Study On Numerical Simulation Of Heat Transfer Characteristic Of Cryogenic Heat Exchanger In BOG Reliquefaction System

Cryogenic heat exchanger, which is one of the most energy consumption sections, is thesignificant equipment in the natural gas BOG reliquefaction system. Research of heat transfercharacteristic of heat exchanger is meaningful for intensifying heat exchanger’s function,promoting heat transfer efficiency and lowering investment. And the heat transfer regulationis useful for operating the reliquefaction system steadily. With development and advancementof computational fluid dynamics, heat transfer theory and computer technique, numericalsimulation has become a great important experiment approach for researching and analysingheat transfer characteristic of heat exchanger.A three-dimension geometry model of heat exchanger is established on the basis oftube-and-shell heat exchanger design standards and is meshed by the CFD pretreatmentsoftware GAMBIT. Because of nature gas is a multicomponent compound, its thermalphysical parameters, such as density, specific heat capacity, coefficient of heat conducitivityand viscosity, is computed base on SRK equation of gas state and principle of comparisoncondition in the software ASPEN PLUS. Using CFD-software FLUENT, selecting standardk-ε model and definiting boundary conditions, heat transfer process of one shell-side coldfluid refrigerating two tude-side hot fluids in the cryogenic heat exchanger is numericalsimulated. And the distribution of temperature field, velocity field and pressure field isillustrated in this paper.According to which heat exchanger tube will accessess nature gas, it can be divided intoseven tube-side fluid configurations. Compare the simulation resulfs of heat transferperformance with different tube-side fluid configurations to analyse the outlet temperature ofall the fluid and heat transfer function and resistance performance of the heat exchanger. Andarrival at a conclusion is that nature gas obtains deffierent refrigeration capacity in differentconfiguration.With the same operation condition, simulate the heat exchanger with differentrefrigerants such as propylene, propane and nitrogen and analyse the temperature drop extentof the nature gas and the effect of heat exchanger’s performance. The result shows that whenusing propane as the refrigerant nature gas can get lower temperature and the heat exchangercan rececve better combination property.Altering the fluid’s inlet velocity of temperature, to simulate heat exchanger withdifferent operating condition and analyse the change law of the fluid’s outlet temperature andthe thermal load and the affection degree of nature gas’s temperature in different tude-side fluid configuration. While the inlet operating condition of shell-side propylene changing,outlet temperature of nature gas in is affected more greatly; while the inlet operating conditionof tude-side propylene changing, the effect is not obvious; and while the operating conditionof nature gas changing, heat exchanger’s parameter in configuration-7is affected moregreatly.