The turbine in a steam power plant takes steam from a boiler at 427 °C and exhausts into a low temperature reservoir at 77 °C. What is the maximum possible efficiency?
Correct answer: A. 50%
- A. 50%
- B. 40%
- C. 60%
- D. 70%
Explanation
To find the maximum possible efficiency of the steam turbine, we use the Carnot efficiency formula: η = (T1 - T2) / T1, where T1 and T2 are the absolute temperatures of the heat source and sink, respectively. Convert the given temperatures from Celsius to Kelvin: T1 = 427°C + 273 = 700K, T2 = 77°C + 273 = 350K. Substituting these values into the formula gives η = (700K - 350K) / 700K = 0.5, or 50%. This is why option A is correct. Options B, C, and D are incorrect because they do not match the calculated efficiency using the Carnot formula.
This question appeared on the UHS MDCAT 2010 paper, which you can sit online with every answer explained.
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