WorksheetsHeat Transfer and Thermodynamics MCQs
Total questions: 56
Worksheet time: 31mins
It refers to the ratio of the internal thermal resistance of a solid to the boundary layer thermal resistance (or external resistance of the body).
Biot number
Prandtl number
Nusselt number
Reynolds number
It refers to the ratio of the rate of heat transferred by conduction to the rate of energy stored.
Reynolds number
Fourier’s number
Biot number
Prandtl number
A hot block is cooled by blowing cool air over its top surface. The heat that is first transferred to the air layer close to the block is by conduction. It is eventually carried away from the surface by:
Conduction
Radiation
Thermal
Convection
It is term used to describe the energy of a body that can be transmitted in the form of heat.
Enthalpy
Thermal energy
Entropy
Internal energy
Which of the following is the equivalent heat transferred of a gas undergoing isometric process?
Change in enthalpy
Change in entropy
Change in internal energy
Work nonflow
What do you call a substance that is able to absorb liquids or gases and is usually used for removing liquids (or gases) from a given medium or region?
Absorbent
Liquefier
Adsorbent
Adhesive
In which direction that heat is transferred through conduction?
Increasing temperature
Decreasing temperature
Increasing and decreasing temperature
Constant temperature
Which of the following statements is based on Prevost theory of heat exchange?
All bodies above absolute zero emit radiation
The substance moves because of the decrease in its density which is caused by increase of temperature
The substance moves because of the application of mechanical power such as a fan
Heat transfer in most of the cases occurs in combination of conduction, convection and radiation
Which of the following is the emissivity of white body?
Zero
0.5
1
0
The mechanism of heat transfer in which there is no medium (i.e. water, air, solid concrete) required for the heat energy to travel is:
Conduction
Radiation
Convection
Diffusion
The temperature potential between temperature at the two ends of a heat exchanger are given by:
The algorithmic mean temperature difference
The Stefan-Boltzmann law
Fourier's law
Kirchhoff's law
Which of the following best describe function of heat exchanger?
Increase the water temperature entering the system
Transfer heat from one fluid to another
Evaluate the total energy content of the flow
Exchange heat to increase energy to the flow
What refers to a form of energy associated with the kinetic random motion of large number of molecules?
(a)
How much is the part of light that is absorbed by the body that transmits and reflects 80% and 10% respectively?
10%
30%
20%
5%
In convection heat transfer, what happens to the heat transfer coefficient if the viscosity of the fluid increases?
The heat transfer coefficient will increase
The heat transfer coefficient will decrease
The heat transfer coefficient remains constant
None of the above
How do you call a phenomenon wherein the heat is transferred by motion of fluid under the action of mechanical device?
Forced convection
Natural convection
Forced conduction
Thermal radiation
In condition heat transfer, what happens to the heat transfer per unit time when the thermal conductivity decreases?
The heat flow will increase
The heat flow remains constant
The heat flow will decrease
The heat flow will partially increase and then will decrease
Which of the following is the driving force in heat transfer?
Temperature gradient
Thickness gradient
Viscosity gradient
Dielectric gradient
Which of the following is the measure of the relative effectiveness of momentum and energy transport by diffusion in the velocity and thermal boundary layer?
Nusselt’s number
Prandtl number
Reynold’s number
Dimensional measurement
Which of the following is the property of the solid that provides the measure of the rate of heat transfer to the energy storage?
Thermal efficiency
Thermal diffusivity
Thermal conductivity
Two metals were kept together at room temperature and it was found out that one is colder than one another. Which of the following is the best reason why one metal is colder than the other?
The heat transfer coefficient of one metals is of higher
One metal is of lower temperature as compared to the other
One metal is of higher temperature as compared to the other
The thermal conductivity of one metal is high as compared to the other
In convection heat transfer, what happens to the heat transfer coefficient if the viscosity of the fluid decreases?
The heat transfer coefficient also increases
The heat transfer coefficient will decrease
The heat transfer coefficient remains constant
The heat transfer coefficient partially increases the decreases
A body that is hot compared to its surroundings illuminates more energy than it receives, while its surrounding absorbs more energy than they give. The heat is transferred from one to another by energy of wave motion. What is this mode of heat transfer?
Radiation
Conduction
Convection
Condensation
What do you call theoretical body where absorptivity and emissivity are independent of the wavelength over the spectral region of the irradiation and the surface emission?
White body
Opaque body
Black body
Transparent body
Which of the following is the structure designed to prevent the spread of the having a fire resistance rating of not less than four hours?
