properties of fluid and its characteristics

1

PROPERTIES OF FLUID AND ITS

CHARACTERISTICS

AN INTERNSHIP REPORT

SUBMITTED

BY

SURAJ PANDIYAN. S (AME18202)

BE(ME) - 18

ACADEMY OF MARITIME EDUCATION AND TRAINING(AMET) (Declared as Deemed to be University u/s 3 of UGC Act 1956)

135, EAST COAST ROAD, KANATHUR, CHENNAI - 603 112.

TAMILNADU, INDIA

A Report on Internship

In

Department of BE Marine Engineering

By

Student Name: Suraj Pandiyan S

Register Number: Ame18202

Roll No:2876B Year:2nd Year

Group: 5

Batch:B.E.M.E-18 Subject: Fluid Mechanics

Code: UDMC405

CERTIFICATE

This is to certify that the project entitled “Properties of fluids” is to

bonafide work carried out by the students of AMET UNIVERSITY,

KANATHUR (CHENNAI) during the year 2019 -2020 for the partial

fulfillment of the requirements for the award of the Degree of

Bachelor of a Marine Engineering.

INTERNAL GUIDE EXTERNAL EXAMINER

HEAD OF THE DEPARTMENT

PLACE : AMET UNIVERSITY

BE MARINE ENGINEERING

Properties of fluids And its characteristics:

In this essay we will be seeing the properties of fluid

which greatly influence the working of fluids in both practical

and theoretical practices. The following are some of the

fundamental properties of fluids.

1. Mass density.

2. Specific Weight

3. Specific Volume

4. Specific Gravity

5. Viscosity

6. Compressibility

7. Vapour Pressure

8. Surface Tension

9. Capillary

10. Fluid Dynamics

11. Euler’s Theorem

12. Bernoulli’s Theorem

Mass density:

Mass density is a quantitative expression of the amount of

mass contained per unit volume. The standard unit is

kilograms per meter cubed (kg/m3).

The symbol most often used for density is:

(the Greek letter rho).

Mass density represents the mass (or number of particles)

per unit volume of a substance, material or object. Most

substances (especially gases) increase in density as their

pressure increases or as their temperature decreases.

Mass density can help to predict chances of corrosion of

substances. Measuring mass density can help to predict a

material's inherent defects which can ultimately cause

different forms of corrosion.

Mass density is also known as density.

Specific weight:

The specific weight, also known as the unit weight, is

the weight per unit volume of a material.

A commonly used value is the specific weight

of water on Earth at 4°C, which is 9.807 kN/m3 or

62.43 lbf/ft3.

The terms specific gravity, and less often specific weight, are

also used for relative density. A common symbol for specific

weight is γ, the Greek letter Gamma.

In fluid mechanics, specific weight represents the force

exerted by gravity on a unit volume of a fluid. For this reason,

units are expressed as force per unit volume (e.g., N/m3 or

lbf/ft3). Specific weight can be used as a characteristic

property of a fluid.

Specific Volume:

Specific volume of a fluid is defined as the ratio of the volume

of a fluid to the mass of the fluid. In other words it may also

be defined as volume per unit mass of a fluid.

Specific volume = (volume of fluid)/(mass of fluid)

specific volume = V/m = 1/ρ

Specific Gravity:

Specific gravity is defined as the ratio of the density of a fluid

to the density of a standard fluid. For liquids, water is taken

as the standard fluid whereas for gases air is taken as the

standard fluid. It is denoted by the symbol S.

specific gravity, S = (density of liquid)/(density of water)

= (density of gas )/(density of air)

The density of water is taken as 1000 kg/ cubic metre

Viscosity:

The viscosity of a fluid is a measure of its resistance to

deformation at a given rate. For liquids, it corresponds to the

informal concept of "thickness": for example, syrup has a

higher viscosity than water.

Viscosity can be conceptualized as quantifying the

internal frictional force that arises between adjacent layers of

fluid that are in relative motion. For instance, when a fluid is

forced through a tube, it flows more quickly near the tube's

axis than near its walls. In such a case, experiments show that

some stress (such as a pressure difference between the two

ends of the tube) is needed to sustain the flow through the

tube. This is because a force is required to overcome the

friction between the layers of the fluid which are in relative

motion: the strength of this force is proportional to the

viscosity.

A fluid that has no resistance to shear stress is known as

an ideal or inviscid fluid. Zero viscosity is observed only

at very low temperatures in superfluid’s. Otherwise,

the second law of thermodynamics requires all fluids to have

positive viscosity; such fluids are technically said to be

viscous or viscid. A fluid with a high viscosity, such as pitch,

may appear to be a solid.

Compressibility:

compressibility (also known as the coefficient of

compressibility or isothermal compressibility) is a measure of

the relative volume change of a fluid or solid as a response to

a pressure (or mean stress) change. In its simple form, the

compressibility β may be expressed as

where V is volume and p is pressure. The choice to define

compressibility as the negative of the fraction makes

compressibility positive in the (usual) case that an increase in

pressure induces a reduction in volume.

The specification above is incomplete, because for any object

or system the magnitude of the compressibility depends

strongly on whether the process is isentropic or isothermal.

Accordingly, isothermal compressibility is defined.

Vapour Pressure:

Vapor pressure or equilibrium vapor pressure is defined as

the pressure exerted by a vapor in thermodynamic

equilibrium with its condensed phases (solid or liquid) at a

given temperature in a closed system. The equilibrium vapor

pressure is an indication of a liquid's evaporation rate. It

relates to the tendency of particles to escape from the liquid

(or a solid). A substance with a high vapor pressure at normal

temperatures is often referred to as volatile. The pressure

exhibited by vapor present above a liquid surface is known as

vapor pressure. As the temperature of a liquid increases, the

kinetic energy of its molecules also increases. As the kinetic

energy of the molecules increases, the number of molecules

transitioning into a vapor also increases, thereby increasing

the vapor pressure.

The vapor pressure of any substance increases non-linearly

with temperature according to the Clausius–Clapeyron

relation. The atmospheric pressure boiling point of a liquid

(also known as the normal boiling point) is the temperature

at which the vapor pressure equals the ambient atmospheric

pressure. With any incremental increase in that temperature,

the vapor pressure becomes sufficient to

overcome atmospheric pressure and lift the liquid to form

vapor bubbles inside the bulk of the

substance. Bubble formation deeper in the liquid requires a

higher temperature due to the higher fluid pressure, because

fluid pressure increases above the atmospheric pressure as

the depth increases. More important at shallow depths is the

higher temperature required to start bubble formation. The

surface tension of the bubble wall leads to an overpressure in

the very small, initial bubbles.

The vapor pressure that a single component in a mixture

contributes to the total pressure in the system is

called partial pressure. For example, air at sea level, and

saturated with water vapor at 20 °C, has partial pressures of

about 2.3 kPa of water, 78 kPa of nitrogen, 21 kPa

of oxygen and 0.9 kPa of argon, totalling 102.2 kPa, making

the basis for standard atmospheric pressure.

Surface Tension:

Surface tension is the tendency of liquid surfaces to shrink

into the minimum surface area possible. Surface tension

allows insects (e.g. water striders), usually denser than water,

to float and slide on a water surface.

