L5 slide 10: Energy balance for a tank being filled (ENGR5003)

L5 slide 10: Energy balance for a tank being filledFrom lectureCurrent specThird1 marks2 min

ENGR5003 Lecture 5, slide 10 (Q3 - The energy equation for unsteady flow)

A rigid tank initially contains a quantity of air. A valve is opened and air flows into the tank. The tank is insulated, and there is no shaft work. Which statement best describes the energy balance for the tank?

Formulas you may need

Unsteady-flow energy equation (no heat, no work, KE and PE neglected, inflow only): $d(mu)_{CV} = h_{in}\,dm_{in}$ (on the formula sheet)

AThe energy of the tank remains constant because it is insulated.BThe energy entering with the flowing air increases the energy stored in the tank.CThe energy entering the tank is completely converted into kinetic energy.DThe internal energy of the tank must decrease because air is flowing through the valve.