Experimental study on flow boiling heat transfer of LNG in a vertical smooth tube

•The heat flux influences the flow boiling heat transfer of LNG strongly at low quality.•The mass flux strongly influence the flow boiling of LNG.•The influence of tube diameter is weak in the experimental work.•The correlation by Zou et al. [16] is the best for prediction at present.

An experimental apparatus is set up in this work to study the upward flow boiling heat transfer characteristics of LNG (liquefied natural gas) in vertical smooth tubes with inner diameters of 8 mm and 14 mm. The experiments were performed at various inlet pressures from 0.3 to 0.7 MPa. The results were obtained over the mass flux range from 16 to 200 kg m−2 s−1 and heat fluxes ranging from 8.0 to 32 kW m−2. The influences of quality, heat flux and mass flux, tube diameter on the heat transfer characteristic are examined and discussed. The comparisons of the experimental heat transfer coefficients with the predicted values from the existing correlations are analyzed. The correlation by Zou et al. [16] shows the best accuracy with the RMS deviation of 31.7% in comparison with the experimental data.