Ultrasonic Enhancement of Heat and Mass Transfer in Sorption Processes

提高吸附系统等余热制冷系统性能的一种方法是有针对性地应用超声波能量，这可能使充分利用大量的低温热源来提供冷却成为可能。该项目探索了超声波能量如何与低温热源相结合，通过提高制冷剂蒸汽从固体吸附剂表面释放的速度来实现更高效率的吸附制冷。这实际上创造了一种热力压缩机，取代了传统的电动压缩机。然而，目前超声与被吸附的液体制冷剂相互作用的机理尚不清楚，这些都是通过实验和理论模型来检验的。该项目还涉及重大的教育和外联活动。到目前为止，还没有关于热激活热泵技术的集中的、在线的、开源的资源。除了汇编和提供开源模拟代码和性能数据，使设计改进的系统变得更容易之外，还开发了在线教育模块，以增进学生和从业人员对该领域的理解，从而促进环境友好型热泵技术的更广泛开发和采用。尽管先前的工作清楚地表明了通过应用超声波能量来改善解吸的潜力，但总的来说，这项先前的工作侧重于系统级的影响，而不是局部的详细测量，这将使人们能够更好地理解。例如，改善的解吸有多少是由于局部加热，有多少是由于机械压缩/解压、声学软化等其他影响？我们的工作不是强调这种系统级的性能，而是专注于详细的、本地化的测量和分析，以提高对这些耦合的热量和质量传输过程的基本了解，这些过程不仅对吸附冷却至关重要，而且对于干燥剂干燥、食品干燥等也是至关重要的。除了之前研究的硅胶/水系统之外，我们还探索了更广泛的吸附剂/制冷剂。有趣的是，超声波的应用可能会使新的吸附材料得以利用，例如高吸水性聚合物(通常用于一次性尿布)，它可以在水中吸收高达自身重量2000倍的水。在没有超声波的情况下，由于再生所需的高温，聚合物的使用受到限制，甚至被禁止。通过研究高吸水性聚合物等替代材料，我们能够极大地扩展可考虑应用于吸附制冷的吸附剂/制冷剂对的种类。

One way to improve the performance of waste-heat activated cooling systems, such as adsorption systems, is by targeted application of ultrasonic energy, which may make possible the use of abundant low-temperature heat sources to provide cooling. This project explores how ultrasonic energy, combined with low-temperature heat sources, can realize higher-efficiency adsorption cooling by increasing the rate at which refrigerant vapor is released from the surface of a solid adsorbent. This in effect creates a thermal compressor that replaces the conventional electric-powered compressor. At this point, however, the mechanisms by which ultrasound interacts with adsorbed liquid refrigerant are not clear, and these are examined through both experiments and theoretical modeling. This project also involves significant educational and outreach activities. To date there has been no central, online, open-source resource for thermally activated heat pump technologies. In addition to assembling and making available open-source simulation codes and performance data that make it easier to design improved systems, online educational modules are developed for enhancing the understanding of students and practitioners in this field and thus promote wider development and adoption of environmentally friendly heat pump technologies.Although prior work clearly indicates the potential to improve desorption by applying ultrasonic energy, in general this prior work focused on system-level effects rather than local detailed measurements that would enable improved fundamental understanding. For example, how much of the improved desorption is due to localized heating, and how much is due to other effects such as mechanical compression/decompression, acoustic softening, etc.? Our work, rather than emphasizing such system-level performance, instead focuses on detailed, localized measurements and analysis to improve fundamental understanding of these coupled heat and mass transport processes that are crucial not only for adsorption cooling, but also for desiccant drying, food drying, etc. We also explore a much wider range of adsorbents/refrigerants, in addition to the silica gel/water system studied earlier. Interestingly, the application of ultrasound may enable new adsorbent materials to be utilized, such as superabsorbent polymers (commonly used in disposable diapers) that can absorb up to 2000 times their own weight in water. Without ultrasound, the use of polymers is limited or even prohibited because of the high temperatures needed for regeneration. By examining alternative materials like superabsorbent polymers we are able to greatly expand the variety of adsorbent/refrigerant pairs that can be considered for application in adsorption cooling.