Thermal power Pt produced by a circulating fluid with a flow rate q [kg/s], whose temperature increases from T1 to T2:
where cs is the specific heat of the fluid under consideration (Jkg-1°C-1); the problem is exactly the same when the opposite situation is considered (a fluid that cools down, thereby changing its temperature from T2 to T1).
Calculating the thermal energy Et created in a period of time t:
The thermal energy Et of a fluid or solid of mass m [kg] at a temperature T with respect to a reference temperature Tr [°C]:
For cs, see point a).
Thermal power Pt transmitted by an environment at temperature T1 to an environment at temperature T2>T (the two environments are separated by a wall with a surface area of S [m2] and thermal conductivity k [Wm-2°C-1]):
for calculation of the energy see point b).