Research On Durability Test Facility For Heat Meters

As an important measuring instrument and basis of heat metering trade settlement,long-term operation stability and accuracy of measurement is very important for heat meter.The durability test is a main means and method to test the heat meter running for a long time.At present,there are mainly two kinds of durability test facilities for 2400 h and 300 h.The 4000 times alternating impact test is a test method proposed by European standard EN1434-2015,which simulates the actual heating process,and the test time is about 14 days.The development of the4000 times alternating impact test equipment is still in its early stage in China.There are technical difficulties in energy consumption control,device efficiency and so on.In this thesis,a heat meter durability test facility is developed,which can realize4000 times accelerated test,and also complete the durability test of 2400 h and 300 h.Through hydraulic calculation and heat loss calculation,the main equipment such as water pumps,heating pipes are selected.This facility is designed by combination of dual water supply systems and the double test pipelines.During the durability test,the valves,flow meters and other equipment are not affected by the wear test,to ensure the reliability and normal operation of the facility.In the meanwhile,the facility can make fast switching between different working states of the heat meters to achieve the higher wear intensity.During the 4000 times alternating impact test,according to the feedback of the liquid level sensor in the water tank,the PLC can control the corresponding valves to be opened or closed,and the water in the high level water tank can be diverted to the tank with low water level.This can avoid the overflow caused by high level and solve the problem of water balance in cold and hot water tanks.The facility can solve this problem through the design of valve switching control,making the high temperature water flow back to the hot water tank and the low temperature water flow back to the cold water tank,reducing the starting frequency of the heating tube and refrigeration unit,so as to decrease the energy consumption of the facility.The optimal control method of the facility in different flow rate is obtained by the test and theoretical computation.When the instantaneous flow rate is 15m3/h,the optimized control method can save 1840 kWh of electricity in one durability test.In this thesis,4000 times accelerated tests and 2400 h durability tests are carried out to verify that the facility temperature,instantaneous flow rate,pressure and wear strength meet the requirements of the European standard.It was shown that,by the comparison of the two kinds of durability test method,a complete experiment of 4000 times alternating impact test can save power consumption about 4109 kWh than the 2400 h test.Compared with the other 4000 times alternating impact test facilities,the efficiency this new facility can be doubled under the same conditions.If 6 instruments are tested at one time,the power consumption of the pumps can be saved about 67.2 kWh.The durability test facility for heat meter can carry out durability test for heat meters with different working principles,and form a complete set of evaluation test method,so as to form the performance evaluation system of heat meters.