A simulation of thermal coupling characteristics on deep-sea residual oil recovery via pipeline using thermophysical properties

Deep-sea residual oil has been recognized as a significant environmental hazard due to its poor low-temperature fluidity and complex recovery processes necessitating urgent solutions. A segmented regulated two stage heating transport method is proposed, with a high-precision thermo-fluid coupling model that integrates thermophysical properties to characterize oil thermal coupling characteristics. Dimensional analysis further identifies multi-properties correlations for convective heat transfer coefficient and oil temperature that govern the thermo-fluid dynamics interaction. Numerical simulations reveal that transport distance, heat flux density, and mass flux collectively regulate convective heat transfer efficiency and temperature distribution. It is shown that oil temperatures reduce oil viscosity, thereby enhancing convective heat transfer between the thermal boundary layer oil and the pipe wall; as transport distance increases, accumulated heat and thermophysical properties stabilize simultaneously. A dual-properties regulation mechanism is identified between heat flux density and mass flux: within 180-540 kg/(m²·s), outlet thermal boundary layer oil temperature linearly responds to heat flux density (K = 0.04); exceeding 720 kg/(m²·s), temperature regulation efficiency decreases by 30%, accompanied by a downstream shift of temperature peak region under high mass flux conditions. This method provides reliable theoretical foundations for deep-sea low-temperature residual oil recovery.