If _______ heating has higher heat transfer rates than _______ heating, then why is ________ difficult to be used.

Indirect, Direct, no difficulty, they’re used

Direct, Indirect, no difficulty, they’re used

Direct, Indirect, coil is difficult to clean and is prone to bacterial growth

Indirect, Direct, no difficulty, they’re used

Indirect, Direct, coil is difficult to clean and is prone to bacterial growth

Which of the following heat exchangers are used for the quick exchange of heat?

Scraped surface heat exchangers

Which of the following is an advantage of using pumps as heat transfer equipment?

Taking them to a heat exchanger where the area used for heat transfer can be easily changed

No stirrer required & taking them to a heat exchanger where the area used for heat transfer can be easily changed

External heat exchangers are gaining popularity as they’ve several advantages over conventional methods. Still, there is a major drawback. Which among the following is it?

Some shear-sensitive cells might get damaged due to abrasion

It is difficult for pumps to withstand high temperature without leakages of the fluid

Which of the following is untrue about scraped surface heat exchangers?

They’re suitable for fouling fluids

They’re unsuitable for viscous fluids

They’re suitable for fouling fluids

They’re used for continuous operation and have a double pipe

Which of the following is true about loss factor of food?

It is desirable quality of food

It is the ability of food to absorb waves

Although microwave heating can be used for drying of food containing uneven water content, it is isn’t done for certain food products like garlic. Why?

Essential oils being stripped off

No pasteurization & Essential oils being stripped off

Contamination takes place to high extend in Plate heat exchangers.

False, they cannot be used for viscous liquids

True, the space between plates is too less

False, they cannot be used for viscous liquids

True, they can be used for thin liquids only

Microwave heating is good for puffed products. Why?

The rate of heat transfer is less than the rate of moisture loss

The heat transfer in these food items takes place so fast that instead of shrinking of the food items due to loss of moisture content, they stay intact and hence puffed

Which of the following is true about Natural Convection?

Due to gravity and natural buoyant forces

Dependent on viscosity, density and thermal conductivity

__________ is when nucleate boiling transforms to film boiling.

Critical temperature & Leiden frost point

Hannah heats refrigerated rice which has been devoid of moisture and become dry. She heats it in a microwave. It gets unevenly heated. What should she do?

She should heat it using equipment that offers conduction or convection

Water should be added for even heating

She should heat it using equipment that offers conduction or convection

Why is better to use a Jacketed vessel in the dairy industry than a stainless steel container directly?

To have a better temperature control

The temperature of food in the film = temperature of the wall which is very high. Hence, jacketed vessels are needed

Which of the following sentences is true?

Indirect heating has higher heat transfer rates than direct heating

Direct heating has higher heat transfer rates than indirect heating

Indirect heating has higher heat transfer rates than direct heating

Both of them have the same heat transfer rates

A food industry keeps food cool in a very crude manner, by radiation. It paints its walls white and not black, because of _____

Kirchhoff’s Law & Stephan-Boltzmann Law

69 + Mcqs in Food Engineering and Heat Transfer in Food Engineering Page 1 McqOptions

1.	Statement 1: Difference between 1-1 and 1-2 heat exchanger is that 1-2 has both counter AND co current, whereas 1-1 has only co-current.Statement 2: 1-2 heat exchanger requires a high pressure drop.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

2.	Penetration depth of food refers to the depth inside the food inside which the heat generation drops to 37%.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» B. False

Discussion

3.	Any food item should be subjected to micro frequencies such that, the dielectric constant is _____ and loss factor is _____
A.	Maximum, minimum
B.	Maximum, maximum
C.	Minimum, minimum
D.	Minimum, maximum
Answer» D. Minimum, maximum

Discussion

4.	In a jacketed vessel, the only way to increase the heat transfer rates is to increase the temperature difference.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» B. False

Discussion

5.	Statement 1: Unsteady state heat transfer equation can be used when there is negligible internal resistance.Statement 2: Unsteady state heat transfer equation can be used for liquid food items which are well stirred, because, temperature gradient within won’t be there.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

6.	Statement 1: Radiation is NOT heat.Statement 2: Maximum value of absorptivity is 1.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

