41. Unit of thermal diffusivity is
(a) m2/hr
(b) m2/hr°C
(c) kcal/m2 hr
(d) kcal/m.hr°C
(e) kcal/m2 hr°C.
Ans: a
43. Thermal conductivity of wood depends on
(a) moisture
(b) density
(c) temperature
(d) all of the above
(e) none of the above.
Ans: d
44. In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
(a) convection
(b) radiation
(c) conduction
(d) both convection and conduction
(e) none of the above.
Ans: c
45. Film coefficient is defined as Inside diameter of tube
(a) Equivalent thickness of film
(b) Thermal conductivity Equivalent thickness of film Specific heat x Viscosity
(c) Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity
(d) Film coefficient x Inside diameter Thermal conductivity
(e) none of the above.
Ans: b
46. Heat conducted through unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called
(a) thermal resistance
(b) thermal coefficient
(c) temperature gradient
(d) thermal conductivity
(e) heat-transfer.
Ans: d
49. The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as
(a) emissivity
(b) transmissive
(c) reflectivity
(d) intensity of radiation
(e) absorptivity.
Ans: d
50. Emissivity of a white polished body in comparison to a black body is
(a) higher
(b) lower
(c) same
(d) depends upon the shape of body
(e) none of the above.
Ans: b
Read More Questions:
Heat Transfer - Mechanical MCQs Part1
Heat Transfer - Mechanical MCQs Part2
(a) m2/hr
(b) m2/hr°C
(c) kcal/m2 hr
(d) kcal/m.hr°C
(e) kcal/m2 hr°C.
Ans: a
43. Thermal conductivity of wood depends on
(a) moisture
(b) density
(c) temperature
(d) all of the above
(e) none of the above.
Ans: d
44. In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
(a) convection
(b) radiation
(c) conduction
(d) both convection and conduction
(e) none of the above.
Ans: c
45. Film coefficient is defined as Inside diameter of tube
(a) Equivalent thickness of film
(b) Thermal conductivity Equivalent thickness of film Specific heat x Viscosity
(c) Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity
(d) Film coefficient x Inside diameter Thermal conductivity
(e) none of the above.
Ans: b
46. Heat conducted through unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called
(a) thermal resistance
(b) thermal coefficient
(c) temperature gradient
(d) thermal conductivity
(e) heat-transfer.
Ans: d
49. The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as
(a) emissivity
(b) transmissive
(c) reflectivity
(d) intensity of radiation
(e) absorptivity.
Ans: d
50. Emissivity of a white polished body in comparison to a black body is
(a) higher
(b) lower
(c) same
(d) depends upon the shape of body
(e) none of the above.
Ans: b
Read More Questions:
Heat Transfer - Mechanical MCQs Part1
Heat Transfer - Mechanical MCQs Part2
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