Steady-state operating data are shown in the figure for an open feedwater heater. Heat transfer from the feedwater heater to its surroundings occurs at an average outer surface temperature of 50°C at a rate of 100 kW. Ignore the effects of motion and gravity and let T 0 = 25°C, p0 = 1 bar. Determine (a) the ratio of the incoming mass flow rates, ?̇# /?̇ $ . (b) the rate of exergy destruction, in kW.

The manufacturer of the device claims that it accepts a heat transfer at a rate of QH = 3.0 kW from a low-grade source of geothermal heat at TH = 80ºC and rejects heat at rate QC to the atmosphere at TC = 20ºC. The device operates at steady state and produced work at a rate of W= 2.5 kW. There are no other heat or work transfers from the device. a.) What is the rate at which the device rejects heat to the atmosphere, QC ? b.) Is this device possible? Justify your answer using an entropy balance.

Steam is accelerated in a nozzle from a velocity of 80 to an unknown outlet velocity. S = The area at the inlet to the nozzle is A₁ 50 cm². The temperature and pressure at the inlet to the nozzle are T₁ = 400°C and p₁ = 50 bar, respectively, and the outlet temperature and pressure are T₂ = 300°C and Qout = 120 kW P2 = 20 bar, respectively. During the steady-state flow, heat is lost from the nozzle walls at a rate of 120 kW. For the nozzle: 1 2 400 300 a) Determine the mass flow rate of the steam entering the nozzle, in units of [] b) Determine the velocity at the outlet of the nozzle, in units of [m/s] c) Determine the area at the outlet of the nozzle, in units of [cm²] State T, °C P, bar 60 20 V, m 3 kg 0.04739 0.1308 m vel₁ 80- S A₁ = 50 cm² T₁ = 400 °C P₁ = 50 bar kJ kg kg 2892.9 3177.2 2807.9 3069.5 U, kJ — 1 h, (2) P2 = 20 bar T2 = 300 °C