At liquid–air interfaces, surface tension results from the

greater attraction of liquid molecules to each other (due

to cohesion) than to the molecules in the air (due

to adhesion). The net effect is an inward force at its surface

that causes the liquid to behave as if its surface were covered

with a stretched elastic membrane. Thus, the surface comes

under tension from the imbalanced forces, which is probably

where the term "surface tension" came from . Because of the

relatively high attraction of water molecules to each other

through a web of hydrogen bonds, water has a higher surface

tension (72.8 millinewtons per meter at 20 °C) than most

other liquids. Surface tension is an important factor in the

phenomenon of capillarity.

Surface tension has the dimension of force per unit length, or

of energy per unit area. The two are equivalent, but when

referring to energy per unit of area, it is common to use the

term surface energy, which is a more general term in the

sense that it applies also to solids.

In materials science, surface tension is used for either surface

stress or surface energy.

Due to the cohesive forces a molecule is pulled equally in

every direction by neighbouring liquid molecules, resulting in

a net force of zero. The molecules at the surface do not have

the same molecules on all sides of them and therefore are

pulled inward. This creates some internal pressure and forces

liquid surfaces to contract to the minimum area. The forces

of attraction acting between the molecules of same type are

called cohesive forces while those acting between the

molecules of different types are called adhesive forces. The

balance between the cohesion of the liquid and its adhesion

to the material of the container determines the degree

of wetting, the contact angle and the shape of meniscus.

When cohesion dominates (specifically, adhesion energy is

less than half of cohesion energy) the wetting is low and the

meniscus is convex at a vertical wall (as for mercury in a glass

container). On the other hand, when adhesion dominates

(adhesion energy more than half of cohesion energy) the

wetting is high and the similar meniscus is concave (as in

water in a glass).

Capillary:

Capillary action (sometimes capillarity, capillary

motion, capillary effect, or wicking) is the ability of

a liquid to flow in narrow spaces without the assistance of, or

even in opposition to, external forces like gravity. The effect

can be seen in the drawing up of liquids between the hairs of

a paint-brush, in a thin tube, in porous materials such as

paper and plaster, in some non-porous materials such as

sand and liquefied carbon fibre, or in a biological cell. It

occurs because of intermolecular forces between the liquid

and surrounding solid surfaces. If the diameter of the tube is

sufficiently small, then the combination of surface

tension (which is caused by cohesion within the liquid)

and adhesive forces between the liquid and container wall

act to propel the liquid.

Fluid Dynamics:

It describes the flow of fluids—liquids and

gases. It has several subdisciplines, including aerodynamics

(the study of air and other gases in motion) and

hydrodynamics (the study of liquids in motion). Fluid

dynamics has a wide range of applications, including

calculating forces and moments on aircraft, determining the

mass flow rate of petroleum through pipelines, predicting

weather patterns, understanding nebulae in interstellar

space and modelling fission weapon detonation.

Fluid dynamics offers a systematic structure—which

underlies these practical disciplines—that embraces

empirical and semi-empirical laws derived from flow

measurement and used to solve practical problems. The

solution to a fluid dynamics problem typically involves the

calculation of various properties of the fluid, such as flow

velocity, pressure, density, and temperature, as functions of

space and time.

Before the twentieth century, hydrodynamics was

synonymous with fluid dynamics. This is still reflected in

names of some fluid dynamics topics, like

magnetohydrodynamics and hydrodynamic stability, both of

which can also be applied to gases.[1]

Euler’s Equation:

Bernoulli’s Equation:

Conservation of Energy

Sum of kinetic energy and gravitational potential energy

is constant.

Kinetic energy =

Gravitational potential energy = mg h

To apply this to a falling droplet we have an initial velocity of

zero, and it falls through a height of h.

Initial kinetic energy = 0

Initial potential energy = mg h

Final kinetic energy =

Final potential energy = 0

Notice that the pressure is constant.

Initial kinetic energy + Initial potential energy = Final

kinetic energy + Final potential energy

In this way , the velocity of a drop of water can calculated in

theory. It is also applied to any case. For example to

calculate the velocity of water exiting an orifice:

Initial kinetic energy = 0

Initial potential energy = mg z1

Final kinetic energy = 0.5 mu2

Final potential energy = mgz2

• Bernoulli’s Equation

Bernoulli’s equation is one of the most important and useful

equations in fluid mechanics. It may be written,

2

2

221

2

11

22gz

g

u

g

pz

g

u

g

p

We see that from applying equal pressure or zero velocities

we get the two equations from the section above. They are

both just special cases of Bernoulli’s equation.

Bernoulli’s equation has some restrictions in its

applicability, they are:

- Flow is steady;

- Density is constant (which also means the fluid is

incompressible);

- Friction losses are negligible.

All these conditions are impossible to satisfy at any

instant in time! Fortunately for many real situations

where the conditions are approximately satisfied, the

equation gives very good results.

By the principle of conservation of energy the total

energy in the system does not change, Thus the total

head does not change. So the Bernoulli equation can be

written,

.2

2

constHzg

u

g

p

An example of the use of the Bernoulli equation.

When the Bernoulli equation is combined with the continuity

equation the two can be used to find velocities and pressures

at points in the flow

A fluid of constant density ρ = 960 kg / m3 is flowing

steadily through the above tube. The diameters at

the sections are d1 = 100 mm and d2 = 80 mm. The gauge

pressure at 1 is p1 = 200 kN/ m2 and the velocity

here is u1 = 5 m/ s. We want to know the gauge pressure at

section 2.

The tube is horizontal, with z1 = z2 so Bernoulli gives us

the following equation for pressure at section 2:

)(2

2

2

2

112 uupp

But we do not know the value of u2 . We can calculate

this from the continuity equation: Discharge into

the tube is equal to the discharge out i.e.

A1u1 = A2u2

u2 = 7.8125 m/s

p2 = 217.3 kN/m2

INTERNSHIP ALLOCATION REPORT 2019-20

Name of the Department: BE MARINE ENGINEERING

(In view of advisory from the AICTE, internships for the year 2019-20 are offered by the

Department itself to facilitate the students to take up required work from their home itself during

the lock down period due to COVID-19 outbreak)

Name of the Programme : MARINE ENGINEERING

Year of study and Batch/Group : 2nd YEAR BE (ME)18 G-4

Name of the Mentor: MR. HARISH KUMAR J

Title of the assigned internship :

FLUID MECHANICS

Nature of Internship : Individual

Reg No of cadet who is assigned with this internship:

AME18202

Total No. of Hours Required to complete the Internship: 45 HOURS

Signature of the Mentor

Signature of the Internal

Examiner

Signature of HoD/Programme

Head

INTERNSHIP EVALUATION REPORT 2019-20

Name of the Department: Marine Engineering


Department itself to facilitate the students to take up required work from their home itself during

the lock down period due to COVID-19 outbreak)

Name of the Student Suraj Pandiyan S

Register No and Roll No AME18202

2876B

Programme of study FLUID MECHANICS

Year and Batch/Group 2nd YEAR BEME18 G-05

Semester IV

Title of Internship

1) Properties Of Fluids.

2) Bernoulli’s Equation.

