Monday, 21 September 2015

Engineering terms

Torque or Turning Force:
 
It is the total amount of force which is required to create acceleration on moving substance.



Couple:
 
Two forces those acts on equally, parallely & oppositely on two separate points of same material.



Moment:
 
It is the amount of moving effect which is gained for action of turning force.


Stress:
 
It is the force that can prevent equal & opposite force. That means, it is the preventing force. If one force acts on outside of a material, then a reactive force automatically acts to protest that force. The amount of reactive force per unit area is called stress. e.g. Tensile Stress, Compressive Stress, Thermal Stress.


Strain:
 
If a force acts on a substance, then in that case if the substance would deform. Then the amount of deformation per unit length of that substance is called strain.


Spring:
 
It is one type of device which is being distorted under certain amount of load & can also go to its original face after the removal of that load.

Its function:

To store energy.

To absorb energy.

To control motion of two elements.



Stiffness:
 
Load per unit deflection. The amount of load required to resist the deflection.



Specific Weight:
 
Weight per unit volume of the fluid.



Specific Volume:
 
Volume per unit mass of the fluid.



Specific Gravity:
 
It is the ratio of specific weight of required substance to specific weight of pure water at 4 degree centigrade temperature.



Specific heat:
 
The amount of heat required to increase 1 unit temperature of 1 unit mass.



Viscosity:
Dynamic Viscosity:
 
The amount of resistance of one layer of fluid over other layer of fluid.



Kinematic Viscosity:
 
It is the ratio of dynamic viscosity to density.



Buoyancy:
 
When a body is immersed in a liquid, it is lifted up by a force equal to weight of liquid displaced by the body. The tendency of liquid to lift up an immersed body is buoyancy. The upward thrust of liquid to lift up the body is called buoyancy force.

Bernoulli's Equation:
 
P/γ +V²/2g +Z = Constant

Where, P = pressure,V = velocity,Z = Autumn Head

Devices for fluid:

Venturimeter:
It measures discharge of fluid.


Notches :
It measures discharge of fluid.


Orifice meter:
It measures the flow rate of fluid.


Pitot tube :
It measures velocity of fluid.



Mach Number:
 
It is the ratio of the velocity of fluid to the velocity of sound.
M=1 ----------------- Sonic flow
M> (1-6) ----------- Super-Sonic flow
M>6 ---------------- Hyper-Sonic flow

Fluid discharge/Fluid flow:
Quantity of fluid flowing per second.

(through a section of pipe/ through a section of channel)

Q=AV

where, V= velocity of fluid,A= cross-sectional area of pipe/channel
Note: 1m³ = 1000 L1 cusec = 1 ft³/sec1 ft = 0.3048 m



Hydraulic Machine:
 
Turbine,Pump,Compressor etc.


Draft tube:
It attaches with reaction turbine . Its function is to reduce energy loss from reaction turbine & it also reduce pressure at outlet which is must blow the atmospheric pressure.


Thermodynamics Law:
 
Zeroth Law
First Law of Thermodynamic
Second Law of thermodynamic

Zeroth Law:
If two body are in thermal equilibrium with a third body then these two body are also in thermal equilibrium with each other.


First Law of Thermodynamics:
In a closed system, work deliver to the surrounding is directly proportional to the heat taken from t



Thermodynamics Law:
 
Zeroth Law
First Law of Thermodynamic
Second Law of thermodynamic

Zeroth Law:
If two body are in thermal equilibrium with a third body then these two body are also in thermal equilibrium with each other.


First Law of Thermodynamics:
In a closed system, work deliver to the surrounding is directly proportional to the heat taken f
he surrounding. And also, In a closed system, work done on a system is directly proportional to the heat deliver to the surrounding.


Second Law of Thermodynamics:
It is impossible to make a system or an engine which can change 100 percent input energy to 100 percent output.


Entropy:
It is a thermodynamic property.

ds = dq/T

where, ds = change of entropy, dq = change of heat, T = Temperature.

