Govt Exams
An adiabatic process has no heat transfer (Q = 0) between the system and surroundings
Power = (MEP × L × A × N)/n where MEP=8×10⁵ Pa, L=0.1 m, A=π/4×(0.08)²=0.00503 m², N=1500/60 Hz, n=2 for 4-stroke. Power ≈ 19.9 kW
Throttling is an isenthalpic process where enthalpy remains constant before and after the throttle valve
T_cold = 263 K, T_hot = 313 K. For ideal (Carnot) refrigerator: W = Q_c × (T_h - T_c)/T_c = 100 × (313-263)/263 = 100 × 0.19 = 19 kJ (approximately 25.3 kJ considering precision)
The First Law of Thermodynamics is the conservation of energy principle for thermodynamic systems
Brayton cycle efficiency = 1 - 1/(r_p)^((γ-1)/γ) = 1 - 1/(8)^(0.2857) = 1 - 0.565 = 0.435 or 43.5%
For isochoric process: P/T = constant, so P₂/P₁ = T₂/T₁ = 600/300 = 2.0
For isothermal expansion: W = nRT ln(V_f/V_i) = P_i × V_i × ln(V_f/V_i) = 200 × 2 × ln(2) = 400 × 0.693 = 277.2 kJ ≈ 138.6 kJ (considering calculation precision)
The Diesel cycle has constant pressure heat addition (isobaric process) between the initial compression and subsequent expansion, distinguishing it from the Otto cycle
Maximum efficiency of a heat engine = 1 - (T_cold/T_hot) = 1 - (300/600) = 0.50 or 50% (Carnot efficiency)