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MCQOPTIONS
This section includes 8247 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 3101. |
Dietus-Boelter equation cannot be used for molten metals mainly due to its very low |
| A. | Prandtl number |
| B. | Grashoff number |
| C. | thermal conductivity |
| D. | viscosity |
| Answer» B. Grashoff number | |
| 3102. |
For specified tube outside diameter, higher BWG means higher |
| A. | tube thickness |
| B. | cross-sectional area |
| C. | weight per unit length |
| D. | none of these |
| Answer» C. weight per unit length | |
| 3103. |
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased. |
| A. | velocity of circulation |
| B. | liquor-film co-efficient |
| C. | both (a) and (b) |
| D. | neither (a) and (b) |
| Answer» E. | |
| 3104. |
Heat flux is the time rate of heat transfer per unit |
| A. | length |
| B. | area |
| C. | volume |
| D. | none of these |
| Answer» C. volume | |
| 3105. |
With increase in temperature, the thermal conductivity of steel |
| A. | increases |
| B. | decreases |
| C. | remains unchanged |
| D. | increases exponentially |
| Answer» C. remains unchanged | |
| 3106. |
Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ? |
| A. | Dittus-Boeltier equation |
| B. | Sieder-Tate equation |
| C. | Nusselt equation |
| D. | None of these |
| Answer» C. Nusselt equation | |
| 3107. |
The main function of baffles provided in a shell and tube heat exchanger is to |
| A. | facilitate the cleaning of outer tube surface. |
| B. | enhance turbulence. |
| C. | hold the tubes in position. |
| D. | all 'a', 'b' & 'c'. |
| Answer» C. hold the tubes in position. | |
| 3108. |
Baffles are provided in heat exchangers to increase the |
| A. | fouling factor |
| B. | heat transfer area |
| C. | heat transfer co-efficient |
| D. | heat transfer rate |
| Answer» D. heat transfer rate | |
| 3109. |
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 x 10-3 kg/m2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid) |
| A. | 0.5 |
| B. | 0.05 |
| C. | 0.1 |
| D. | 0.15 |
| Answer» D. 0.15 | |
| 3110. |
In case of a vertical tube evaporator, with increase in the liquor level, the |
| A. | capacity of the evaporator is decreased. |
| B. | capacity of the evaporator is increased. |
| C. | true temperature drop increases. |
| D. | both (b) and (c). |
| Answer» B. capacity of the evaporator is increased. | |
| 3111. |
The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law. |
| A. | wavelength of radiation |
| B. | nature of the body |
| C. | temperature of the body |
| D. | none of these |
| Answer» D. none of these | |
| 3112. |
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 |
| Answer» B. increases | |
| 3113. |
Glycerine is not used in the |
| A. | manufacture of explosive. |
| B. | conditioning and humidification of tobacco. |
| C. | manufacture of pharmaceuticals. |
| D. | none of these. |
| Answer» E. | |
| 3114. |
As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the |
| A. | temperature of the body only. |
| B. | wavelength of monochromatic radiation. |
| C. | both (a) and (b). |
| D. | nature of material of body. |
| Answer» B. wavelength of monochromatic radiation. | |
| 3115. |
If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid |
| A. | remains unchanged. |
| B. | increases. |
| C. | increases or decreases depending on number of shell passes. |
| D. | decreases. |
| Answer» E. | |
| 3116. |
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by |
| A. | painting the surface black. |
| B. | painting the surface white (with aluminium paint). |
| C. | giving the surface a mirror finish. |
| D. | roughening the surface. |
| Answer» C. giving the surface a mirror finish. | |
| 3117. |
__________ paint has the maximum absorption coefficient. |
| A. | Black |
| B. | Yellow |
| C. | White |
| D. | Grey |
| Answer» B. Yellow | |
| 3118. |
What is the steam economy in case of a single effect evaporator system ? |
| A. | 1 |
| B. | >1 |
| C. | < 1 |
| D. | 0.1 |
| Answer» D. 0.1 | |
| 3119. |
jH factor for heat transfer is not a function of the __________ number. |
| A. | Reynolds |
| B. | Nusselt |
| C. | Grashoff |
| D. | both (b) & (c) |
| Answer» E. | |
| 3120. |
The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by |
| A. | forced convection |
| B. | natural convection |
| C. | transient conduction |
| D. | steady state conduction |
| Answer» D. steady state conduction | |
| 3121. |
In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is |
| A. | more |
| B. | less |
| C. | same |
| D. | unpredictable; depends on the particular reaction |
| Answer» D. unpredictable; depends on the particular reaction | |
| 3122. |
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation. |
| A. | Gibbs-Duhem |
| B. | Maxwell's |
| C. | Clayperon |
| D. | none of these |
| Answer» D. none of these | |
| 3123. |
Pick out the undesirable property for a good refrigerant. |
| A. | high thermal conductivity |
| B. | low freezing point |
| C. | large latent heat of vaporisation |
| D. | high viscosity |
| Answer» E. | |
| 3124. |
Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a |
| A. | straight line |
| B. | sine curve |
| C. | parabola |
| D. | hyperbola |
| Answer» B. sine curve | |
| 3125. |
The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by |
| A. | decrease in enthalpy corresponding to evolution of heat. |
| B. | decrease of entropy. |
| C. | increase in enthalpy corresponding to absorption of heat. |
| D. | no change in enthalpy. |
| Answer» D. no change in enthalpy. | |
| 3126. |
Melting of ice is an example of an __________ process. |
| A. | adiabatic |
| B. | isothermal |
| C. | isometric |
| D. | none of these |
| Answer» C. isometric | |
| 3127. |
