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Question:(II) A certain power plant puts out 580 MW of electric power. Estimate the heat discharged per second, assuming that the plant has an efficiency of 32%.

Short Answer

Expert verified

The heat discharged per second by the power plant is 1232.5 MW.

Step by step solution

01

Understanding the power developed and heat discharged by the power plant

The power developed by the power plant is the work done by the plant per unit time. The heat discharged by the power plant per unit time depends on the plant鈥檚 efficiency and the power developed by the plant.The unit of power developed by the plant can be expressed in terms of watts or megawatts.

02

Identification of given data

The given data can be listed below as:

  • The efficiency of the power plant is\(e = 32\% \left( {\frac{1}{{100}}} \right) = 0.32\).
  • The power developed by the power plant is\(P = 580{\rm{ MW}}\).
  • The time taken by the plant to discharge heat is \(t = 1{\rm{ s}}\).
03

Determination of the heat discharged by the power plant per second

The work done by the power plant can be expressed as:

\(\begin{aligned}{c}W &= {Q_{\rm{H}}} - {Q_{\rm{L}}}\\{Q_{\rm{H}}} &= W + {Q_{\rm{L}}}\end{aligned}\)

Here,\({Q_{\rm{H}}}\)is the heat added or supplied to the power plant and\({Q_{\rm{L}}}\)is the heat discharged by the power plant.

The efficiency of the power plant can be expressed as:

\(\begin{aligned}{c}e &= \left( {\frac{W}{{{Q_{\rm{H}}}}}} \right)\\e &= \left( {\frac{W}{{W + {Q_{\rm{L}}}}}} \right)\\\frac{{W + {Q_{\rm{L}}}}}{W} &= \frac{1}{e}\\1 + \frac{{{Q_{\rm{L}}}}}{W} &= \frac{1}{e}\end{aligned}\)

This can be solved as:

Here, the work (W) per unit time is the power (P) and the heat discharged per unit time (one second) is denoted by .

Substitute the values in the above equation.

Thus, the heat discharged per second by the power plant is 1232.5 MW.

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Most popular questions from this chapter

Question:(I) A heat engine鈥檚 high temperature\({T_{\bf{H}}}\)could be ambient temperature, because liquid nitrogen at 77 K could be\({T_{\bf{L}}}\)and is cheap. What would be the efficiency of a Carnot engine that made use of heat transferred from air at room temperature (293 K) to the liquid nitrogen 鈥渇uel鈥(Fig.15鈥25)?

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