Flow evaporation heat transfer of liquefied natural gas in a spiral pipe based on fluid coupling

In the extraction and usage of liquefied natural gas (LNG) cold energy, the heat transfer research of cryogenic fluid in spiral coil is mostly under the simplified condition of constant boundary temperature or constant heat flux density. This paper focuses on the actual situation of fluid–fluid coupling heat transfer in spiral coil. Under the condition of variable physical parameters, computational fluid dynamics numerical analysis is carried out on the non-customized numerical model through the Realizable k-ε turbulence model, and the influence of LNG flow and evaporation heat transfer characteristics in spiral coil is studied by changing the heat transfer structure. The results show that the heat transfer under non-constant boundary conditions is more in line with the actual heat transfer, and the spiral radius has the greatest influence on the heat transfer coefficient. When the spiral radius increases from 40 to 100 mm, the heat transfer coefficient decreases by 60.14%.