In adiabatic process, entropy can not change. Actually, lacking or mal-adroitness of transferring energy of a system is entropy.


Calorific Value of fuel:
It us the total amount of heat obtained from burning 1 kg solid or liquid fuel.

Boiler/Steam

Generator:
It is a closed vessel which is made of steel. Its function is to transfer heat to water to generate steam.


Economiser:
It is a part of boiler. Its function is to heat feed water which is supplied to boiler.


Super heater:
It is a part of boiler. Its function is to increase temperature of steam into boiler.


Air-Preheater:
It is a part of boiler. Its function is to preheats the air to be supplied to furnace and it recover heat from exhaust gas.


Boiler Draught:
It is an important term for boiler. It is the difference of pressure above and below the fire grate. This pressure difference have to maintain very carefully inside the boiler. It actually maintained the rate of steam generation. This depends on rate of fuel burning. Inside the boiler rate of fuel burning is maintained with rate of entry fresh air. If proper amount of fresh air never entered into the boiler, then proper amount of fuel inside the boiler never be burnt. So, proper fresh air enters into the boiler only by maintaining boiler draught.


Nozzle:
Nozzle is a duct of varying cross-sectional area. Actually, it is a passage of varying cross-sectional area. It converts steam's heat energy into mechanical energy. It is one type of pipe or tube that carrying liquid or gas.

Scavenging:
It is the process of removing burnt gas from combustion chamber of engine cylinder.


Supercharging:
Actually, power output of engine depends on what amount of air enter into the engine through intake manifold. Amount of entry air if increased, then must be engine speed will increased. Amount of air will be increased by increasing inlet air density. The process of increasing inlet air density is supercharging. The device which is used for supercharging is called supercharger. Supercharger is driven by a belt from engine crankshaft. It is installed in intake system.


Turbocharging:
Turbocharging is similar to the supercharging. But in that case turbocharger, it is installed in exhaust system whereas supercharger is installed in intake system. Turbocharger is driven by force of exhaust gas. Generally, turbocharger is used for 2-stroke engine by utilising exhaust energy of the engine, it recovers energy otherwise which would go waste.


Governor:
Its function is to regulate mean speed of engine when there are variation in the load. If load increases on the engine, then engine's speed must decrease. In that case supply of working fluid have to increase. In the other way, if load decrease on the engine, then engine' speed must increase. In that case supply of working fluid have to decrease.Governor automatically, controls the supply of working fluid to the engine with varying load condition.


Flywheel:
It is the one of the main parts of the I.C. engine. Its main function id to store energy in the time of working stroke or expansion stroke. And, it releases energy to the crankshaft in the time of suction stroke, compression stroke & exhaust stroke. Because, engine has only one power producing stroke.

Rating of fuel:
S.I. Engine:
Octane number. Octane number indicates ability of fuel to resist knock.
 

Stoichiometric ratio:
It is the chemically correct air-fuel ratio by volume. By which theoretically sufficient oxygen will be gotten to burn all combustible elements in fuel completely.


Heat Transfer:
It is a science which deals with energy transfer between material bodies as a result of temperature difference.There are three way to heat transfer such as-
Conduction, Convection & Radiation


Thermal Conductivity:
It is the quantity of heat flows between two parts of solid material by conduction. In this case following consideration will be important fact-

Time------ 1 sec

Area of that solid material-------- 1 m²

Thickness of that solid material------ 1m

Temperature difference between two parts of that material------ 1k


Heat Exchanger:
It is one type of device which can transfer heat from one fluid to another fluid. Example- Radiator, intercooler, preheater, condenser, boiler etc.


Refrigeration:
It is the process of removing heat from a substance. Actually, extraction of heat from a body whose temperature is already below the temperature of its surroundings.


1 tonne of refrigeration:
It is amount of refrigeration effect or cooling effect which is produced by uniform melting of 1 tonne ice in 24 hours from or at 0 degree centigrade or freezing 1 tonne water in 24 hours from or at 0 degree centigrade.


Humidification:
It is the addition of moisture to the air without change dry bulb temperature.