Duration of Internship 45 Hours

Mentor of the Student MR. HARISH KUMAR J

Evaluation by the Department

Sl

No. Criterion Max. Marks Marks Allotted

1 Regularity in maintenance of the diary. 10

2 Adequacy & quality of information recorded 10

3 Drawings, sketches and data recorded 10

4 Thought process and recording techniques used 5

5 Organization of the information 5

6 Originality of the Internship Report 20

7 Adequacy and purposeful write-up of the Internship Report 10

8 Organization, format, drawings, sketches, style, language etc.

of the Internship Report 10

9 Practical applications, relationships with basic theory and

concepts 10

10 Presentation Skills 10

Total 100

Signature of the Mentor Signature of the Internal

Examiner


Head

1

PUMPS AND TURBINES


SUBMITTED

BY

DHURUVA R SHETTY (AME18170)

BE(ME) - 18

ACADEMY OF MARITIME EDUCATION AND TRAINING (AMET)

(Declared as Deemed to be University u/s 3 of UGC Act 1956)


TAMILNADU, INDIA

INTERNSHIP AT HOME

A Report on Internship

In

Department of BE MARINE ENGINEERING

By

Name : DHRUVA R SHETTY

Register Number : AME18170

Roll No : 2844B

Year : 2ND YEAR

Batch : BE(ME)-18

Group : 05

Subject Code : UDMC405

Subject : FLUID MECHANICS

CERTIFICATE

This is to certify that the project entitled “Pumps & Turbines” is to

bonafide work carried out by the students of AMET UNIVERSITY,

KANATHUR (CHENNAI) during the year 2019 -2020 for the partial

fulfillment of the requirements for the award of the Degree of Bachelor

of a Marine Engineering.



PLACE : AMET UNIVERSITY

BE MARINE ENGINEERING

1. INTRODUCTION – Pumps & Turbines

2. Dynamic Pump

• Centrifugal Pumps

• Vertical Centrifugal Pumps

• Horizontal Centrifugal Pumps

• Submersible Pumps

• Fire Hydrant Systems

3. Positive Displacement pumps

• Diaphragm Pumps

• Gear Pumps

• Peristaltic Pumps

• Lobe Pumps

• Piston Pump

4. Turbines

• Water Turbine

• Steam Turbine

• Gas Turbine

• Wind Turbine

5. Conclusion

CONTENT

Different Types of Pumps: Working and

Their Applications

There are different types of pumps available in the market. This

assignment will assist you to know the main functionalities of each

type of pump. The type of pump, as well as selection, mainly depend

on our requirement. The application mainly includes the type of fluid

you desire to pump, the distance you desire to move the fluid, and

the quantity you require to get over a particular time frame.

However, it is complicated to recognize accurately what kind of

pump you must select. The identifying of the pump can be done with

the design as well as positions. To make simpler things while seeking

to choose your exact pump, and the pumps can be classified into two

types which function in extremely dissimilar ways & generally

summarize most of the pump designs.

Types of Pumps

• Pumps are classified into two types namely Dynamic pumps

as well as Positive Displacement Pumps.

CLASSIFICATION OF PUMPS

• Dynamic pumps are classified into different types but some of them

are discussed below like Centrifugal, Vertical centrifugal, Horizontal

centrifugal, Submersible, and Fire hydrant systems.

1. Centrifugal pump

Centrifugal Pumps are devices that are used to transport fluids

by the conversion of rotational kinetic energy energy to

hydronamic energy to

the fluid flow. The

rotational energy

typically comes from an .

The impeller and blades rotate, they

electric motor or steam

turbine

transfer momentum to incoming fluid. The fluid accelerates

radially outward from the pump chasing and a vacuum is created

at the impellers eye that continuously draws more fluid into the

pump. As the fluid’s velocity increases its kinetic energy

increases. Fluid of high kinetic energy is forced out of the

impeller area and enters the volute. In the volute the fluid flows

through a continuously increasing cross-sectional area, where

the kinetic energy is converted into fluid pressure.

2. Vertical Centrifugal pump

Centrifugal pumps are also called as cantilever pumps. These

pumps use an exclusive shaft & maintain design that permits the

volume to fall within the pit as the bearings are external to the

pit. This mode of pump utilizes no filling container to cover the

shaft however in its place uses a throttle bushing. A parts washer

is the common application of this kind of pump.

3. Vertical Centrifugal pump

• These types of pumps include a minimum of two otherwise more

impellers. These pumps are utilized in pumping services. Every

stage is fundamentally a divide pump. All the phases are in a

similar shelter & mounted on a similar shaft. On a solo

horizontal shaft, minimum eight otherwise additional stages can

be mounted. Every stage enhances the head by around an equal

amount. Multi-stage pumps can also be single otherwise double

suction on the first impeller. All kinds of pumps have been

providing as well as servicing this type of centrifugal pumps.

4. Submersible pump

These pumps are also named as stormwater, sewage, and septic

pumps. The applications of these pumps mainly include building

services, domestic, industrial, commercial, rural, municipal, &

rainwater recycle applications.

• These pumps are apt for shifting

stormwater, subsoil water, sewage, black

water, grey water, rainwater, trade waste,

chemicals, bore water, and foodstuffs. The

applications of these pipes mainly include

in different impellers like closed,

contrablock, vortex, multi-stage, single

channel, cutter, otherwise grinder pumps.

For

different applications, there is an extensive selection is

accessible which includes high flow, low flow, low head,

otherwise high head5).

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5. Fire pump system

A fire pump is a part of a fire sprinkler system's water supply and

powered by electric, diesel or steam. The pump intake is either

connected to the public underground water supply piping, or a static

water source (e.g., tank, reservoir, lake). The pump provides water

flow at a higher pressure to the sprinkler system risers and hose

standpipes. A fire pump is tested and listed for its use specifically for

fire service by a third-party testing and listing agency, such as UL or

FM Global Fire hydrant pump systems are also named as hydrant

boosters, fire pumps, & fire water pumps. These are high force water

pumps intended to enhance the capacity of firefighting of

construction by increasing the force within the hydrant service as

mains is not sufficient. The applications of this system mainly include

irrigation as well as water transfer.

• Positive displacement pumps are classified into different types

but some of them are discussed below:

1. Diaphragm pump Diaphragm pumps also known as AOD pumps (Air operated

diaphragms), pneumatic, and AODD pumps. The applications of these

pumps mainly include in continuous applications like in general

plants, industrial and mining. AOD pumps are particularly employed

https://en.wikipedia.org/wiki/Fire_sprinkler



https://en.wikipedia.org/wiki/Piping



https://en.wikipedia.org/wiki/Product_certification



https://en.wikipedia.org/wiki/Underwriters_Laboratories



https://en.wikipedia.org/wiki/FM_Global




where power is not obtainable, otherwise in unstable and combustible

regions.

These pumps are also utilized for transferring chemical, food

manufacturing, underground coal mines, etc.

These pumps are responding pumps and include

two

diaphragms which are driven with condensed air. The section of air

by transfer valve applies air alternately toward the two diaphragms;

where every diaphragm contains a set of ball or check valves.

2. Gear pump

These pumps are a kind of

rotating positive dislocation pump, which means they force a stable

amount of liquid for every revolution. These pumps move liquid

with machinery coming inside and outside of mesh for making a

non-exciting pumping act. These pumps are capable of pumping on

high forces & surpass at pumping high thickness fluids efficiently.

