The Study On Heat Transfer Of Buried Pipelines Under The Unsteady Environment Temperature

It is an effective measure of reducing energy-consume to lower the temperature of petroleum transportation for transporting heated petroleum in the pipelines. Because the change of temperature field of pipelines in different districts and date can not be exactly identified, the temperature of transporting petroleum becomes generally higher. In addition, inevitably, the heated transporting pipeline is often halted, and the petroleum viscosity will be increased with the decreasing of petroleum temperature. When the petroleum temperature decreases to a definite value, it will be difficult to transport again. In order to avoid the happening of pipeline freezing, it is studied the medium temperature drop in the pipelines under the conditions of the unsteady environment temperature and different laying complexion. It is exactly calculated the permission time and the temperature drop when the transportation is halted.To solve the problems above, it is studied the change regularity of the temperature field influenced by the unsteady environment temperature in Northeast China, on the basis of which it is also studied the heat transfer problem of buried pipelines when steady run and halt. They are established the physical model and mathematical model in accordance with actual engineering. The numerical theory of finite difference is applied. On the platform of Visual Basic, it is designed the program, which can solve the problems of temperature field distribution of the buried pipeline and the temperature drop at any time of the year.It is completely considered the influence of variably physical property upon heat transfer of pipeline in the algorithms. It is simulated temperature fields in different pipelines with variably physical property of medium by the way of numerically simulating technology. It is analyzed the temperature field of the earth that is influenced by the unsteady environment temperature in detail, and the temperature field of buried pipelines is simulated under the different condition. At the same time, it is also discussed the physical property of the medium.Results of software calculation are exact to some extent. In order to the reliability, the results are corrected by comparing with actual test data, so it can reflect actual circumstance and be applied to engineering.This study can provide scientific criterion for actual product management and it can be directly applied to analyze the pipelines of Northeast China. It is important to guide the transporting petroleum production, the safe running of pipelines and the energy saving in the oilfield.