\documentclass[tikz,border=6pt]{standalone}
\usepackage{luacoolprop}
\pgfplotsset{compat=1.18}

\begin{document}
\begin{tikzpicture}
  \begin{loglogaxis}[
    width=13cm,
    height=8cm,
    xlabel={$v/\si{\cubic\metre\per\kilogram}$},
    ylabel={$p/\si{\bar}$},
    grid=both,
    title={PV background families and process paths}
  ]
    \LCPAddPVPlots[
      fluid=R134a,
      isotherm=true,
      isentrope=true,
      quality step=0.2,
      temperature values={-20,0,20,40,60},
      entropy values={1.7,1.9},
      labels=false
    ]
    \LCPAddPVProcess[
      fluid=R134a,
      type=isobar,
      from={p=2bar,Q=0},
      to={p=2bar,Q=1},
      color=black,
      label={evaporation},
      mark endpoints=true,
      export coordinates=DemoPV,
      log coordinates=true
    ]
    \LCPAddPVProcess[
      fluid=R134a,
      type=isentropic,
      from={p=2bar,Q=1},
      to={p=12bar,s=\DemoPVToEntropySI},
      color=purple,
      label={compression}
    ]
  \end{loglogaxis}
\end{tikzpicture}
\end{document}