A gear pump doesn’t contain any valves to cause losses like

friction & also high impeller velocities. So, this pump is

compatible for handling thick liquids like fuel as well as grease

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oils. These pumps are not suitable for driving solids as well as

harsh liquids.

3. Peristaltic pump

Peristaltic pumps are also named as tube pumps, peristaltic pumps.

These are a kind of positive displacement pumps and the applications

of these pumps mainly involve in processing of chemical, food, and

water treatment industries. It makes a stable flow for measuring &

blending and also capable of pumping a variety of liquids like

toothpaste and all kinds of chemicals.

4. Lobe pump

These pumps offer different characteristics like an excellent high

efficiency, rust resistance, hygienic qualities, reliability, etc. These

pumps can handle high thickness fluids & solids without hurting

them. The working of these pumps can be related to gear pumps, apart

from the lobes which do not approach into contact by each other.

Additionally, these pumps have superior pumping rooms compare

with gear pumps that allow them to move slurries. These are made

with stainless steel as well as extremely polished.

5. Piston pump

• Piston pumps are one kind type of positive dislocation pumps

wherever the high force seal responds through the piston. These

pumps are frequently used in water irrigation, scenarios

requiring high, reliable pressure and delivery systems for

transferring chocolate, pastry, paint, etc.

Piston Pumps

• Thus, this is all about classification of pumps like centrifugal &

positive displacement. These are used in different kinds of

buildings to make simpler the movement of liquid materials. The

https://www.elprocus.com/microcontroller-based-automatic-irrigation-system/





https://en.wikipedia.org/wiki/Pump







pumps which are used in housing & commercial can handle

water. Fire pumps supply a rushed water supply for automatic

sprinklers and firefighters, and booster pumps supply clean

water to higher floors in apartments.

A turbine is a rotating part which converts kinetic energy of a working

fluid into useful mechanical energy and/or electrical energy.

There are set of blades mounted on a rotor which helps in extracting

energy from the moving fluid. The efficiency of turbines depends on

the design of the blades. The 4 types of turbines are

• Water turbines

• Steam turbines

• Gas turbines and Wind turbines

PART – 2

Turbines used in hydro power plants: -

The turbines used in hydroelectric power plants are water turbines

which have water as their working fluid.

First of all, millions of liters of water are collected in the dam. More

the height of dam, more the pressure. The highly pressurized water is

then made to flow via large pipe called as penstock.

The turbine is located at the end of penstock from where the

pressurized water strikes the blades of turbine at high velocity

making it to rotate. This turbine is connected to a generator which

generates electricity. The shape of turbine blades depends upon the

pressure & velocity of water.

Water turbines are classified into 2 types-

1. Impulse type

2. Reaction type

Impulse type turbines- Impulse turbines basically work on Newton’s 2nd law. In impulse

turbines, number of elliptical half sized buckets are fitted instead of

blades on the rotor hub. When water strike the buckets at high speed,

the rotor starts rotating. In short, the kinetic energy of water gets

converted into Mechanical energy. Thus, electricity is generated when

one end of the turbine shaft is connected to generator.

Example – Pelton turbine

Reaction turbines- The turbine blades or the impeller blades are designed in such a way

that a force is generated on one side when water flows through it just

like an airfoil. The force produced by airfoil is responsible for lift of

aeroplane. Similarly, here, that force makes the blades rotate.

Example – Kaplan turbine

Different types of turbines have their own ideal operating conditions.

→ Pelton turbines are preferred where low discharge rate can be

obtained and high head available

→ Kaplan turbines require high discharge rate along with low or

medium

→ Francis turbine work on medium flow rate & medium head.

Francis turbine is a combination of impulse & reaction turbine.

Francis turbines are most widely used turbines because they offer the

highest efficiency & could also work in wide range of operating

conditions.

1m head of water = 9810 Pa (100m of head is almost 7 times of

atmospheric pressure)

Turbines used in thermal power plants: - Also called as steam turbines, they are used in nuclear & thermal

powerplants where water is heated to form steam & then flowed

through turbines to produce electricity. Alike water turbines, steam

turbines are also classified into impulse & reaction types but the

arrangement & design is different. All the modern steam turbines are

a combination of impulse & reaction type.

Blades of Impulse & Reaction turbines

Steam turbines consist not only rotating blades called as rotor but also

static blades called as stator. Rotors & stators are placed alternately in

order to extract most energy out of it. This method is called as

compounding.

Also, if you observe, the moving buckets in impulse turbine are

designed to get pushed by the steam. While the rotor blades in

reaction turbine are aerofoiled shape, which lets itself generate

reaction & also let steam maintain its velocity.

Section view of a steam turbine

In the image: The steam first flows through high pressure

(H.P) turbine followed by intermediate pressure (I.P)

turbine. Then again after reheating the steam, it is made to

flow through low pressure (L.P) turbines (huge set of

blades).

The reason behind increase in blade sizes from inner side

to outer side is because steam expands while losing its

pressure & kinetic energy & giving it to turbines.

Gas turbines: -

Parts of a gas turbine, popularly called as jet engine.

Gas turbines in other words are internal combustion engines, which

are not only used in powerplants for generating electricity but also for

propelling airplanes & helicopters. Gas turbines as a whole system

has a axial compressor at the inlet. These are sets of rotating blades

which suck huge amount of air & compress it which also increases the

temperature. This air is then supplied to the combustion chamber.

Fuel is added into the combustion chamber & ignitor ignites the fuel.

https://i0.wp.com/mechstuff.com/wp-content/uploads/2018/01/steam-turbine.png

http://mechstuff.com/tag/internal-combustion-engine/



Thus, large amount of exhaust gases is produced which are made to

flow through turbines.

The different types of gas turbines/jet engines are –

1. Turbojet

2. Turbofan

3. Turbojet

4. Turboshaft

5. Ramjet

WIND TURBINE

Wind turbines are a boon to mankind- affordable, clean & sustainable.

Some windfarms are so big that they could produce 50MW of power.

Well, coming to working of wind turbines, the story remains same as

other turbines. The rotor has 3 blades & are designed in such a way

that when wind flows straight through them, they start rotating. The

only problem here is wind turbines rotate at a very low of RPM. The

low RPM doesn’t produce electricity of required frequency & that is

why we require a gearbox which increases the speed of shaft. The

output shaft is then connected to the generator.

https://i0.wp.com/mechstuff.com/wp-content/uploads/2015/12/Jet_engine.png

The 3 primary types of wind turbines are –

1. Horizontal-axis wind turbines (HAWT)

2. Savonius vertical-axis wind turbine (Savonius VAWT)

3. Derrius vertical-axis wind turbine (Derrius VAWT)

CONCLUSION

From this assignment I would conclude that pumps and turbines play

a vital role in engineering field, both been a key player in science and

technology advancement which has mainly helped the mankind with

its application in domestic use and in other fields like in agriculture,

firefighting, lifting water from tanks.

While turbines have helped in power generation using steam, water

and wind which is a natural convention of energy freely available in

nature.

Thank you, for giving me an opportunity to do this assignment.

