How to Calculate Efficiency and Heat Rejection in an Engine?

In summary, the conversation discusses heat system efficiency and the calculation of heat rejected in a cycle. The first law of thermodynamics is mentioned, stating that the net energy taken and work done is zero. The formula for efficiency is also provided.
  • #1
jin
8
0
heat system efficiency??

So lost..so what am i suppose to do??

'An engine absorbs 400J of heat and does 120J of work in each cycle'

a)what is its efficiency?
b)how much heat is rejected in each cycle?
 
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  • #2
For a cycle, that is, when after a process, a system comes back to its original state, the difference of the net energy taken and work done by it is zero - first law of thermodynamics.

[tex]Efficiency = \frac{work done}{energy taken}[/tex]


spacetime
www.geocities.com/physics_all/index.html
 
  • #3
so...i just go 120/400 x 100?

how do i calculate th heat rejected in the cycle?? the left over? 400-120??
 
  • #4
correct!

spacetime
 
  • #5
thanks! can u help me with the others on another post?? please ><
 

1. What is heat system efficiency and why is it important?

Heat system efficiency refers to how effectively a heating system converts fuel or energy into heat for a space. It is important because a more efficient system will use less energy and result in lower heating costs.

2. How is heat system efficiency measured?

Heat system efficiency is typically measured by the Annual Fuel Utilization Efficiency (AFUE) rating. This is a percentage that represents the amount of fuel that is converted into heat compared to the amount of fuel that is lost through combustion or other processes.

3. What factors affect heat system efficiency?

Several factors can affect heat system efficiency, including the age and condition of the system, the type of fuel used, and the maintenance and upkeep of the system. Proper insulation and weatherization of the space can also impact efficiency.

4. How can I improve the efficiency of my heat system?

Regular maintenance and tune-ups by a professional can help improve the efficiency of a heat system. Upgrading to a newer, more efficient system or adding insulation to the space can also improve efficiency. Utilizing a programmable thermostat and keeping the system clean can also help.

5. Is it worth investing in a high-efficiency heat system?

While high-efficiency heat systems may have a higher upfront cost, they can result in significant long-term savings on energy bills. Additionally, they are better for the environment as they use less energy and produce fewer emissions. It is important to consider the specific needs and budget of your space before making a decision.

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