Related Questions

Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity?
A CO2
B N2
C O2
D CO
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
A Decreases
B Increases
C Remains unchanged
D Increases exponentially
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
A $$\frac{1}{{\text{k}}}$$
B k
C k2
D $$\frac{1}{{{{\text{k}}^2}}}$$
Low thermal conductivity of heat insulating materials is due to its
A Dense structure
B High proportion of air space
C High specific heat
D None of these
Which of the following acts as an insulator against heat, cold and as a shock-absorber in the body?
A Dermis
B Epidermis
C Subcutaneous fat layer
D None of the above
How are the efficiencies of any heat engine (miu) and reversible heat engine (miuR) compared, when both are operating between same heat source and same heat sink?
A miu = miuR
B miu>miuR
C miu
D none of these
The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
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
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
Which of the metals has the maximum thermal conductivity?
A Iron
B Aluminium
C Silver
D Copper

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