Heat Exchanger Questions

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40 Questions

What is the primary function of a super heater?

To increase the total energy content of the flow

What is the term for the series of processes that eventually bring the system back to its original condition?

Cycle

What is the name of the theoretical body that emits a continuous light-ray spectrum when heated to incandescence?

Black body

Why are pipes usually insulated?

To minimize heat loss

What type of heat transfer occurs due to density differential?

Convection

What is the unit of exposure in radiological effects?

Number of ions produced per mass of air x coulombs per kg

What is the process of heat transfer through a substance?

Conduction

What type of heat exchanger is used to heat water to a point that dissolved gases are liberated?

Deaerator

What is the term used to describe the condition when the change in temperature of one steam is numerically equal to the average driving force?

Condition when the change in temperature of one steam is numerically equal to the average driving force

In which type of flow can the Dritus Boelter equation be applied?

Turbulent flow

What is the term used to describe a type of radiation consisting of singly charged particles that generate to intermediate distance?

Beta radiation

What is the energy of a body that can be transmitted in the form of heat?

Heat energy

In an isometric process, the heat transferred is equal to the change in which thermodynamic property?

Enthalpy

What is the term used to describe a substance that is able to absorb liquids or gases and is used for removing them from a given medium or region?

Adsorbent

What type of heat exchanger is referred to as a 1-2 heat exchanger?

Single pass on shell side and double pass on tube side

Which of the following is used as an entrainer in acetic acid – water separation?

Methyl alcohol

What is the primary reason why metals are good conductors of heat?

Metals contain free electrons

Which of the following does not affect the rate of heat flow through a slab of material?

The specific heat of the material

What is the primary function of a thermal radiator?

To transfer heat using moving liquids

What makes styrofoam a good insulating material?

It contains many tiny pockets of air

What happens to the surrounding when water vapor condenses?

It warms the surrounding

What does the rate of radiation not depend on?

The thickness of the radiating body

Which of the following is not a good conductor of heat?

Asbestos

Which of the following is not a unit of the rate of heat transfer?

Btu/Hp-hr

What is the value of 'a' for triatomic gases according to Maxell's theory for thermal conductivity of gases and vapors?

1.7

Which of the following thermal conductivities uses the Sutherland equation?

Thermal conductivities of gases

What happens to the thermal conductivity of pure metals at extremely high temperatures?

It remains almost constant except for ferromagnetic materials

Which of the following liquids has the highest thermal conductivity?

Glycerin

Which of the following is not a type of heat exchanger?

Water hammer

What type of heat exchanger involves fluid flow in the same direction with changing temperatures?

Parallel flow

How does the thermal conductivity of diatomic gases change with increasing temperature?

It increases

What device is used to measure the amount of infrared radiation emitted by each portion of a person's skin?

Thermograph

What is necessary for an object to float in a fluid?

Its density is less than that of the surrounding fluid

At what temperature must an object be at in order to emit electromagnetic radiation?

Above 0 ˚K

What is the process called when a solid changes directly into a gas without becoming a liquid?

Sublimation

At what temperature can freeze drying take place?

Below the triple point of water

What happens when a vapor condenses into a liquid?

It evolves heat

What is the term for the ratio of the radiation of an actual body to the radiation of a blackbody?

Emissitivity

How is water mainly cooled in a cooling tower?

Through evaporation

What type of heat transfer occurs when heat is transferred from one point to another by actual movement of substance?

Convection

Study Notes

Heat Exchangers

  • A 1-2 heat exchanger refers to a single pass on the shell side and a double pass on the tube side.
  • In sugar mills, juice is evaporated in short vertical tube evaporators.
  • A correction of LMTD (Log Mean Temperature Difference) is essential in case of cross flow heat exchangers.

Radiation

  • Alpha radiation consists of singly charged particles that generate to intermediate distances.
  • The energy of a body that can be transmitted in the form of heat is referred to as internal energy.
  • A black body is a theoretical body that, when heated to incandescence, would emit a continuous light-ray spectrum.
  • The radiant heat transfer depends on temperature.
  • An object must be at a temperature above 0°C to emit electromagnetic radiation.

Heat Transfer

  • Heat transfer due to density differential is known as convection.
  • The rate of heat transfer through a slab of material does not depend on the specific heat of the material.
  • The primary function of a thermal radiator is to transfer heat from a hot body to a cold body.
  • Styrofoam is a good insulating material because it contains many tiny pockets of air.

Conduction

  • The passing of heat energy from molecule to molecule through a substance is known as conduction.
  • Metals are good conductors of heat because they contain free electrons.
  • The thermal conductivity of metals does not change significantly with temperature.

Miscellaneous

  • The function of a superheater is to increase the total energy content of the flow.
  • A series of processes that eventually bring the system back to its original condition is known as a cycle.
  • Insulating pipes helps to minimize heat loss.
  • The rate of radiation does not depend on the thickness of the radiating body.
  • Asbestos is not a good conductor of heat.
  • The thermal conductivity of gases and vapors can be calculated using Maxwell's theory.
  • Sutherland's equation is used to calculate the thermal conductivity of gases.
  • Water has the highest thermal conductivity among liquids.
  • A thermograph is used to measure the amount of infrared radiation emitted by each portion of a person's skin.

Multiple choice questions about heat exchangers, including temperature drop, heat transfer surface area, and fluid flow. Useful for mechanical engineering students.

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