Wang X.-D.Wang Z.-X.Duan Y.-Y.An B.Lee D.-J.2019-05-142019-05-14201418761070https://scholars.lib.ntu.edu.tw/handle/123456789/408237An efficient algorithm for evaluating thermodynamic properties on p-h thermodynamic surface of water and steam is proposed based on bi-quadratic spline interpolation method. With focus on discontinuities of first- or second-order derivatives of thermodynamic property z(p,h) at the saturated p-h line, the p-h surface at 100kJ/kg?h?4180kJ/kg and 0.001MPa?p?100MPa was divided into single- and two-phase regions. The spline function zSPL(p,h) in two-phase regime was calculated using one-dimensional spline function hsat SPL(p) at the saturated p-h line and the corresponding spline function zSPL(p,h) in single-phase region. For zSPL(p,h) in the single-phase region, virtual two-phase region data evaluated through curve extension approach was adopted for increased accuracy of zSPL(p,h) near the saturated p-h line. Non-uniform grid lines and bisection algorithm were also introduced to reduce the memory loadings. Calculation results of TSPL(p,h), £lSPL(p,h) and sSPL(p,h) show with the spline functions developed in this paper were 2.47-94.1 times faster in computing speed and 1-4 orders of magnitude higher consistency with IAPWS-95 than IAPWS-IF97. We proposed that the currently developed spline algorithm and optimization algorithm are applicable to efficient evaluation of thermodynamic properties of water and steam on p-s, h-s or other state surfaces. ? 2013 Taiwan Institute of Chemical Engineers.ComputationP-h surfaceSpline interpolationSteamThermodynamic propertiesWater[SDGs]SDG6journal article10.1016/j.jtice.2013.06.0162-s2.0-84894672568https://www.scopus.com/inward/record.uri?eid=2-s2.0-84894672568&doi=10.1016%2fj.jtice.2013.06.016&partnerID=40&md5=a21b7d2884a4871e90e917e4cb4ed3af