Study Of Operation Optimization For Cold Source System Of Central Air-conditioning Based On TRNSYS

In China, with the increase of building energy consumption, building energy saving, especially in large public buildings,is paid more and more attention. Central air-conditioning system is a major energy consumer in large public buildings. There are a lot of energy waste phenomena in the process of operation. So we should strengthen the management and set reasonable operation parameters. The energy consumption of cold source system accounts for more than 60% of total energy consumption of central air-conditioning system. The optimization of cold source system operation parameters are very important for the economic operation of the whole system.In this paper, the central air-conditioning system of a large public building in Guangzhou is chosen as the research object. Operating data of cold source system are acquired through the monitoring and management system of central air-conditioning. And mathematical models of chillers, pumps and cooling towers are established. Besides, their accuracy is verified. Thanks to the custom component creating function of TRNSYS software, components of cold source system equipments are programmed, compiled and generated with mathematical models established before. These components can be called directly by TRNSYS. Control component of Matlab is established. And with other necessary auxiliary components added, TRNSYS simulation platform of the cold source system of central air-conditioning is established.Influence factors on the cold source system equipments are analyzed. With the analysis results,the influence of variable flow of chilled water and cooling water on the operation efficiency of chilled water system and cooling water system is analyzed respectively. Analysis results show that the optimal chilled water flow that make the operation efficiency highest does exist under certain conditions. So does the cooling water flow.Cold source system operation parameters optimization model is established after selecting optimization variables, establishing the objective function, determining the constraints and processing constraints. Genetic algorithm is used to solve the optimization model. With cooling load, outdoor temperature and humidity known, optimization is conducted on the simulation platform. The optimal values of chilled water supply temperature, chilled water flow, cooling water flow, cooling tower air volume are acquired, which makes the EERr(energy efficiency ratio of refrigeration system) highest. The comparison with actual operation parameters shows that the total energy consumption decrease 7.07% and that the optimization method is feasible.