Membrane distillation (MD) is a membrane-based thermal desalination process capable of treating hypersaline brines. Standard MD systems rely on preheating the feed to drive the desalination process. However, relying on the feed to carry thermal energy is limited by a decline of the thermal driving force as the water moves across the membrane, and temperature polarization. In contrast, supplying heat directly into the feed channel, either through the membrane or other channel surfaces, has the potential of minimizing temperature polarization, increasing single-pass water recoveries, and decreasing the number of heat exchangers in the system. When solar thermal energy can be utilized, particularly if the solar heat is optimally delivered to enhance water evaporation and process performance, MD processes can potentially be improved in terms of energy efficiency, environmental sustainability, or operating costs. Here we describe an MD process using layered composite membranes that include a high-thermal-conductivity layer for supplying heat directly to the membrane-water interface and the flow channel. The MD system showed stable performance with water flux up to 9 L/m²/hr, and salt rejection >99.9% over hours of desalinating hypersaline feed (100 g/L NaCl). In addition to bench-scale system, we developed a computational fluid dynamics model that successfully described the transport phenomena in the system.

膜蒸馏（MD）是基于膜的热脱盐工艺，能够处理高盐盐水。标准的MD系统依靠预热进料来驱动脱盐过程。然而，当水穿过膜移动时，热驱动力的下降和温度极化限制了依靠进料携带热能。相反，通过膜或其他通道表面直接将热量供应到进料通道中，有可能使温度极化最小化，增加单程水的回收率，并减少系统中热交换器的数量。当可以利用太阳能时，特别是如果以最佳方式传递太阳能以增强水的蒸发和处理性能时，MD流程可以在能源效率，环境可持续性或运营成本方面进行改进。在这里，我们描述了一种使用分层复合膜的MD工艺，该复合膜包括一个高导热层，用于直接向膜-水界面和流动通道提供热量。MD系统表现出稳定的性能，水流量高达9 L / m² / hr，在脱盐过盐水（100 g / L NaCl）的过程中，每小时脱盐率> 99.9％。除台式系统外，我们还开发了计算流体动力学模型，该模型成功地描述了系统中的传输现象。