Simulation And Analysis Of Chilled Water System Of Gas-fired Air-conditioner

The use of gas-fired absorption chiller is gaining popularity in the air-conditioning industry because it can relax the environment pollution and it also contributes to the reduction of electricity demand during peak cooling seasons by shifting to gas or oil, and especially is important in new distributed energy system. But the great cost during its operation became hindrance for its development. Among so many factors that affect the energy exhaust, the control issue is an important aspect. How to specify reasonable set points for each local control variable through supervisory control during part load has great influence on system energy requirement. Especially in chilled water system with complicated pipeline and many control variables, even a small improvement can cause significant reductions in energy use. The foundation of optimal control is system model and this paper developed gas-fired air-conditioner chilled water system simulation model suitable for system supervisor and optimal control.First it is necessary to develop basic component models that could accurately reflect actual characteristic of each component. Direct-fired absorption chiller, cooling tower, cooling-coil and pump are important components of chilled water system. According to basic theory of physics, flowage and heat transfer, this paper developed direct-fired absorption chiller model based on single-effect absorption chiller model. Also this paper developed cooling tower model, cooling-coil model, constant-speed pump and variable-speed pump model and the mixer model of cooling water and chilled water, based on modification, improvement and accession of relevant models. Also gave these models validation by experiment data that was supported by manufacturer or document, and the result showed that these models have relatively high accuracy without too complicated calculation, and suitable for system simulationThen according to the mass flow and energy flow among the system, the simulation model of gas-fired air-conditioner chilled water system was developed based on the former component models. And by considering that the chilled water system was influenced by the temperature and flow rate of chilled (cooling) water, air flow rate of cooling tower and temperature of supply air etc, a system simulation calculation method was developed. An actual gas-fired air-conditioner system was selected to test to validate the system simulation model. The comparison of simulation...