Design And Analysis Of A Dynamic Distributed Secondary Pump Heating System In A University

In recent years,the heating technology has rapidly developed,the dynamic distributed heating system comes into being with the further deepening of research.Universities have large building density,many types of buildings which have different working times.As a result,the heating requirements of different buildings are also different.This paper takes a university as the research object,and designs the dynamic distributed heating system on the secondary network.Firstly,the paper checks the data of the existing central heating system,calculates the heat load of 19.11 MW and the power is 105.77 kW,calculates the hydraulic pressure and draws the water pressure diagram.The data of the existing central heating system is checked to analyze its energy consumption,and then further to calculate the proportion of the energy consumption of the control valve in the traditional central heating system,and the results show that the energy consumption of the control valve accounts for 37.91%of the total power of the pumps.Secondly,the dynamic distributed heating system is designed.By comparing the characteristics and application of different types of dynamic distributed heating systems,it is determined that this project is designed as a dynamic distributed secondary pump heating system.The fixed step method is used to analyze the change of the total power and the number of pump configurations of the dynamic distributed secondary pump heating system scheme when the zero pressure difference point is set with a step length of 1 mH₂O as the position of the zero pressure difference point moves.A variety of system configuration schemes have been designed based on setting zero pressure difference points at different hydraulic positions.It is found that as the zero pressure difference point moves backwards along the heating source,the total power and the number of pumps will not change before the throttling loss occurs in the system.After that,although the number of pumps in the system begins to decrease,the total energy consumption of the system increased rapidly.The total system power is at least 84.05 kW while the number of pumps is 49.Afterwards,energy-saving and economic analysis of each system scheme under time-dividing heating is carried out.Energy-saving analysis introduces an energy-saving rate algorithm.Compared with traditional central heating systems,it is found that as the zero pressure difference point moves backward from the heating source,the energy saving rate of the dynamic distributed heating system gradually decreases.When the system power load is concentrated on the heating source pump,the energy saving rate begins to rapidly decrease,and the maximum energy saving rate is 29.2%;Economic analysis introduces annual cost and investment recovery period evaluation indicators.The change trend of the two indicators due to time-dividing heating is not the same as the change of the total system power.The annual cost index increases rapidly after the system power load is concentrated on the heating source pump,but before this,the growth rate is slow;The investment recovery period gradually decreased from the zero pressure difference point at the heating source,from 4.24 years to 3.78 years.Finally,the comprehensive analysis determined that the optimal dynamic distributed secondary pump system design scheme is to set the zero pressure difference point at the heating source.The initial investment of the system is 110946 RMB,the annual net income is 26145.2 RMB,and the annual operating cost is 106281.3 RMB.The cost is113677.7 RMB,and the investment recovery period is 4.24 years,which meets the requirements of economy and energy saving.