A New Method for the Calculation of Gases Enthalpy

In this paper, the authors have investigated newpolynomial functions for the determination ofEnthalpy for various gases, and for their mixture, inICE applications.Several polynomial functions have beeninvestigated to determine the best matching functionrespect to experimental data. The polynomialfunctions investigated are: simple polynomials,exponential polynomials and logarithmic polynomials(third, fourth and fifth order).The best polynomial functions have the functionalform of a V order Logarithmic Polynomial, and canbe used in temperature ranges of practical interest.Logarithmic Polynomial (L.P.) coefficients havebeen obtained by least squares matching withthermodynamic property data from the JANAF tables.Values of the specific heat have been calculated asa function of temperature, and they have beencompared with experimental ones, in order to evaluatethe percent error.Logarithmic Polynomials (L.P.s) have beencalculated for various gases: Technical air (21% O2),N, O, H, H2, O2, N2, CO, OH, NO, CO2 and H2O.In literature there are many works which presentmathematical functions of Enthalpy vs Temperature.A comparison between the polynomial functions thatare present in literature and V order L.P. has beeneffected. The new L.P.s point out a major precisionrespect to the other polynomial functions, and thepossibility to utilise a single L.P. for a widetemperature range, according to a good accuracy withexperimental data.