Study On Operation Optimization Strategy Of Air Conditioning System Based On Feature Recognition

Since more than 80% operation time of air-conditioning system is under partial load,the air-conditioning system with optimal performance under rated conditions is difficult to operate efficiently under partial load.There is the potential to further improve the efficiency of air-conditioning system by optimizing operation parameters.It will be easy to optimize operation parameters of air-conditioning system under partial load with simulation tools.When simulating and modeling a practical exsited building air-conditioning system,it is difficult to get the specific configuration parameters of each components in the system which leads to the accurate simulation on the basis of them hard to achieved,it makes limitations of common modeling methods in the practical application.This dissertation establishes models of air-conditioning system based on a feature recognition modeling method,and the optimization algorithm is combined with the models to optimize operation parameters of air-conditioning system.It is of great value to realize the energy-saving operation of air-conditioning system under partial load.A novel modeling method which makes unknown structure parameters lumped and obtains them(i.e.the characteristic parameters,which are unique for each device)with measured data is proposed,based on which the air-conditioning system models are developed.An experimental platform for comprehensive performance of air-conditioning system was set up to verify the accuracy of the simulation model established,and simulations and experiments were compared under variable chilled water flow,variable chilled water temperature and variable air flow of cooling coil conditions respectively.The results show that with the feature recognition method,the air-conditioning system models can achieve a high accuracy,compared with experimental results,relative errors of simulated performance parameters,such as refrigerating capacity,COP(coefficient of performance),comprehensive efficiency and dehumidification capacity are all within 10%.In simulation processes,the optimization algorithm is introduced to find the optimal operation conditions,which is an important way to solve the problem of simulation optimization of air-conditioning system quickly and effectively.Thus the simple penalty function mode search method was applied to the simulation optimization of air-conditioning system.The optimized parameters obtained by this optimization algorithm were compared with the actual operating ones of air-conditioning system,and the results show that under the premise of satisfying the same refrigerating capacity,the comprehensive efficiency in sumulation after optimization increases by more than 11%,compared with that in experiments.At the same time,the influence of optimization initial value and range of optimization variables on the calculation speed and accuracy of the optimization algorithm were explored,which provides theoretical basis for the selection of initial value and range of value of each variable.In order to optimize the overall energy efficiency of air-conditioning system,the optimization strategies for single chiller air-conditioning system and multiple chiller air-conditioning system under partial load was studied with the simple penalty function mode search method.For single chiller air-conditioning system,the changes of performance parameters with different outdoor meteorological conditions and different load rates were studied.The results show that with the decrease of load rates,the COP increases after the first decreases,and the comprehensive efficiency of air-conditioning system increases slowly and then decreases rapidly.What’s more,the COP and the comprehensive efficiency varying with load rates under different outdoor meteorological conditions are the same.The optimization strategies under two different load distribution schemes were explored for two-chiller systems.The results show that when the total load of the air-conditioning system is greater than 35%,the two chillers should each bear 50% of the cooling load,and when the air-conditioning load is less than 35%,the main chiller should assume all the load and the another chiller should be closed.The optimization strategy is suitable for different outdoor meteorological conditions.