IMPROVEMENT OF NATURAL GAS LIQUEFACTION AND SUPERCOOLING PROCESS IN HORIZONTAL CHANNELS OF PRINTED CIRCUIT HEAT EXCHANGERS: BUOYANCY ANALYSIS

Applying printed circuit heat exchangers (PCHEs) in small-scale natural gas liquefaction refineries can be a practical innovation for the expansion of such liquefaction units in industrial zones as well as areas far from the national natural gas network. After an overview of the state of the art related to the small-scale LNG refineries, the lack of applying PCHEs was observed. The gravitational and centrifugal buoyancy for a horizontal C-shaped channel of a PCHE have been studied numerically. OpenFOAM (version v1606+) software was used to model the cooling process. The most common component of natural gas is methane, so methane has been considered as the heat transfer fluid in this study. The dome-shaped distribution of the Grashof number reveals that mixed convection heat transfer becomes more active around the pseudo-critical point. Greater flattening of the C-shaped zigzags can cause an average increase of 49% for the centrifugal Grashof number in the supercritical process and a 30.9% increase for the gravitational Grashof number in the trans-critical process. As the zigzags become sharper, an increase of 29.12% in the Nusselt number for the supercritical process and 30.81% for the trans-critical process will be reached and the total entropy generation experiences a decrease of about 41.37% for the supercritical process and 32.03% for the trans-critical process. The proximity of the synergy number to one radian indicates that geometrical changes in the channel enhance heat transfer. The results can help to improve and develop the design of PCHEs for natural gas liquefaction process in small-scale refineries.