Drying of a solid involves __________ transfer. (A) Only heat (B) Only mass (C) Both heat and mass (D) None of these

Drying of a solid involves __________ transfer.

(A) Only heat

(B) Only mass

(C) Both heat and mass

(D) None of these

by

1 Answer

Answer :

(C) Both heat and mass

by

Related questions

Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to Nusselt number in heat transfer and Schmidt number to Prandtl number (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger (D) Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger

Pick out the correct statement. (A) Bound moisture is removed during constant rate drying period (B) Free moisture is removed during falling rate drying period (C) The sum of free moisture and equilibrium moisture in a solid is called the critical moisture (D) The driving force for mass transfer in a wet solid is its free moisture content

Description : Pick out the correct statement. (A) Bound moisture is removed during constant rate drying period (B) Free moisture is removed during falling rate drying period (C) The sum of free moisture and ... (D) The driving force for mass transfer in a wet solid is its free moisture content

Last Answer : (D) The driving force for mass transfer in a wet solid is its free moisture content

Heat transfer by __________ is almost absent in case of fluidised bed drying operation. (A) Radiation (B) Conduction (C) Convection (D) Both (B) & (C)

Description : Heat transfer by __________ is almost absent in case of fluidised bed drying operation. (A) Radiation (B) Conduction (C) Convection (D) Both (B) & (C)

Last Answer : A) Radiation

With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Description : With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Last Answer : (A) Increases

For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same. (A) Unsaturated surface (B) Constant rate (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same. (A) Unsaturated surface (B) Constant rate (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) and (B)

Binary distillation involves the mass transfer by __________ at the gas￾liquid interface. (A) Unidirectional diffusion from liquid to gas phase (B) Unidirectional diffusion from gas to liquid phase (C) Either 'a' or 'b' (D) A counter diffusion at an almost equal molar rate

Description : Binary distillation involves the mass transfer by __________ at the gas￾liquid interface. (A) Unidirectional diffusion from liquid to gas phase (B) Unidirectional diffusion from gas to liquid phase (C) Either 'a' or 'b' (D) A counter diffusion at an almost equal molar rate

Last Answer : (D) A counter diffusion at an almost equal molar rate

Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. (A) Increases (B) Decreases (C) Does not affect

Description : Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. (A) Increases (B) Decreases (C) Does not affect

Last Answer : (B) Decreases

Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of catalyst, if it doesnot entail a chain mechanism.(A) Proportional to(B) Independent of(C) Inversely proportional to(D) Proportional to the square o

Description : Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of ... to (B) Independent of (C) Inversely proportional to (D) Proportional to the square o

Last Answer : (A) Proportional to

Refrigeration cycle (A) Violates second law of thermodynamics (B) Involves transfer of heat from low temperature to high temperature (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : Refrigeration cycle (A) Violates second law of thermodynamics (B) Involves transfer of heat from low temperature to high temperature (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (B) Involves transfer of heat from low temperature to high temperature

During drying of a solid, the critical moisture content increases with (A) Decreased drying rate (B) Increased thickness of the solid (C) Increased drying rate (D) Both (B) and (C)

Description : During drying of a solid, the critical moisture content increases with (A) Decreased drying rate (B) Increased thickness of the solid (C) Increased drying rate (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

The falling rate period in the drying of a solid is characterised by (A) Increase in rate of drying (B) Increasing temperatures both on the surface and within the solid (C) Decreasing temperatures (D) None of these

Description : The falling rate period in the drying of a solid is characterised by (A) Increase in rate of drying (B) Increasing temperatures both on the surface and within the solid (C) Decreasing temperatures (D) None of these

Last Answer : (B) Increasing temperatures both on the surface and within the solid

Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is (A) Insoluble in the liquid (B) Soluble in the liquid (C) Non-ideal in nature (D) At a fixed temperature

Description : Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is (A) Insoluble in the liquid (B) Soluble in the liquid (C) Non-ideal in nature (D) At a fixed temperature

Last Answer : (A) Insoluble in the liquid

Adsorption is a unit operation which generally involves __________ systems. (A) Liquid-solid (B) Gas-solid (C) Fluid-solid (D) Solid-solid

Description : Adsorption is a unit operation which generally involves __________ systems. (A) Liquid-solid (B) Gas-solid (C) Fluid-solid (D) Solid-solid

Last Answer : (C) Fluid-solid

Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger calculations (Δt) weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted (D) In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Description : Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger ... vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton

Description : Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton

Last Answer : (A) Schmidt

Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton

Description : Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton

Last Answer : (A) Sherwood

__________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower. (A) Sherwood (B) Stanton (C) Lewis (D) Peclet

Description : __________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower. (A) Sherwood (B) Stanton (C) Lewis (D) Peclet

Last Answer : (C) Lewis

The relation, Sc = Pr = 1, is valid, when the mechanism of __________ transfer is same. (A) Heat and mass (B) Mass and momentum (C) Heat and momentum (D) Heat, momentum and mass

