Continuation to the Technical Q&A posted on 9th April 2015

91

What is Kinematic Viscosity?

Kinematic viscosity ( , Greek nu) is defined as the ratio of dynamic viscosity and density.

i.e.

It is the property of a fluid that quantifies resistance to flow of the fluid.

92

What is Temperature?

It is the property that determines the degree of hotness or coldness or the level of heat intensity of a fluid.

Temperature is measured by using temperature scales.

There are 3 commonly used temperature scales. They are:

1. Celsius (or centigrade) scale

2. Fahrenheit scale

3. Kelvin scale (or absolute temperature scale)

Kelvin scale is widely used in engineering. This is because, this scale is independent of properties of a substance.

93

 

Define ‘Mass’.

Mass (symbolized m) is a dimensionless quantity, representing the amount of matter contained in a particle or object.

The standard unit of mass in the International System (SI) is the kilogram (kg).

Mass is measured by determining the extent to which a particle or object resists a change in its direction or speed when a force is applied.

 

94

What is a Material balance?

Material balances are statements on the conservation of mass.

Material quantities, as they pass through processing operations, can be described by material balances.

Mass In = Mass Out + Mass Stored

 Raw Materials = Products + Wastes + Stored Materials.

 ΣmR = ΣmP + Σ mW + ΣmS 

 (Where Σ (sigma) denotes the sum of all terms).

 ΣmR = ΣmR1 + Σ mR2 + ΣmR3   = Total Raw Materials

 ΣmP = ΣmP1 + Σ mP2 + ΣmP3    = Total Products.

 ΣmW= ΣmW1 + Σ mW2 + ΣmW3 = Total Waste Products

 ΣmS = ΣmS1 + Σ mS2 + ΣmS3     = Total Stored Products.

95

What is an Energy balance?

Energy quantities can be described by energy balances, which are statements on the conservation of energy.

The energy coming into a unit operation can be balanced with the energy coming out and the energy stored.

 Energy In = Energy Out + Energy Stored 

 

ΣER = ΣEP + ΣEW + ΣEL + ΣES

 

Where

 

ΣER = ER1 + ER2 + ER3 + ……. =   Total Energy Entering

 

ΣEp = EP1 + EP2 + EP3 + ……. =   Total Energy Leaving with Products

 

ΣEW = EW1 + EW2 + EW3 + …   =   Total Energy Leaving with Waste Materials

 

ΣEL = EL1 + EL2 + EL3 + ……. =   Total Energy Lost to Surroundings

 

ΣES = ES1 + ES2 + ES3 + …….   =   Total Energy Stored

96

What is an Energy and Material balance diagram?

Energy and material quantities can both be described by energy and material balance diagram, which reflects both the conservation of energy & mass.

(Energy and Material balance)

The mass and energy going into the box must balance with the mass and energy coming out.

96

 

What is a Sankey Diagram?

The Sankey diagram is very useful tool to represent an entire input and output energy flow in any energy equipment or system such as boiler generation, fired heaters, furnaces after carrying out energy balance calculation.

(Energy balance of a reheating furnace)

This diagram represents visually, various outputs and losses so that one can focus on finding improvements in a prioritized manner. 

 

97

 

What is a steady flow?

Steady-state flow refers to the condition, where the fluid properties at a point in the system do not change over time.

 

Where P is any property of the fluid.

98

 

What is an Un-steady flow?

Unsteady-state flow refers to the condition, where the fluid properties at a point in the system changes over time.

99

 

Define Second?

 

Second is defined as the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom, at rest at a temperature of 0 K.

 

100

 

What are ‘fundamental units’?

 

A set of fundamental units is a set of units for physical quantities from which every other unit can be generated.

In the International System of Units, there are seven fundamental units: kilogram, meter, candela, second, ampere, kelvin, and mole.