Power Plant Efficiency & Heat Dissipation Calculations

In summary, the conversation discusses a power plant that generates 400 MW of electric power with an efficiency of 40%. The problem asks for the rate at which the plant dissipates heat and the flow rate of a river needed to carry away the waste heat without exceeding a temperature rise of 3°C. The solution involves calculating the wasted energy and using the specific heat of water to determine the necessary flow rate. The conversation also notes one assumption about all wasted energy being lost as heat.
  • #1
Martinii
2
0
[SOLVED] Power plant

Hi! Here i have a problem : A power plant generates 400 MW of electric power.It has an effieciency of 40%.
a) At what rate does it dissipate heat?
b)If the waste heat is carried away by a river, and the temperature rise of the river must not exceed 3°C, what flow rate is required in the river?


Here is what i have tried:

a)
Pel=400 MW
η=40%=0.4
Pth=Pel/η=1000 MW

b) Pwaste=W/t Q=W=m*c*ΔT m=ρ*V

Pwaste=(ρ*V*c*ΔT)/t V/t= Volume Flow = V°= Pwaste/(ρ*c*ΔT)

Pwaste= Pth-Pel=600 MW and then calculations

I am not quite sure whether this way is correct or not.I will be happy if someone can tell me his opinion.
 
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  • #2
Seems right to me, although there is at least one assumpution which is implied:
1. All of the wasted energy is lost as heat.
Fairly reasonable, there's bound to be some light and sound etc. but the vast majority will definitely be heat.

I don't fully understand your notation for Pwaste, but it looks pretty good. I guess one assumes that the river isn't below 0 C, and you can look up the specific heat of water, so that's no biggy. Seems like you got it.
 
  • #3
Yeah , i think i got it! Thanks anyway :)
 

1. What is power plant efficiency?

Power plant efficiency is a measure of how well a power plant converts the energy from its fuel into electricity. It is typically expressed as a percentage and can range from 30% to 50% for most power plants.

2. How is power plant efficiency calculated?

Power plant efficiency is calculated by dividing the actual energy output by the theoretical maximum energy output. The theoretical maximum is calculated by multiplying the heat content of the fuel by the efficiency of the power plant's steam cycle.

3. What factors affect power plant efficiency?

Several factors can affect power plant efficiency, including the type of fuel used, the age and condition of the plant's equipment, and the design and operation of the plant. Other factors such as ambient temperature and humidity can also impact efficiency.

4. What are heat dissipation calculations?

Heat dissipation calculations are used to determine how much heat is being released from a power plant into the surrounding environment. This is important for environmental and safety reasons, as excessive heat dissipation can have negative impacts on the ecosystem and nearby communities.

5. How are heat dissipation calculations performed?

Heat dissipation calculations involve measuring the temperature of the air and water around the power plant and using formulas to calculate the amount of heat being released. Factors such as the plant's heat output, wind speed, and water flow rate are taken into account to determine the total heat dissipation.

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