What should be the mean effetive pressure ?

In summary, the 4 stroke, single cylinder engine in this conversation develops 7.5 KW brake power at 60 rev/sec with a mechanical efficiency of 80%. Its compression ratio is 7 and the maximum pressure reached in the cycle is 34 bar. Using the law PV=constant with n=1.38, the mean effective pressure can be calculated by finding the net work and displacement volume of the engine.
  • #1
falik
6
0
A 4 stroke, single cylinder engine working on constant volume cycle, developes 7.5 KW brake power at 60 rev/sec the mechanical efficiency being 80%. The pressure at the beginning of compression is 0.97 bar, the engine has a volumetric compression ratio of 7 and the maximum pressure reached in the cycle is 34 bar. If both compression and expansion is according to the law PV= costant where n=1.38, calculate Indicate Mean Effective Pressure ?
 
Engineering news on Phys.org
  • #2
bump ! anyone ?
 
  • #3
Homework questions are best answered in the relevant forum. Also, if you're expecting an answer within 7 hours of posting a question, you may be disappointed.
 
  • #4
It is presure that is mesured on the "motor table" (i don' know how to say in english, maybe dyno table?).
 
  • #5
Please refer all future HW questions to the HW Forum. Anyway...

The mean effective pressure (MEP) is the theoretical constant pressure that if acted one the piston for the entire stroke would produce the same amount of work actually developed. This can be shown mathematically as:

MEP = net work for one cycle / displacement volume

You first need to determine the work created from one cycle. Then using either the air standard analysis or the cold air standard analysis you need to work backwards to determine the displacement volume of the engine. Once those two parameters are found, you can then easily find the MEP.
 

Related to What should be the mean effetive pressure ?

1. What is the definition of mean effective pressure (MEP)?

Mean effective pressure (MEP) is a measure of the average pressure throughout the power stroke of an engine cycle. It is calculated by dividing the work done in a cycle by the displacement volume of the engine.

2. Why is mean effective pressure important in engine design?

MEP is a key factor in determining an engine's performance and efficiency. It is used in the design process to optimize engine parameters such as compression ratio, valve timing, and fuel injection timing.

3. How is mean effective pressure measured?

MEP can be measured using a pressure transducer installed in the cylinder or by using a dynamometer. The dynamometer measures the torque produced by the engine, which can then be used to calculate MEP.

4. What factors can affect mean effective pressure?

The main factors that can affect MEP are engine speed, air-fuel ratio, ignition timing, and engine load. Changes in these parameters can lead to variations in MEP and ultimately impact engine performance.

5. What is considered a good mean effective pressure for an engine?

The ideal MEP for an engine will depend on its design and purpose. In general, higher MEP values indicate better engine performance and efficiency. However, the optimal MEP will vary depending on the type of engine and its intended use.

Similar threads

  • Thermodynamics
Replies
20
Views
2K
  • Mechanical Engineering
Replies
1
Views
871
Replies
5
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
22K
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
2K
  • Mechanical Engineering
Replies
5
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
4K
  • Introductory Physics Homework Help
Replies
1
Views
2K
Back
Top