chǎn)生影響。因此,有必要對此進行定量研究,本文采用室內(nèi)熱濕平衡方程來研究變水溫對室內(nèi)溫濕度的影響,室內(nèi)熱濕平衡方程為:G F (i N -i 0+G W ( i N -i 2=0(4G F d 0+G W d 2+W =(G F +G W d N(5式中G F ,G W 風機盤管送風量和室內(nèi)新風量;i 0,i 2風機盤管送風焓值和新風送風焓值;d 0,d 2風機盤管送風含濕量和室內(nèi)新風的含濕量,i 1N ,d 1N 室內(nèi)實際計算焓值和室內(nèi)實際計算含濕量,Q 室內(nèi)余熱量,W 室內(nèi)余濕量。根據(jù)以上分析

9、,編制程序,程序設計流程如圖3所示。圖3室內(nèi)溫濕度計算流程圖下面通過實例來說明部分負荷時冷水溫度變化對室內(nèi)參數(shù)的影響。某空調(diào)房間,室內(nèi)總余熱量Q =31314kW ,總余濕量W =01264g/s ,夏季室內(nèi)計算參數(shù)為:t N =25,N =50%,當?shù)卮髿鈮毫?0113kPa 。新風機組和風機盤管都是定型的。新風量L =90m 3/h ,新風比為15%。討論當由于室外氣象條件引起室內(nèi)余熱總量變化,總余濕量不變時,負荷率與冷水溫512005年第10期(總第279期節(jié)能E NERGY C ONSERVATI ON 度以及新風送風干球溫度的關系。根據(jù)上述公式編制的程序,通過迭代運算,求得結(jié)果如表

10、2所示:表2部分負荷時送風參數(shù)和室內(nèi)參數(shù)負荷率/%10090807060冷水溫度/781291410161118新風送風干球溫度/16121519151615151514 FCU送風干球溫度/11151312141816141811室內(nèi)干球溫度/25112419241524132411室內(nèi)相對濕度/%4918521855581663從表2可以看到:當室內(nèi)處于部分負荷狀態(tài)時,通過調(diào)節(jié)冷水供水溫度,可以將室內(nèi)溫濕度控制在舒適標準范圍之內(nèi)。實際上隨著室外干濕球溫度的下降,室內(nèi)余濕量也會有所降低,所以實際室內(nèi)相對濕度會略有一定程度的降低。因此,對于舒適性空調(diào)系統(tǒng)采用變水溫質(zhì)調(diào)節(jié)是可以滿足要求的。4結(jié)語

11、對于風機盤管加新風系統(tǒng),質(zhì)調(diào)節(jié)方法是可行的,不僅節(jié)能,且也能滿足一般舒適性空調(diào)對于溫濕度的要求。如當負荷率為70%時,采用10的冷水供水溫度,與設計工況相比,離心式機組耗電量下降了515%,螺桿式機組耗電量下降了912%,節(jié)能效果明顯。由于冷水溫度的提高,使得末端空氣處理設備的除濕能力下降,室內(nèi)相對濕度變大,使得冷水溫度的提高受到一定的限制。當室內(nèi)負荷為60%,采用1118的冷水溫度,室內(nèi)相對濕度就達到了63%,所以,對舒適性空調(diào)系統(tǒng),冷水溫度的提高一般以不超過12為宜。參考文獻1陸瓊文,劉傳聚,曹靜.浦東國際機場變空調(diào)供水溫度節(jié)能運行方案分析J.暖通空調(diào),2003,33(2:123-125.

12、 2劉金平,周登錦.空調(diào)系統(tǒng)變冷水溫度調(diào)節(jié)的節(jié)能分析J.暖通空調(diào),2004,34( 5:90-91.3 韓偉國,陸亞俊.風機盤管加新風空調(diào)系統(tǒng)值比較設計方法J.暖通空調(diào),2002,35(2:80-83.作者簡介:許遠超(1979-,男,碩士研究生,(收稿日期:2005-07-26(上接第5頁圖8壓降與雷諾數(shù)的關系圖9T/P與雷諾數(shù)的關系為,采用各向異性多孔介質(zhì)能較好地反映殼側(cè)的流場情況,可以用來解決實際工程問題。提出的殼程流場改進方法,即在增加折流板的缺口高度的同時再加入分隔板的殼程流場改進方法,既能減小殼程壓降起到節(jié)能降耗的作用,又能均化流場、減小死區(qū),起到強化傳熱的作用,同時還提高了管束的

13、抗流體誘導振動的性能,具有很好的工程應用前景。參考文獻1林瑞泰.多孔介質(zhì)傳熱傳質(zhì)引論M.北京:科學出版社,1995.2陶文銓.數(shù)值傳熱學(第2版M.西安:西安交通大學出版社,2001.3解衡,高祖瑛.管殼式換熱器流場三維數(shù)值模擬J.核科學與工程,2002,22(9:240-249.4鄧斌,陶文銓.管殼式換熱器殼側(cè)湍流流動的數(shù)值模擬與實驗研究J.西安交通大學學報,2003,37(9:889-893.5蒸汽發(fā)生器編寫組.蒸汽發(fā)生器M.北京:原子能出版社.1982.130-135.6王楊君,鄧先和,陳潁,李志武.平行流分隔板管殼式換熱器殼側(cè)流場與傳熱性能J.化工學報,2004,55(2:275-27

14、9.7嚴良文,王志文.折流板換熱器的數(shù)值模擬及場協(xié)同分析J.石油機械,2005,33(4:13-15.作者簡介:劉敏珊(1943-,女,河南商丘人,教授,博士生導師,研究方向:從事過程裝備C AD/C AE/C AM、數(shù)值模擬及強化傳熱方面的研究。(收稿日期:2005-08-29E nergy Conservation(MonthlySponsor:Liaoning Provincial Institute of Science andT echnology In formationPublisher:Energy C onservationMagazine PublishingH ouseC

