Thermal enhancement is known to be an efficient way to decrease the residual saturation of some common dense non-aqueous phase liquids (DNAPLs) after pumping. However, the effect of transient heat transfer during the recovery of a high-viscosity contaminant, such as coal tar, in highly permeable porous media is still unknown. A 2D tank experimental setup allowing monitoring of temperature and saturation fields during DNAPL pumping has been developed. Experiments were run under isothermal and non-isothermal conditions, at low and high flow rates. We investigated the presence of viscous fingering and how that influences the shape of the cone of depression, as well as the residual saturation. The saturation fields show that less viscous fingering occurs in pre-heated cases and that heating increases the recovery efficiency. Increasing the temperature increases the critical velocity and the viscosity ratio and helps to stabilize the interface between the non-wetting and wetting phase. Observations were first made on an oil and ethanol fluid pair because its properties were known, before extending the experiments to a coal tar and water fluid pair. Residual oil saturation after pumping was decreased by 6–16% in all pre-heated conditions. Pumping at low flow rate in these conditions leaves the smallest oil residual saturation (20%) after pumping. A low flow rate increases the recovery efficiency by reducing viscous fingering and by spreading the generated heat to a larger part of the tank. Finally, results on coal tar pumping show that the high thermal conductivity of water helps in keeping the temperature high during pumping. The residual coal tar saturation was reduced from 40% at 20 °C to 28% when pre-heating the tank. Operating at a low flow rate and with a uniform temperature is the key to recovering the highest amount of a viscous DNAPL such as coal tar from the soil and satisfying cleanup goals when using thermally enhanced pumping.

众所周知，热增强是一种降低泵送后一些常见致密非水相液体 (DNAPL) 残余饱和度的有效方法。然而，在高渗透性多孔介质中回收高粘度污染物（如煤焦油）期间瞬态传热的影响仍然未知。已开发出一种二维罐实验装置，可在 DNAPL 泵送过程中监测温度和饱和场。实验在等温和非等温条件下以低流速和高流速进行。我们研究了粘性指法的存在以及它如何影响凹陷锥的形状以及残余饱和度。饱和场表明在预热的情况下发生的粘性较小的指进，加热提高了采收率。提高温度会增加临界速度和粘度比，并有助于稳定非润湿相和润湿相之间的界面。在将实验扩展到煤焦油和水流体对之前，首先对油和乙醇流体对进行了观察，因为它的性质是已知的。在所有预热条件下，泵送后的残余油饱和度降低了 6-16%。在这些条件下以低流量泵送会在泵送后留下最小的残余油饱和度 (20%)。低流速通过减少粘性指入和通过将产生的热量散布到罐的较大部分来提高回收效率。最后，煤焦油泵送的结果表明，水的高导热性有助于在泵送过程中保持高温。预热罐时，残余煤焦油饱和度从 20 °C 时的 40% 降至 28%。在低流速和均匀温度下运行是从土壤中回收最高量的粘性 DNAPL（如煤焦油）并在使用热增强泵送时满足清理目标的关键。