The Design And Application Study Of Hot Water Flux Standard Instrument

As the proposal of "The quantity of heat should be measured" and "One household one calorimeter" were put forward, calorimeters were widely used and their detective instrumentation was paid more and more attention. But presently, the detection of flux sensor in the calorimeter was made under the cold water condition. The flux sensor contacted with the detected medium which resulted in the influence of thermal expansion and cold shrinkage to its measure mechanism (cassette mechanism).Thus its measurement error was different at the different water temperatures.In view of the property of the flux standard instrument of static state mass method with high accuracy and low efficiency, and that of standard meter method with simple structure and high efficiency, this instrument adopted water tower voltage stabilization method, combined mass method with standard meter method, made the reasonable uncertainty distribution to let every index meet with the relative regulation. Standard flowmeter adopted electromagnetic flowmeter with high accuracy.The hot water flux standard instrument studied in this thesis chose volume dyadic electric heater, whose total heat power was 120 kW .There were 13 set heating tubes in it, and two were 5 kW in the heat power and the rest were 10 kW. 13 set tubes were all put in use at the beginning .When they reached the designed working temperature, only one of 5 kW was left to supply the heat loss. This design could detect the flowmeter under hot water condition, and the water temperature could be adjusted between the indoor temperature and 95℃.To relieve the heat loss, some heat preservation measures were made at all the pipelines and water boxes in this instrument and the closed commutator was used to decrease the error of the fluid splash and evaporation. At the same time, the computer and PLC were used together to realize the automotive control of information collection, conversion and data processing.