Humidification Flashcards
This is the temperature at which a vapor-gas mixture becomes saturated when cooled at constant humidity.
a. wet-bulb temperature
b. dew point temperature
c. saturation temperature
d. dry-bulb temperature
b
This is the temperature of a vapor-gas mixture as ordinarily determined by immersion of a thermometer in the mixture.
a. wet-bulb temperature
b. dew point temperature
c. saturation temperature
d. dry-bulb.temperature
d
If the partial pressure of the vapor in a gas-vapor mixture is, for any reason, less than the equilibrium vapor pressure of the liquid at the same temperature, the mixture is
a. saturated
c. supersaturated
b. unsaturated
d. sub-cooled
b
This is a steady-state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapor-gas mixture.
a. wet-bulb temperature
b. dew point temperature
c. saturation temperature
d. dry-bulb temperature
a
In order for the gas to be dehumidified, as in the water vapor-air mixture, the humidity of the gas must be
a. greater than the gas-liquid interface
b. equal with the gas-liquid interface
c. less than the gas-liquid interface
d. saturated
a
In dehumidification, where the Lewis Number is equal to one, the operating line on the gas-enthalpy-liquid temperature graph
a. is below the equilibrium curve
b. coincides with the equilibrium curve
c. is above the equilibrium curve
d. intersects the equilibrium curve
c
The process which illustrates the principle of adiabatic humidification is
a. cooling tower
b. spray chamber
c. air conditioner
d. heated dryer
b
Fogging is a result of a condition whereby the gas becomes
a. saturated with vapor
b. unsaturated with vapor
c. supersaturated with vapor
d. liquid due to cooling
c
Air conditioning involves
a. stripping
b. humidification
c. dehumidification
d. evaporative cooling
c
A sling psychrometer is whirled on a fast spin when measuring the wet bulb temperature of ambient air
a. since centrifugal force helps in stabilizing the mercury level in the thermometer
b. to remove excess water in the cloth wrapped around the mercury bulb
c. to minimize the effect of radiation on the temperature reading
d. to minimize the effect of convection on the temperature reading
c
In an air-water contact equipment, the individual gas-phase mass transfer coefficient is equal to the over-all mass transfer coefficient since
a. the mass transfer resistance in the liquid-phase is small
b. the mass transfer resistance in the gas-phase is small
c. there is no concentration gradient in the gas-phase
d. there is no concentration gradient in the liquid-phase
a
The enthalpy transfer equation based on Merkel’s procedure of determining the volume of a cooling tower is a convenient way of
a. eliminating the complications introduced by the effect of sensible and latent heats
b. eliminating the determination of interfacial temperature and humidity
c. eliminating the complications of a non-adiabatic dehumidification of air
d. eliminating the effect of the resistance to heat transfer in the liquid phase
b
In adiabatic humidification, it is possible to maintain the temperature of water constant since
a. according to the phase-rule, the degrees of freedom is 3
b. the system can be well insulated from the surroundings
c. the temperature of the air can also be maintained constant
d. the increase in the humidity of the air is very small
b
Besides measuring the dry bulb and wet bulb temperatures in determining the humidity of air, another method may be used. This is by
a. measuring the specific heat of the air
b. measuring the enthalpy of the air
c. measuring the dew point of the air
d. measuring the specific volume of the air
c
In terms of heat transfer, the use of a cooling tower is said to be more efficient and more economical compared to an ordinary heat exchanger since
a. large volume of air is available and free
b. temperature profiles of air and water can cross each other
c. large amount of water can be processed
d. a cooling tower is much smaller and cheaper than a heat exchanger
b
