02 Polytropic transformations of ideal gases

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L.D.D Advanced Building Physics - Polytropic transformations of ideal gases L.D.D The molar entropy of an ideal gas with constant cv is: Remember Mayer's relation: cp - cv = R  Molar entropy for an ideal gas with constant cp and cv: If we consider a transformation of a system, we can define the molar heat along a x transformation, represented by cx, as the ratio of the heat transferred along an infinitesimal stretch of the transformation x (positive if entering the system) to the temperature variation along the same stretch of the transformation x, divided by the number of moles that make up the system. L.D.D In case of ideal gas, we know: 1) Mayer's relation: cp - cv = R 2) Coefficient of thermal expansion at constant pressure: α = 1/T 3) Isothermal compressibility coefficient: KT = 1/P  We can define Polytropic Transformation a transformation along which the molar heat is constant, for which is valid:  Characteristic equation of the generic polytropic transformation: L.D.D