De-humidification:
It is the removal of moisture from the air without change dry bulb temperature.


Gear Train:
Meshing of two or more gear. It can transmit power from one shaft to another shaft.


Heat Treatment:
Operation involving heating and cooling of a metal in solid state for obtaining desirable condition without being changed chemical composition.Its object-increase hardness of metal.increase quality of metal ( heat, corrosion,wear resistance quality )improve machinability.


Ferrous Metal:
1. Cast Iron - (2-6.67)%C, Si, Mn, P, S

2. Steel - (0-2)%C

3. Wrought Iron - 99.5% Fe


Non-Ferrous Metal:
1. Brass - (Cu+Zn)

2. Bronze -

(Sn+Cu) ------ Tin Bronze

(Si+Cu) ------- Silicon Bronze

(Al+Cu) ------- Aluminium Bronze


Allowance:
It is the difference between basic dimension of mating parts. That means, minimum clearance between mating parts that can be allowed.


Tolerance:
It is the difference between upper limit of dimension. It is also the permissible variation above and below the basic size. That means maximum permissible variation in dimensions.


Clearance:
It is the difference in size between mating parts. That means, in that case the outside dimension of the shaft is less than internal dimension of the hole.


Stiffness:
It is the ability to resist deformation.


Toughness:
It is the property to resist fracture.


Fatigue:
When a material is subjected to repeated stress below yield point stress, such type of failure is fatigue failure.


Nuclear Fission:
It is a nuclear reaction by which one big nucleus divided into two or more nucleus.


Nuclear Fusion:
It is also a nuclear reaction by which one big nucleus will produced by adding two small nucleus.


Welding:
It is the process of joining two similar or dissimilar metal by fusion.


Arc Welding -

* need D.C current

* produced (6000-7000) Degree Centigrade Temperature


Gas Welding -

* Oxy - acetylene flame join metals

* Oxygen & acetylene gas works

* produced 3200 Degree Centigrade Temperature



Machine Tool:
It is the power driven tool. It cut & form all kinds of metal parts.

Example - 1. Lathe 2. Drill Press 3. Shaper 4. Planer 5. Grinding 6. Milling 
7. Broaching 8. Boring


Cutting Tool:

Tool Materials for Cutting Tool:
1. High Carbon Steel

2. High Speed Steel (W+Cr+V)

3. Carbide (W Carbide+Ti Carbide+Co Carbide)


Indexing:

It is the method of dividing periphery of job into equal number of division. Actually, it is the process of dividing circular or other shape of workpiece into equal space, division or angle.



Jig:
  It is one type of device which hold & locate workpiece and also guide & control cutting tool. It uses in drilling, reaming and tapping.



Fixture:
It is one type of device which hold and locate workpiece. It uses in milling, grinding, planning & turning.

Sunday, 13 September 2015

SOLAR POWERED AIR CONDITIONER


Powering AC with solar energy

Introduction

Summer is the time when you wished you had an Air Conditioner. But, you would rather detest the idea because of the staggering electricity bills you would get once you start using the AC. And it would be a miracle if you could use an AC without paying those hefty electricity bills. In that case, it seems a miracle has just happened!
How about utilizing the free energy of the sun to power up your AC?
The hottest months usually, happens to be also the sunniest. You can use the scorching summer heat to actually remove the heat from your room with the help  Photovoltaics (PVs) to power your AC. Photovoltaics are collection of cells which have photovoltaic material that makes use solar radiation to develop direct current electricity. For achieving the best performance the PVs are connected to a solar tracker so as to align themselves towards the sun to receive the maximum amount of solar radiation. The use of a solar tracker would improve the performance of the PVs by whopping 50% in summer.
The use of Concentrated Solar power systems (CSP ) further enhances the utilization of solar power by making use of mirrors to concentrate solar energy onto a photovoltaic cell.  Since CSP systems  are bigger in construction and expensive they are seldom used to generate power for an air conditioner.
A typical air conditioner consists of the following
1)      Condensing coil
2)      Expansion valve
3)      Evaporator Coil
4)      Compressor
Once, the direct current developed by the PVs is fed to the Air Condition unit, you have an Air Conditioner which works on Solar Panels and you can be free from the tension of electricity bills draining your pockets.
Excess power if developed can be used to power other electrical appliance or sold back to a power grid! Ultimately the success of the system would depend upon the cost effectiveness.

