The Thermal Performance Study Of Solution Cycle Exhaust Heat Recovery System

A great quantity heat, moist and toxic substance is produced during the industrialprocesses, causes poor indoor environment, seriously impact the health of the staffs, anddestroys the outside atmosphere environment when they are discharged outdoor. For thishigh temperature, high moist and toxic substance exhaust, exhaust heat recoverytechnology based on solution cycle is proposed. Heat and mass transfer in heat and masstower is the core of the technolog, how to correctly recognize and scientificly evaluate heatand mass transfer process is the basis of optimizing the exhaust heat recovery system andthe premise of the research and development high-performance and efficient heat reclaimsystems. The research method of numerical simulation is used in this article, themechanism and character of the industrial buildings, solution heat transfer and masstransfer is discussed. The research contents and results are as follows:Firstly, industrial building energy consumption, building exhaust and air-conditioningcharacteristic are analyzed. Industrial building energy consumption is high. A lot of heat,moist and toxic substance are produced during the industrial processes. And thecomponents of exhaust are complex. Energy recovery is very difficulty because thedistance between exhaust system and fresh air system is far. Based on the character of theindustrial building, solution cycle exhaust heat recovery system is proposed and differentoperating modes exhaust heat recovery handled process is analyzed.Secondly, the thermal condition of thermal mass tower is analyzed by heat and masstransfer theory in liquid desiccant process, established control unit equations are used bythe NTU-Le model, and numerical simulation is utilized by Matlab. Compared with thesurface steam pressure, corrosivity and energy storage capacity of three different salinesolution, the analyzed results show that the performance of the Llicl solution is better thanthe other two solution. Thirdly, the heat and moisture transfer process between air and solution in the thermalmass tower is analyzed by numerical simulation, and the air physical parameters, solutionphysical parameters and heat and mass driving force distribution are researched and theaffection degree of this process is analyzed. The study results show that: all the air physicalparameters decrease following the flow direction; saline solution physical parametersincrease following the flow direction and the parameters increase fast near the air entrance;the heat and mass potential decrease following the air flow direction and the heat potentialpadding the upper decrease faster than the bottom; gas liquid ratio R≈0.8~1.2is theoptimal gas liquid ratio; the entrance temperature and humid difference between the wet airand the salt solution requires different optimal size tower packing; increasing NUTnumber can improve heat and mass transfer; the influence of Le to the heat and masstransfer process is not obvious.Fourthly, by building the exergy analysis model, the thesis study on the exergyanalysis and matching ability of the exhaust air heat recovery system of solutioncirculating. The results show that the exergy efficiency enhanced with the increase ofgas-liquid ratio, in the end it comes to the balance; the greater inlet concentration solutionthe exergy efficiency low more instead; the matching ability of counter flow pattern insome condition can reach to100%.Finally, based on the above analysis, the thesis advances some measures forimproving the application of h eat and mass single tower and heat and mass double towercombined operation in this exhaust air heat recovery system of solution circulatingrespectively, reducing the reversible loss of the heat and mass tower to achieve the goal forimproving the total efficiency in the system.