A. Prandtl number
B. Grashoff number
C. Thermal conductivity
D. Viscosity
Related Mcqs:
- The Dittus-Boelter equation for convective heat transfer [(i.e. h = 0.023 (K/D) (Re)0.8 (Pr)0.4] cannot be used for________________?
A. Low Reynold’s number
B. Very low Grashoff number
C. Molten metals
D. All A., B. and C. - Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid ___________________?
A. For fluids in laminar flow
B. For fluids in turbulent flow
C. When Grashoff number is very important
D. For liquid metals - For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus- Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of________________?
A. 1
B. 1.74
C. 6.1
D. 37 - Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________?
A. Between two bodies in physical contact with each other
B. Between two bodies not in physical contact with each other
C. From one part of a body to the another part of the same body
D. Both B & C - _____________ equation relates the thermal conductivity of a solid to its temperature ?
A. Antoine
B. Kopp’s
C. Lee’s
D. Kistyakowsky - When warm and cold liquids are mixed, the heat transfer is mainly by_______________?
A. Conduction
B. Convection
C. Radiation
D. Both A. & C. - Water is normally used as a coolant in the heat exchange equipments mainly because of its___________________?
A. Abundance & high heat capacity
B. Low density
C. Low viscosity
D. High fluidity - Vacuum is generally maintained in the vapour space of an evaporator mainly to__________________?
A. Get economical temperature difference by using moderate pressure steam
B. Facilitate forward feeding in multiple effect evaporation
C. Concentrate heat sensitive materials
D. Achieve very high concentration of the final product - The type of liquor circulation system to be ‘ employed in evaporators (viz. natural or forced circulation) is determined mainly by the ______________ of the liquid?
A. Viscosity
B. Density
C. Thermal conductivity
D. Corrosive nature - The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid_________________?
A. Its evaporation loss
B. Excessive corrosion
C. Uneconomic LMTD
D. Decrease in heat exchanger efficiency