7.	If _______ heating has higher heat transfer rates than _______ heating, then why is ________ difficult to be used.
A.	Direct, Indirect, no difficulty, they’re used
B.	Direct, Indirect, coil is difficult to clean and is prone to bacterial growth
C.	Indirect, Direct, no difficulty, they’re used
D.	Indirect, Direct, coil is difficult to clean and is prone to bacterial growth
Answer» C. Indirect, Direct, no difficulty, they’re used

Discussion

8.	Which of the following heat exchangers are used for the quick exchange of heat?
A.	Shell and tube heat exchangers
B.	Plate heat exchangers
C.	Scraped surface heat exchangers
D.	Jacketed Vessels
Answer» C. Scraped surface heat exchangers

Discussion

9.	Which of the following is an advantage of using pumps as heat transfer equipment?
A.	No stirrer required
B.	Taking them to a heat exchanger where the area used for heat transfer can be easily changed
C.	No stirrer required & taking them to a heat exchanger where the area used for heat transfer can be easily changed
D.	None of the mentioned
Answer» D. None of the mentioned

Discussion

10.	Statement 1: In coiled heat exchanger, the coils can be present inside and outside the vessel.Statement 2: The coils can have either hot/cold fluid present inside them or even electrical coils can be present.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

11.	External heat exchangers are gaining popularity as they’ve several advantages over conventional methods. Still, there is a major drawback. Which among the following is it?
A.	Some shear-sensitive cells might get damaged due to abrasion
B.	It is difficult for pumps to withstand high temperature without leakages of the fluid
C.	All of the mentioned
D.	None of the mentioned
Answer» D. None of the mentioned

Discussion

12.	Which of the following is untrue about scraped surface heat exchangers?
A.	They’re unsuitable for viscous fluids
B.	They’re suitable for fouling fluids
C.	They’re used for continuous operation and have a double pipe
D.	None of the mentioned
Answer» B. They’re suitable for fouling fluids

Discussion

13.	Which of the following is true about loss factor of food?
A.	It is desirable quality of food
B.	It is the ability of food to absorb waves
C.	It is represented by Ɛ
D.	All of the mentioned
Answer» E.

Discussion

14.	Which of the following is a parameter to be checked before choosing the shape of the pitch in heat exchangers?
A.	Easiness to clean
B.	High heat transfer
C.	Cost
D.	All of the mentioned
Answer» E.

Discussion

15.	One disadvantage of microwave cooking is that the energy efficiency in this process is less.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» C. May be True or False

Discussion

16.	Statement 1: Microwave heating helps save electricity.Statement 2: The quality of product in microwave heating is good hence rejections are lesser.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

17.	Although microwave heating can be used for drying of food containing uneven water content, it is isn’t done for certain food products like garlic. Why?
A.	No pasteurization
B.	Essential oils being stripped off
C.	None of the mentioned
D.	No pasteurization & Essential oils being stripped off
Answer» E.

Discussion

18.	According to Nusselt’s film theory, the film thickness decreases as we move from bottom to top. The heat transfer increases.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» C. May be True or False

Discussion

19.	Statement 1: Film-type condensation has a higher heat transfer co-efficient than drop-wise condensation.Statement 2: Drop-wise condensation is easier to maintain than Film-type condensation
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» D. False, True

Discussion

20.	Statement 1: Drop-wise condensation takes place on a smooth surface.Statement 2: All the resistance to heat transfer lies in the film formed during Film-type condensation.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» E.

Discussion

21.	Statement 1: In microwave heating, heat is not applied to the food item.Statement 2: Radiation doesn’t gives even drying whereas microwave heating does.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

22.	Which of the following is NOT a part of the microwave heating system?
A.	Magnetron
B.	Anode
C.	Cathode
D.	None of the mentioned
Answer» E.

Discussion

23.	Contamination takes place to high extend in Plate heat exchangers.
A.	True, the space between plates is too less
B.	False, they cannot be used for viscous liquids
C.	Cannot be determined
D.	True, they can be used for thin liquids only
Answer» B. False, they cannot be used for viscous liquids

Discussion

24.	Microwave heating is good for puffed products. Why?
A.	The rate of heat transfer is less than the rate of moisture loss
B.	The heat transfer in these food items takes place so fast that instead of shrinking of the food items due to loss of moisture content, they stay intact and hence puffed
C.	None of the mentioned
D.	All of the mentioned
Answer» C. None of the mentioned

Discussion

25.	Statement 1: Nucleate Boiling is when a layer of film is formed in the beginning.Statement 2: Boiling starts with the bottom layer which heats up, becomes light and goes up. That way everything becomes hot and there is not temperature difference and hence no heat transfer.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» E.

