Application of Packed Bed Chemical Looping (Unmixed) Combustion for water heating: Modelling and CFD simulation for Reduction cycle

•Chemical Looping / Unmixed combustion (CLC/UMC) application for water heating•Model development and CFD simulation of proposed design for reduction cycle•Non-linear kinetics involved in reduction reaction is incorporated in CFD model•Continuous water heating with sustained reduction in the bed is achievable•Feasibility of water heating with combined oxidation-reduction cycle of UMC confirmed A packed bed reactor based Chemical Looping (Unmixed) Combustion (PBR - CLC/ UMC) is a plausible alternative process to premixed combustion. Application of UMC for heating air has been demonstrated in an earlier work using an annular PBR system which was not found to be suitable for heating water. In another study, the design was modified, investigated for heating water, flowing in the laminar region, for the oxidation cycle with Cu based metal and was found feasible. In the present work, the reduction cycle (methane with CuO), which is relatively less exothermic and has non-linear kinetics, with water heating in the proposed system is investigated by carrying out modeling and simulation studies to confirm the heat transfer related operational feasibility for possible representative parameters. The results showed that continuous water heating with sustained bed operation (temperature > 773K) is achievable and can be used to identify the best operating ranges of various parameters as suggested by the effect of parameters studies. The results obtained in the oxidation cycle (earlier study) and the reduction cycle (this work) indicate that the proposed design can be used for water heating over a complete cycle. The results thus provide a strong basis for developing a UMC-based steam boiler. [Display omitted]