Question

Oil enters a counterflow heat exchanger at 525 K with a mass flow rate of 10 kg/s and exits at 275 K. A separate stream of liquid water enters at 20°C, 5 bar. Each stream experiences no significant change in pressure. Stray heat transfer with the surroundings of the heat exchanger and kinetic and potential energy effects can be ignored. The specific heat of the oil is constant, c = 2 kJ/kg · K. If the designer wants to ensure no water vapor is present in the exiting water stream, what is the minimum mass flow rate for the water, in kg/s?

Answer #1

Oil enters a counterflow heat exchanger at 525 K with a mass
flow rate of 10 kg/s and exits at 275 K. A separate stream of
liquid water enters at 20°C, 5 bar. Each stream experiences no
significant change in pressure. Stray heat transfer with the
surroundings of the heat exchanger and kinetic and potential energy
effects can be ignored. The specific heat of the oil is constant, c
= 2 kJ/kg · K. If the designer wants to ensure...

Oil enters a counterflow heat exchanger at 600 K with a mass
flow rate of 10 kg/s and exits at 350 K. A separate stream of
liquid water enters at 20°C, 5 bar. Each stream experiences no
significant change in pressure. Stray heat transfer with the
surroundings of the heat exchanger and kinetic and potential energy
effects can be ignored. The specific heat of the oil is constant,
c = 2 kJ/kg · K.
If the designer wants to ensure...

Air enters a counterflow heat exchanger operating at steady
state at 22°C, 0.1 MPa and exits at 7°C. Refrigerant 134a enters at
0.2 MPa, a quality of 0.21, and a mass flow rate of 30 kg/h.
Refrigerant exits at 0°C. There is no significant change in
pressure for either stream. (a) For the Refrigerant 134a stream,
determine the rate of heat transfer, in kJ/h (b) For the
refrigerant stream evaluate the change in flow exergy rate, in
kJ/h. (c) For...

Cold water enters a counter flow heat exchanger at 20ºC at a
rate of 10 kg/s, where it is heated by a hot water stream that
enters the heat exchanger at 80ºC at a rate of 2 kg/s. Assuming the
specific heat of water to remain constant at Cp=4.18 kJ/(kg.ºC),
determine the maximum heat transfer rate and the outlet
temperatures of the cold and the hot water streams.

Water is used to cool R-134a in the condenser of a heat
exchanger. The refrigerant enters the counter-flow heat exchanger
at 800 kPa, 80 0C and a mass flow rate of 2 kg/s. The refrigerant
exits as a saturated liquid. Cooling water enters the condenser at
500 kPa and 18 0C and leaves the condenser at 30 0C. Determine the
necessary mass flow rate of water. Each fluid is assumed to flow at
constant pressure.

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...

An adiabatic counterflow heat exchanger receives 0.3
m3/s of saturated steam vapor at 200 kPa and condenses
it to a saturated liquid on the shell side. Water
enters the tubes at 25 C and leaves at 40 C. Determine
the second law efficiency for the heat exchanger.

heat transfer problem
A counterflow concentric tube heat exchanger is used to cool
lubricant oil of a big gas turbine. The cooling water's flow rate
through the interior aluminum tube (Di= 25mm) is 0.2kg/seg, while
the oil's flow rate through the exterior ring (Do= 45mm) is
0.1kg/seg. The oil and the water enter at 100°C and 30°C
respectively. How long does the tube have to be for oil to leave at
60°C?
Oil at 80°C
Cp = 2131 J/Kg K...

Cold water leading to a shower enters a well-insulated,
thin-walled, double-pipe, counterflow heat exchanger at 10C at a
rate of 1.15kg/s and is heated to 70C by hot water that enters at
85C at a rate of 1.6kg/s. Use data from the tables to Determine the
rate of entropy generation in the heat exchanger. Answer in
kW/K.

A thin-walled double pipe counter flow heat exchanger is to be
used to cool oil (cp = 2200 j/kg*K) from 150 ℃ to 30 ℃ at a rate of
2.1 kg/s by water (cp= 4180 J/kg*K) that enters at 20 ℃ at a rate
of 1.2 kg/s. The diameter of the tube is 2.5 cm, and its length is
10 m.
Using Excel (a) Determine the overall heat transfer coefficient
of this heat exchanger. (b) Investigate the effects of oil...

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