A spherical thermocouple junction of diameter 0.706 mm is to be used for measurement of temperature of a gas stream. The convective heat transfer coefficient on bead surface is \(400~\frac{W}{{{m^2} - K}}\). The thermo physical properties of thermocouple material are \(k = 20~\frac{W}{{m - K}},\ c = 400\frac{J}{{kg - K}},\ \rho = 8500~\frac{{kg}}{{{m^3}}}\). If the thermocouple initially at 30°C is placed in a hot stream of 300°C, the time taken by the bead to reach 298°, is

A spherical thermocouple junction of diameter 0.706 mm is to be used f

1.	A spherical thermocouple junction of diameter 0.706 mm is to be used for measurement of temperature of a gas stream. The convective heat transfer coefficient on bead surface is \(400~\frac{W}{{{m^2} - K}}\). The thermo physical properties of thermocouple material are \(k = 20~\frac{W}{{m - K}},\ c = 400\frac{J}{{kg - K}},\ \rho = 8500~\frac{{kg}}{{{m^3}}}\). If the thermocouple initially at 30°C is placed in a hot stream of 300°C, the time taken by the bead to reach 298°, is
A.	2.35 sec
B.	4.9 sec
C.	14.7 sec
D.	29.4 sec
Answer» C. 14.7 sec

Discussion

No Comment Found

Related MCQs

The oven of an electric store, of total outside surface area 2.9 m2 dissipates electric energy at the rate of 600 W. The surrounding room air is at 20 degree Celsius and the surface coefficient of heat transfer between the room air and the surface of the oven is estimated to be 11.35 W/m 2 degree. Determine the average steady state temperature of the outside surface of the store
The following data pertains to a hollow cylinder and a hollow sphere made of same material and having the same temperature drop over the wall thicknessInside radius = 0.1 m and outside surface area = 1 square meterIf the outside radius for both the geometrics is same, calculate the ratio of heat flow in the cylinder to that of sphere?
If we increase the thickness of insulation of a circular rod, heat loss to surrounding due to
A spherical vessel of 0.5 m outside diameter is insulated with 0.2 m thickness of insulation of thermal conductivity 0.04 W/m degree. The surface temperature of the vessel is – 195 degree Celsius and outside air is at 10 degree Celsius. Determine heat flow
A spherical vessel of 0.5 m outside diameter is insulated with 0.2 m thickness of insulation of thermal conductivity 0.04 W/m degree. The surface temperature of the vessel is – 195 degree Celsius and outside air is at 10 degree Celsius. Determine heat flow per m2 based on inside area
The thermal resistance for heat conduction through a hollow sphere of inner radius r1 and outer radius r2 is
A bar of Cu of length 75 cm and a steel bar of 125 cm length are joined together end to end. Both the bars are having same diameter of 2 cm. The free ends of the Cu and the steel bars are maintained at 100°C and 0°C respectively. The curved surfaces of the bars are thermally insulated, what is the approximate temperature at Cu-steel junction? (consider conductivity k of Cu = 400 Js-1m-1 C-1 and k for steel 50 Js-1m-1 C-1)
In a composite slab, the temperature at the interface(Tinter) between two materials is equal to the average of the temperatures at the two ends. Assuming steady one-dimensional heat conduction, which of the following statements is true about the respective thermal conductivities?
Critical radius of insulation of a hollow cylinder is
Lumped heat capacity approach of transient heat conduction analysis is used:

Discussion

No Comment Found

Related MCQs

Reply to Comment