In counter current flow heat exchanger, the logarithmic temperature difference between the fluids is ________ as compared to parallel flow heat exchanger.

A Same
B Less
C Greater
D None of these

Correct Answer: Greater

The exchanger is performing at its best when the outlet temperatures are equal. Counter flow heat exchangers are inherently more efficient than parallel flow heat exchangers because they create a more uniform temperature difference between the fluids, over the entire length of the fluid path.
Bissoy MCQ
#Mechanical Engineering #Heat And Mass Transfer

Related Questions

LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger is
A Higher
B Lower
C Same
D Depends on the area of heat exchanger
For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is ________ that for counter flow.
A Equal to
B Less than
C Greater than
D None of these
In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is
A Minimum
B Maximum
C Zero
D Infinity
In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference
A Is always less than arithmetic average value
B Is always more than arithmetic mean value and the geometric mean value
C Is always less than arithmetic mean value, but more than geometric mean value
D May be either more or less than geometric mean and arithmetic mean value depending upon whether the flow of stream is co-current or counter-current
In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always
A [

A.

B. > 1

B 1
C ∞
Log mean temperature difference in case of counter flow compared to parallel flow will be
A Same
B More
C Less
D Depends on other factors
A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires
A Less heating surface
B More space
C Lower maintenance cost
D None of these
Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
A Parallel flow with equal heat capacities
B Counter flow with equal heat capacities
C Counter flow with unequal heat capacities
D Parallel flow with unequal heat capacities
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
A Finned tube heat exchanger with air inside and steam outside
B Finned tube heat exchanger with air outside and steam inside
C Shell and tube heat exchanger with air inside tubes and steam on shell side
D Shell and tube heat exchanger with air on shell side and steam inside tubes
LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is
A 0
B 1
C >1

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