Experimental investigation on downward flow boiling heat transfer characteristics of propane in shell side of LNG spiral wound heat exchanger

•New heat transfer data for shell side of spiral wound heat exchanger were obtained.•Flow boiling heat transfer characteristics were analyzed.•Flow patterns in the shell side of spiral wound heat exchanger were observed.•A heat transfer correlation with good accuracy was proposed. For designing LNG spiral wound heat exchangers (SWHE), the boiling heat transfer mechanism of two-phase hydrocarbon refrigerant flowing downward in shell side should be known. In this study, an explosion-proof experimental rig was established for measuring heat transfer coefficients (HTC) and observing flow patterns. The test section contains three-layer tube bundles to emulate the actual structure and flow conditions of an SWHE. Propane as one main component of shell-side refrigerant is used as the tested fluid. The experimental conditions cover heat fluxes of 4~10 kW⋅m−2, mass fluxes of 40~80 kg (m2⋅s)−1 and vapor qualities of 0.2~1.0. The results indicate that HTC initially increases and then decreases with the increment of vapor quality, representing a maximum at a vapor quality of 0.8~0.9; the effect of heat flux on HTC increases with the increment of heat flux. A correlation of HTC was developed covering 98% of the experimental data within a deviation of ±20%.