Boilers

A boiler (or steam generator, as it is commonly called) is a closed vessel in which water, under pressure is transform into steam by the application of heat. Open vessels and those generating steam at atmospheric pressure are not considered to be boilers.

 In the furnace the chemical energy in the fuel is converted into heat, and it is the function of the boiler to transfer this heat to the water in the most efficient manner. thus the primary function of a boiler is to generate steam at pressure above atmospheric by the absorption of heat that is produced in the combustion of fuel .

A boiler should be designed to absorb the maximum amount of heat released in the process of combustion. This heat is transmitted to the boiler by radiation, conduction, and convection, the percentage of each depending on the boiler design. 

Boiler types :

1) Fire-tube boilers : are so named because the product of combustion pass through tubes that are surrounded by water. They may be either internally fired or externally fired. 

2) Water-tube boilers :is one in which the products of combustion pass around tubes containing water.

3) package boiler 

Nomographs in hybrid system

A Nomograph is a kind of chart that conveys the relationship between

different sets of numbers. The hybrid operation nomographs below

convey the relationship between RPM for MG1, MG2 and the engine.

Because MG1, MG2 and the engine are mechanically connected in the

Planetary Gear Set, if one of the components changes rpm, the rpm of

the other components will be affected. So in the nomograph, the rpm

values of the 3 power sources maintain a relationship in which they are

always connected by a straight line.

Figures down below shows nomographs for different  modes of Toyota Prius

1. Ready-on

 

2. Starting out

3. Engine starting

4. Light acceleration with engine

5. Low speed cruising 

6. Full acceleration

7. High speed cruising 

 

8. Maximum speed

9. Braking

10. Reverse 

Hybrid system overview

The hybrid system is the wave of the future, and now there are more incentives to purchase one. Owners of the Prius, or any other hybrid gas-and-electric vehicle, may be eligible for a federal income tax deduction. According to the internal revenue service, hybrid vehicles qualify for a long-standing tax deduction that applies to vehicles powered by clean burning fuels. The policy allows a one-minute deduction, which can be claimed by the consumer for claimed by the consumer for the year the car was first put in use.

In its simplest form, a hybrid system combines the best operating characteristics of an internal combustion engine and an electric motor more sophisticated hybrid systems, such the Toyota hybrid system,  recover energy otherwise lost to heat in the brakes and use it to supplement the power of its fuel-burning engine. These sophisticated techniques allows the Toyota hybrid system to achieve superior fuel efficiency and a massive reduction in CO2.

Hybrid system components:-

• IC engine {internal combustion engine}
• Motor generator 1
• Motor generator 2
• Planetary gear set 
• Inverter 
• HV Battery 
• HV ECU

/-Motor generator 1 

MG1

Motor generator 1 operates as the control element for the power splitting planetary gear set. It recharges the HV battery and also supplies electrical power to drive motor generator 2. MG1 effectively controls the continuously variable transmission function of the trans-axle and operates as the engine starter. 

/-Motor generator 2

MG2 is used for motive force at low speeds and supplemental force at high speeds. It provides power assist to the engine output as needed and helps the vehicle achieve excellent dynamic performance. It also function as a generator during regenerative braking.

/-The planetary gear unit

Is a power splitting device. MG1 is connected to the sun gear, MG2 is connected to the ring gear and the engine output shaft is connected to the planetary carrier. These components are user to combine power delivery from the engine and MG2, and to recover energy to the HV battery.

/-Inverter

Current between MG1,MG2 and the HV battery is controlled by the inverter. The inverter converts high voltage battery DC to AC power, and it rectifies high voltage AC from MG1 and MG2 to recharge the HV battery.

/-HV battery 

The battery stores power recovered by MG2 during regenerative braking and power generated by MG1. The battery supplies power to the electric motor when starting off or when additional power is required.

 *THS (2001−2003 Prius)   

 38 Nickel−Metal Hydrid modules 

Total voltage: 273.6V

 *THS−II (2004 and later Prius) 

    28 Nickel−Metal Hydride modules

Total voltage: 201.6V

  

Atkinson cycle

THE ATKINSON CYCLE

the Atkinson cycle significantly improved the fuel-efficiency of a four-stroke spark ignition engine through one particularly ingenious modification.