COST ESTIMATION:

The cost of the solar panel (240 V) itself is about $650. The cost of the air conditioner and other accessories will come around another $600. So the total cost will be about $1200 but if you can obtain second hand materials it will be much economical. (The cot estimation is approximate)
reference video : https://youtu.be/qTYGloPSGec


GRAVITY POWER GENERATION MECHANISM

Introduction

The energy sources for man are drying up. The era of fossil fuels is going to end very soon. Scientists are now working on to find new renewable sources of energy. Along with renewable energy sources like light and wind comes gravity.
Gravity is a phenomenon that existed from the very beginning of the universe but only discovered by Sir Isaac Newton not more than 400 years ago. Recently scientists started generating energy from gravity.
The basic concept of a gravity power generating mechanism is simple. When a body goes down from a higher altitude to a lower one its potential energy is converted into kinetic energy via linear motion. This motion is converted circular motion and is then converted to electricity using a dynamo.
One challenge in this mechanism is about getting continuous supply of energy. A body cannot go downward infinitely, but for continuous power generation this practically impossible scenario is necessary.
An interesting solution for this problem was invented by Mr. Rajesh Mulchandani and he has applied for patent. He uses gravity and buoyancy of water to generate a continuous up and down motion. The mechanism consists of a water filled tank with 50-60meters high with 2 balanced masses capable of moving using both buoyancy and gravity.

gravity power generation mechanism
gravity power generation mechanism
As a final year mechanical engineering project this may be too expensive. But there may be more simple ideas to generate motion continuously.
reference video : https://youtu.be/L0CrqYjX-d8,
                     https://youtu.be/pw3lpFvuzps
reference link : http://www.freepatentsonline.com/20090115195.pdf

HYDROGEN (WATER) POWERED VEHICLE

Introduction 


Finally the science of Hydrogen automotive power has been made a reality! Technically a device that converts the energy stored in hydrogen into motion can be called a Hydrogen engine. Hydrogen would make a great fuel for the environment since burning Hydrogen produces nothing but water!
Hydrogen Powered car essentially consists of the following
1)      Fuel tank
Liquid hydrogen is stored in a tank at the rear of the car and is pumped forward to the fuel cell stack as and when required.
2)      Fuel Cell Stack
When Hydrogen is combined with Oxygen in a fuel cell a chemical reaction creates electricity.

Hydrogen Powered vehicle


     















1)      Battery Pack
The battery pack is periodically recharged by the fuel cell. The power from the battery pack is used to provide rapid acceleration.
2)      Electric Motor
The stack provides electricity for the electric motor that powers the vehicle
Right from the year 1625, when Johann Baptista van Helmont discovered the gas, Hydrogen; people were curious enough to find the uses of the new found gas. It nearly took a mind boggling 181 years to develop an internal combustion engine which runs on a mixture of hydrogen and water by the icon of 18th century who is none other than, Francois Issac de Rivaz. The Swiss inventor, is credited with the development and construction of the world’s first IC engine back in 1806. From then onwards, it was always a challenge to develop the best IC engine. This has lead to developing different varieties of engines.
A pictorial representation of the Hydrogen powered vehicle is shown below.
Hydrogen Powered vehicle


How a Differential Works and Types of Differentials

Introduction




Reference video : https://youtu.be/gIGvhvOhLHU
                             https://youtu.be/FwhrmFuov-4

Howercraft

Introduction

 Howercraft is like a miracle machine ,it can works on water as well as land.



