Study on the Strategy of Path Optimization on the Process of Air Handling Based on Genetic Algorithm Jiwan Hu, Jianjian Li, Wude Xie, Qiang Peng

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1 d Iteratioal Coferece o Electroics, Network ad Computer Egieerig (ICENCE 016 Study o the Strategy of Path Optimizatio o the Process of Air Hadlig Based o Geetic Algorithm Jiwa Hu, Jiajia Li, Wude Xie, Qiag Peg Uit of PLA, Wuha, Hubei hujiwa1@163com Keywords: Air-coditioig uit; Psychrometric chart; Geetic algorithm; Optimal path Abstract With its great ability o cotrollig air parameters, combied air-coditioig uit is playig a icreasigly importat role i civilia life, idustrial productio ad eve military fields Because of the variety of varied path, while the eviromet chaged, the optimal varied path ca t be got, ad the uit ca t be i the best operatig state, which waste the eergy serious Through the aalysis of the structure ad priciples of the uit, the paper aimed at studyig the air coditio o the psychrometric chart Ad the use geetic algorithm to get the optimal value, fially the optimal varied path i the process of air treatmet, which improvig the efficiecy of the uit greatly, ad reducig the eergy cosumptio Air-coditioig Uit Structure The meas that the uit treated air icludes supplyig air, filtratig, coolig, heatig, dehumidifyig, humidifyig ad so o Differet fuctioal sectios correspod to differet devices, icludig forced draught fa, primary efficiecy filter, electric heater, frot surface air coolers, after surface air coolers, disc dehumidifier, ad humidifier The air-coditioig uit structure is show i Figure 1 Figure 1 air-coditioig uit structure diagram The correspodig fuctios of the mai eergy cosumptio equipmet are show below: Forced draught fa: Trasferrig the outside air to the pipe of uit Primary efficiecy filter: Filterig the dust i the air ad improvig the quality of the air Electric heater: Heatig the air through the heat geerated by the curret through the resistace wire Surface air coolers: The purpose is coolig air through exchagig the heat ad moisture ad usig the refrigerat as medium Disc dehumidifier: Whe the air through the dehumidificatio zoe, the water is absorbed, so the effect of dehumidifyig air is achieved Humidifier: The stailess steel electric heatig pipe was used to heatig the water i the tak, ad the the steam was geerated which would be sprayed ito the air, so the air was cleared ad humidified Aalysis o characteristics of operatig coditios The chage of air coditio is a very complicated process, a sigle mathematical formula or a diagram is difficult to reflect the air hadig process [] The state of the air is characterized by the 016 The authors - Published by Atlatis Press 614

2 psychrometric chart i egieerig Based o the calculatio formula of ethalpy ad moisture cotet of the moist air which is composited by 1 kg dry air uder certai atmospheric pressure, the psychrometric chart was desiged which toke the temperature as vertical coordiates ad the moisture cotet as horizotal coordiates The meas that differet devices dispose air is varied Whe through heater, the air is heated while the moisture cotet is uchaged Whe through surface air coolers, the air is cooled while the moisture cotet is costat or the temperature ad the moisture cotet of the air are both reduced Whe through humidifier, the air is humidified while the temperature is costat Whe through disc dehumidifier, the air is dehumidified while the ethalpy is costat The chaged process is reflected i psychrometric chart as show i figure 3 Figure 3 the process that devices dispose air Coditio of high-temperature ad high-humidity The operatig coditio of high-temperature ad high-humidity is a more complicated coditio There are differet ways whe the status of air chages from high-temperature ad high-humidity status to target status, but some ways is impossible i actual operatio, so the air ca oly be cooled ad dehumidified uder this coditio The devices with coolig fuctio icludes frot surface air coolers ad after surface air coolers, with dehumidifyig fuctio icludes disc dehumidifier, ad the positio of the three devices i the uit is: frot surface air coolers, after surface air coolers ad disc dehumidifier Ay combiatio of the three devices ca achieve the chage that the air chaged from fresh status to target status Whe the three devices are all opeed, the air is cooled while the moisture cotet is costat whe through the frot surface air cooler Before the temperature drops to the dew poit temperature, the disc dehumidifier begis workig ad the air is dehumidified while the ethalpy is costat Because of the temperature risig i the dehumidifyig process, the after surface air cooler should be opeed to cool the air uder costat moisture cotet, the the target temperature ad humidity The process that the air i the circumstaces cotais: supplyig air, cooled uder costat moisture cotet, dehumidified while the ethalpy is costat, cooled more, ad supplyig air, which is defied as situatio1 The correspodig devices that are eeded to ope iclude: forced draught fa, frot surface air coolers, disc dehumidifier, after surface air coolers, ad forced draught fa, which is defied as combiatio 1 Whe the frot surface air cooler is closed, the process that the air i the circumstaces cotais: supplyig air, dehumidified while the ethalpy is costat, cooled more, ad supplyig air, which is defied as situatio The correspodig devices that are eeded to ope iclude: forced draught fa, disc dehumidifier, after surface air coolers ad forced draught fa, which is defied as combiatio Whe the after surface air cooler is closed, the process that the air i the circumstaces cotais: supplyig air, cooled uder costat moisture cotet ad supplyig air which is defied as situatio 3 The correspodig devices that are eeded to ope iclude: forced draught fa, frot surface air coolers, disc dehumidifier ad forced draught fa, which is defied as combiatio 3The chage process is show i figure 4 615

