Changes in pipeline fluid temperature can be attributed to many effects, including heating due to operating pump units or compressors, or cooling when the pressure drops below the dew point in a gas pipeline. The typically dominant effect for temperature change along the pipeline length is due to the transfer of heat to or from the surrounding ground cover. There are instances where viscous effects are significant, giving rise to a "frictional heating" effect. This paper intends to analyze the frictional heating effect for pumped fluids in the liquid, supercritical and superheated phases. The approach is to assume an adiabatic pipeline and to consider the Joule Thomson effect in detail. The focus is on hydrocarbons in liquid phase, although some interesting gas phase examples are presented. The destruction of mechanical energy into internal energy is typically implicit in the complete solution of the conservation equations. The aim here is to assist with quantification of the particular effect to confirm whether it remains significant enough to warrant careful consideration, or to dismiss it as negligible. Example real pipeline data is presented in the interest of comparing with the predictions. Derivations are provided using the first law along with available empirical data.
The simulation of pressure in a pipeline is highly dependent on the density of the transported fluid. Density is highly temperature dependent; hence it is important to have a realistic and accurate temperature profile. Numerous physical effects cause temperature to vary along a flowing pipeline and the dominant effect for temperature change along the pipeline length is generally due to the transfer of heat to or from the surrounding ground cover. This paper considers the contribution to the temperature variation along the pipelines due to the turbulent viscous frictional heating effect. The frictional heating effect is discussed for pumped fluids that exist in the liquid, supercritical and superheated phases. The intention is to determine the direction and amount that temperature changes as pressure changes. Also explored are the frictional effects that cause the pressure to drop. For example, how does the velocity influence the pressure drop and hence the temperature? The background behind the theoretical basis is described followed by an introduction to the Joule Thomson coefficient and Inversion curves. A subcritical (liquid phase) fluid is described along with an example taken from practice. The supercritical and superheated regimes are also described followed by a comparison with a real-world example.
The total energy of a flowing compressible pipeline system consists of four parts: internal, kinetic, potential and flow energies. The combination of internal energy and flow work is termed "enthalpy". The changes in kinetic and potential energy are considered negligible in this analysis. From the first law of thermodynamics an energy balance between the inlet and outlet of the pipeline is performed. Since the purpose is to study the frictional effect at steady state conditions, the heat transfer and external work interactions are considered to be zero.
