Research On Optimization Control Of Air Conditioning Cooling Water System

As China’s public building area continues to rise and the application of central air-conditioning is more and more extensive,many problems in design and operation are exposed: 1.the cooling tower water imbalance and overflow phenomenon occurs in parallel operation;2.In the design of the central air-conditioning system,in order to meet the design conditions,the pumps,fans and other equipment are usually selected according to a certain margin,resulting in the system being in the largest part(such as 95%).Running below 65% of the load,a lot of energy is wasted.Therefore,research on energy conservation in central air conditioning systems is of great significance.The optimized control method of the cooling water system proposed in this paper can make the cooling water system always operate at the lowest energy consumption according to the changes of outdoor air and load conditions.Before studying the control method in detail,a central air-conditioning cooling water system in Wuhan was taken as the research object.Firstly,the phenomenon of hydraulic imbalance occurred when the cooling tower was operated in parallel was analyzed.The FLUENT software was used to simulate the phenomenon and solution.The results show that the balance pipe diameter is increased.The problem of hydraulic imbalance occurs in the parallel cooling tower can be effectively solved.An improved calculation method for the balance pipe diameter of cooling tower is proposed.The method was verified by numerical simulation.The results show that the calculation method has less error with the simulated result,which can be used in the calculation and design of the cooling pipe balance pipe diameter in actual engineering.In order to further study the optimization control algorithm of the cooling water system,the mathematical model of the cooling tower and the chiller was first established,and the model was verified by experimental data.The results show that the difference between the model calculation results and the test results is small,which can be applied to the simulation of air conditioning systems.The cooling water system simulation platform was established in the TRNSYS software using the above model.Furthermore,a simple energy consumption model for cooling water system and online parameter control method for model parameters suitable for online optimization control are proposed.The simulation control platform based on the cooling water system was used to verify the optimal control effect based on the model under high load and low load conditions.The results showed that both conditions compared to the conventional mode of operation of the model-based optimal control,the control mode in a high load and low load conditions the energy saving rate was 5.45%,7.16%,respectively.