Entropy and exergy analysis of a hollow fiber membrane humidifier

•The hollow fiber membrane humidifier (HFMEH) is proposed for air humidification.•A lumped parameter heat and mass transfer model in the HFMEH is established.•The entropy generation rate and exergy destruction models in the HFMEH are established.•The exergy destruction and entropy generation rate can be decreased by about 5.9%-11.9%.•The width-height ratio between 1.5 and 1.75 may be a better choice.