Thermohydraulic modeling in transient state for evaluation of pipeline shutdown and restart procedures

In order to study shutdown and re-start in heavy crude oil pipelines, a model was developed that simulates, in a transient state, the behavior of pressure, flow and temperature variables, averaged over the cross-sectional area and as a function of time and the axial coordinate. The model was validated with actual operational data from a test case. Results obtained by the model developed were compared with available operating data for an industrial heavy crude oil pipeline, demonstrating good prediction of the pressure distribution and temperatures in the steady state. In the case of pressure boundary condition, the operating flow in the steady state was underestimated with respect to the reference data, thus, it is necessary for applications where greater precision in the results is required and to improve the calculation model for the friction coefficient and its relation to temperature. Also, the governing equations are converted to dimensionless expressions in order to obtain the dimensionless numbers relevant to the re-start operation for crude oil pipelines.