Work Done By Engine/Heat Engine

In summary, the conversation discusses how to calculate the work done by a cycle/heat engine, specifically using a P-v diagram and an equation. The speaker has the necessary state/process data and is looking for help with the equation and further reading on the subject. They mention the type of cycle being "Otto" or "Diesel" and share the formulas for calculating work for different types of processes (constant volume, constant pressure, and constant temperature). They also mention being unsure about whether they are working with an isothermal or polytropic process. The conversation ends with the speaker sharing two plots on the performance of Otto and Diesel cycles.
  • #1
EngNoob
38
0
Hi

Can some one help me out on how to calculate the work done by a cycle/heat engine?

I am looking to calculate this in a graphical form, using P-v diagram and a numerical form, using an equation of work.

I have state/process data for for cycle for volume an pressure for point 1-2/2-3/3-4/4-1.

I have a compression and expansion index.

If anyone could help me out with the equation to use i would be real happy.

If anyone can point me in the direction of some further reading on this subject i would be greatful too.
 
Engineering news on Phys.org
  • #2
What kind of cycle? Get your air tables out and look up the enthalpy/energy values.
Then you calculate the net work as a sum of the difference in enthalpies for the points that generate or input work.
 
  • #3
The Cycle would be "Otto" or "Diesel" heat engine.

I think i have the formulas.

Constant Volume: W = 0

Constant Pressure: W = P(V_2 - V_1)

Constant Tempreture: W = P_2 * V_2 * ln (V_2/V_1)

However, i am unsure if i am working with an ISOTHERMAL process vs POLYTROPIC process.

The pressure increases whilst the volume decreases, does this indicate Polytropic or Isothermal
 
  • #4
Hi there:

Check out your post on compression and expansion.

The same material covers this post.

Here are two plots regarding the performance of Otto Cycle and Diesel Cycle.

Slide44.GIF


Slide51.GIF


Thanks,

Gordan
 
Last edited:

FAQ: Work Done By Engine/Heat Engine

What is the definition of work done by an engine?

The work done by an engine is the amount of energy that is converted into a usable form, such as mechanical work or electrical energy, by the engine.

How is the work done by an engine calculated?

The work done by an engine can be calculated by multiplying the force applied by the engine by the distance the force is applied over. This is known as the work-energy principle.

How does a heat engine convert heat into work?

A heat engine converts thermal energy into mechanical work by using the temperature difference between a hot reservoir and a cold reservoir. This temperature difference allows for the transfer of heat from the hot reservoir to the cold reservoir, which drives a series of processes that ultimately result in work being done.

What factors affect the efficiency of a heat engine?

The efficiency of a heat engine depends on several factors, including the temperature difference between the hot and cold reservoirs, the type of working fluid used, and the design of the engine. Generally, a higher temperature difference and a more efficient design will result in a higher efficiency.

How does the Carnot cycle relate to the work done by a heat engine?

The Carnot cycle is a theoretical cycle that describes the most efficient way for a heat engine to convert heat into work. It serves as a benchmark for comparing the performance of real heat engines, and the work done by a heat engine can be calculated by comparing its efficiency to the efficiency of a Carnot engine operating between the same temperature reservoirs.

Similar threads

Why are gas turbine engines not used in cars? Is what I think correct?
Replies
19
Views
833
On-demand steam engine idea
Replies
14
Views
2K
Can a turbo expander convert more heat to work than a piston expander?
Replies
2
Views
940
How does a 4-piston, 4 stroke internal combustion engine work?
Replies
11
Views
3K
Engineering explanation please (pipe welded to a wall)
Replies
5
Views
1K
Calculating the work needed to compress a volume of air
Replies
2
Views
2K
Partial Thermo analysis of a Crower engine
Replies
5
Views
1K
Chemistry Work done by heat engine that uses exhaust from heat pump
Replies
1
Views
636
Did working as a MechE help you learn about tools in a machine shop?
Replies
10
Views
2K
Limiting factor in design of small gas turbine w/ LOW self sustain speed
Replies
5
Views
1K

Hot Threads

Recent Insights

Back
Top