The four basic phases of the Otto cycle remained but Atkinson introduced a new timing sequence to delay the closing of the intake valve during the compression stroke. Keeping the intake valve open slightly longer effectively reduced the engine’s displacement during the intake cycle but retained the full ratio of expansion in the combustion or power stroke.

In simple terms, the Atkinson cycle was designed to minimise the use of fuel during the intake stroke yet exploit the part of the cycle that generates power.

All explained in the video below:

  https://youtu.be/uhtMEvfZkdM

Rankine Cycle

The figure above shows Rankine cycle which includes the following  processes :

2-3 Boiler : in this stage compressed water at point (2) enters the boiler to increase it's temperature by heat exchange between fire and water, it then leaves as superheated vapor at point (3).This process called Isobaric process since the pressure during this process remains constant .

3-4 Turbine : superheated vapor (high pressure and high temperature) enters the turbine, during this process the vapor will expand and rotate the blades of the turbine. the turbine connected with electrical generator to produce electricity,after this vapor leaves the turbine as mixture of liquid and vapor state at low pressure at point (4).This process called Isentropic process that means equal entropy process.

4-1 Condenser :  isobaric process, the mixture will condensate by convection or conduction heat transfer between the air or the pipes of cooled water, so it will leave as saturated liquid at point (1). 

1-2 Pump : isentropic process in which the saturated liquid will increase it's pressure and leave the pump as compressed liquid to enter the boiler again. 

Gearbox

Introduction:-

An automobile requires high torque when climbing hills and when starting, even though they are performed at low speeds. On other hand, when running
at high speeds on level roads, high torque is not required because of momentum.  So requirement of a device is occur, which can change the vehicle’s torque and its speed according to road condition or when the driver need. This device is known as transmission box.

Function of transmission box (gear box) in automobile:

The transmission box which is also known as the gear box is the second element of the power train in an automobile. It is used to change the speed and torque of vehicle according to variety of road and load condition. Transmission box change the engine speed into torque when climbing hills and when the vehicle required. Sometimes it is known as torque converter. Main functions of a gear box is as follow:

1. Provide the torque needed to move the vehicle under a variety of road and load conditions. It does this by changing the gear ratio between the engine crankshaft and vehicle drive wheels.

2. Be shifted into reverse so the vehicle can move backward.

3. Be shifted into neutral for starting the engine.

Main components of a gear box:

In any device two or more component works together and fulfills the required function. In a transmission box four components are required to fulfill its function. These components are-

1. Counter shaft:

Counter shaft is a shaft which connects with the clutch shaft directly. It contains the gear which connects it to the clutch shaft as well as the main shaft. It may be run runs at the engine speed or at lower than engine speed according to gear ratio.

2. Main shaft:

It is the shaft which runs at the vehicle speed. It carries power form the counter shaft by use of gears and according to the gear ratio, it runs at different speed and torque compares to counter shaft. One end of this shaft is connects with the universal shaft.

3. Gears:

Gears are used to transmit the power form one shaft to another. They are most useful component of transmission box because the variation is torque of counter shaft and main shaft is depend on the gear ratio. The gear ratio is the ratio of the driven gear teeth to the driving gear teeth. If gear ratio is large than one, the main shaft revolves at lower speed than the counter shaft and the torque of the main shaft is higher than the counter shaft. On other hand if the gear ratio is less than one, than the main shaft revolves at higher speed than the counter shaft and the torque of the main shaft is lower than the counter shaft. A small car gear box contains four speed gear ratio and one reverse gear ratio.

4. Bearings:

Whenever the rotary motion, bearings are required to support the revolving part and reduce the friction. In the gear box both counter and main shaft are supported by the bearing.

Working of a principle gear box:

In a gear box, the counter shaft is mashed to the clutch with a use of a couple of gear. So the counter shaft is always in running condition. When the counter shaft is bring in contact with the main shaft by use of meshing gears, the main shaft start to rotate according to the gear ratio. When want to change the gear ratio, simply press the clutch pedal which disconnect the counter shaft with engine and change connect the main shaft with counter shaft by another gear ratio by use of gearshift lever. In an gear box, the gear teeth and other moving metal must not touch. They must be continuously separated by a thin film of lubricant. This prevents excessive wear and early failure. Therefor a gearbox runs partially filled with lubricant oil. 

