Analysis On Entropy Production Rate In Pipeline Process Of Waxy Crude Oil

This paper was financially supported by National Natural Science Foundation ofChina (No.51106020, No.51174042, No.51051002), PetroChina Innovation Foundation（2012D-5006-0610） and Youth Scholar Backbone Supporting Plan Project ofHeilongjiang General Colleges and Universities (1252G005).Heated oil transportation is required for most crude oil produced in China belong tohigh paraffin content and solidifying point. In order to overcome the friction loss andelevation difference during the transportation, oil transfer pump is required to be equippedto provide pressure. In order to reduce friction loss, piping systems also need to beequipped with heating device. These transport equipment mainly consume electricity andfuel, which make the continuous operation pipeline become large energy consumption.With continuous increasing demand of oil product in china, energy consumption ofpipeline will also increase even further, which brings more challenges to economicoperation and management of pipeline. From the point of thermodynamics, there existvarious irreversible coupling phenomena such as diffusion, heat transfer and fluid flowduring the transportation of crude oil. Physical model for irreversible process during thewaxy crude oil transportation is established based on the results of precedent researches.And on the basis of existing universal equation for entropy generation rate, the “flow” and“force” of various irreversible coupling phenomena such as heat transfer, viscosity anddiffusion is derived, and mathematical model for entropy generation rate during the crudeoil transportation is also established. On the foundation of these equations for entropygeneration rate, suitable “flow” and “force” is chosen and phenomenological equationwhich reflects the relationship between process rate and power is also deprived.Phenomenological coefficient is set as interaction strength index of oil transportationprogress.“Flow” and “force” in phenomenological equation that can be coupled isdetermined by using Curie principle, and then the computing method forphenomenological coefficient between three kinds of irreversible phenomenon is given.The comparing of thermo-economic optimize and the minimum optimize results of entropygeneration rate indicates that the best transportation temperature corresponds to the lowestpipeline operation cost, and the minimum optimize results is not affected by current priceand so on. Therefore, minimum optimize results of entropy generation rate design hasbetter feasibility when compared with thermo-economic optimization techniques, thus it deserves the widespread use in the optimal design of crude oil transportation.