Regards

Shashank.k




Department itself to facilitate the students to take up required work from their home itself

during the lock down period due to COVID-19 outbreak)

Name of the Programme: MARINE ENGINEERING

Year of study and Batch/Group : 2nd YEAR BE (ME)18 G-05

Name of the Mentor: MR. HARISH KUMAR J

Title of the assigned internship:

FUEL AND LUBRICATION TECHNOLOGY

Nature of Internship : Individual

Reg No of Cadet who is assigned with this internship:

AME18170




Examiner


Head






Name of the Student DHRUVA R SHETTY


2844B

Programme of study FUEL AND LUBRICATION TECHNOLOGY

Year and Batch/Group 2nd YEAR BEME18 G-05

Semester IV

Title of Internship PUMPS

TURBINES


Mentor of the Student MR. HARISH KUMAR J


Sl

No. Criterion Max. Marks Marks Allotted







7 Adequacy and purposeful write-up of the Internship

Report 10

8 Organization, format, drawings, sketches, style,

language etc. of the Internship Report 10

9 Practical applications, relationships with basic theory

and concepts 10


Total 100

Signature of the Mentor Signature of the Internal

Examiner


Head

1

LEIDEN FROST EFFECT


SUBMITTED

BY

BALAJI PRASAD. N (AME18142)

BE(ME) - 18

ACADEMY OF MARITIME EDUCATION AND TRAINING (AMET)

(Declared as Deemed to be University u/s 3 of UGC Act 1956)


TAMILNADU, INDIA

INTERNSHIP AT HOME

A Report On Internship

In

Department of BE MARINE ENGINEERING

By

Name: Balaji Prasad. N

Register Number: AME18142

Roll No: 2816B

Year: 2nd YEAR

Batch: BE (ME)-18

Group: 4

Subject Code: UDME405

Subject: FLUID MECHANICS

CERTIFICATE

This is to certify that the project entitled “Leiden frost effect” is to bo-

nafide work carried out by the students of AMET UNIVERSITY, KANATHUR (CHENNAI) during the year 2019 -2020 for the partial ful-

fillment of the requirements for the award of the Degree of Bachelor of a

Marine Engineering.



PLACE : AMET UNIVERSITY BE MARINE ENGINEERING

INTRODUCTION

We are going to go through the subject fluid mechanics. We are going to go

through the topics of

LEIDENFROST POINT

HEAT TRANFER CORRELATIONS

PRESSURE FIELD IN LEIDENFROST DROPLET

LEIDENFROST TEMPRATURE AND SURFACE TENTION EFFECT

REACTIVE LEIDENFROST EFFECT

The Leiden frost effect is a physical phenomenon in which a liquid, close to a surface that is

significantly hotter than the liquid's boiling point produces an insulating vapor layer that keeps

the liquid from boiling rapidly. Because of this 'repulsive force', a droplet hovers over the

surface rather than making physical contact with the hot surface.

LEIDENFROST POINT

• The Leidenfrost point signifies the onset of stable film boiling.

• It represents the point on the boiling curve where the heat flux is at the minimum and

the surface is completely covered by a vapor blanket.

• Heat transfer from the surface to the liquid occurs by conduction and radiation through

the vapor. In 1756, Leidenfrost observed that water droplets supported by the vapor film

slowly evaporate as they move about on the hot surface.

• As the surface temperature is increased, radiation through the vapor film becomes more

significant and the heat flux increases with increasing excess temperature.

IN DETAIL

• The effect can be seen as drops of water are sprinkled onto a pan at various times as it

heats up. Initially, as the temperature of the pan is just below 100 °C (212 °F), the water

flattens out and slowly evaporates, or if the temperature of the pan is well below 100 °C

(212 °F), the water stays liquid. As the temperature of the pan goes above 100 °C

(212 °F), the water droplets hiss when touching the pan and these droplets evaporate

quickly. Later, as the temperature exceeds the Leidenfrost point, the Leidenfrost effect

comes into play. On contact with the pan, the water droplets bunch up into small balls of

water and skitter around, lasting much longer than when the temperature of the pan was

lower. This effect works until a much higher temperature causes any further drops of

water to evaporate too quickly to cause this effect.

• This is because at temperatures above the Leidenfrost point, the bottom part of the water

droplet vaporizes immediately on contact with the hot pan. The resulting gas suspends

the rest of the water droplet just above it, preventing any further direct contact between

the liquid water and the hot pan. As steam has much poorer thermal conductivity than

the metal pan, further heat transfer between the pan and the droplet is slowed down dra-

matically. This also results in the drop being able to skid around the pan on the layer of

gas just under it.

• The temperature at which the Leidenfrost effect begins to occur is not easy to predict.

Even if the volume of the drop of liquid stays the same, the Leidenfrost point may be

quite different, with a complicated dependence on the properties of the surface, as well

as any impurities in the liquid. Some research has been conducted into a theoretical

model of the system, but it is quite complicated. As a very rough estimate, the Lei-

denfrost point for a drop of water on a frying pan might occur at 193 °C (379 °F).

• The effect was also described by the eminent Victorian steam boiler designer, Sir Wil-

liam Fairbairn, in reference to its effect on massively reducing heat transfer from a hot

iron surface to water, such as within a boiler. In a pair of lectures on boiler design,he cit-

ed the work of Pierre Hippolyte Boutigny (1798-1884) and Professor Bowman of King's

College, London in studying this. A drop of water that was vaporized almost immediate-ly at 168 °C (334 °F) persisted for 152 seconds at 202 °C (396 °F). Lower temperatures

in a boiler firebox might evaporate water more quickly as a result; compare Mpemba ef-

fect. An alternative approach was to increase the temperature beyond the Leidenfrost

point. Fairbairn considered this too, and may have been contemplating the flash steam

boiler, but considered the technical aspects insurmountable for the time.

• The Leidenfrost point may also be taken to be the temperature for which the hovering

droplet lasts longest.

• It has been demonstrated that it is possible to stabilize the Leidenfrost vapour layer of

water by exploiting superhydrophobic surfaces. In this case, once the vapour layer is es-

tablished, cooling never collapses the layer, and no nucleate boiling occurs; the layer in-

stead slowly relaxes until the surface is cooled.

• Leidenfrost effect has been used for the development of high sensitivity ambient mass

spectrometry. Under the influence of Leidenfrost condition the levitating droplet does

not release molecules out and the molecules are enriched inside the droplet. At the last

moment of droplet evaporation all of the enriched molecules release in a short time do-

main and thus increase the sensitivity

• A heat engine based on the Leidenfrost effect has been prototyped. It has the advantage

of extremely low frictio

ZUBER’S EQUATIONS

The minimum heat flux for a large horizontal plate can be derived from Zuber's equation

Where the properties are evaluated at saturation temperature. Zuber's constant, C is approxi-

mately 0.09 for most fluids at moderate pressures.

HEAT TRANFER CORRELATIONS

The heat transfer coefficient may be approximated using Bromley's equation,[6]

Where, is the outside diameter of the tube. The correlation constant C is 0.62 for horizontal cyl-

inders and vertical plates and 0.67 for spheres. Vapor properties are evaluated at film tempera-

ture.

For stable film boiling on a horizontal surface, Berenson has modified Bromley's equation to

yield,

For vertical tubes, Hsu and Westwater have correlated the following equation,[10]

Where, m is the mass flow rate in at the upper end of the tube

At excess temperatures above that at the minimum heat flux, the contribution of radiation be-

comes appreciable and becomes dominant at high excess temperatures. The total heat transfer

coefficient can be is thus a combination of the two. Bromley has suggested the following equa-

tions for film boiling boiling from the outer surface of horizontal tubes.