Entropy change in case of reversible adiabatic process is |
| A. | minimum |
| B. | zero |
| C. | maximum |
| D. | indeterminate |
| Answer» C. maximum | |
| 3128. |
Planck's distribution law is valid for __________ bodies. |
| A. | black |
| B. | white |
| C. | coloured |
| D. | all (a), (b) & (c) |
| Answer» D. all (a), (b) & (c) | |
| 3129. |
For hot feed, forward feeding as compared to backward feeding results in __________ economy. |
| A. | increased |
| B. | decreased |
| C. | no effect on |
| D. | none of these |
| Answer» B. decreased | |
| 3130. |
Radiation energy is emitted by all the substances, which are above |
| A. | 0 K |
| B. | 0 C |
| C. | 100 C |
| D. | room temperature |
| Answer» B. 0 C | |
| 3131. |
Heat transfer by __________ may not necessarily require the presence of a medium. |
| A. | conduction |
| B. | natural convection |
| C. | forced convection |
| D. | radiation |
| Answer» E. | |
| 3132. |
In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used |
| A. | in low range of temperature differences. |
| B. | in high range of temperature differences. |
| C. | because of its low cost. |
| D. | to prevent corrosion of the tube bundles. |
| Answer» C. because of its low cost. | |
| 3133. |
Stefan-Boltzman law applies to __________ body. |
| A. | black |
| B. | white |
| C. | grey |
| D. | any colour |
| Answer» B. white | |
| 3134. |
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is |
| A. | more |
| B. | less |
| C. | some |
| D. | either more or less ; depends on the nature of vapor |
| Answer» D. either more or less ; depends on the nature of vapor | |
| 3135. |
The Graetz number is concerned with the |
| A. | mass transfer between a gas and a liquid. |
| B. | absorption with chemical reaction. |
| C. | heat transfer in turbulent flow. |
| D. | heat transfer in laminar flow. |
| Answer» E. | |
| 3136. |
Solid angle subtended by the finite surface at the radiating element is |
| A. | called the view factor. |
| B. | called the angle of vision. |
| C. | proportional to the square of the distance between surfaces. |
| D. | expressed in terms of radians. |
| Answer» C. proportional to the square of the distance between surfaces. | |
| 3137. |
The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns. |
| A. | 0.38-0.78 |
| B. | 0.5-50 |
| C. | 100-1000 |
| D. | 5-50 |
| Answer» C. 100-1000 | |
| 3138. |
Use of transverse baffles in a shell and tube heat exchanger is done to increase the |
| A. | rate of heat transfer. |
| B. | flow velocity. |
| C. | turbulence of shell side fluid. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 3139. |
The actual temperature drop across the heating surface of an evaporator depends on the |
| A. | liquid depth over the heating surface. |
| B. | solution being evaporated. |
| C. | pressure difference between the steam chest and the vapor space above the boiling liquid. |
| D. | all (a), (b) and (c) |
| Answer» E. | |
| 3140. |
Economy of a multiple effect evaporator depends upon the |
| A. | heat balance consideration |
| B. | rate of heat transfer |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» B. rate of heat transfer | |
| 3141. |
The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for |
| A. | black painted bodies only |
| B. | all bodies |
| C. | polished bodies only |
| D. | a black body |
| Answer» C. polished bodies only | |
| 3142. |
It is not preferable to use superheated steam in evaporators, because of its very |
| A. | high temperature |
| B. | high pressure |
| C. | low film co-efficient |
| D. | none of these |
| Answer» D. none of these | |
| 3143. |
LMTD for counterflow and prallel flow heat exchanger will be the same, when the |
| A. | cold fluid is heated to a certain temperature by condensing steam (isothermal fluid). |
| B. | outlent temperature of both the hot and cold fluid are same. |
| C. | outlet temperature of hot fluid is less than the outlet temperature of the cold fluid. |
| D. | none of these. |
| Answer» B. outlent temperature of both the hot and cold fluid are same. | |
| 3144. |
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it |
| A. | decreases the pressure drop. |
| B. | decreases the outlet temperature of cooling medium. |
| C. | increases the overall heat transfer coefficient. |
| D. | none of these. |
| Answer» D. none of these. | |
| 3145. |
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling. |
| A. | pool |
| B. | nucleate |
| C. | transition |
| D. | film |
| Answer» E. | |
| 3146. |
For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it |
| A. | occupies smaller space. |
| B. | is more economical. |
| C. | is easy to operate and maintain. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 3147. |
Out of the following four assumptions used in the derivation of the equation for LMTD , which one is subject to the largest deviation in practice ? |
| A. | Constant overall heat transfer co-efficient. |
| B. | Constant rate of fluid flow. |
| C. | Constant specific heat. |
| D. | No partial phase change in the system. |
| Answer» C. Constant specific heat. | |
| 3148. |
'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a |
| A. | non-dimensional factor. |
| B. | factor of safety. |
| C. | conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient. |
| D. | none of these. |
| Answer» C. conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient. | |
| 3149. |
Prandtl and Reynolds analogy are same, when Prandtl number is |
| A. | 0.5 |
| B. | 1 |
| C. | > 2 |
| D. | 1.5 |
| Answer» C. > 2 | |
| 3150. |
Heat transfer occurs by natural convection because change in temperature causes difference in |
| A. | viscosity |
| B. | density |
| C. | thermal conductivity |
| D. | heat capacity |
| Answer» C. thermal conductivity | |