The present work investigates heat transfer through natural convection using a series of experiments and computational modeling using Computational Fluid Dynamics (CFD) simulations in a one-meter bundle pipe with three internal pipes. The exact complex geometry is modeled where the flow channel is reduced through a spiral groove attached to a rod inside the internal tubes which was challenging compared to the flow in circular pipes in previous studies. To support the computational modeling investigations, convective heat transfer analysis is also studied through experiments with water as the production and heating fluids. Further, simulations are carried out with water-crude oil and aqueous ethylene glycol-water as the heating mediums and production fluids, respectively. Based on the heat transfer rates estimated from experimental data and CFD simulation results for the respective tubes, a modification to an existing Nusselt number is proposed for the range of temperature and flow rates used in the experiments. The proposed model, Nu_i= Pr_i^m Ra_iⁿ, was validated against experimental data and a good agreement with R² values of more than 0.94 was achieved.

本工作研究了在具有三个内部管道的一米长管束中使用一系列实验和计算模型（通过计算流体动力学（CFD）模拟）通过自然对流进行的热传递。对精确的复杂几何形状进行了建模，其中通过连接在内管内部的一根杆上的螺旋槽减少了流道，这比以前的研究中的圆形管中的流动具有挑战性。为了支持计算模型研究，还通过以水为生产和加热流体的实验研究了对流换热分析。此外，分别使用原油和石油乙二醇-水作为加热介质和采出液进行模拟。根据从实验数据估计的传热速率和各个管的CFD模拟结果，对实验中使用的温度和流速范围提出了对现有Nusselt数的修改。建议的模型，NU_我= 镨_我^中号太阳神_我^Ñ，针对被实验数据和有R有很好的一致性验证的^2项超过0.94的值达到了。