Document Type
Dissertation
Degree
Doctor of Philosophy (PhD)
Major/Program
Mechanical Engineering
First Advisor's Name
Cheng-Xian Lin
First Advisor's Committee Title
Committee chair
Second Advisor's Name
Yiding Cao
Second Advisor's Committee Title
Committee member
Third Advisor's Name
Norman Munroe
Third Advisor's Committee Title
Committee member
Fourth Advisor's Name
Ali Siahpush
Fourth Advisor's Committee Title
Committee member
Fifth Advisor's Name
Gang Quan
Fifth Advisor's Committee Title
Committee member
Sixth Advisor's Name
Nezih Pala
Sixth Advisor's Committee Title
Committee member
Keywords
Transport membrane condenser, Waste heat recovery, Heat exchanger, Tube bundles, Ceramic nanoporous membrane
Date of Defense
9-20-2018
Abstract
Transport Membrane Condenser (TMC) is an innovative technology based on the property of a nano-scale porous material which can extract both waste heat and water from exhaust gases. This technology tremendously improves the efficiency of boilers and gas/coal combustors by lowering waste heat and increasing water recovery. Contaminants in the flue gases, such as CO2, O2, NOx, and SO2 are inhibited from passing through the membrane by the membrane’s high selectivity. The condensed water through these tubes is highly pure and can be used as the makeup water for many industrial applications. The goal of this research is to investigate the heat transfer, condensation rate, pressure drop and overall performance of crossflow heat exchangers. In this research, a numerical model has been developed to predict condensation of water vapor over and inside of nano-porous layers. Both capillary condensation inside the nanoscale porous structure of the TMC and the surface condensation were considered in the proposed method using a semi-empirical model. The transport of the water vapor and the latent heat of condensation were applied in the numerical model using the pertinent mass, momentum, turbulence and energy equations.
By using the proposed model and simulation procedure, the effect of various inlet parameters such as inlet mass flow rate, inlet temperature, and water vapor content of the inlet flow on the performance of the cross-flow TMC heat exchanger was studied to obtain the optimum performance of the heat exchangers at different working conditions. The performance of the TMC heat exchangers for inlet flue gas rate 40 to 120 kg/h, inlet water rate 60 to 140 kg/h, inlet flue gas relative humidity 20 to 90%, and tube pitch ratio 0.25 to 2.25 has been studied. The obtained results show that the water condensation flux continuously increases with the increase of the inlet flue-gas flow rate, water flow rate, and the flue-gas humidity. The total heat flux also follows the same trend due to the pronounced effect of the latent heat transfer from the condensation process. The water condensation flux and the overall heat transfer increase at the beginning for small values of the tube pitches and then decreases as the tube pitch increases furthermore. In addition to the cross-flow TMC heat exchangers, the performance of a shell and tube TMC heat exchanger for high pressure and temperature oxy-combustion applications has been investigated. The performance analysis for a 6-heat exchanger TMC unit shows that heat transfer of the 2-stage TMC unit is higher than the 2-stage with the same number of the heat exchanger in each unit.
Identifier
FIDC006986
Recommended Citation
Soleimanikutanaei, Soheil, "Modelling, Design, and Optimization of Membrane based Heat Exchangers for Low-grade Heat and Water Recovery" (2018). FIU Electronic Theses and Dissertations. 3921.
https://digitalcommons.fiu.edu/etd/3921
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