Heat And Mass Transfer Flashcards
In industrial crystallization from a solution, the two phase mixture of mother liquor and crystals of al sizes, which occupies the crystallizer and is withdrawn as product is called
Magma
In practice, slow cooling maintaining a low level of supersaturation produces ______ crystals and fast cooling produces ________crystals.
Large, small
It is the process by which crystalline bodies are created within a supersaturated fluid.
Nucleation
When a solution si cooled to produce a supersaturated solution and hence to cause crystallization, the heat that must be removed is the sum of the ________ necessary to cool the solution and the heat of crystallization.
Sensible heat content
To remove all the moisture from a wet solid, it requires exposure to
Perfectly dry air
The portion of water in the wet solid that cannot be removed by the air in its contact is called
Equilibrium moisture content
Moisture contained by a substance in excess of the equilibrium moisture is called
Free moisture
When drying banana chips under the sun, the rate of drying is faster on a
Hot and windy day
The critical moisture content in case of drying indicates
Beginning of falling rate period
In drying at the falling rate period, the rate at which moisture is removed from the solid material
Decreases with time
Heat sensitive materials like certain pharmaceuticals and food stuff can be dried
By freeze drying
Evaporation is also sometimes called as
Water distillation
The concentration of glycerin from a water solution by the application of heat is
Evaporation
The total amount of evaporation an evaporator is capable of producing per unit of time
Capacity
When the pressure of the chamber is decreased, the boiling point of the solution inside the chamber will
Decrease
A heat transfer device that is normally used to liquefy vapors is
Condenser
The temperature driving force in an evaporator is determined as the difference between the condensing steam temperature and
Boiling point of the solution
In a country where capital is scarce and energy cost is low, which is appropriate to install?
Single effect evaporator
The fresh feed enters at the coldest effect
Feed-backward
In commercial practice, the areas in all effects for a multiple effect evaporator are
Constant
A multiple effect evaporator ______ the steam cost.
Decreases
______ of the vapor is recovered and reuse in the multiple effect evaporator.
Latent heat
It is the decomposition and growth on body walls, and specially on heating surfaces, of a material undergoing an irreversible chemical reaction in the evaporator.
Scaling
It is the formation of deposits other than salt or scale and maybe due to corrosion.
Fouling