3 Figure 4 the path diagram of varied air status i high-temperature ad high-humidity Figure 5 the path diagram of varied air status i high-temperature ad low-humidity From figure 4, we ca kow that the air i the varied process will experiece multiple itermediate states poits The correspodig devices will cosume a certai amout of electric eergy whe the air chaged from oe state poit to aother poit, ad the amout of eergy cosumptio depeds o the actual cotrol parameters of the devices so whe the optimal itermediate state poit is determied, the optimal cotrol parameters i the actual operatio will be determied too, which ca esure that the uit ca work with the miimum eergy cosumptio poit Coditio of high-temperature ad low-humidity Like with the aalysis of the operatig coditio of high-temperature ad high-humidity, whe the air chaged from the status of high-temperature ad low-humidity, the air will be cooled ad humidified The devices with coolig fuctio icludes frot surface air coolers ad after surface air coolers, with humidifyig fuctio icludes humidifier, ad the positio of the three devices i the uit is: frot surface air coolers, after surface air coolers ad humidifier Ay combiatio of the three devices ca achieve the chage that the air chaged from fresh status to target status Whe the three devices are all opeed, the process that the air i the circumstaces cotais: supplyig air, cooled uder costat moisture cotet, cooled more, humidified while the temperature is costat ad supplyig air, which is defied as situatio 1 The correspodig devices that are eeded to ope iclude: forced draught fa, frot surface air coolers, after surface air coolers, humidifier ad forced draught fa, which is defied as combiatio 1 Whe the after surface air cooler is closed, the process that the air i the circumstaces cotais: supplyig air, cooled uder costat moisture cotet, humidified uder costat temperature ad supplyig air which is defied as situatio The correspodig devices that are eeded to ope iclude: forced draught fa, frot surface air coolers, humidifier ad forced draught fa, which is defied as combiatio Whe the frot surface air cooler is closed, the process that the air i the circumstaces cotai: supplyig air, cooled uder costat moisture cotet, humidified uder costat temperature ad supplyig air which is defied as situatio 3 The correspodig devices that are eeded to ope iclude: forced draught fa, after surface air coolers, humidifier ad forced draught fa, which is defied as combiatio 3The chage process is show i figure 5 Coditio of low-temperature ad low-humidity This coditio is relatively uusual i actual eviromet Like with the aalysis of the operatig coditio of high-temperature ad high-humidity, whe the air chaged from the status of low-temperature ad low-humidity, the possible process icludes: Situatio 1: supplyig air, heated uder costat moisture cotet, humidified uder costat temperature, heated uder costat moisture cotet ad supplyig air Situatio : supplyig air, heated uder costat moisture cotet, humidified uder costat temperature ad supplyig air The differet ways of combiatio of the correspodig devices are exist: Combiatio 1: Forced draught fa, heater, humidifier, heater, ad forced draught fa; 616

