Humid/dehumidification

Question 1

is a unit operation in which water is transferred from the liquid phase to the gas phase of a mixture of air and water vapor.

Answer 1

Humidification

Question 2

Humidification therefore serves two purposes:

Answer 2

cooling of liquid water and increasing the humidity of the air.

Question 3

is the reverse process of humidification, that is, the transfer of water vapor is from the gas phase to the liquid phase.

Answer 3

Dehumidification

Question 4

the function of which is to cool a gas-vapor mixture below its dew point temperature to condense out some of the vapor content

Answer 4

Chiller

Question 5

It is a practical form of humidification equipment used only for small scale operations. The liquid is sprayed as mist through the gas stream; and mass and heat transfers occur.

Answer 5

Spray chamber

Question 6

It is used for large-scale cooling of water

Answer 6

Cooling Tower

Question 7

Cooling Tower is often made up of

Answer 7

wood although aluminum, steel, brick, and concrete construction have been used

Question 8

It is used to dehumidify air or to remove a single component from a noncondensable gas

Answer 8

Packed Tower

Question 9

is the measure of water content in humid air

Answer 9

Humidity

Question 10

actual mass of H2O vapor present in the air-water vapor mixture

Answer 10

Absolute Humidity

Question 11

is the ratio of the partial pressure of H2O vapor in air to saturation pressure (otherwise known as vapor pressure) of H2O in the same temperature

Answer 11

Relative Humidity

Question 12

it is also known as the percent of saturation humidity (𝑌∗)

Answer 12

Relative Humidity

Question 13

is the ratio of absolute humidity to the saturation humidity

Answer 13

Percent Humidity

Question 14

• is the ratio of volume of air to mass of dry air
• it is used as conversion factor (CF) in determining the volumetric and mass flow rates of air
• it represents the volume of dry air (DA) plus the volume of the vapor it contains

Answer 14

Humid Volume

Question 15

represents the amount of heat required to raise the temperature of 1g or 1lb plus whatever vapor it may contain by 1°C or 1°F

Answer 15

Humid Heat

Question 16

• represents the enthalpy of DA and H2O(V)

Answer 16

Total enthalpy

Question 17

Temperature of air measured by the ordinary thermometer.
- is a tmospheric temperature.
- indicator of heat content
- actual or given temperature of air

Answer 17

Dry bulb temperature

Question 18

Temperature of air also measured by the ordinary thermometer but the only difference is that the bulb of the thermometer is covered by the wet cloth. When the air comes in contact with the wet cloth it absorbs some moisture and gives up some heat, due to which the temperature of the air reduces.
- Indirectly indicates the moisture content present in the air.
- It is affected by the RH of the air.

Answer 18

Wet Bulb Temperature

Question 19

• The temperature to which a vapor-gas mixture must be cooled at constant humidity to become completely saturated.
• The temperature at which vapor begins to condense when the gas phase is cooled at P = k.
• Temperature at which PPvapor is equal to the VP of the liquid at gas temperature.

Answer 19

Dew Point Temperature

Question 20

the temperature at which the vapor gas mixture would reach if it were saturated through an adiabatic process

Answer 20

Adiabatic Saturation Temperature

Question 21

the ratio of heat transfer coefficient to the product of mass transfer coefficient and humid heat

Answer 21

Psychrometric ratio

Question 22

Use in the determination of properties of gas vapor mixture.
- Refers mainly to the systematized knowledge of the properties of air and water but its broader meaning includes the principles which govern the properties and behavior of mixtures of the so-called “fixed” gases with condensable vapors.

Answer 22

Psychrometry

Question 23

• formally known as Psychrometric chart
• convenient diagram showing the vapor mixture

Answer 23

Humidity chart

Question 24

is the measure of the amount of vapor in the gas.

Answer 24

Saturation

Question 25

is the measure of the vapor in the gas to the maximum amount of vapor that the gas can hold.

Answer 25

Relative Saturation

Question 26

– Simplest unit operations where both heat and mass transfer occur simultaneously

Answer 26

Humidification and Dehumidification

Question 27

Humidification and Dehumidification - Two components and two phases:

Answer 27

 Liquid phase (H2O)
 Gas phase (non-condensable air)

Question 28

RH is affected by

Answer 28

𝑇𝑑𝑏 (size of the glass) and H (amount of water present)

Question 29

A liquid at its bubble point =

Answer 29

saturated liquid

Question 30

A liquid below to bubble point =

Answer 30

subcooled liquid

Question 31

A vapor at its dew point =

Answer 31

saturated vapor