Taking the working medium

i.e.wet air

in the wet-air turbine and compressed air energy-accumulating system as the object of study

the thermo-physical properties of wet air under high-temperature and high-pressure have been studied by using the Pen-Robinson equation(PR equation).Directing against the water content in wet air is a strong polarized substance

the parameter a in gravitational term of said PR equation has been modified

and the compress factor of saturated wet air within 5 MPa being calculated.Result shows that the modified PR equation(MPR equation) has same precision as that of the Hyland and Wexler model;by using the MPR equation

the enthalpy deviation of wet air under defferent operating conditions has been calculated

and compared with the result calculated by using PR equation.The influence of pressure

temperature

and water content upon the thermo-phsical properties of wet air has been analysed by using the MPR equation.