4 Combiatio 1: Forced draught fa, heater, humidifier, ad forced draught fa The chage process is show i figure 6 Figure 6 the path diagram of varied air status i low-temperature ad low-humidity Figure 7 the path diagram of varied air status i low-temperature ad high-humidity Coditio of low-temperature ad high-humidity Like with the aalysis of the operatig coditio of high-temperature ad high-humidity, whe the air chaged from the status of low-temperature ad high-humidity, the possible process icludes: Situatio 1: supplyig air, heated uder costat moisture cotet, dehumidified uder costat ethalpy, heated uder costat moisture cotet ad supplyig air Situatio : supplyig air, heated uder costat moisture cotet, dehumidified uder costat ethalpy ad supplyig air The differet ways of combiatio of the correspodig devices are exist: Combiatio 1: Forced draught fa, heater, disc dehumidifier, heater, ad forced draught fa; Combiatio 1: Forced draught fa, heater, disc dehumidifier, ad forced draught fa The chage process is show i figure 7 Parameter Optimizatio The optimizatio research of the uit usually ivolves may problems such as multi variable, time variat, oliear ad strog couplig Traditioal optimizatio algorithm caot achieve the purpose of optimal cotrol While as a ew kid of optimizatio algorithm, geetic algorithm ca solve the above problems The importat calculatio method to optimizatio research of uit is to global optimizig the cotrol parameters i real time ad olie [3] [4] The simulatio model of geetic algorithm is based o MATLAB software, specific processes iclude: Determiatio of the legth of biary strig Biary codig is used as the codig method of the paper Biary codig is oe of the most frequetly used methods It is a set of symbols made up of biary symbols, whose legth is related to the accuracy of the solutio ad the of optimizatio parameters Specific operatios are as follows: The parameters that represets i the rage [a,b] are represeted as a biary strig, the accuracy is precise to decimal places to The closed iterval [a, b] is divided ito ([ b a] parts The rage of [ b a] is determied m m 1 [ b a] So the legth of biary strig eeds at least m Parameter Selectio Geetic algorithm is a calculatio based o populatio The size of populatio should ot be too large ad the geeral rage is i 0 to 0 The size of populatio i the paper is 0 After repeater screeig ad verificatio, the crossover probability is determied as 07 ad mutatio probability is determied as 008 The size of the umber of iteratios is correspodig to the speed ad accuracy of solutio If the umber of iteratios is too small, it is easy to cause miscarriage of justice ad the 617

5 accuracy of the solutio will be reduced If the umber of iteratios is too large, the speed of solutio will be reduced too ad the computig cycle will be exteded Fially the umber of iteratios is determied as 0 by the collatio ad aalysis of data Determiatio of Objective Fuctio The miimum value of the total eergy cosumptio is optimized by takig the total eergy cosumptio as objective fuctio ad takig the parameters that eed to be optimized as argumets The total eergy correspoded to differet combiatios of devices is differet The respective model of objective fuctio is established to aalyze ad simulate, ad fially the optimal combiatios is determied by comparig the total eergy cosumptio Biary Decodig The parameters that had bee optimized eed decodig calculatio ad the covert to decimal parameters For example, if a biary strig such as ( bb 1 bb 1 wat to traslate ito the correspodig real value betwee [a, b] Specific decodig operatio is: The biary are represeted as a decimal umber: l 1 1 l 1 ( bb bb = ( b = x Reals that correspodig to x rage i [a, b] is:, b a x= 10 + x 1 Aalysis of Result, Combied with the actual eviromet, the parameters i actual operatio is optimal aalyzed uder the coditio of high-temperature ad humidity ad the coditio of low-temperature ad high-humidity, the optimizatio result is show below The optimizatio ad aalysis of the coditio of high-temperature ad humidity The selected temperature of the fresh air is 14 degrees Celsius ad the moisture cotet is selected as 7376 (kg/kg dry air The target temperature is selected as 1600 degrees Celsius ad the target moisture cotet is selected as 3000 (kg/kg dry air The fa is iput as variable frequecy, ad the the iitial frequecy is set as 35HZ The three parameters correspodig to situatio 1 are eed to be optimized: the target temperature behid the frot surface air cooler, the target moisture cotet behid disc dehumidifier ad the target temperature behid the after surface air cooler The optimizatio process of optimal eergy cosumptio correspodig to situatio 1 is show i figure 8 Figure 8 the relatio betwee eergy cosumptio Figure 9 the relatio betwee eergy cosumptio value correspodig to situatio 1 ad iteratio value correspodig to situatio ad iteratio From figure 8, we ca kow that: after 76 iteratios, the eergy cosumptio of the system is achieved ad is kept i kw The the optimal operatio parameters are achieved while is existed as biary strigs So these parameters are eeded to be recoded The legth of biary strig of sigle variables is determied as through calculatios, so the legth of the whole strig i situatio 1 is 30, which ca be represeted asb 9 b8 b1b Amog them, 0 618

