Question

A system at 500 K receives 7200 kJ/min of heat from a source at 1000 K The ambient temperature is 300 K The system and source temperature remain constant during heat transfer The decrease in available energy due to heat transfer through finite temperature difference is

• A. 5040 kJ/min
• B. 2880 kJ/min
• C. 2060 kJ/min
• D. 2160 kJ/min

Hint:

The formula ∆Q = Q x (1 − T2 / T1) helps in determining the decrease in available energy due to heat transfer

Answer 1

The Correct Option is A

The reduction in available energy is computed using the following formula:

\( \Delta Q = \dot{Q} \left( 1 - \frac{T_2}{T_1} \right) \)

With the parameters: \( \dot{Q} = 7200 \, \text{kJ/min}, \, T_1 = 1000 \, K, \, \text{and} \, T_2 = 300 \, K \). Substituting these values results in:

\( \Delta Q = 7200 \times \left( 1 - \frac{300}{1000} \right) = 7200 \times 0.7 = 5040 \, \text{kJ/min} \)