Question

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.

Answer #1

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...

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 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...

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...

Saturated water vapor leaves a steam turbine at a flow rate of
1.47 kg/s and a pressure of 0.51 bar. The vapor is to be completely
condensed to saturated liquid in a shell-and-tube heat exchanger
that uses city water as the cold fluid. The water enters the
thin-walled tubes at 17oC and is to leave at 57.6
oC. Assuming an overall heat transfer coefficient of
2000 W/m2K, determine the required heat exchanger
surface area and the water flow rate. cp,c...

A counter current double pipe heat exchanger is used to boil but
not superheat water at 100 DegreeC at rate of about 0.1 kg/s. This
is achieved by flowing hot oil at 400 DegreeC through the inner
pipe at a rate of 5 kg/s.
Latent heat of water: 2265 kJ/kg
Heat capacity of water: 4180 J/kgK
Heat capacity of the oil: 1800 J/kgK
What is the temperature of he hot oil leaving the heat
exchanger?
What is the overall heat...

A heat exchanger uses saturated steam at 375 K to heat cold
water entering at 280 K and leaving at 301 K only the latent heat
of vaporization is removed from the steam. i.e. the steam is
condensed and saturated water exit the exchanger. a) what is the
LMTD for a counter current heat exchanger? b) what is the LMTD for
a parallel or cocurrent heat exchanger? c) if the counter current
heat exchanger has a duty (Q) of 81000...

A heat exchanger uses saturated steam at 375 K to heat cold
water entering at 280 K and leaving at 301 K. Only the latent heat
of vaporization is removed from the steam, i.e. the steam is
condensed and saturated water exits the exchanger. (a) What is the
LMTD for a counter-current heat exchanger? (b) What is it for a
parallel heat exchanger (c) If the counter-crrent heat exchanger
has a duty(Q) of 81000 kJ/hour and an overall heat transfer...

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.

Methane enters a heat e xchanger at a volumetric flow rate of
145.0 m 3 /min, at an absolute pressure of 1.013 bar and
temperature of 15.0°C. At these conditions, the specific enthalpy
of methane is - 23.181 kJ/kg. The methane leaves the heat exchanger
at an absolute pressure of 1.0 13 bar and temperature of 60.0°C.
The corresponding specific enthalpy at these conditions is 78.656
kJ/kg. The methane is heated by a stream of saturated steam
entering the heat...

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