Description : The relation, Sc = Pr = 1, is valid, when the mechanism of __________ transfer is same. (A) Heat and mass (B) Mass and momentum (C) Heat and momentum (D) Heat, momentum and mass

Last Answer : (A) Heat and mass

In case of cooling towers, the ratio of the rates of heat and mass transfer is indicated by the __________ number. (A) Lewis (B) Grashoff (C) Sherwood

Description : In case of cooling towers, the ratio of the rates of heat and mass transfer is indicated by the __________ number. (A) Lewis (B) Grashoff (C) Sherwood

Last Answer : (A) Lewis

In case of a close thermodynamic system, there is __________ across the boundaries. (A) No heat and mass transfer (B) No mass transfer but heat transfer (C) Mass and energy transfer (D) None of these

Description : In case of a close thermodynamic system, there is __________ across the boundaries. (A) No heat and mass transfer (B) No mass transfer but heat transfer (C) Mass and energy transfer (D) None of these

Last Answer : (B) No mass transfer but heat transfer

The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T

Description : The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T

Last Answer : (B) T

Flights in a rotary dryer are provided to (A) Lift and shower the solids thus exposing it thoroughly to the drying action of the gas (B) Reduce the residence time of solid (C) Increase the residence time of the solid (D) None of these

Description : Flights in a rotary dryer are provided to (A) Lift and shower the solids thus exposing it thoroughly to the drying action of the gas (B) Reduce the residence time of solid (C) Increase the residence time of the solid (D) None of these

Last Answer : (A) Lift and shower the solids thus exposing it thoroughly to the drying action of the gas

A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process? (A) Flow rate of inlet air (B) Relative humidity of outlet air (C) Humidity of inlet air (D) Temperature of the solid

Description : A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process? (A) Flow rate of inlet air (B) Relative humidity of outlet air (C) Humidity of inlet air (D) Temperature of the solid

Last Answer : (D) Temperature of the solid

In the constant rate period of the rate of drying curve for batch drying, (A) Cracks develop on the surface of the solid (B) Rate of drying decreases abruptly (C) Surface evaporation of unbound moisture occurs (D) None of these

Description : In the constant rate period of the rate of drying curve for batch drying, (A) Cracks develop on the surface of the solid (B) Rate of drying decreases abruptly (C) Surface evaporation of unbound moisture occurs (D) None of these

Last Answer : (C) Surface evaporation of unbound moisture occurs

It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%). (A) 15 min (B) 51 min (C) 71 min (D) 94 min

Description : It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The ... 5%). (A) 15 min (B) 51 min (C) 71 min (D) 94 min

Last Answer : (C) 71 min

Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant (A) Humidity (B) Velocity (C) Temperature (D) All (A), (B) & (C)

Description : Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant (A) Humidity (B) Velocity (C) Temperature (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T

Description : The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T

Last Answer : (C) T

During the constant rate period of drying of a solid, (A) Increased air humidity decreases the rate of drying (B) Increasing the air temperature decreases the drying rate (C) Surface evaporation of unbound moisture occurs (D) None of these

Description : During the constant rate period of drying of a solid, (A) Increased air humidity decreases the rate of drying (B) Increasing the air temperature decreases the drying rate (C) Surface evaporation of unbound moisture occurs (D) None of these

Last Answer : (C) Surface evaporation of unbound moisture occurs

The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which ‘D’ is the diffusivity of solute, is (A) D/a (B) D/2a (C) Proportional to √D (D) Dependent on the Reynolds number

Description : The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which ‘D’ is the diffusivity of solute, is (A) D/a (B) D/2a (C) Proportional to √D (D) Dependent on the Reynolds number

Last Answer : (D) Dependent on the Reynolds number

A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (ke ff) is given by (A) ke ff = k + kg (B) ke ff = (k+ kg )/2 (C) ke ff = (kkg ) 1/2 (D) 1/ke ff = 1/k + 1/kg

Description : A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (ke ff) is given by (A) ke ff = k + kg ( ... + kg )/2 (C) ke ff = (kkg ) 1/2 (D) 1/ke ff = 1/k + 1/kg

Last Answer : (D) 1/ke ff = 1/k + 1/kg

Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the (A) Existence of thermal boundary layer (B) Temperature gradient produced due to density difference (C) Buoyancy of the bubbles produced at active nucleation site (D) None of these

Description : Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the (A) Existence of thermal boundary layer (B) Temperature gradient produced ... difference (C) Buoyancy of the bubbles produced at active nucleation site (D) None of these

Last Answer : (D) None of these

Heat transfer rate to the charge/stock in a furnace does not depend upon the (A) Type of fuels viz. solid, liquid or gaseous (B) Flue gas temperature (C) Emissivity of refractory walls (D) Initial temperature of the charged stock

Description : Heat transfer rate to the charge/stock in a furnace does not depend upon the (A) Type of fuels viz. solid, liquid or gaseous (B) Flue gas temperature (C) Emissivity of refractory walls (D) Initial temperature of the charged stock

