Simulation Of Convection Heat Transfer And Interface Absorption Of Ionic Liquid [EMIM][Tf₂N] With Latiice Boltzmann Method

Absorption heat pump and absorption chillers are effective energy-saving devices which utilize low-grade industrial waste as a drive force, it can be widely used in the heating and cooling of residential and commercial building. Currently, working pair of absorption heat pump and absorption chillers are mainly LiBr/H2O and NH3/H2O. However, LiBr/H2O working pairs is not only easy to corrode metal, and but also easy to crystallize in runtime, so has higher demand for equipment and operating conditions. NH3/H2O working pairs is toxic, and it isn’t suitable for a wide range of applications. Therefore, the development of new working pair is very necessary.Ionic liquid is a kind of green solvents which can dissolve organics and inorganics, it has many natural characteristic:small vapor pressure, thermal stability and designability, etc. some ionic liquids can also be dissolved with water, alcohol and other substances in any proportion. Recently, many scholars have proposed the ionic liquid can be used as an ideal absorbent.The lattice Boltzmann method is a kind of mesoscopic numerical simulation method, this numerical method is based on the molecular kinetic theory, the collision theory and statistical mechanics, which caculate the distribution function of particles, the particles undergo collision and migration, and ultimately get the macroscopic quantities. After this process it is possible to simulate fluid flow, heat transfer and mass transfer problems. Compared with the traditional computational fluid method, the lattice Boltzmann method has a natural paralleism, high computational efficiency, simple program, uncomplex boundary conditions and other advantages. Meanwhile the lattice Boltzmann method can handle complex boundary, thereby it can simulation multicomponent flow and multiphase flow problems.In this paper, the natural convection, heat transfer and heat transfer mechanism of ionic liquid [EMIM][Tf2N] in the cavity is researched with the single-phase lattice Boltzmann model. The results showed that the ionic liquid heat transfer worse than water; the natural convection heat transfer of ionic nanofluid [EMIN][Tf2N]-Al2O3 was simulated using two-phase and single-phanse LB model, the results show that the heat transfer effect of ionic nanofluid increases with the Rayleigh number and the volum fraction of nanoparticles increases. The two-phase LB model also show the same trend. However, comparision of these models of ionic nanoliquid heat transfer, two-phase model has more heat transfer effect than single-model. The ionic liquid [EMIM][Tf2N] absorbing CO2 will accompany by Rayleigh convection. The concentration perturbation model is used to calculate the suitable rang of the model parameters of ionic liquid [EMIM][Tf2N]-CO2 system and are finaly obtained 0.04≤P≤0.2; 0<△C≤10-7kg/m3, Only in this rang of the model parameters, the theory predicted and calculated values can match.