Heat and mass transfer in cross-flow air-to-air membrane heat exchanger in heating mode

•Local Nusselt numbers equations for finned membrane channel are obtained.•CFD and finite difference heat transfer modelling results are within 1.6% difference.•Condensation and frost formation is influenced by membrane water vapour permeability. The main objective of the paper is numerical simulation and analysis of heat and mass transfer, condensation and frost formation conditions in cross-flow membrane-based heat exchanger. To get the desired results, the following problems were solved: numerical models for heat transfer under uniform wall temperature for parallel plates channel without/with fins were developed; numerical models were validated using literature data; local Nusselt number equations were obtained for parallel plates channel without/with fins; numerical models for heat and mass transfer in cross-flow membrane-based heat exchanger were developed incorporating local Nusselt numbers for finite difference method; numerical models were validated using ε-NTU method and experimental data from laboratory; effectiveness, condensation and frosting conditions in cross-flow membrane-based heat exchanger were numerically studied for different water vapour permeability coefficients, outside air temperature and inside air relative humidity.