1. Steam enters a nozzle operating at steady state at 30 bar, 320°C, with a velocity of 100 m's. The exit pressure and t

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1 Steam Enters A Nozzle Operating At Steady State At 30 Bar 320 C With A Velocity Of 100 M S The Exit Pressure And T 1 (56.09 KiB) Viewed 13 times

1. Steam enters a nozzle operating at steady state at 30 bar, 320°C, with a velocity of 100 m's. The exit pressure and temperature are 10 bar and 200°C, respectively. The mass flow rate is 2 kg/s. Neglecting heat transfer and potential energy, determine: a) The exit velocity, in m's. b) The inlet and exit flow areas, in cm? 2. A compressor operates at steady state with Refrigerant 134a as the working fluid. The refrigerant enters at 0.24 MPa, 0°C, with a volumetric flow rate of 0.64 m/min. The diameters of the inlet and exit pipes are 3 and 1.5 cm, respectively. At the exit, the pressure is 1.0 MPa and the temperature is 50°C. If the magnitude of the heat transfer rate from the compressor to its surroundings is 5% of the compressor power input, determine the power input, in kW. 3. At steady state, a refrigeration cycle removes 150 kJ/min of energy by heat transfer from a space maintained at -50°C and discharges energy by heat transfer to surroundings at 15°C. If the coefficient of performance of the cycle is 30 percent of that of a reversible refrigeration cycle operating between thermal reservoirs at these two temperatures, determine the power input to the cycle, in kW. 4. A heating system must maintain the interior of a building at 20°C during a period when the outside air temperature is 6°C and the heat transfer from the building through its roof and walls is 3 x 10 kJ. For this duty heat pumps are under consideration that would operate between the dwelling and a) the ground at 16°C, b) a pond at 11°C, c) the outside air at 6°C. For each case, evaluate the minimum theoretical net work input required by any such heat pump, inkl. 5. A gas mixture consists of 2 kg of N and 3 kg of He. Determine a) the composition in terms of mass fractions. b) the composition in terms of mole fractions. c) the heat transfer, in kJ, required to increase the mixture temperature from 21 to 66°C, while keeping the pressure constant.