A. Is a dimensionless quantity
B. Does not provide a safety factor for design
C. Accounts for additional resistances to heat flow
D. None of these
Related Mcqs:
- With the increase of temperature, the Col-burn jH factor_____________________?
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease; depending on temperature - Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface) ?
A. U1 – U2
B. 1/U1 – 1/U2
C. 1/U2 – 1/U1
D. U2 – U1 - Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling ?
A. Square pitch
B. Triangular pitch
C. Diagonal square pitch
D. None of these - The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is _____________________?
A. 1200 W/m2.K
B. 894 W/m2.K
C. 333 W/m2.K
D. 287 W/m2.K - In SI units, fouling factor is expressed in __________________?
A. m2°K/W
B. W/m2°K
C. m2°K
D. m°K/W - ‘Fouling factor’ used in the design of a multipass shell and tube heat exchanger is a_____________________?
A. Non-dimensional factor
B. Factor of safety
C. Conversion factor for individual film heat transfer co-efficient to overall heat transfer coefficient
D. None of these - Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C?
A. 40
B. 95
C. 70
D. 50 - For what value of Prandtl number, the Col-burn analogy is valid ?
A. 0.06 to 120
B. 0.6 to 120
C. 1 to 103
D. 1 to 50 - Nusselt number (for forced convection heat transfer) is a function of the _____________ number?
A. Prandtl
B. Reynolds
C. Both A. & B.
D. Neither A. nor B. - In counter flow compared to parallel flow, ?
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
