Transport Phenomena in Energy Conversion Systems

通过与反应的竞争，输送现象在决定发电用能量转换系统（如内燃机和燃料电池）的效率和排放方面起着主导作用。内燃机是当今能源系统的主要组成部分，但排放有害化学物质和全球变暖气体；具有水排放的燃料电池被认为是未来可持续能源系统必不可少的清洁能源转换。该研究的长期目标是研究具有成本效益的高效清洁能源系统的输运现象，并将其作为实际应用的长期目标，以及1)低排放的高效直接喷射内燃机和2)制造质子交换膜燃料电池（pemfc）的低成本大批量生产技术作为短期目标。因此，拟议的研究的目标是在今天和未来产生最大的影响。在直喷式汽油机中，燃料喷雾撞击燃烧室壁面，形成一层薄薄的燃料膜；膜团不能在靠近壁的地方完全燃烧，成为主要的排放源。PEMFC的制造是商业化的瓶颈，它涉及到在衬底表面喷涂催化剂墨水（一种分散有催化剂纳米颗粒的液体溶液），当液体蒸发时形成催化剂层。两者的核心是喷雾对被液体薄膜覆盖的加热表面的冲击，具有重要的基础和实际意义。为了实现这些目标，将进行实验和数值研究，以提高对基本认识，并将开发新的方法：1)利用喷雾撞击产生的飞溅来减少/消除发动机表面液体燃料膜，以减少/消除相关排放；2)消除喷雾沉积过程中的飞溅，避免昂贵的催化剂浪费，同时控制表面液体蒸发过程，以达到PEMFC制造所需的质量和一致性。目前的研究现状是，在喷雾撞击过程中溅射始终存在，但只是部分液体溅射。提出的研究计划将有助于提高对具有传热传质的多相流的认识，特别是在基本方面有或没有固体颗粒的喷雾-表面相互作用；这将有助于在实践中减少高效直喷发动机的排放，并有助于降低成本，提高pemfc的性能和耐用性，从而实现可靠和持续的大批量生产。此外，所开发的知识和专业知识以及培养的高素质人才将扩大和提高加拿大汽车和燃料电池工业的能力，为加拿大知识型经济的发展做出贡献。开发的清洁能源技术将具有显著的环境效益。

Transport phenomena play a dominant role in determining the efficiency and emissions of energy conversion systems for power generation, such as internal combustion engines (ICEs) and fuel cells, through competition with reaction. ICEs are a major part of today's energy systems, but with emissions of harmful chemicals and global warming gases; fuel cells with emission of water are considered clean energy conversion essential for future sustainable energy systems. The proposed research focuses on the study of transport phenomena for cost-effective high-efficiency clean energy systems for practical applications as a long-term objective, and 1) low-emission high-efficiency direct injection ICEs and 2) low-cost high-volume production techniques for the fabrication of proton exchange membrane fuel cells (PEMFCs) as a short-term objective. Hence the proposed research is targeted for maximum impact today and in the future. In direct injection gasoline engines, fuel sprays impinge on the combustion chamber walls creating a thin fuel film; the film mass cannot be burned completely near the wall and becomes a major source of emissions. PEMFC fabrication is a bottleneck in commercialization, and it involves spraying catalyst ink, a liquid solution with catalyst nanoparticles dispersed, on a substrate surface to form catalyst layers when the liquid is evaporated. Central to both is the impingement of sprays on a heated surface covered by a thin film of liquid, and has significant fundamental and practical importance. To achieve the objectives, both experimental and numerical studies will be carried out to improve the fundamental understanding, and novel approaches will be developed 1) to use the splash created by spray impingement to reduce/eliminate the surface liquid fuel film in engines for the reduction/elimination of the associated emissions; and 2) to eliminate splash during spray deposition, avoiding expensive catalyst waste while controlling the surface liquid evaporation process to achieve the desired quality and consistency in the PEMFC fabrication. The current state of the art is that splash in spray impingement always exists, but only partial liquid splashes. The proposed research program will help improve the knowledge of multi-phase flow with heat and mass transfer in general, and specifically spray-surface interaction laden with and without solid particles on the fundamental side; and will help in practice reduce the emission of high-efficiency direct-injection engines, and will help reduce the cost and enhance the performance and durability of PEMFCs that can be manufactured reliably and consistently in large volume. Further, the knowledge and expertise developed and high-quality personnel trained will expand and enhance the capability of Canadian automotive and fuel cell industry, contributing to the development of knowledge-based Canadian economy. The clean energy technology developed will have significant environmental benefits.