Topic: Thermodynamics
A steam engine intakes 100 gm of steam at 100 C per minute and cools it down to 20 C. Calculate the heat rejected by the steam engine per minute (consider Latent Heat of vaporization of steam = 540 cal/gm and Cp = 1 cal/gm C)
- A. 6.2 x 10^4 kcal
- B. 62 x 10^4 cal
- C. 6.2 x 10^4 cal
- D. 620 x 10^4 kcal
Answer: C. 6.2 x 10^4 cal
Explanation: The total heat rejected per minute involves condensing the steam and then cooling the water. Heat rejected Q_R = (m * Cp * delta_T) + (m * L). Substituting the given values: Q_R = (100 * 1 * (100 - 20)) + (100 * 540) = (100 * 80) + 54000 = 8000 + 54000 = 62000 cal, which is equal to 6.2 x 10^4 cal.