Last Answer : (A) Type of fuels viz. solid, liquid or gaseous

The third law of thermodynamics states that the (A) Heat capacity of a crystalline solid is zero at absolute zero temperature (B) Heat transfer from low temperature to high temperature source is not possible without external work (C) Gases having same reduced properties behaves similarly (D) None of these

Description : The third law of thermodynamics states that the (A) Heat capacity of a crystalline solid is zero at absolute zero temperature (B) Heat transfer from low temperature to high temperature source is ... without external work (C) Gases having same reduced properties behaves similarly (D) None of these

Last Answer : (A) Heat capacity of a crystalline solid is zero at absolute zero temperature

Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid

Description : Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid

Last Answer : (A) Inversely with thermal conductivity

A 2-4 heat exchanger involves (A) Only counter-flow of fluids (B) Only parallel-flow of fluids (C) Both counter and parallel-flow of the fluids (D) Smaller pressure drop compared to 1-2 exchanger

Description : A 2-4 heat exchanger involves (A) Only counter-flow of fluids (B) Only parallel-flow of fluids (C) Both counter and parallel-flow of the fluids (D) Smaller pressure drop compared to 1-2 exchanger

Last Answer : (C) Both counter and parallel-flow of the fluids

Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer (B) Prandtl number in heat transfer is analogous to Schmidt number in mass transfer (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer (D) Reynolds number remains the same in both heat and mass transfer

Description : Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer ... heat transfer (D) Reynolds number remains the same in both heat and mass transfer

Last Answer : (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer

Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low interfacial tension (C) When Henry's law constant is very small, then the mass transfer rate is controlled by the gas film resistance (D) Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension

Which of the following is concerned with both heat and mass transfer? (A) Lewis relationship (B) Nusselt number (C) Kutateladze number (D) Froude number

Description : Which of the following is concerned with both heat and mass transfer? (A) Lewis relationship (B) Nusselt number (C) Kutateladze number (D) Froude number

Last Answer : (A) Lewis relationship

Analogy between mass and heat transfer is not applicable in case of (A) Same velocity profile or equal eddy diffusivities (B) Thermal or pressure mass diffusion (C) Viscous heating or chemical reaction (D) Both (B) and (C)

Description : Analogy between mass and heat transfer is not applicable in case of (A) Same velocity profile or equal eddy diffusivities (B) Thermal or pressure mass diffusion (C) Viscous heating or chemical reaction (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

____ and ____ are already solid and lend themselves to sun or tray drying. a. Cheese, meats c. Cheese, vegetables b. Fruits, vegetables d. Fruits, meats

Description : ____ and ____ are already solid and lend themselves to sun or tray drying. a. Cheese, meats c. Cheese, vegetables b. Fruits, vegetables d. Fruits, meats

Last Answer : b. Fruits, vegetables

Design of heterogamous catalytic reactor involves consideration of __________ steps. (A) Only chemical (B) Only physical (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Design of heterogamous catalytic reactor involves consideration of __________ steps. (A) Only chemical (B) Only physical (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

One of the methods of purification of leach liquor is ion exchange, which involves (A) Exchange between two liquid phases (B) Exchange between a gaseous phase and a liquid phase (C) Exchange between a liquid phase and an organic resin phase (D) Exchange between a solid phase and a gas phase

Description : One of the methods of purification of leach liquor is ion exchange, which involves (A) Exchange between two liquid phases (B) Exchange between a gaseous phase and a liquid phase (C) Exchange between a liquid phase and an organic resin phase (D) Exchange between a solid phase and a gas phase

Last Answer : (C) Exchange between a liquid phase and an organic resin phase

n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In each batch about 120 kgs of material is dried. a. The quantity of moisture removed per batch. b. What is the total quantity ( sensible & latent) of heat required to evaporate the moisture, if the latent heat of water is 540 kcal/kg at atmospheric conditions, Ignore heat absorbed by the solids c. Find the quantity of steam required for the drying process (per batch), if steam at 4 kg/cm2 is used for generating hot air in the dryer and the dryer efficiency is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Description : n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture  is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In  each batch about 120 ... dryer and the dryer efficiency  is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Last Answer : Given that   Qty of material dried per batch - 120 Kgs  Moisture at inlet - 60% a. The quantity of moisture removed per batch.  Water quantity in a wet batch - 120 x 0.6 = 72 Kgs.  Quantity of bone dry ... - 48/0.95 = 50.5 Kgs.  Equivalent water in a dry batch - 50.5 - 48 = 2.5 Kgs.

Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent

Description : Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent

Last Answer : (D) Highly turbulent

jH factor for heat transfer is not a function of the __________ number. (A) Reynolds (B) Nusselt (C) Grashoff (D) Both (B) & (C)

Description : jH factor for heat transfer is not a function of the __________ number. (A) Reynolds (B) Nusselt (C) Grashoff (D) Both (B) & (C)

Last Answer : (D) Both (B) & (C)

Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff

Description : Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff

Last Answer : (D) Prandtl & Grashoff