Question

1. A feedwater heater operating at steady state has two inlets and one exit. At inlet 1, water vapor enters at p1 = 7 bar, T1 = 200oC with a mass flow rate of 40 kg/s. At inlet 2, liquid water at p2 = 7 bar, T2 = 40oC, density = 992.260 kg/m3 enters through an area A2 = 25 cm2. Liquid water at 7 bar with a density of 902.527 kg/m3 exits at exit 3 with a volumetric flow rate of 0.06 m3/s. Draw the diagram and identify the inputs, output, and the system. Write the general form of Conservation of Mass equation, and simplify it for this case.

a) Determine the mass flow rate at inlet 2, in kg/s.

b) Determine the mass flow rate at the exit, in kg/s.

c) Determine the velocity at inlet 2, in m/s.

Answer #1

Steam enters a control volume operating at steady state at 3 bar
and 160 ◦ C with a volumetric flow rate of 0.5 m3 /s. Saturated
liquid leaves the control volume through exit #1 with a mass flow
rate of 0.1 kg/s, and saturated vapor leaves through exit #2 at 1
bar with a velocity of 5 m/s. Determine the area of exit #2, in m2
.

A mixing chamber has 2 inlets, first, steam water enters at 12
bar and 1173.15 K , then, saturated liquid enters at 12 bar and 80
kg/min. The exit conditions are 12 bar and 120 kg/min. Obtain the
mass flow rate (kg/s) at which steam water enters, the temperature
at the exit (C°) and the quality of substance at the exit. Ignore
the changes of kinetic and potencial energy.

a
mixing chamber has 2 inlets, first, steam water enters at 12 bar
and 1173.15 K , then, saturated liquid enters at 12 bar and 80
kg/min. The exit conditions are 12 bar and 120 kg/min. Obtain the
mass flow rate (kg/s) at which steam water enters, the temperature
at the exit (C°) and the quality of substance at the exit. Ignore
the changes of kinetic and potencial energy.

A power plant operates on a regenerative vapor power cycle with
one open feedwater heater. Steam enters the first turbine stage at
12 MPa, 560°C and expands to 1 MPa, where some of the steam is
extracted and diverted to the open feedwater heater operating at 1
MPa. The remaining steam expands through the second turbine stage
to the condenser pressure of 17 kPa. Saturated liquid exits the
open feedwater heater at 1 MPa. The net power output for the...

A two-part compressor operates with steady state conditions. The
exit of the first part of the compressor is also the inlet of the
second part of the compressor. In the first part of the compressor,
air is compressed from 1.5 bar, 350 K to 5.5 bar with a mass flow
rate of 7.2 kg/sec. In the second part of the compressor, air is
compressed from 5.5 bar to 9.5 bar with a mass flow rate of 5.8
kg/sec. Each unit...

Consider a mixing chamber where two separate streams
of fluid mix and then exit as a single stream. One of the stream
that enters the mixing chamber is superheated steam at 5 bar and
2000C. The other stream that enters the mixing chamber is a liquid
water at 5 bars and 400C. The two streams mix in the mixing chamber
and exit as a single stream. The single stream that exits is
saturated liquid at 5 bar. Determine the ratio...

A horizontal steady-state turbine is being designed to serve as
an energy source for a small electrical generator. (assume its
adiabatic and frictionless) The power required from the turbine is
1037 kW. The inlet to the turbine is steam at T1 = 600 0 C and P1 =
10 bar, with a mass flow rate of 2.5 kg/s. The inlet pipe is 10 cm
in diameter. The conditions at the turbine exit are T2 = 400 0 C
and P2...

Air at 95°F, 1 atm, and 10% relative humidity enters an
evaporative cooler operating at steady state. The volumetric flow
rate of the incoming air is 1765 ft3/min. Liquid water
at 68°F enters the cooler and fully evaporates. Moist air exits the
cooler at 70°F, 1 atm. There is no significant heat transfer
between the device and its surroundings and kinetic and potential
energy effects can be neglected.
a)Determine the mass flow rate of the dry air in lb(dry
air)/min....

Refrigerant 134a is the working fluid in an ideal
vapor-compression refrigeration cycle operating at steady state.
Refrigerant enters the compressor at 1 bar, -12°C, and the
condenser pressure is 9 bar. Liquid exits the condenser at 32°C.
The mass flow rate of refrigerant is 7 kg/min. Determine:
(a) the magnitude of the compressor power, in kW. (b) the
refrigeration capacity, in tons. (c) the coefficient of
performance.

a tube-within-a-tube heat
exchanger operating at steady state is composed of one pipe
containing
Refrigerant 134a and another pipe containing an ideal gas with
constant specific heat at constant
pressure of 1.2 kJ/(kg∙K). The refrigerant 134a enters the heat
exchanger in a saturated liquid state
and exits the heat exchanger in a saturated vapor state. The
temperature and mass flow rate of the
refrigerant 134a are -20° C and 3 kgs/s, respectively, at both its
inlet and outlet. The ideal...

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