In which component is the energy balance described by q = h1 - h2?

In which component is the energy balance described by q = h1 - h2?

• A. Condenser
• B. Boiler
• C. Turbine
• D. Pump

Answer: (A)

In a steady-flow component where only heat transfer occurs and kinetic/potential changes are negligible, the energy balance is Q_dot = ṁ (h_in − h_out). The heat transferred per unit mass is the difference in specific enthalpy between the inlet and outlet. For a condenser, steam enters at a high enthalpy and leaves as liquid at a much lower enthalpy. Since h1 > h2, the difference h1 − h2 is positive, and this difference times the mass flow rate equals the heat rejected to the surroundings. That matches the form q = h1 − h2, describing the energy balance in the condenser. In a boiler, the enthalpy increases (h_out > h_in), so the relevant expression would involve h_out − h_in for heat added. In a turbine, the enthalpy decreases and the energy extracted is work, not heat (neglecting heat transfer). In a pump, work input raises enthalpy, also not a heat transfer balance. So the component where the energy balance is described by q = h1 − h2 is the condenser.

In a steady-flow component where only heat transfer occurs and kinetic/potential changes are negligible, the energy balance is Q_dot = ṁ (h_in − h_out). The heat transferred per unit mass is the difference in specific enthalpy between the inlet and outlet.

For a condenser, steam enters at a high enthalpy and leaves as liquid at a much lower enthalpy. Since h1 > h2, the difference h1 − h2 is positive, and this difference times the mass flow rate equals the heat rejected to the surroundings. That matches the form q = h1 − h2, describing the energy balance in the condenser.

In a boiler, the enthalpy increases (h_out > h_in), so the relevant expression would involve h_out − h_in for heat added. In a turbine, the enthalpy decreases and the energy extracted is work, not heat (neglecting heat transfer). In a pump, work input raises enthalpy, also not a heat transfer balance.

So the component where the energy balance is described by q = h1 − h2 is the condenser.