Question

In a steady flow fan, 130kJ of work is done to the air. The specific volume, pressure, and speed at inlet are 0.33m³/kg, 100kPa, and 18m/s. The inlet duct is 25m above the floor, and the discharge duct is at floor level. The discharge conditions are 0.16 m³/kg, 105kPa, and 290m/s. The total heat loss between the inlet and the discharge is 13kJ/kg of fluid. In flowing through the fan, how much is the change in internal energy?

Answer 1

The change in internal energy of the air flowing through the fan is 117 kJ/kg.

Step-by-step explanation:

In order to calculate the change in internal energy, we need to consider the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system.

In this case, the work done to the air is 130 kJ, and the total heat loss is 13 kJ/kg of fluid.

Using the equation ΔU = Q - W, where U is the change in internal energy, Q is the heat added, and W is the work done, we can calculate the change in internal energy as follows:

ΔU = 130 kJ - 13 kJ/kg = 117 kJ/kg.