Control Mode Of Pump Variable Water Flow For Ground-source Heat Pump

Depending on the building load characteristics of the specific project, this paperensures that ground-source heat pump system can be applied in xi ’an hospital airconditioning system. According to the xi ’an typical meteorological year data, the hourlyload buildings is been simulated using the DeST software and the average load and totalload is further analysed. Finally the design of soil source heat pump air conditioningsystem of the hospital is completed.This article through the analysis of the hot and cold load distribution rate ofhospital buildings conclude that the units’ running time with20%partial loads accountsfor65.9%of the total running time in summer, and the running time with40%-60%partial loads account for41.3%of the total running time in winter. Units for a long timeare all under the partial loads operation, which indicates that the ground-source heatpump is determined to use variable frequency pump control. Pump Regulate the flow ofwater through frequency control of motor speed, making its size to meet therequirements of the design or operation.The paper choice the model of pump according to the practice engineering, usingMATLAB engineering software to map the performance curve of differentconfiguration scheme. The power of the pump of different configuration scheme isdiscussed based on the energy saving principle of frequency control of motor speed,finding out the energy saving efficiency of the pump of different pump configurationscheme applying the graphical method. Theoretical analysis results show that: When specific speed is0.5, both pumps adopt frequency conversion control modes, and theenergy efficiency (compared with throttling) was72.8%; And if a water pump isfrequency conversion, a constant speed pump, the energy saving efficiency is only12%(compared with throttle regulation). There is a great energy saving space when thefrequency conversion adjustment is used，and the operation cost of generating unitsdecrease sharply.There is a close relationship between energy-saving efficiency of frequencyconversion regulating way of the water pump and the features of channels. Take thetypical day of a hospital in xi ’an as an example, according to the same target flow, therelations is reached between constant pressure value and energy saving benefits thewater pump variable speed. When the constant pressure value increases, the energyefficiency will be lower. When the constant pressure value increases80%, the pump’spower consumption is in35kW-55kW, which is2-7times as much as the value in20%;energy efficiency is only15%to70%of20%constant voltage value. So the setting ofthe constant pressure values of differential pressure control modes should base on thecharacteristics of the system and the distribution of flow in a running cycle.