The effective radiation coefficient , can be expressed as,

Where, is the emissivity of the solid and is the Stefan-Boltzmann constant

https://en.wikipedia.org/wiki/Leidenfrost_effect#cite_note-ReferenceA-6

https://en.wikipedia.org/wiki/Leidenfrost_effect#cite_note-ReferenceB-10

Pressure field in a Leidenfrost droplet

The equation for the pressure field in the vapor region between the droplet and the solid surface

can be solved for using the standard momentum and continuity equations. For the sake of

simplicity in solving, a linear temperature profile and a parabolic velocity profile are assumed

within the vapor phase. The heat transfer within the vapor phase is assumed to be through

conduction. With these approximations, the Navier-Stokes equation can be solved to get the

pressure field.

Continuity equation

A continuity equation in physics is an equation that describes the transport of some

quantity. It is particularly simple and powerful when applied to a conserved quantity, but

it can be generalized to apply to any extensive quantity.

Since mass, energy, momentum, electric charge and other natural quantities are con-

served under their respective appropriate conditions, a variety of physical phenomena

may be described using continuity equations.

Continuity equations are a stronger, local form of conservation laws. For example, a

weak version of the law of conservation of energy states that energy can neither be cre-

ated nor destroyed—i.e., the total amount of energy in the universe is fixed.

This statement does not rule out the possibility that a quantity of energy could disappear

from one point while simultaneously appearing at another point. A stronger statement is

that energy is locally conserved: energy can neither be created nor destroyed, nor can it

"teleport" from one place to another—it can only move by a continuous flow.

A continuity equation is the mathematical way to express this kind of statement. For ex-

ample, the continuity equation for electric charge states that the amount of electric

charge in any volume of space can only change by the amount of electric current flowing

into or out of that volume through its boundaries

Vapour

In physics, a Vapour and is a substance in the gas phase at a temperature lower than

its critical temperature, which means that the vapor can be condensed to a liquid by in-

creasing the pressure on it without reducing the temperature. A vapor is different from

an aerosol.

An aerosol is a suspension of tiny particles of liquid, solid, or both within a gas.

For example, water has a critical temperature of 647 K (374 °C; 705 °F), which is the

highest temperature at which liquid water can exist.

In the atmosphere at ordinary temperatures, therefore, gaseous water (known as water

vapor) will condense into a liquid if its partial pressure is increased sufficiently.

A vapor may co-exist with a liquid (or a solid). When this is true, the two phases will be

in equilibrium, and the gas-partial pressure will be equal to the equilibrium vapor pres-

sure of the liquid (or solid)

Thermal conduction

Thermal conduction is the transfer of internal energy by microscopic collisions of par-

ticles and movement of electrons within a body.

The colliding particles, which include molecules, atoms and electrons, transfer disor-

ganized microscopic kinetic and potential energy, jointly known as internal energy.

Conduction takes place in all phases: solid, liquid, and gas. The rate at which energy is

conducted as heat between two bodies depends on the temperature difference (and

hence temperature gradient) between the two bodies and the properties of the conductive

interface through which the heat is transferred.

Heat spontaneously flows from a hotter to a colder body. For example, heat is conducted

from the hotplate of an electric stove to the bottom of a saucepan in contact with it.

In the absence of an opposing external driving energy source, within a body or between

bodies, temperature differences decay over time, and thermal equilibrium is approached,

temperature becoming more uniform.

LEIDENFROST TEMPRATURE AND SURFACE TENTION EFFECT

The Leidenfrost temperature is the property of a given set of solid-liquid pair. The

temperature of the solid surface beyond which the liquid undergoes Leidenfrost

phenomenon is termed as Leidenfrost temperature.

The calculation of Leidenfrost temperature involves the calculation of minimum film

boiling temperature of a fluid. Berenson obtained a relation for the minimum film boiling temperature from minimum heat flux arguments.

While the equation for the minimum film boiling temperature, which can be found in the

reference above, is quite complex, the features of it can be understood from a physical

perspective. One critical parameter to consider is the surface tention

The proportional relationship between the minimum film boiling temperature and

surface tension is to be expected since fluids with higher surface tension need higher

quantities of heat flux for the onset of nucleate boling.

Since film boiling occurs after nucleate boiling, the minimum temperature for film

boiling should have a proportional dependence on the surface tension. Henry developed a model for Leidenfrost phenomenon which includes transient wetting

and micro layer evaporation.

Since the Leidenfrost phenomenon is a special case of film boiling, the Leidenfrost

temperature is related to the minimum film boiling temperature via a relation which

factors in the properties of the solid being used.

While the Leidenfrost temperature is not directly related to the surface tension of the

fluid, it is indirectly dependent on it through the film boiling temperature. For fluids with

similar thermo physical properties, the one with higher surface tension usually has a

higher Leidenfrost temperature.

For example, for a saturated water-copper interface, the Leidenfrost temperature is 257 °C (495 °F). The Leidenfrost temperatures for glycerol and common alcohols are

significantly smaller because of their lower surface tension values

Surface tension

Surface tension is the tendency of liquid surfaces to shrink into the minimum surface

area possible. Surface tension allows insects (e.g. water striders), usually denser than

water, to float and slide on a water surface.

At liquid–air interfaces, surface tension results from the greater attraction of liquid mol-

ecules to each other (due to cohesion) than to the molecules in the air (due to adhesion).

The net effect is an inward force at its surface that causes the liquid to behave as if its

surface were covered with a stretched elastic membrane.

Thus, the surface comes under tension from the imbalanced forces, which is probably

where the term "surface tension" came from. Because of the relatively high attraction of

water molecules to each other through a web of hydrogen bonds, water has a higher sur-

face tension (72.8 millinewtons per meter at 20 °C) than most other liquids.

Surface tension is an important factor in the phenomenon of capillarity.

Surface tension has the dimension of force per unit length, or of energy per unit area.

The two are equivalent, but when referring to energy per unit of area, it is common to

use the term surface energy, which is a more general term in the sense that it applies also

to solids.

Nucleate boiling

Nucleate boiling is a type of boiling that takes place when the surface temperature is

hotter than the saturated fluid temperature by a certain amount but where the heat flux is

below the critical heat flux.

For water, as shown in the graph below, nucleate boiling occurs when the surface

temperature is higher than the saturation temperature (TS) by between 10 °C (18 °F) to

30 °C (54 °F). The critical heat flux is the peak on the curve between nucleate boiling

and transition boiling.

The heat transfer from surface to liquid is greater than that in film boiling.

Two different regimes may be distinguished in the nucleate boiling range. When the

temperature difference is between approximately 4 °C (7.2 °F) to 10 °C (18 °F) above

TS, isolated bubbles form at nucleation sites and separate from the surface.

This separation induces considerable fluid mixing near the surface, substantially increas-

ing the convective heat transfer coefficient and the heat flux. In this regime, most of the

heat transfer is through direct transfer from the surface to the liquid in motion at the sur-

face and not through the vapor bubbles rising from the surface.

Between 10 °C (18 °F) and 30 °C (54 °F) above TS, a second flow regime may be ob-

served. As more nucleation sites become active, increased bubble formation caus-

es bubble interference and coalescence. In this region the vapor escapes as jets or col-

umns which subsequently merge into slugs of vapor.

