Superheating and supercharging characteristics of moving shock in wet steam flows

Abstract

Some specific thermodynamic properties of R718 such as the fundamental gasdynamic derivative Γ=υ3(∂2ρ/∂υ2)s/2c2, the thermal effect derivative ∂T/∂p, and the sound speed have presented. The positive values of the fundamental gasdynamic derivative of R718 near the vapor–liquid equilibrium line, ensures wet steam flow could not occur the nonclassical behavior like expansion shocks. The large ∂T/∂p derivative values of R718 vapor exhibits remarkable thermal effect for both steady and unsteady supercharging processes at high vacuum. The unsteady interaction behaviors between the aerodynamic gaswaves like shock and expansion waves and the contact faces, et al. for wet steam flows in the shock tube, were then intensively studied. And the supercharging characteristics of moving shocks for wet steam vacuum flows coupled with the homogenous condensation in rarefaction zone demonstrated the economic feasibility of wave rotor used for R718 vapor compression refrigeration technology and for vapor recompression in multi-effect distillation technology (MED). The superheating ability of moving shockwaves showed a promising technology of generating the superheated steam without the problems of critical heat flux (CHF), over this threshold there would be a dangerous high wall temperature of heat exchanging tubes.