A Non-Equilibrium Liquid-Gas Ejection Model for Ekalina Cycle

The EKalina absorption power cycle has shown great advantage on low grade heat recovery. However, the liquid-gas ejector in the EKalina cycle experiences with a complicated desorption/absorption driven heat/mass transfer and phase transition process, and the theoretical description method for this ejection process is far than satisfactory. This paper proposes for the first time a non-equilibrium two phase absorption ejection model for the ammonia-water binary absorption mixture based liquid-gas ejector. By modifying the traditional ejection model with the nucleation and the chemical reaction driving force, this model can describe the delayed phase transition mechanism, the desorption/absorption of the ammonia-water binary mixture and the shock phenomenon in the liquid-gas ejector. A comparison study between the proposed model and the traditional ejection model is conducted, the flow and phase transition behavior of the binary mixture in axial direction as well as the ejector performance under typical EKalina cycles’ working conditions are analyzed. The results show that in the nozzle section the phase transition drastically occurs and the corresponding nucleation rate suddenly reaches the highest level of 4.99 [[EQUATION]] 10 11 m 3 ·s -1 at 18.5K superheat temperature. Comparing with the traditional liquid-gas ejector, in the EKalina ejector the ejection coefficient is significantly increased from 10 -3 to 10 -2 magnitude. The ejection coefficient of three typical EKalina cycles driven by heat source of 298-423K reaches 0.055-0.072