Fire escape
Fire exit
Fire shield
Fire wall
Which of the following heat exchange device used to provide heat transfer between the exhaust gases and air prior to the entrance of a combustor?
Regenerator
Economizer
Condenser
Reheater
Which of the following transfer of heat is involve in changing of boiling water (at 100°C) to vapor at the same temperature?
Conduction
Convection
Radiation
Latent heat
Which of the following is the science of the temperature?
Cryogenics
Thermo-kinetics
Thermodynamics
Ergonomics
Which of the following thermal state of the body considered as reference to communicate heat to the other bodies?
Temperature
Pressure
Internal energy
Entropy
The true mean temperature different is also known as:
The average mean temperature difference
The algorithmic mean temperature difference
The trigonometric mean temperature difference
The exponential temperature difference
Which of the following can be a geometric view factor of a gray body?
The heat transfer by conduction occurs in which of the following?
Only in liquids
Only in solids
Only in liquids and gases
In solids, liquid and gases
Which of the following reasons why one gram of steam at 100°C causes more serious burn than gram of water at 100°C?
Steam is less dense than boiling water
The steam has higher specific heat
Steam contains more internal energy
Steam is everywhere thus it strikes greater force
What usually happens when vapor condenses into liquid?
It absorbs heat
It rejects heat
Its temperature increases
Its temperature decreases
Which of the following has the highest thermal conductivity?
(a)
Which of the following is the requirement of the temperature of a body for it to emit radiation?
Above zero Celsius
Above zero kelvin
Above of the temperature of the surroundings
High enough for it to glow
Which of the following is the color of iron when it is heated to a highest temperature?
White
Red
Orange
Yellow
Which of the following is the reason why metals are good conductors of heat?
Metals contain free electrons
Metals have atoms the frequently collide one another
Metals have reflecting surfaces
Atoms in metals are very far to each other
The rate at which heat flows through a slab of some material does not depend on which of the following?
The thickness of the slab
The area of the slab
The temperature difference between two faces
The specific heat of the material
Which of the following is the primary function of a thermal radiator?
To transferring the heat by using moving fluids
To transfer heat from hot to cold body by using a forced-draft fan
To transfer heat by allowing molecules to vibrate one to another
To transfer heat with or without a medium
What is the reason why Styrofoam is a good insulating material?
Because it contains many tiny pocket of air
Styrofoam is a white object
The structure of Styrofoam is very unstable and heat cannot flow
Styrofoam structure is very dense
What usually happens to the surroundings when water vapor condenses?
It warms the surrounding
The surrounding temperature decreases
It neither warm nor cold the surrounding
The surroundings will be dehumidified
The rate of radiation does not depend on which of the following?
Temperature of the radiating body
The emissivity of the radiation surface
The area of the radiating body
The thickness of the radiating body
Which of the following is not a good conductor of heat?
Metals
Rocks
Glass
Asbestos
Which of the following is not a unit of the rate of heat transfer?
Watt
Btu per hour
Cal/s
Btu/Hp-hr
The thermal conductivity does not depend on which of the following?
A. Chemical composition
B. Physical state or texture
C. Temperature and pressure
D. Gravitational pull
Which of the following is the value of “a” for triatomic gases?
1.7
2.4
1.3
2.4
Which of the following conductivities where Sutherland equation is used?
Thermal conductivities of solids
Thermal conductivities of gases
Thermal conductivities of metals
Thermal conductivities of liquids
For pure metals, what happens to the thermal conductivity if the temperature is extremely high?
Approaches infinity
Decreases except for ferrous metals
Almost constant except for ferromagnetic materials
Increases except for steel
Which of the following liquids that has the highest thermal conductivity?
Gasoline
Glycerin
Water
Alcohol
Which of the following is not a heat exchanger?
Condenser
Boilers
Evaporators
Water hammer
Which of the following heat exchangers where fluid flow in the same direction and both are of changing temperatures?
Parallel flow
Cross flow
Counter flow
Mixed flow
What happens to the thermal conductivity of diatomic gases if the temperature is increase?
The thermal conductivity will also increase
The thermal conductivity decreases
The thermal conductivity remains constant
The thermal conductivity partially increases then decreases
What device is used to measure the amount of infrared radiation in each portion of a person’s skin that is emitted?
Thermograph
Thermometer
Pyrometer
Potentiometer
The heat transfer by convection occurs in which of the following?
Only in gases
Only in liquids
Only in gases and liquids
Only in gases and solids
In convection heat transfer, what mechanism heat transfer where the fluid moves due to the decrease in its density caused by increase in temperature?
Forced convection
Natural convection
Density convection
Radial convection
