Study On The Application Of The Air Conditioning System Based On Low Grade Energy-bus In Typical Buildings

With the improvement of people's requirements for building thermal comfort and beautiful,central air conditioning system has become an indispensable and important equipment in all kinds of new public buildings.The traditional air conditioning system is always criticized because of its high energy consumption,overheating in inner zone,cross infection,and so on.In this paper,the central air conditioning system based on low grade energy-bus(referred to as air conditioning system based on energy-bus)is studied,which can solve the disadvantages of the traditional centralized air conditioning system by using a highly efficient distributed indoor terminal,bus-type water loop and the low grade energy.In view of the system,the following aspects are studied:Firstly,introduce the structure,characteristics and working principle of air conditioning system based on energy-bus,and the working and energy-saving principle of water-cooled air conditioner combined with heat pipe(referred to as heat pipe composite unit)of the important parts of the system are expatiated in detail.According to the difference of the cold and heat source of the system,several existing air conditioning system based on energy-bus forms are introduced in this paper.Based on the vapor compression refrigeration mode,the main parts of heat pipe composite unit were designed,and the heat pipe cooling mode was checked.Secondly,the mathematical models of main components of the air conditioning system based on energy-bus were established.The steady state distribution parameter models are established for the finned tube heat exchanger and the casing tube heat exchanger,for compressor and expansion valve,the lumped parameter models are established.The computational model for the thermodynamic properties of the refrigerant was established by using Cleland's simplified computational model.The mathematical models of the dynamic operation of each mode of the heat pipe composite unit are constructed,and the models are solved by discrete method.At the same time,the mathematical models of cooling tower,circulating pump and soil heat transfer were established.Thirdly,this paper takes a 26400m2 office building in Beijing as the research object,builds the building model with DeST software,and simulates its annual hourly load.Based on the mathematical models of each components and their coupling relationship,the annual dynamic mathematical model of the air conditioning system based on energy-bus was established.Based on the established system model and the simulated hourly load and environmental parameters,the performance of the system under different water ring temperature settings was studied through the preparation of Matlab program.Finally,According to the established system model and the optimal water ring temperature,the annual operating characteristics of the system were simulated.Comparing with the traditional water loop heat pump system and fan coil system,the energy saving of the air conditioning system based on energy-bus was investigated.Change the load standard of the building interior,investigate the energy consumption change of the system under different internal load,and compare the energy-saving change with the traditional air-conditioning system.Change the cold and heat source of the air conditioning system based on energy-bus,compare the energy consumption of the system under different conditions of cold and heat source.The simulation results show that:the air conditioning system based on energy-bus has a greater energy-saving advantages in refrigeration and heat and cold distribution.The research work in this paper provides a reference for the application of the air conditioning system based on energy-bus,and also has important value for promoting the energy saving of central air conditioning system.