A. IR
B. I2R
C. IR2
D. I2R2
Related Mcqs:
- A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________________?
A. Greater than that for un-insulated steam pipe
B. Less than that of the un-insulated steam pipe
C. Equal to that of the un-insulated steam pipe
D. Less than the steam pipe with 5 cms insulation - If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows _____________ law?
A. Parabolic
B. Hyperbolic
C. Linear
D. Logarithmic - If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows ____________ law?
A. Hyperbolic
B. Parabolic
C. Linear
D. Logarithmic - A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when_________________?
A. CPA > CPB
B. CPA < CPB
C. kA < 0.5 kB
D. kA >2 kB - The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by ______________ times, when the number of tube passes is increased to 8?
A. 20.8
B. 40.8
C. 40.4
D. 20.4 - 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 - 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 - Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?
A. Surrounding temperature
B. Average temperature of the fin
C. Temperature of the fin end
D. Constant temperature equal to that of the base - Which of the following situations can be approximated to a steady state heat transfer system ?
A. A red hot steel slab (having outside surface temperature as 1300°C) exposed to the
atmospheric air at 35°C
B. 10 kg of dry saturated steam at 8 kgf/cm2 flowing through a short length of stainless steel pipe
exposed to atmospheric air at 35°C
C. Boiling brine kept in open vessel when the bottom surface temperature of the vessel is
maintained constant at 180°C
D. A sub-cooled refrigerant liquid at 8°C flowing at the rate of 6 Kg/minute through a copper
pipe exposed to atmospheric air at 35°C - Steady state one dimensional heat flow by conduction as given by Fourier’s low does not assume that_______________?
A. There is no internal heat generation
B. Boundary surfaces are isothermal
C. Material is anisotropic
D. Constant temperature gradient exists
