Modeling and thermal resistance analysis of LNG gasification in ambient air vaporizers.

Liquefied natural gas (LNG) ambient air vaporizer (AAV) has attracted more attention because of its economy, popularity, and environmental protection; however, the low efficiency of AAV is the bottle-neck of its wide application. In order to find the effective methods of solving this problem, we proposed a mathematical model to evaluate the thermal resistances of LNG AAV. Besides, a thorough comparison of different correlations for natural convection and flow boiling is conducted. The results indicate that: (1) Obvious deviations are found between various heat transfer correlations. (2) The total thermal resistance of AAV increases with operation time. (3) The airside thermal resistance accounts for more than 90% of the total thermal resistance, and the percentage of frost thermal resistance is higher than 50% after 8 hours. (4) When air temperature is higher or lower than a transition temperature, the heat transfer performance of AAV enhances.