A gas mixture of 50 wt% argon and 50 wt% helium flows through a horizontal tube at 1 kg s⁻¹ and is heated from 300 K to 400 K at 1 bar (ideal gas, negligible KE/PE changes). Specific enthalpies (kJ kg⁻¹): Argon 348→400, Helium 1574→2092. At steady state, the heat input required (in kW) is ___________ (rounded off to the nearest integer).

Question

Accepted Answer

The correct answer is 285. GATE 2026 official key: 285. Steady-flow energy balance (negligible KE/PE): Q = Σ ṁᵢΔhᵢ. With 0.5 kg/s each of argon and helium: Q = 0.5×(400−348) + 0.5×(2092−1574) = 26 + 259 = 285 kW.