HOW TO MAKE A HOVERCRAFT


        The idea of making a Hovercraft dates back to 1716 when Emmanual Swedenborg recorded a design, but it was short lived.  In 1870, Sir John Thornycroft filled patents involving air lubricated hulls. And it was in 1959 a hovercraft was built, by Christopher Sydney Cockerell  by discovering the Momentum Curtain theory. Hover craft also called Air cushion vehicle (ACV) travels on any kind of flat surface. It is supported by a cushion of pressurized air.


Design
  1. Can be powered by one or more engines
  2. Small crafts have a single engine with the drive split through a gear box 
  3. Usually one engine drives the fan responsible for lifting the vehicle
  4. The other forces air from
hovercraft

Working
Two main principles:
1)      Lift
2)      Propulsion
  1. A skirt is required to quarantine airflow 
  2. No contact with ground hence friction is eliminated
  3. The shape of the body affects stability
  4. All parts are essential for proper working

Parts
1)      Lifting fan: Usually a centrifugal fan is preferred. When rotated air is sucked into the center hole, it is coupled via a gearbox and connected to the engine
2)      Thrust propellers: An aircraft type propeller with variable type pitch blades. Diameter ranges from nine feet to nineteen feet. In bigger crafts the propellers are rotated while in smaller ones, rudders are used.
3)      Skirt: Flexible strip which is fitted below the bottom edges of the plenum chamber. Skirt design is the most sensitive design parameter as it protects the craft and helps to lift it even higher.

hovercraft diagram

In theory hovercrafts are simple machines but a plethora of problems exist to make a functioning hovercraft. The plans as well as the design must be flawless. To build a hovercraft one must be well aware of the demands of construction. Only then can one design a hovercraft.

Uses : In transport.


Reference video : https://youtu.be/1OMSdA4-Gn4

Fuel Efficiency in All Wheel Drive (AWD) System

Introduction


        What people look for when buying a car? Many things, we do a lot of research before making such an investment. And one of the major features we look into is its fuel efficiency. The race to produce the most fuel efficient engine is now going on in India. Each month car companies are proving that this race will go on for a while (The last car released Honda Jazz has an FE of 27 km/litre for its diesel model, this was unthinkable a few years ago.
         We, mechanical engineers, know that a 2 WD vehicle is more fuel efficient than a 4WD one. Though the car companies in India except Mahindra & Toyota (for SUVs) are not coming with any 4 WD vehicles now, it could be the next trend in Indian automobile industry.
           This final year mechanical project is about creating a software simulation system to find out the power losses in the propeller shafts of All Wheel Drive (AWD) vehicles. The simulation program developed is called ‘Propeller Shaft Calculator’. This calculator is not an actual computer program but rather a ‘MS Excel’ program which contains rows and columns where you can input different dimensions and it calculates and outputs the apt dimensions for the new energy efficient propeller shaft.
           In this project different components of an AWD system is studied closely to see if there are any potential ways to reduce power loss. The components for the study involves propeller shaft, joints and bearings of the AWD system. The aim of this project is to create a simple tool that will help in the making of a better fuel efficient propeller shaft.

The aims of this project include:
• Obtain deeper knowledge about the chosen parts on the propeller shaft to find the greatest causes to power losses and to give proposals how these can be reduced.

• Write a report with facts about the propeller shaft and its components that can be used as a support while designing an efficient driveline.

• Create a program that calculates the different angles and directions between the parts on the propeller shaft after inserted specific data.

• Create a model for calculating the natural frequency of the propeller shaft.

• Get to know engineers within the Automotive industry.

• Learn how a modern AWD-system works.

• Increase the knowledge about the car manufacturing industry.

Last but not the least, this program doesn’t calculate the power losses on different joints of the propeller shaft.

