\usemodule[t][luacoolprop]
\pgfplotsset{compat=1.18}
\starttext
\LCPPTDiagram[
  fluid=R134a,
  temperature axis unit=celsius,
  pressure axis unit=bar,
  isentrope=true,entropy values={1.4,1.7,2.0},
  isenthalp=true,enthalpy values={200,300,400},
  isochore=true,specific volume values={0.001,0.01,0.1}]
\stoptext

.