Research On Flow And Heat Measurement In Heating Process

Cogeneration is an effective way to improve the efficiency of energy utilization in the world.Its value,efficiency and function have been widely recognized.However,the uncertainty of measurement of heat output in cogeneration is relatively large,and the measurement methods are also different.The trade volume of heat supply in our country is larger,and the North's single heat trade settlement for winter heating can reach more than ten million yuan.Therefore,it is very important to improve the accuracy of heat metering in the heat accumulating system of heat supply system to ensure the fairness and fairness of the heat supply and demand in the process of transaction.This research begins with the analysis of the temperature parameters of the heating system.In the heat calculation method,the enthalpy difference method is used to improve the uncertainty of the measurement of heat energy.Through the combination of high precision network acquisition system and visual field operation software,a set of instrument network is established.Automatic test system.In the course of the study,it is found that the measuring instruments used for measuring the temperature of supply and return water,such as the matching temperature sensor,that is,when the two temperature sensors are in the same direction when measuring the same temperature and the standard temperature are worth the difference,the temperature sensor with relatively low accuracy level can also meet the accuracy of heating metering.In this study,Visual Basic language is used to realize the software of various heat metering models.The calculation of the flow rate of standard orifice must be completed through the geometric size,differential pressure and temperature of the orifice plate.Compared with other flow meters,the calculation of the standard orifice plate is the most complicated.Therefore,the flow measurement of heating calculation software is based on orifice plate.The parameters of hot water and steam are calculated by two formulas of IFC-67 and IAPWS-IF97 respectively.The heating system used for heating in winter usually has three measuring methods: supply and return metering,supply and supplement metering and water supply metering.Among them,the metering of water supply has been rarely used because of the large measurement error.In this study,through the analysis of measurement uncertainty of two methods of calculation and supplement measurement,it is found that the uncertainty of heat measurement can reach 0.85%(k=2),and a qualitative leap from 1.81% to 5.02%(k=2).By analyzing the uncertainty of heat measurement in the heating system,it is found that when the uncertainty of the heat measurement is 0.85%(k=2),the cost of the system can be reduced when the measuring instruments used for the measurement of pressure and temperature meet the requirements of the corresponding measurement accuracy grade.