Discussion

26.	Statement 1: hd/k is _____Statement 2: _____ is the ratio of convective heat transfer to conductive heat transfer.
A.	Prandtl number, Prandtl number
B.	Nussel number, Nussel number
C.	Pictet number, Pictet number
D.	Fourier number, Fourier number
Answer» C. Pictet number, Pictet number

Discussion

27.	Which of the following is true about Natural Convection?
A.	Low heat transfer
B.	Due to gravity and natural buoyant forces
C.	Dependent on viscosity, density and thermal conductivity
D.	All of the mentioned
Answer» E.

Discussion

28.	NFo= (αtₜ)/s². Here ‘s’ stands for half slab thickness. Based on this data, ‘s’ for a chapatti/ dosa will be _____
A.	Half slab thickness
B.	Full slab thickness
C.	One and a half slab thickness
D.	Double slab thickness
Answer» C. One and a half slab thickness

Discussion

29.	Statement 1: When heat transfer takes between a solid surface and a fluid, an insulating film layer is formed. More is the agitation; more is the thickness of the film.Statement 2: Within the film, the temperature varies from the wall to the temperature of the bulk.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» E.

Discussion

30.	__________ is when nucleate boiling transforms to film boiling.
A.	Critical temperature
B.	Leiden frost point
C.	Critical temperature & Leiden frost point
D.	None of the mentioned
Answer» C. Critical temperature & Leiden frost point

Discussion

31.	Statement 1: Generally, in small scaled jacketed pans, food products like jams, sauces etc are made.Statement 2: Baffles provide structural support to tubes, but they cannot prevent channeling.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» B. True, True

Discussion

32.	For a copper pipe, k = 0.3534, temperature difference = 60, B = 0.0125 and A = 850. What is the value of q?
A.	1442 W
B.	1442 kW
C.	1565 W
D.	1565 kW
Answer» C. 1565 W

Discussion

33.	Statement 1: Scraping improves heat transfer co-efficient by 5 times in case of non-Newtonian fluids.Statement 2: In food industry, major physical changes to food items when they’re processed, take place like transformation from Newtonian to Non-Newtonian fluids. Hence, scraped surface heat exchangers are very beneficial.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

34.	Hannah heats refrigerated rice which has been devoid of moisture and become dry. She heats it in a microwave. It gets unevenly heated. What should she do?
A.	Water should be added for even heating
B.	She should heat it using equipment that offers conduction or convection
C.	None of the mentioned
D.	All of the mentioned
Answer» B. She should heat it using equipment that offers conduction or convection

Discussion

35.	Statement 1: Nₚᵣ= (Cₚμ)/kStatement 2: If Nₚᵣ is lesser than 1, Thermal Boundary layer is thinner than Hydrodynamic Boundary layer.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» B. True, True

Discussion

36.	Why is better to use a Jacketed vessel in the dairy industry than a stainless steel container directly?
A.	To prevent milk from charring
B.	To have a better temperature control
C.	The temperature of food in the film = temperature of the wall which is very high. Hence, jacketed vessels are needed
D.	All of the mentioned
Answer» E.

Discussion

37.	Which of the following is a synonym for loss factor of food?
A.	Loss tangent
B.	Dielectric loss
C.	Loss tangent & Dielectric loss
D.	None of the mentioned
Answer» D. None of the mentioned

Discussion

38.	Frozen foods have a higher transfer co-efficient hence they lose heat faster than other food items when exposed to the outside environment.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» B. False

Discussion

39.	Statement 1: When the average radius gives an error, log mean radius is used.Statement 2: Log mean radius is given by rL= ( r₀– rᵢ )/(ln(r₀/rᵢ))
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

40.	Which of the following sentences is true?
A.	Direct heating has higher heat transfer rates than indirect heating
B.	Indirect heating has higher heat transfer rates than direct heating
C.	Both of them have the same heat transfer rates
D.	Cannot be determined
Answer» B. Indirect heating has higher heat transfer rates than direct heating

