Temperature of hot gases flowing in a pipe is measured by a thermocouple inserted in the thermal well. The thermal well made of ______________ will facilitate the most accurate measurement of the temperature ?

Related Mcqs:

1. Reynolds number of a fluid flowing in a circular pipe is 10,000. What will be the Reynolds number when the fluid velocity is decreased by 30% & the pipe diameter is increased by 30% ?

   A. 9,100
   B. 13,000
   C. 7,000
   D. 2,550

2. A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness ______________ metre?

   A. 0.01
   B. 0.1
   C. 0.25
   D. 0.5

3. The pressure drop per unit length for laminar flow of fluid through a long pipe is proportional to (where, A = cross-sectional area of the pipe & D = Diameter of the pipe) ?

   A. A
   B. D
   C. 1/A
   D. 1/A2

4. The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K) ?

   A. T
   B. 1/T
   C. T2
   D. 1/T2

5. Hot dipping process is used for coating a low melting point metal (e.g. Pb, Sn, Zn) on iron, steel & copper having relatively higher melting points. Which of the following is not a hot dipping process ?

   A. Galvanising
   B. Tinning
   C. Sherardizing
   D. None of these

6. The following thermocouple may be used for measuring temperature upto 1873°K__________________?

   A. Chromel-alumel
   B. Copper-constantan
   C. Platinum-platinum rhodium
   D. Iron-constantan

7. In case of water (Prandtl number ≈ 6) flowing over a flat plate heated over the entire length, the thermal boundary layer thickness as compared to hydrodynamic boundary layer thickness is ?

   A. Less
   B. More
   C. Equal
   D. Unpredictable

8. In a counter flow heat exchanger, hot fluid enters at 170°C & leaves at 150°C, while the cold fluid enters at 50°C & leaves at 70°C. The arithmetic mean temperature difference in this case is ______________ °C?

   A. 20
   B. 60
   C. 120
   D. ∞

9. Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans ?

   A. Emissivity of pipe surface
   B. Diameter & length of the pipe
   C. Temperature of hot pipe surface & that of air in the room
   D. None of these

10. Maximum amount of thermal radiation is emitted at all wavelengths at any specified temperature by a/an ______________ body?

    A. Grey
    B. Black
    C. Opaque
    D. White