15、hief Editor:ZH ANG Wei2huaAddress:N o.274Qingnian Boulevard Shenyang CityLiaoning Province ChinaPost Code:110016ABSTRACTSOctober2005N o.10T otal Issue N o.279Numerical simulation of fluid flow in shell side of segmentalb affle heat exch anger and structure optimizationLIU M in2shan,DONG Qi2wu,LIU Qi

16、anA three dimensional numerical m odel based on s oftware F LUE NT using porous media and distributed resistance method to simulate fluid field in shell side of single segment baffle heat exchanger.The three dimensional m odel was validated by com paris on the com puted data with the experimental da

17、ta.Based on the result,a new method was put forward to decrease the pressure drop of shell-side and to elim inate the dead spaces of heat trans fer.Through numeri2 cal simulation,it can be concluded that the im proved fluid flow in the shell side of the heat exchanger not only has low pressure drop

18、but als o has excel2 lent field synergy,at the same time the tube bundles ability of resisting fluid induced vibration was im proved.K ey w ords:single segmental baffle heat exchanger;numerical simula2 tion;intensification heat trans fer in the shell side of single segmental baffle heat exchange;ene

19、rgy conservation.3Numerical simulation of effect ofnatural ice storeage with conical iceLI Y e2fa,ZHANG Y ou2wei Based on the local meteorological conditions,the relationship of efficien2 cy of ice storeage in winter utilizing conical ice between ice storeage and ra2 dius of conical ice.Application

20、of this method will make both econom ic and s ocial benefit.K ey w ords:natural ice storeage;efficiency of ice storeage;conical ice6 The mech anism of w et-membrane humidifier andanalysis on its influence factorsHUANG Qiu2ju,LIU Nai2ling The wet-membrane hum idifier utilizes the method of equal enth

21、alpy hu2 m idification to hum idify the air.It only consumes the electricity of the air blower and circulating water pum p,having advantages of sim ple structure and saving energy.From the hum idification mechanism of the wet-membrane hu2 m idifier,this paper has studied the hum idification performa

22、nce of the wet-membrane hum idifier,and analyzed the factors that affect the performance of it,and finally introduced the application of the wet-membrane hum idifier in brief,which has very im portant meaning for im proving the hum idification effi2 ciency of wet-membrane hum idifier and popularizin

23、g it.K ey w ords:wet-membrane hum idifier;hum idification mechanism; in fluence factor8Studies on combined heating systemof gas-ch amber and solar energyMA Liang2tao T o clarify of the combined Heating System of G as-Chamber and S olar Energy,clarify the way of make and control.T o sure the econom i

24、c on the basic of com fortable and satis factory.K ey w ords:gas-chamber;the heating system of s olar energy;the combined heating system12 Study on energy saving of variable chilled w atertemperature in fan-coil plus fresh air systemsXU Y uan2chao,LI Su2long S tudies the effects of variable chilled

25、water tem perature on heat trans fer and dehum idifying of the term inal equipment as well as chiller in fan-coil plus fresh air systems.Writes com putational program by virtue of balance e2 quations about heat and mass.Indicates that quality regulation meets demand in tem perature and hum idity and

26、 has obvious energy saving effect for com fort -type air conditioning systems.K ey w ords:part load;fan-coil units;variable chilled water tem pera2 ture;energy saving14 Biom ass-gasifier steam-injected gas turbine cycleLI Hai2ying,GUO Min2chen,LU Fang2chen It introduces the characteristic of biomass

27、 and in fluence to environment and the characteristic of STIG cycle.It em phases on the characteristic and demand of gasifier,clean system and gas turbine in the biomass-gasifier power generation system,from the point of match of BIG/STIG cycle system. At last,it points that our country should devel

28、op the technology of biomass-gasifier power generation and gives s ome advice.K ey w ords:biomass;gasifier;BIG/STIG cycle23Control circuit theory and m aintaintechnology of air-conditioning in familyLIN Li W ith the lives enhancement of the people,the air conditionings enter home everywhere.But in o

29、rder to extend the technology of variable frequency variable speed,this papers introduced the basic theory of air-conditioning, especially analysed the circuit gram and maintain technology.It is very im por2 tant for the people whose job is busy with maintain.K ey w ords:variable frequency variable

30、speed;control circuit;main2 tain technology26 R esearch on safe assessment low vacuumtherm al dilation of heating unitZ ANG Y an2guang This paper analyzes the im pact of axial thrust and thermal dilation on the safe operation of the unit after the m odification and puts forward s ome neces2 sary saf

31、ety measures.K ey w ords:heating unit;axial thrust;thermal dilation;safe assess2 ment31E nergy b alance analysis and energy-savingcountermeasure of heavy oil gathering systemXU Xiu2mei,LI Dong2ming,WANG Zhi2guo Setting up an energy balance analysis m odel of heavy oil gathering system and gives eval

32、uation index and calculation formula.Using survey data,one heavy oil gathering system is calculated and analysed.According to the result of calculation,s ome suggestions of reducing systematic energy consum ption is pat forward.K ey w ords:heavy oil gathering;energy balance;energy-saving39W ays of s

33、aving energy resources inresidential architecture in countrysideLI Jiang N owadays under the situation of large am ount of building and its exten2 sive distribution in our countryside,this articl recom end the ways of saving en2 ergy res ources in residential architecture in countryside.From the tw o ways,that is saving energy res ources in production of building m aterials and in current sit2 uations,and point out,to act from fact and adjust m easure t