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The utilization of the spiral tube heat exchanger (SHE) has become increasingly prevalent in large-scale liquefaction processes. However, the flow pattern and frictional pressure drop of two-phase flow in the spiral tube have been scarcely studied, particularly under offshore sloshing conditions. An experimental system had been developed to explore the flow pattern and frictional pressure drop characteristics of mixed hydrocarbon fluid in a spiral tube. Moreover, these have been developed in order to examine the effects of sloshing style (roll, pitch, heave), sloshing period (5–15 s), sloshing amplitude (5–15° or 50–150 mm), mass flux (200–800 kg/(m2·s)), vapor quality (0–1), and saturation pressure (2–4 MPa) on the frictional pressure drop of methane/ethane mixture in the spiral tube. The results indicated that sloshing conditions reduce the frictional pressure drop, thereby enhancing fluid flow. A correlation was established to predict the sloshing factor of frictional pressure drop, and the MARD under verification conditions was 6.04%. Furthermore, three flow pattern boundaries were proposed based on We* as an indicator. [ABSTRACT FROM AUTHOR]

Spiral wound tube heat exchanger (SWHE) was confirmed as the core equipment of natural gas liquefaction (LNG). However, there was rare experimental research on large-scale SWHE for LNG, and the theory of heat transfer is not perfect. To investigate the tube-side flow and heat transfer characteristics in spiral tubes, an experimental system was proposed. To ensure the accuracy of the experimental data, the heat transfer coefficients of liquid propane under different conditions were measured, and the data acquired through the experiment were compared with two classical heat transfer correlation (Dittus–Boelter and Geielinski) under the identical working conditions. The applicability of the existing correlation was analyzed using the experimental data, and a novel heat transfer correlation was developed. As indicated by the results, the deviation between the experimental system and the classical correlation under the identical working condition was lower than ±10%. Furthermore, the error comparison between the novel correlation prediction value and the experimental data was less than ±15%. [ABSTRACT FROM AUTHOR]

The maldistribution of working medium restricts the heat transfer performance of the spiral-wound heat exchangers (SWHEs), especially when the heat exchangers are applied in floating production storage and offloading platform. Therefore, the maldistribution in the SWHEs needs to be studied under sloshing conditions. In the investigation, a novel distributor named "disc distributor" is designed and its distribution characteristic is analysed under sloshing conditions experimentally. The impacts of sloshing amplitude, sloshing periods, mass flow rate and structural parameters on flow uniformity are discussed. The results show that based on steady condition the augmentation of the sloshing amplitude makes the liquid uniformity deteriorate by 14.2–56.0%, and the enlargement of the sloshing period improves the liquid flow uniformity by 12.8–28.3%. The elevation of the mass flow rate promotes the flow uniformity by 23.8–27.0% and 13.9–32.4% under steady and sloshing conditions, respectively. The variation of hole diameter exacerbates distribution performance of the distributor by 5.3–18.4% and 2.5–22.3% under steady and sloshing conditions separately. Heave condition always has less influence on the flow uniformity of the distributor than other sloshing conditions. [ABSTRACT FROM AUTHOR]

• A numerical model of liquid injected seal is built and validated. • Gas velocity has stronger effect on flow uniformity than liquid velocity. • Liquid pressure drop is always larger than that of gas under the same condition. • An empirical correlation of flow uniformity in liquid injected seal is obtained. • The empirical correlations for pressure drop in liquid injected seal are obtained. For two-phase refrigerant flow, the maldistribution at the entrance of plate-fin heat exchangers (PFHEs) is a severe issue which tends to make the thermal performance of heat exchangers worse. Especially when PFHEs are applied in the field of liquefied natural gas (LNG), the non-uniformity restricts the natural gas liquefaction efficiency of PFHEs. To improve the thermal performance and liquefaction efficiency, a distributor named liquid injected seal is added at the entrance of PFHEs and its maldistribution is analyzed numerically by ANSYS FLUENT. Firstly, a numerical model of liquid injected seal is built and verified by the experimental data. Then, the effects of gas and liquid velocity of refrigerant on the flow uniformity are analyzed. It indicates that the velocity of gas phase is more effective on the distribution characteristic of the distributor than that of liquid phase. In addition, the pressure drop of the distributor is also studied under varied gas and liquid velocities. It is found that the liquid pressure drop is larger than gas pressure drop under the same condition. Further, an empirical correlation for maldistribution is obtained to predict the maldistribution of gas-liquid refrigerants, and empirical correlations for pressure drop in liquid injected seal in PFHEs are proposed. This investigation provides support for the improvement of efficiency of LNG. [ABSTRACT FROM AUTHOR]