6 b9 b8 b1b is represeted as the biary strig of the target temperature behid the frot surface air 0 cooler, b19 b1 8 b11b is represeted as the biary strig of the target moisture cotet behid disc dehumidifier, b9 b8 b1b is represeted as the biary strig of the target temperature behid the 0 after surface air cooler Based o the decodig operatio i the last sectio, the three biary strigs are decoded First the biary are coverted to decimal : 9 l l ( b9b8 b1b0 = ( b = x1 0 l l ( b19b18 b11b = ( b = x 19 l l ( b9b8 b1b0 = ( b = x3 The x 1 x x 3 are coverted to real i correspodig rage: ( t max ( mi 1 = B o t B o x x 1 ( d max ( mi = 10 + Z o d ( t Z o max ( mi x x 10 3 = + 3 H o t H o x x 1 1 The three parameters correspodig to situatio are eeded to be optimized: the target temperature behid disc dehumidifier, the target moisture cotet behid disc dehumidifier ad the target temperature behid the after surface air cooler The optimizatio process of optimal eergy cosumptio correspodig to situatio is show i figure 9 From figure 9, we ca kow that: after 18 iteratios, the eergy cosumptio of the system is achieved ad is kept i kw The three parameters correspodig to situatio 3 are eeded to be optimized: the target temperature behid the frot surface air cooler, the target temperature behid disc dehumidifier ad the target moisture cotet behid disc dehumidifier The optimizatio process of optimal eergy cosumptio correspodig to situatio is show i figure 9 0 Figure the relatio betwee eergy cosumptio Figure 11 the relatio betwee eergy cosumptio value correspodig to situatio ad iteratio value correspodig to situatio ad iteratio From figure, we ca kow that: after 88 iteratios, the eergy cosumptio of the system is 4 achieved ad is kept i 61 kw, the target temperature behid the frot surface air cooler is 193, the target temperature behid disc dehumidifier is 1605, the target moisture cotet behid disc dehumidifier is 3004(kg/kg dry air By comparig the three values of eergy cosumptio of three combiatios, the value of eergy cosumptio i combiatio is the lowest, so the optimal operatio state of uit is determied: forced draught fa, disc dehumidifier, after surface air coolers ad forced draught fa The optimizatio ad aalysis of the coditio of low-temperature ad high-humidity Combied with the study o the characteristics of the workig coditios of the first sectio, we ca kow that there are three paths uder the coditio of low-temperature ad high-humidity ad three combiatios Like with the aalysis of the coditio of high-temperature ad humidity, The selected temperature of the fresh air is 44 degrees Celsius ad the moisture cotet is selected as 776 (kg/kg dry air The target temperature is selected as 1600 degrees Celsius ad the target moisture cotet is selected as 3500 (kg/kg dry air The the lowest value of eergy cosumptio is took as objective fuctio ad the costrait coditios of ifluece factors of eergy 619

7 cosumptio is determied, the the operatio parameters are optimized by geetic algorithm, ad fially the optimal path uder this coditio is determied by comparig the value of eergy cosumptio of the three combiatio: supplyig air, heated uder costat moisture cotet, dehumidified uder costat ethalpy ad supplyig air, the combiatio of the correspodig devices are: forced draught fa, heater, disc dehumidifier, ad forced draught fa The optimizatio process of optimal eergy cosumptio correspodig to situatio is show i figure 11 From figure 11, we ca kow that: after 76 iteratios, the eergy cosumptio of the system is achieved ad is kept i kw The optimal operatio parameters are determied: the target temperature uder heater is 1560, the target temperature behid disc dehumidifier is 1603 ad the target moisture cotet behid disc dehumidifier is 3435(kg/kg dry air Coclusio Aalysis of the above results showed that: the strategy of path optimizatio o the process of air hadig based o geetic algorithm ca optimize the path of air hadig i real time ad olie, which ca keep the operatio parameter i optimal poit of the status, ad the cotrol cycle would be reduced greatly, the operatio efficiecy would be improved greatly ad the eergy cosumptio would be reduced effectively Referece [1] Zhao Rogyi, Fa Cuyag, Xue Diahua etc Air Coditioig [M] Beijig: Chia Buildig Idustry Press, 009 [] Wu Zejiag Psychrometric calculatio sheets for air hadig process [J] HV&AC, 011, 41(:48-50 [3] Zhou Zhi, Ga Shuchua Study o Optimizatio of Cotrol Parameters Based o Geetic Algorithm [J] Computer Applicatios: 007, 7: [4] Zhao Yafa, Wag Ruihua, Wag Pu The Applicatio of Geetic Algorithm i the Eergy Optimizatio Cotrol of the VAV system [J] Cotrol Egieerig, 009, 16(S1: [5] Lei Yigjie The MATLAB Toolbox ad Applicatio Based o Geetic Algorithm [M] Xi a: Xi a Electroic Siece & Techology Uiversity Press, 005 [6] Tag Jua Simulatio Aalysis of Eergy Cosumptio Model of Air Coditioig System Based o MATLAB Simulik [J] Buildig Eergy & Eviromet, 0, 9(: