3.2.1 Using absolute temperatures, the enthalpy at the pre-heater inlet and outlet in kJ/s

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3.2.1 Using absolute temperatures, the enthalpy at the pre-heater inlet and outlet in kJ/s

Step 1: Convert the air temperatures from Celsius to Kelvin.
The pre-heater increases the air temperature from $18 \text{ °C}$ by $22 \text{ °C}$.
Inlet air temperature: $T_{air,in} = 18 \text{ °C} = 18 + 273.15 = 291.15 \text{ K}$
Outlet air temperature: $T_{air,out} = 18 °C + 22 °C =