Discussion

41.	In deep freezers, the walls absorb heat from food materials by _____ and keep them cool.
A.	Conduction
B.	Convection
C.	Radiation
D.	None of the mentioned
Answer» D. None of the mentioned

Discussion

42.	Statement 1: Radiation dryers are used to dry grains and reduce their moisture content before storage.Statement 2: Baking ovens are used both for making the dough and after that’s made, making biscuits by cutting them and baking them further. This entire process uses radiation.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

43.	Radiation dryers use _____
A.	Ultraviolet rays
B.	Infrared radiation
C.	Visible range
D.	None of the mentioned
Answer» C. Visible range

Discussion

44.	Freezer is at -18 °C. Will will be Radiative heat transfer if meat is at 298k, its emissivity is 0.82 and average area is 0.045m².Either use Stefan Boltzmann law or take hᵣ (radiative heat transfer co-efficient) as 0.227.ε = ( Tₐᵥ/100 )³
A.	7.61
B.	6.94
C.	8.43
D.	None of the mentioned
Answer» B. 6.94

Discussion

45.	The emission of radiation by any body is independent of the radiation by any body next to it.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» B. False

Discussion

46.	A food industry keeps food cool in a very crude manner, by radiation. It paints its walls white and not black, because of _____
A.	Kirchhoff’s Law
B.	Stephan-Boltzmann Law
C.	Kirchhoff’s Law & Stephan-Boltzmann Law
D.	None of the mentioned
Answer» B. Stephan-Boltzmann Law

Discussion

47.	Statement 1: Radiation needs a medium to travel.Statement 2: Thermal radiation takes place at a certain temperature for every body.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» D. False, True

Discussion

48.	Dittus-boelter equation is applicable for fluids with phase change.
A.	True
B.	False
C.	May be True or False
D.	Can't say
Answer» C. May be True or False

Discussion

49.	Statement 1: Radiation is the transfer of heat by electromagnetic waves.Statement 2: When heat is radiated from a hot source, the amount of heat received by the body depends on the nature of the body.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» C. False, False

Discussion

50.	Statement 1: Sieder-Tate and Dittus-boelter equations imply only to laminar flow conditions.Statement 2: Under laminar conditions, the same equation applies both to Newtonian and Non-Newtonian fluids.
A.	True, False
B.	True, True
C.	False, False
D.	False, True
Answer» D. False, True

Discussion

Explore topic-wise MCQs in Food Engineering.

Statement 1: Difference between 1-1 and 1-2 heat exchanger is that 1-2 has both counter AND co current, whereas 1-1 has only co-current.Statement 2: 1-2 heat exchanger requires a high pressure drop.

Penetration depth of food refers to the depth inside the food inside which the heat generation drops to 37%.

Any food item should be subjected to micro frequencies such that, the dielectric constant is _____ and loss factor is _____

In a jacketed vessel, the only way to increase the heat transfer rates is to increase the temperature difference.

Statement 1: Unsteady state heat transfer equation can be used when there is negligible internal resistance.Statement 2: Unsteady state heat transfer equation can be used for liquid food items which are well stirred, because, temperature gradient within won’t be there.

Statement 1: Radiation is NOT heat.Statement 2: Maximum value of absorptivity is 1.

If _______ heating has higher heat transfer rates than _______ heating, then why is ________ difficult to be used.

Which of the following heat exchangers are used for the quick exchange of heat?

Which of the following is an advantage of using pumps as heat transfer equipment?

Statement 1: In coiled heat exchanger, the coils can be present inside and outside the vessel.Statement 2: The coils can have either hot/cold fluid present inside them or even electrical coils can be present.

External heat exchangers are gaining popularity as they’ve several advantages over conventional methods. Still, there is a major drawback. Which among the following is it?

Which of the following is untrue about scraped surface heat exchangers?

Which of the following is true about loss factor of food?

Which of the following is a parameter to be checked before choosing the shape of the pitch in heat exchangers?

One disadvantage of microwave cooking is that the energy efficiency in this process is less.

Statement 1: Microwave heating helps save electricity.Statement 2: The quality of product in microwave heating is good hence rejections are lesser.

Although microwave heating can be used for drying of food containing uneven water content, it is isn’t done for certain food products like garlic. Why?

