The Eduladder is a community of students, teachers, and programmers just interested to make you pass any exams. So we help you to solve your academic and programming questions fast.
In eduladder you can Ask,Answer,Listen,Earn and Download Questions and Question papers.
Watch related videos of your favorite subject.
Connect with students from different parts of the world.
Apply or Post Jobs, Courses ,Internships and Volunteering opportunity. For FREE
See Our team
Wondering how we keep quality?
Got unsolved questions? Ask Questions

CE2352-DESIGN-OF-STEEL-STRUCTURES-->View question

What is compression ratio?

What is compression ratio


Asked On2017-05-17 07:23:51 by:scribed

Taged users:


Likes:
Be first to like this question

Dislikes:
Be first to dislike this question
Talk about this  Like  Dislike
View all qusetions
Answers
The comparison ratio of the maximum to minimum volume in the cylinder of an internal combustion engine.
In a piston engine, it is the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke.
For example, a cylinder and its combustion chamber with the piston at the bottom of its stroke may contain 1000 cc of air (900 cc in the cylinder plus 100 cc in the combustion chamber). When the piston has moved up to the top of its stroke inside the cylinder, and the remaining volume inside the head or combustion chamber has been reduced to 100 cc, then the compression ratio would be proportionally described as 1000:100, or with fractional reduction, a 10:1 compression ratio.
A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air–fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher efficiency is created because higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature. It may be more helpful to think of it as an "expansion ratio", since more expansion reduces the temperature of the exhaust gases, and therefore the energy wasted to the atmosphere. Diesel engines actually have a higher peak combustion temperature than petrol engines, but the greater expansion means they reject less heat in their cooler exhaust.
On the other hand, diesel engines operate on the principle of compression ignition, so that a fuel which resists autoignition will cause late ignition, which will also lead to engine knock.
Static compression ratio (CR) is calculated by the formula
{\displaystyle {CR}={\frac {V_{d}+V_{c}}{V_{c}}}}
Where:
Vd = displacement volume. This is the volume inside the cylinder displaced by the piston from the beginning of the compression stroke to the end of the stroke.
Vc= clearance volume. This is the volume of the space in the cylinder left at the end of the compression stroke.
Vd can be estimated by the cylinder volume formula
{\displaystyle V_{d}={\tfrac {\pi }{4}}b^{2}s}
Where:
b= cylinder bore (diameter)
s= piston stroke length
Because of the complex shape of V_{c} it is usually measured directly. This is often done by filling the cylinder with liquid and then measuring the volume of the used liquid.


Answerd on:2019-06-26 Answerd By:KAPILJHADE

Likes:
|KAPILJHADE

Dislikes:
Be first to dislike this answer
Talk about this  Like  Dislike

Stay home and watch eduladder premium videos for free In at this qurentine.


You might like this video:Watch more here

Watch more videos from this user Here

Learn how to upload a video and start earning here

The ratio of the maximum to minimum volume in the cylinder of an internal-combustion engine
Answerd on:2016-01-11 Answerd By:metaphor

Likes:
Be first to like this answer

Dislikes:
Be first to dislike this answer
Talk about this  Like  Dislike

Stay home and watch eduladder premium videos for free In at this qurentine.


You might like this video:Watch more here

Watch more videos from this user Here

Learn how to upload a video and start earning here

The comparison ratio of the maximum to minimum volume in the cylinder of an internal combustion engine.
In a piston engine, it is the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke.
For example, a cylinder and its combustion chamber with the piston at the bottom of its stroke may contain 1000 cc of air (900 cc in the cylinder plus 100 cc in the combustion chamber). When the piston has moved up to the top of its stroke inside the cylinder, and the remaining volume inside the head or combustion chamber has been reduced to 100 cc, then the compression ratio would be proportionally described as 1000:100, or with fractional reduction, a 10:1 compression ratio.
A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air–fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher efficiency is created because higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature. It may be more helpful to think of it as an "expansion ratio", since more expansion reduces the temperature of the exhaust gases, and therefore the energy wasted to the atmosphere. Diesel engines actually have a higher peak combustion temperature than petrol engines, but the greater expansion means they reject less heat in their cooler exhaust.
On the other hand, diesel engines operate on the principle of compression ignition, so that a fuel which resists autoignition will cause late ignition, which will also lead to engine knock.

Static compression ratio () is calculated by the formula

Where:

Vd = displacement volume. This is the volume inside the cylinder displaced by the piston from the beginning of the compression stroke to the end of the stroke.
Vc= clearance volume. This is the volume of the space in the cylinder left at the end of the compression stroke.

Vd can be estimated by the cylinder volume formula

Where:

b= cylinder bore (diameter)
s= piston stroke length

Because of the complex shape of  it is usually measured directly. This is often done by filling the cylinder with liquid and then measuring the volume of the used liquid.



Answerd on:2019-06-22 Answerd By:KAPILJHADE

Likes:
Be first to like this answer

Dislikes:
Be first to dislike this answer
Talk about this  Like  Dislike

Stay home and watch eduladder premium videos for free In at this qurentine.


You might like this video:Watch more here

Watch more videos from this user Here

Learn how to upload a video and start earning here



Lets together make the web is a better place

We made eduladder by keeping the ideology of building a supermarket of all the educational material available under one roof. We are doing it with the help of individual contributors like you, interns and employees. So the resources you are looking for can be easily available and accessible also with the freedom of remix reuse and reshare our content under the terms of creative commons license with attribution required close.

You can also contribute to our vision of "Helping student to pass any exams" with these.
Answer a question: You can answer the questions not yet answered in eduladder.How to answer a question
Career: Work or do your internship with us.Work with us
Create a video: You can teach anything and everything each video should be less than five minutes should cover the idea less than five min.How to upload a video on eduladder