Book Description

The project has developed a nanoporous membrane based water vapor separation technology that can be used for recovering energy and water from low-temperature industrial waste gas streams with high moisture contents. This kind of exhaust stream is widely present in many industrial processes including the forest products and paper industry, food industry, chemical industry, cement industry, metal industry, and petroleum industry. The technology can recover not only the sensible heat but also high-purity water along with its considerable latent heat. Waste heats from such streams are considered very difficult to recover by conventional technology because of poor heat transfer performance of heat-exchanger type equipment at low temperature and moisture-related corrosion issues. During the one-year Concept Definition stage of the project, the goal was to prove the concept and technology in the laboratory and identify any issues that need to be addressed in future development of this technology. In this project, computational modeling and simulation have been conducted to investigate the performance of a nanoporous material based technology, transport membrane condenser (TMC), for waste heat and water recovery from low grade industrial flue gases. A series of theoretical and computational analyses have provided insight and support in advanced TMC design and experiments. Experimental study revealed condensation and convection through the porous membrane bundle was greatly improved over an impermeable tube bundle, because of the membrane capillary condensation mechanism and the continuous evacuation of the condensate film or droplets through the membrane pores. Convection Nusselt number in flue gas side for the porous membrane tube bundle is 50% to 80% higher than those for the impermeable stainless steel tube bundle. The condensation rates for the porous membrane tube bundle also increase 60% to 80%. Parametric study for the porous membrane tube bundle heat transfer performance was also done, which shows this heat transfer enhancement approach works well in a wide parameters range for typical flue gas conditions. Better understanding of condensing heat transfer mechanism for porous membrane heat transfer surfaces, shows higher condensation and heat transfer rates than non-permeable tubes, due to existence of the porous membrane walls. Laboratory testing has documented increased TMC performance with increased exhaust gas moisture content levels, which has exponentially increased potential markets for the product. The TMC technology can uniquely enhance waste heat recovery in tandem with water vapor recovery for many other industrial processes such as drying, wet and dry scrubber exhaust gases, dewatering, and water chilling. A new metallic substrate membrane tube development and molded TMC part fabrication method, provides an economical way to expand this technology for scaled up applications with less than 3 year payback expectation. A detailed market study shows a broad application area for this advanced waste heat and water recovery technology. A commercialization partner has been lined up to expand this technology to this big market. This research work led to new findings on the TMC working mechanism to improve its performance, better scale up design approaches, and economical part fabrication methods. Field evaluation work needs to be done to verify the TMC real world performance, and get acceptance from the industry, and pave the way for our commercial partner to put it into a much larger waste heat and waste water recovery market. This project is addressing the priority areas specified for DOE Industrial Technologies Program's (ITP's): Energy Intensive Processes (EIP) Portfolio - Waste Heat Minimization and Recovery platform.