According to Nusselt’s film theory, the film thickness decreases as we move from bottom to top. The heat transfer increases.

Statement 1: Film-type condensation has a higher heat transfer co-efficient than drop-wise condensation.Statement 2: Drop-wise condensation is easier to maintain than Film-type condensation

Statement 1: Drop-wise condensation takes place on a smooth surface.Statement 2: All the resistance to heat transfer lies in the film formed during Film-type condensation.

Statement 1: In microwave heating, heat is not applied to the food item.Statement 2: Radiation doesn’t gives even drying whereas microwave heating does.

Which of the following is NOT a part of the microwave heating system?

Contamination takes place to high extend in Plate heat exchangers.

Microwave heating is good for puffed products. Why?

Statement 1: Nucleate Boiling is when a layer of film is formed in the beginning.Statement 2: Boiling starts with the bottom layer which heats up, becomes light and goes up. That way everything becomes hot and there is not temperature difference and hence no heat transfer.

Statement 1: hd/k is _____Statement 2: _____ is the ratio of convective heat transfer to conductive heat transfer.

Which of the following is true about Natural Convection?

NFo= (αtₜ)/s². Here ‘s’ stands for half slab thickness. Based on this data, ‘s’ for a chapatti/ dosa will be _____

Statement 1: When heat transfer takes between a solid surface and a fluid, an insulating film layer is formed. More is the agitation; more is the thickness of the film.Statement 2: Within the film, the temperature varies from the wall to the temperature of the bulk.

__________ is when nucleate boiling transforms to film boiling.

Statement 1: Generally, in small scaled jacketed pans, food products like jams, sauces etc are made.Statement 2: Baffles provide structural support to tubes, but they cannot prevent channeling.

For a copper pipe, k = 0.3534, temperature difference = 60, B = 0.0125 and A = 850. What is the value of q?

Hannah heats refrigerated rice which has been devoid of moisture and become dry. She heats it in a microwave. It gets unevenly heated. What should she do?

Statement 1: Nₚᵣ= (Cₚμ)/kStatement 2: If Nₚᵣ is lesser than 1, Thermal Boundary layer is thinner than Hydrodynamic Boundary layer.

Why is better to use a Jacketed vessel in the dairy industry than a stainless steel container directly?

Which of the following is a synonym for loss factor of food?

Frozen foods have a higher transfer co-efficient hence they lose heat faster than other food items when exposed to the outside environment.

Statement 1: When the average radius gives an error, log mean radius is used.Statement 2: Log mean radius is given by rL= ( r₀– rᵢ )/(ln(r₀/rᵢ))

Which of the following sentences is true?

In deep freezers, the walls absorb heat from food materials by _____ and keep them cool.

Statement 1: Radiation dryers are used to dry grains and reduce their moisture content before storage.Statement 2: Baking ovens are used both for making the dough and after that’s made, making biscuits by cutting them and baking them further. This entire process uses radiation.

Radiation dryers use _____

Freezer is at -18 °C. Will will be Radiative heat transfer if meat is at 298k, its emissivity is 0.82 and average area is 0.045m².Either use Stefan Boltzmann law or take hᵣ (radiative heat transfer co-efficient) as 0.227.ε = ( Tₐᵥ/100 )³

The emission of radiation by any body is independent of the radiation by any body next to it.

A food industry keeps food cool in a very crude manner, by radiation. It paints its walls white and not black, because of _____

Statement 1: Radiation needs a medium to travel.Statement 2: Thermal radiation takes place at a certain temperature for every body.

Dittus-boelter equation is applicable for fluids with phase change.

Statement 1: Radiation is the transfer of heat by electromagnetic waves.Statement 2: When heat is radiated from a hot source, the amount of heat received by the body depends on the nature of the body.

Statement 1: Sieder-Tate and Dittus-boelter equations imply only to laminar flow conditions.Statement 2: Under laminar conditions, the same equation applies both to Newtonian and Non-Newtonian fluids.

Any food item should be subjected to micro frequencies such that, the dielectric constant is _ and loss factor is _

If ___ heating has higher heat transfer rates than _ heating, then why is ______ difficult to be used.

Statement 1: hd/k is _Statement 2: _ is the ratio of convective heat transfer to conductive heat transfer.