Interference between the densely populated bubbles inhibits the motion of liquid near the

surface. This is observed on the graph as a change in the direction of the gradient of the

curve or an inflection in the boiling curve.

After this point, the heat transfer coefficient starts to reduce as the surface temperature is

further increased although the product of the heat transfer coefficient and the tempera-

ture difference (the heat flux) is still increasing.

When the relative increase in the temperature difference is balanced by the relative re-

duction in the heat transfer coefficient, a maximum heat flux is achieved as observed by

the peak in the graph. This is the critical heat flux.

At this point in the maximum, considerable vapor is being formed, making it difficult for

the liquid to continuously wet the surface to receive heat from the surface. This causes the heat flux to reduce after this point. At extremes, film boiling commonly known as

the Leidenfrost effect is observed.

The process of forming steam bubbles within liquid in micro cavities adjacent to the wall

if the wall temperature at the heat transfer surface rises above the saturation tempera-

ture while the bulk of the liquid (heat exchanger) is sub cooled. The bubbles grow until

they reach some critical size, at which point they separate from the wall and are carried

into the main fluid stream. There the bubbles collapse because the temperature of bulk fluid is not as high as at the heat transfer surface, where the bubbles were created. This

collapsing is also responsible for the sound a water kettle produces during heat up but

before the temperature at which bulk boiling is reached.

Heat transfer and mass transfer during nucleate boiling have a significant effect on the

heat transfer rate. This heat transfer process helps quickly and efficiently to carry away

the energy created at the heat transfer surface and is therefore sometimes desirable—for

example in nuclear power plants, where liquid is used as a coolant.

Viscosity

The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For

liquids, it corresponds to the informal concept of "thickness": for example, syrup has a

higher viscosity than water.

Viscosity can be conceptualized as quantifying the internal frictional force that arises be-

tween adjacent layers of fluid that are in relative motion. For instance, when a fluid is

forced through a tube, it flows more quickly near the tube's axis than near its walls. In

such a case, experiments show that some stress (such as a pressure difference between

the two ends of the tube) is needed to sustain the flow through the tube.

This is because a force is required to overcome the friction between the layers of the flu-

id which are in relative motion: the strength of this force is proportional to the viscosity.

A fluid that has no resistance to shear stress is known as an ideal or in viscid fluid. Zero

viscosity is observed only at very low temperatures in superfluids.

Otherwise, the second law of thermodynamics requires all fluids to have positive viscos-

ity; such fluids are technically said to be viscous or viscid. A fluid with a high viscosity,

such as pitch, may appear to be a solid.

REACTIVE LEIDENFROST EFFECT

Non-volatile materials were discovered in 2015 to also exhibit a 'reactive Leidenfrost

effect,' whereby solid particles were observed to float above hot surfaces and skitter

around erratically. Detailed characterization of the reactive Leidenfrost effect was

completed for small particles of cellulose (~0.5 mm) on high temperature polished surfaces by high speed photography. Cellulose was shown to decompose to short-chain

oligomers which melt and wet smooth surfaces with increasing heat transfer associated

with increasing surface temperature.

Above 675 °C (1,247 °F), cellulose was observed to exhibit transition boiling with

violent bubbling and associated reduction in heat transfer. Lift-off of the cellulose

droplet (depicted at the right) was observed to occur above about 750 °C (1,380 °F)

associated with a dramatic reduction in heat transfer.

High speed photography of the reactive Leidenfrost effect of cellulose on porous

surfaces (macro porous) was also shown to suppress the reactive Leidenfrost effect and

enhance overall heat transfer rates to the particle from the surface.

The new phenomenon of a 'reactive Leidenfrost (RL) effect' was characterized by a dimensionless quantity (φRL= τconv/τrxn), which relates the time constant of solid particle

heat transfer to the time constant of particle reaction, with the reactive Leidenfrost effect

occurring for 10−1< φRL< 10+1.

The reactive Leidenfrost effect with cellulose will occur in numerous high temperature

applications with carbohydrate polymers including biomass conversion to biofuels,

preparation and cooking of food, and tobacco use.

Cellulose

Cellulose is an organic compound with the formula a polysaccharide consisting of a lin-

ear chain of several hundred to many thousands of β(1→4) linked D-

glucose units. Cellulose is an important structural component of the primary cell

wall of green plants, many forms of algae and the oomycetes.

Some species of bacteria secrete it to form biofilms. Cellulose is the most abun-

dant organic polymer on Earth. The cellulose content of cotton fiber is 90%, that

of wood is 40–50%, and that of dried hemp is approximately 57%.

Cellulose is mainly used to produce paperboard and paper. Smaller quantities are con-

verted into a wide variety of derivative products such as cellophane and rayon.

Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is un-

der development as a renewable fuel source.

Cellulose for industrial use is mainly obtained from wood pulp and cotton.

Some animals, particularly ruminants and termites, can digest cellulose with the help

of symbiotic micro-organisms that live in their guts, such as Trichonympha.

In human nutrition, cellulose is a non-digestible constituent of insoluble dietary fiber,

acting as a hydrophilic bulking agent for feces and potentially aiding in defecation.

Oligomer

An oligomer is a molecular complex of chemicals that consists of a few repeating units,

in contrast to a polymer, where the number of monomers is, in principle, infi-

nite. Dimers, trimers, and tetramers are, for instance, oligomers composed of two, three,

and four monomers, respectively.

In biochemistry, an oligomer usually is a macromolecular complex formed by non-

covalent bonding of a few macromolecules like proteins or nucleic acids.

In this sense, a homo-oligomer would be formed of a few identical molecules and by

contrast, a hetero-oligomer would be made of more than one, different, macromole-cules. An example of a homo-oligomeric protein is collagen, which is composed of three

identical protein chains. The term is used with a meaning similar to that of oligomer in

the context of proteins

Many oils are oligomeric, such as liquid paraffin. Plasticizers are oligomer-

ic esters widely used to soften thermoplastics such as PVC. They may be made

from monomers by linking them together, or by separation from the higher fractions

of crude oil.

Polybutene is an oligomeric oil used to make putty. Greek prefixes are often used to des-

ignate the number of monomer units in the oligomer, for example, a tetramer being

composed of four units and a hexamer of six.

In biochemistry, the term oligonucleotide – or, informally, "oligo" – is used for short, single-stranded nucleic acid fragments, such as DNA or RNA, or similar fragments of

analogs of nucleic acids such as peptide nucleic acid or Morpholinos.

Such oligos are used in hybridization experiments (bound to glass slides

or nylon membranes), as probes for in situ hybridization or in antisense experiments

such as gene knockdowns. It can also refer to a protein complex made of two or

more subunits.

In this case, a complex made of several different protein subunits is called a hetero-

oligomer or heteromer. When only one type of protein subunit is used in the complex, it

is called a homo-oligomer or homomer.

Biofuel

A biofuel is a fuel that is produced through contemporary processes from biomass, ra-

ther than a fuel produced by the very slow geological processes involved in the for-

mation of fossil fuels, such as oil.

Since biomass technically can be used as a fuel directly (e.g. wood logs), some people

use the terms biomass and biofuel interchangeably.

