For optimizing the spiral wound heat exchanger (SWHE), the heat transfer mechanism of mixed hydrocarbon refrigerants flow boiling in shell side of SWHE should be known. In the present study, the heat transfer characteristics of the ethane/propane mixed refrigerants were experimentally investigated, and the ethane molar fractions of the mixed refrigerants cover 0-60%. As the vapor quality increases, the heat transfer coefficient (HTC) of the mixed refrigerant initially increases and then decreases sharply, presenting a maximum value at vapor quality of 0.6-0.8. As the ethane molar fraction increases from 0% to 60%, the HTC decreases maximally by 21% at vapor quality smaller than 0.7, while it increases maximally by 27% at vapor quality larger than 0.7. A heat transfer coefficient correlation for mixed hydrocarbon refrigerants flow boiling in shell side of SWHE was developed, and it agrees well with the experimental data. (C) 2018 Elsevier Ltd. All rights reserved.