A. LMTD is greater
B. Less surface area is required for a given heat transfer rate
C. Both A. and B.
D. More surface area is required for a given heat transfer rate
Related Mcqs:
- LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the ______________ flow?
A. Parallel
B. Mixed
C. Counter flow
D. Same in either A , B. or C. - LMTD for counter-flow and parallel flow heat exchanger will be the same, when the_________________?
A. Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid)
B. Outlet temperature of both the hot and cold fluid are same
C. Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid
D. None of these - 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. < 1
B. > 1
C. 1
D. ∞ - For a counter current heat exchanger with Ti h = 80°C, T°c = 60°C, T°h = 50°C and Ti c = 30°C, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy___________________?
A. d2T/dZ2 > 0
B. d2T/dZ2 = 0
C. d2T/dZ2 < 0
D. dT/dZ = 0 - In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is _____________ the outlet temperature of the cold fluid?
A. Equal to
B. More than
C. Less than
D. Either more or less than (depending upon the fluid) - 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 - Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ?
A. 32
B. 37
C. 45
D. 50 - Heat flux, as defined in heat flow is analogous to _______________ in electricity flow?
A. Current
B. Voltage
C. Resistance
D. None of these - 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
D. < 1 - A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to_____________________?
A. d0.8
B. d-0.2
C. d-1
D. d-1.8
