Research On Parametric Tubular Heat Exchanger And Single-tube Performance Tests

As an important link for grain storage, the development of grain dryingtechnology has become more and more important,which can help people save foodand ensure food quality. It has a certain gap between china and developed countries inthe development of grain drying technology, including the development andapplication of the grain drying equipment and supporting facilities. China’s energystructure is different from the other countries. In the technology maturecountries,they use oil as a dryer heat source when ninety percent of China’s graindrying heat source use coal-fired hot-blast stove to provide heat. The most widelyused is the tube stove. That make research of Heat exchanger become much moreimportant.The heat exchanger is the core component of the hot stove. In this paper, we doresearch on the principle and design method of heat exchanger thermal calculations.Take Tubular heat exchanger as the object of study, which is the commonly used formof heat exchanger, finished the parametric design software of Tubular heat exchangerin LabVIEW environment. According to the known process parameters, with areasonable selection of form, the structural parameters of tube heat exchanger can becalculated. We can easily out put the structural parameters,including the heat transferarea of heat exchanger, diameter of the tubes, tube length, number of tubes, tubespacing, number of round trip of the tubes. Besides, it can provide both sides of thehot and cold fluid heat transfer coefficient and pressure drop parameters,which wereused to check the rationality of the heat exchanger structure. In addition, a single-tubeperformance test rig was designed for heat exchange tubes, and with a data acquisitionsystem supporting. We do research on how the heat exchanger efficiency and heat transfer coefficient change when we pick up different pipe length, diameter andmixture ratio of blowing rate.Through the test to get the following curve:1) The curve of outlet temperature of flue gas with different pipe length、diameter of tube and mixture ratio of air volume.2) The curve of total heat transfer coefficient and heat transfer efficiency withdifferent pipe length.3) The curve of total heat transfer coefficient and heat transfer efficiency withdifferent mixture ratio of air volume.4) The curve of total heat transfer coefficient and heat transfer efficiency withdifferent diameter of tube.Come to the conclusion that, in the test levels listed, when the diameterselection is48mm, efficiency of heat transfer and heat transfer coefficie nt are thebiggest. And on this basis, take the method of orthogonal polynomial regressiondesign to analyze the data of the heat transfer coefficient, which was an importantindex of the heat transfer performance. Determine the mathematical equation of theheat transfer coefficient、the length of the tube and the air flow of two fans. Get theextreme value of the equation，then we got the level of each factor value when theheat transfer coefficient coming to the biggest. In addition,with the orthogonal designand range analysis method, we study on how the length of the tube and air volumeratio to affect the heat transfer efficiency. the optimal level combination weredetermined at last.Single-tube heat exchanger test study provide reference of further optimizationand experimental basis for tube heat exchanger, it is very meaningful.