Research On Scaling Fault Detection And Diagnosis Of Chiller Based On Lumped Parameter Mode

The chiller has the characteristics of stable performance,reliable operation,energy saving and environmental protection,and strong environmental adaptability.At present,it has been widely used as the main cold source of building air-conditioning system.In the operation process,the chiller is prone to fouling,corrosion,blocking and other failures,which leads to the decrease of efficiency and the shortened service life of the equipment,and even affects the safe operation of the whole air-conditioning system.The scaling failure of the hiller is not easy to be found and diagnosed during operation,but scaling will lead to constant attenuation of the performance of the chiller.In a long-term scaling running condition,it have a great influence on the operation energy consumption of the chiller.Therefore,timely and accurate detection and diagnosis of the chiller scaling faults is of great significance for improving the efficiency of the chiller and realizing the energy saving and efficient operation of the air-conditioning system.Therefore,this paper puts forward the method of detecting and diagnosing the scaling fault of the chiller based on the lumped parameters model.Without obtaining the structure parameters and by using the measured data of the chiller,the scaling fault diagnosis model of the chiller is established,which realize online detection and diagnosis of chiller scaling fault.The main research work of this paper is as follows:(1)The scaling diagnosis model construction of the chiller based on the lumped parameters:for the existing chiller,with the lack of evaporator and condenser specific structural parameters,the structure parameters of the evaporator and the condenser are assembled as model paramenters based on the lumped parameters method,and the model paramenters can be formed to characterize the structure of the evaporator and condenser.The characteristic model parameters of the evaporator and condenser are obtained by using the actual operating data of the chiller under the condition of no scaling,thus the scaling diagnosis model of the chiller is established.(2)The study on the detection and diagnosis method of the scaling fault of the chiller:the influence of the fouling on the performance of the chiller is analyzed.The characterization mode of the scaling of the chiller based on the lumped parameter model is studied,and the method of detecting and diagnosing the scaling fault of the chiller based on lumped parameter model is put forward.The water temperature of evaporator and condenser under the no scaling condition is obtained by the operation data of chiller,which is compared with the water temperature of the evaporator and condenser under the actual working condition.It can be used to determine whether scaling is occurring.Compared with the KA,which is the product of the heat transfer coefficient and the heat transfer area,in the actual working condition and no scaling condition of chiller,the heat transfer performance of the chiller evaporator or condenser is diagnosed(3)The verification and application of the detection and diagnosis method of the chiller scaling fault:a chiller test bed was built and the experiment was carried out to verify the accuracy of the chiller model based on the lumped parameters.Based on the lumped parameters model of the chiller and the detection method of the scaling fault of the chiller,the software of the scaling fault detection and diagnosis of the chiller test software is designed and the simulation research is carried out.By changing the fouling thermal resistance coefficient of the condenser and evaporator,the operating performance of the chiller under the operating conditions under different flow and temperature conditions is studied.By comparing the water temperature of the condenser and the evaporator,the scale of the water chiller is measured by comparing the non scale and operating conditions.The scaling fault of the chiller is detected by comparing the water temperature of the condenser and the evaporator in the no scaling and actual conditions.The scaling degree of the chiller is diagnosed by comparing the heat transfer coefficient of the evaporator and condenser under the actual conditions and no scaling condition.The results show that the fouling resistance of the evaporator and condenser increases from 0 to 0.4m~2.K/kW,and the detection method of the scaling fault of the chiller based on the lumped parameters model has good accuracy,and the method of detecting and diagnosing the scale fault of the chiller based on the lumped model is verified.