Refrigeration Cycle

Simple form of refrigeration cycle is shown in the following figure : 

Refrigeration cycle  : is a closed loop where the refrigerant flows through it . 

The Refrigerant enters evaporator at low temperature low pressure, where it absorbs the heat from the refrigerated space by convection heat transfer between the air space and the refrigerant. Refrigerant leaves the evaporator and enters the compressor as a slightly superheated vapor at a low pressure, it then leaves the compressor at high pressure vapor to enters the condenser, in condenser the heat absorbed during evaporated process of the refrigerant, it will rejected by convection heat transfer between the refrigerant and ambient air or cooling water, whereas the refrigerant will condensate and leaves the condenser as a high pressure low temperature liquid. The function of the expansion valve is to reduce the pressure of the refrigerant before entering the evaporator.   

The refrigerant's safety properties :

•  unflamable

• nontoxic 

• does not react with air and materials 

• Cheap and easy production

Most common types of refrigerants :

Freons : R11 , R12 , R22 , R134 , R502 , R717 , R404

ammonia : NH3

Hydraulic Systems

Introduction in to hydraulic systems operation :
These days we use the hydraulic systems in too many sides in our daily life, so what is hydraulics ?
hydraulics is the use for a liquid to transmit power,force or to produce motion.
The basic in any hydraulic system and fluid power is PASCAL LAW.This law states that the presure applied on a fluid is transmitted in all direction with equal force on area.
Now lets talk about the component for basic hydraulic system : (with picture in the end)

1- fluid: it can be any liquid but the most common liquid is petroleum oil because it is works as a lubricant to protect the component from corrosion. 

2-reservoir: it is the storehouse for the liquid.

3-hydraulic pump: to convert the mechanical energy to hydraulic energy.

4- Fluid lines: used to transport the fluid.

5-Hydraulic valves: used to control or directs the flow of the fluid.

6-Filters:help to remove the impurities from the liquid.

7-Actuator : to convert hydraulic energy to a mechanical energy to do the work.

We will take about every thing in the hydraulic system with details .
Wait for us .

Machining Technology

 Machining : it is one of the most important manufacturing process, that use cutting tool, that removes the material (chip) from the work piece , to create and generate required shape of work piece, to done it's function .

most common machining processes :

1. Turning process : a process in which the material removed from the rotating work piece , to create cylindrical shape, by using single sharp edge cutting tool .
2. Drilling process : making a round hole in the work piece by rotating tow sharp edges cutting tool, that penetration in to the work piece .
3. milling process : multiple sharp edges cutting tool , that rotates parallel to the work part plane called ( peripheral milling ) or perpendicular  to work part called (face milling ) .

Introduction to Autotronics engineering

Autotronics engineering

The Autotronics is referred to as modern automotive technology and also commonly known as Automotive Mechatronics Autotronics is the combination of automobile and electronics while hybrid refers to technology that uses two or more distinct power sources to move the vehicle. It deals with computer controlled motor vehicle systems such as Engine Control Unit (ECU-airbag, engine, ABS), engine management, electronic transmission, GPS-based navigation system, stability management systems.

It provides an in-depth understanding of electronic control systems and vehicle sub-systems operation of various computer controlled motor vehicle systems in networked system (CAN Bus and Lin Bus Systems).

The student will also acquire knowledge and skills on automotive electronic problem-solving techniques using state – of – the – art testing and diagnostic equipment to maintain, troubleshoot and repair electrical and electronics systems used in various automotive vehicles. The graduates can be employed in the automotive industry and specialized service centers.

The study includes:- 

• Automotive Electrical and Electronics Systems
• Digital Communication in automotive
• Hybrid & Electronic Vehicles
• Advanced sensors and actuators in automotive
• Engine Management and diagnostic systems

Future careers:-

• Autotronics Specialist
• Specialist/Advisor
• Autotronics Assistant Engineer
• Autotronics Diagnostician

Mechanical engineering

Mechanical engineering includes a wide ranges of works, it is divided to :

1) Design of mechanical systems for facilities such as : HVAC, plumbing, firefighting and water supply .

2) Maintenance works : preventive, predictive, and breakdown maintenance for mechanical machines .

3) Mechanical design of machine elements and machines .