Reference video : https://youtu.be/HJiH3eYfelM

Solar dehydrator using beer cans

Abstract
        Drying is very important process applicable for agricultural and industrial products. Drying is the moisture removing process from the products. Drying reduces the bacterial growth in the products. It will helpful for preserving the products for long time. Solar drying is the oldest method of products drying. Open air solar drying method is used frequently to dry the agricultural products. But this method has some disadvantages. Therefore to avoid disadvantages it is necessary to use the other solar drying methods. Different solar drying methods are direct solar drying, indirect solar drying, and mixed mode solar drying.The device developed and used for proposed drying process with application of solar energy is called the solar dehydrator using discarded beer cans. Solar dryers are also classified with mode of air circulation. In this project, we developed the solar drying and low cost solar drying techniques.
           Sun drying is still the most common method used to preserve agricultural products in most tropical and subtropical countries. However, being unprotected from rain, wind-borne dirt and dust, infestation by insects, rodents and other animal products may be seriously degraded to the extent that sometime become inedible. The resulted loss of food quality in the dried products may have adverse economic effects on domestics and international markets. Some of the problems associated with open-air sun drying can be solved through the use of a solar dryer which comprises of collector, a drying chamber and sometimes a chimney.

          The conditions in tropical countries make the use of solar energy for drying food practically attractive and environmentally sound. Dryers have been developed and used to dry agricultural products in order to improve shelf life. Most of these either use an expensive source of energy such as electricity or a combination of solar energy and some other form of energy. Drying may be an interesting method in order to prevent fresh fruit deterioration. There is spoilage of fruits and other fresh foods that could be preserved using drying techniques in India and other developing countries. Seasonal fruits like mangoes are not presently dried for export, or for local consumption during period of scarcity.

   fig. Types of solar dehydrator


Advantages of Solar Drying System
            Solar dryers have the principal advantage of using solar energy-a free, available, and limitless energy source that is also non polluting. Drying most foods in sunny areas should not be a problem. vegetables, for example, can be dried in 2-1/2.to 4 hours, at temperatures ranging from 43 to 63°Centigrade ( l0 to l45°Fahrenheit). Fruits take longer, from 4 to 6 hours, at temperatures ranging from 43 to 66°Centigrade (110 to 150°Fahrenheit). At this rate, it is possible to dry two batches of food on a sunny day.
            A solar food dryer improves upon the traditional open-air systems in five important ways:
1). It is faster:- Foods can be dried in a shorter amount of time. Solar food dryers enhance drying times in two ways. First, the translucent or transparent glazing over the collection area traps heat inside the dryer, raising the temperature of the air. Second, the capability of enlarging the solar collection area allows for the concentration of the sun's energy.
2). It is more efficient:- Since foodstuffs can be dried more quickly, less will be lost to spoilage immediately after harvest. This is especially true of produce that requires immediate drying such as a grain with a high moisture content. In this way, a larger percentage of food will be available for human consumption. Also, less harvest will be lost to marauding animals, vermin, and insects since the food will be in an enclosed compartment.
3). It is safer:- Since foodstuffs are dried in a controlled environment, they are less likely to be. contaminated by pests, and can be stored with less likelihood of the growth of toxic fungi.
4). It is healthier:- Drying foods at optimum temperatures and in a shorter amount of time enables them to retain more of their nutritional value especially vitamin C. An extra bonus is that foods will look and taste better, which enhances their marketability.
5). It is cheaper:- Using solar energy instead of conventional fuels to dry products, or using a cheap supplementary supply of solar heat in reducing conventional fuel demand can result in a significant cost savings. Solar drying lowers the costs of drying, improves the quality of products, and reduces losses due to spoilage.

Disadvantages of Solar Drying System
            Solar dryers do have short comings. They are of little use during cloudy weather. During fair weather they can work too well, becoming so hot inside at midday as to damage the drying crop. Only with close supervision can this be prevented. As temperatures rise (determined with a thermometer or by experience), the lower vents must be opened to allow greater airflow through the dryer and to keep the temperatures down. Rice, for example, will crack at temperatures above 50°C seed grains can be dried at temperatures no higher than 40 to 45°Centigrade.

Solar Dryer Applications
            Solar energy is use throughout the world to dry food products. List below are a few representative item to show the diversity to which the sun’s energy is put to use
·         Grains
·         Vegetables
·         Meat
·         salt
·         fruits
·         fish
·         clothes.