Study Of Control Strategy Of Chilled Water System Of Gas-fired Air-conditioner

Energy saving is imperative because serious energy problems are associated with central air-conditioning while it supplies man comfort environment.Among so many factors that influent the energy exhaust,the control issue is an inportmant aspect.While the system works under part load condition for management of supervisory control,how to specify the reliable set points for each control variables?how to give the optimal control stratrgies? Such problems can affect greatly the total energy requrirement.Especially in a central chilled water system with complicated pipeline and many control variabies can cause significant reductions in energy use.Although some research has been done in the relative fields,further work is needed.Combined system simulation with control, taken TRNSYS as the simulation platform, built a typical water cooled primary chilled water system digital emulator,introduct separately the part models of the system:thiller,cooling tower,transduction pump,cooling coil and diverter and mixer and so on.As have no the model of direct-fired double-effect H2O-LiBr absorption chiller,compile separately direct-fired double effect H2O-LiBr absorption chilier's four subprograms by FORTRAN language:absorber,evaporator,condenser,high/low temperature generator, high/low temperature heat exchanger,and combine the model of double-effect H2O-LiBr absorption chillier.Using the known parameters of four types units from some company,identify the needed parameters,adopt experiential experiential values for unable getting's parameters.Through the experimental data from the company,validate the mathematical model of H2O-LiBr absorption chillie.The calculation results show that the chiller model adapt to the control and study of air-conditioning chilled water system.According to study,append a transduction pump model for needs.Then using a cooling tower,four cooling coils,a diverter and a mixer,connect the model by certain way,form the closer path,solve various models by adopting certain value computational method,obtain the needed state variables based on the primary physics,fluid and heat transfer theory,and the actual system equipment layout. At last,taken TRNSYS as the simulation platform,started at the primary variable flow strategy and invariable temperature difference and variable temperature difference and invariable flow strategy,consider changing fuel first when the load reduces,analysis the affects on thiller and system performance by changing the chilled water flow or temperature difference, simultaneously explain that consider changing flow first when the load increase by an example. Give a set method of chilled water temperature difference control taken TRNSYS as the simulation platform,and calculate step only several seconds, adapt to the control analysis of air-conditioning chilled water system,and establish the foundation of control study for air-conditioning chilled water system.