# Enthalpy

Written by Jerry Ratzlaff on . Posted in Thermodynamics

Enthalpy, abbreviated as H, measures the sum of internal energy changes in heat under constant pressure of the system.

## Enthalpy formula

 $$\large{ H = U + p \; V }$$

### Where:

 Units English Metric $$\large{ H }$$ = enthalpy of a system $$\large{\frac{Btu}{lbm}}$$ $$\large{\frac{kJ}{kg}}$$ $$\large{ U }$$ = internal energy of work done in a system $$\large{Btu}$$ $$\large{J}$$ $$\large{ p }$$ = pressure $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$ $$\large{ V }$$ = volume of a system $$\large{ft^3}$$ $$\large{m^3}$$