Answer: Vertical lines on pressure enthalpy chart show constant total heat lines.
An enthalpy chart is often used by refrigerant technicians. It can show the A/C cycle. The pressure-enthalpy diagram is a very useful tool used to detect the temperature and pressure at which the refrigerant changes from a gas to a liquid. It can also represent the pressure at which it gets back to a gas.
Identify vertical lines on pressure enthalpy chart
Vertical lines on pressure enthalpy chart shows constant total heat lines. In an enthalpy chart, Vertical lines represent constant enthalpy and horizontal lines will represent constant pressure