Enthalpy
Enthalpy is a thermodynamic property and is also called "heat content at constant pressure". It is defined as:
dh = Cp . dT
dh Differential variation of enthalpy
cp Specific heat of the fluid at constant pressure
dT Differential variation of temperature
cp Specific heat of the fluid at constant pressure
dT Differential variation of temperature
The enthalphy of water at 273 K is by definition zero.