More often than not however, the word biomass simply denotes the biological raw mate-

rial the fuel is made of, or some form of thermally/chemically altered solid end product,

like torrefied pellets or briquettes. The word biofuel is usually reserved for liquid or gas-eous fuels, used for transportation. The EIA (U.S. Energy Information Administration)

follow this naming practice.

If the biomass used in the production of biofuel can regrow quickly, the fuel is generally

considered to be a form of renewable energy.

Biofuels can be produced from plants (i.e. energy crops), or from agricultural, commer-cial, domestic, and/or industrial wastes (if the waste has a biological origin). Renewable

biofuels generally involve contemporary carbon fixation, such as those that occur

in plants or microalgae through the process of photosynthesis.

Some argue that biofuel can be carbon-neutral because all biomass

crops sequester carbon to a certain extent – basically all crops move CO2 from above-

ground circulation to below-ground storage in the roots and the surrounding soil.

For instance, McCalmont et al. found below-ground carbon accumulation ranging from

0.42 to 3.8 tonnes per hectare per year for soils below Miscanthus x giganteus energy

crops, with a mean accumulation rate of 1.84 tonne (0.74 tonnes per acre per year), or

20% of total harvested carbon per year

However, the simple proposal that biofuel is carbon-neutral almost by definition has been superseded by the more nuanced proposal that for a particular biofuel project to be

carbon neutral, the total carbon sequestered by the energy crop's root system must com-

pensate for all the above-ground emissions (related to this particular biofuel project).

This includes any emissions caused by direct or indirect land use change. Many first

generation biofuel projects are not carbon neutral given these demands. Some have even

higher total GHG emissions than some fossil based alternatives.

Some are carbon neutral or even negative, though, especially perennial crops. The

amount of carbon sequestrated and the amount of GHG (greenhouse gases) emitted will

determine if the total GHG life cycle cost of a biofuel project is positive, neutral or nega-

tive. A carbon negative life cycle is possible if the total below-ground carbon accumula-

tion more than compensates for the total life-cycle GHG emissions above ground. In

other words, to achieve carbon neutrality yields should be high and emissions should be

low.

High-yielding energy crops are thus prime candidates for carbon neutrality. The graphic

on the right displays two CO2 negative Miscanthus x giganteus production pathways,

represented in gram CO2-equivalents per megajoule. The yellow diamonds represent

mean values.

Further, successful sequestration is dependent on planting sites, as the best soils for se-

questration are those that are currently low in carbon.

The varied results displayed in the graph highlights this fact. For the UK, successful se-

questration is expected for arable land over most of England and Wales, with unsuccess-

ful sequestration expected in parts of Scotland, due to already carbon rich soils (existing

woodland) plus lower yields.

Soils already rich in carbon includes peatland and mature FROST. Grassland can also be

carbon rich, however Milner et al.

argues that the most successful carbon sequestration in the UK takes place below im-

proved grasslands.

The bottom graphic displays the estimated yield necessary to compensate for related

lifecycle GHG-emissions. The higher the yield, the more likely CO2 negativity becomes.

The two most common types of biofuel are bioethanol and biodiesel.

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced

in sugar or starch crops such as corn, sugarcane, or sweet sorghum. Cellulosic biomass,

derived from non-food sources, such as trees and grasses, is also being developed as

a feedstock for ethanol production.

Ethanol can be used as a fuel for vehicles in its pure form (E100), but it is usually used

as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is

widely used in the United States and in Brazil.

Biodiesel is produced from oils or fats using transesterification and is the most common

biofuel in Europe. It can be used as a fuel for vehicles in its pure form (B100), but it is

usually used as a diesel additive to reduce levels of particulates, carbon monoxide,

and hydrocarbons from diesel-powered vehicles.

CONCLUSION

Thus, in this presentation we saw about the topics:

➢ LEIDENFROST EFFECT

Water droplets at 4 nm and 10 nm were simulated over gold and silicon substrates

at 293 K and 373 K, respectively. At 293 K, both the droplets remained stationary

on the substrate limiting their displacement from their original position. However,

smaller droplets (4 nm) displayed higher random velocity about their mean

position as compared to the 10 nm droplets.

This can be attributed to the fact that smaller droplets have fewer atoms enabling

higher variability for its centroid due to the smaller aggregation pool. The

Leidenfrost effect was observed when droplets were deposited on the heated

substrate at 373 K. This result is in contrast with the Leidenfrost effect at the

macro- and micro-scale which is typically observed for temperatures over 473 K.

At 373 K, the 4 nm droplets presented higher propagation velocities than the

10 nm droplets.

This is due to the fact that smaller droplets have a higher surface to volume ratio

which makes the smaller droplets absorb higher energy per unit volume. Also,

molecules at the surface of the droplet have fewer hydrogen bonds and require

less energy to separate from other molecules.

Thus, when exposed to a heated substrate, the breakage of hydrogen bonds is

accelerated on smaller droplets as they possess proportionally fewer hydrogen

bonds. In addition, the smaller droplets have a lower inertia and thereby are

prominently influenced by the propelling forces of the vapor layer.

Droplets deposited over gold substrate had higher velocities than droplets

deposited over silicon. Silicon substrates are more hydrophilic than gold

substrates, and the affinity between liquid and substrate acts as a restrain to the

droplet movement.

These results reveal the interplay of different process parameters which impact

the Leidenfrost effect, an unexplored phenomenon at the nanoscale.

This research forms a foundation to understand nanoscale droplet propagation

and heat transfer within several droplet based nano- and micro-manufacturing

processes.

This work presented a theoretical background on the Leidenfrost effect and

performed experiments and measurements of the Leidenfrost effect on water

droplets on a hot plate.

Relationship between Oscillation Frequecny and Radii for droplets under three

different oscillation modes . Frequency as a function of wavelength were

compared against the theoretical approximations.

analyzed the heat transfer mechanisms that occur in the droplet using Rayleigh’s

number and found them to be primarily convection.

We also investigated the droplets geometry based on their Bond numbers,

characterizing them as either spherical or cylindrical.

experimentally induced the oscillations using a mechanical impulse generator

which allowed us to induce several different oscillation modes.

analyzed the frequency of oscillation as a function of the mode number and

droplet radius.

presented theoretical approximations for frequency of oscillation and wavelength

and compared them against the experimental results. In all cases the experimental

results were close to the theoretical value.

PHOTOGRAPH






Name of the Programme: MARINE ENGINEERING

Year of study and Batch/Group: 2nd YEAR BE (ME) 18 G-4

Name of the Mentor: HARISH KUMAR. J

Title of the assigned internship:

FLUIED MECHANICS

Nature of Internship: Individual

Reg No of Students who are assigned with this internship:

AME18142




Examiner

Signature of

HOD/Programme Head






Name of the Student BALAJI PRASAD.N


2816B

Programme of study FLUID MECHANICS

Year and Batch/Group 2nd YEAR BE (ME)18 G-4

Semester IV

Title of Internship LEIDENFROST EFFECT


Mentor of the Student MR.J. HARISH KUMAR


Sl

No. Criterion Max. Marks

Marks

Allotted







7 Adequacy and purposeful write-up of the Internship

Report 10

8 Organization, format, drawings, sketches, style,

language etc. of the Internship Report 10

9 Practical applications, relationships with basic theory

and concepts 10


Total 100



Examiner

Signature of

HOD/Programme Head

properties of fluid and its characteristics

Documents