Enthalpy is defined as the sum of [[Internal Energy|internal energy]] and [[Work|work]] flow: $H=U+W_{flow}$ Work flow is the energy required to maintain [[Fluid|fluid]] flow through a [[Control Volume|control volume]]. $W_{flow}=PV$ Enthalpy can be described in terms of specific enthalpy, just as specific internal energy is used to describe internal energy. $h=u+P\nu$ $H=mh$ $ΔH=∑m_eh_e−∑m_ih_i$ $\Delta\dot{H}=∑\dot{m}_eh_e−∑\dot{m}_ih_i$ For [[Ideal Gas|ideal gases]] the change in enthalpy is found to be proportional to the change in [[Temperature|temperature]] of the [[Substance|substance]]: $\Delta h=C_{p0}\Delta T$ Likewise, the change in enthalpy can be found for [[Solid|solids]] by: $\Delta h=C\Delta T$