Diesel Cycle Calculator
Diesel efficiency falls as the cut-off ratio grows: r = 18 with a cut-off ratio of 2 gives η = 63.1578 %.
63.1577531443778 %
Full answer, then cut to fewer decimals (not rounded):
- 63.1577531443778 %
- 63.157753144377 %
- 63.15775314437 %
- 63.1577531443 %
- 63.157753144 %
- 63.15775314 %
- 63.1577531 %
- 63.157753 %
- 63.15775 %
- 63.1577 %
- 63.157 %
- 63.15 %
- 63.1 %
- T₂ after compression
- 953.301 K
- p₂ = p₃
- 5719.81 kPa
- T₃ at cut-off
- 1906.6 K
- T₄ after expansion
- 791.705 K
- Heat added qin = cp(T₃ − T₂)
- 957.591 kJ/kg
- Net work w
- 604.793 kJ/kg
- Mean effective pressure
- 743.751 kPa
Step-by-step solution
- η = 1 − [1/r^(γ−1)] × (ρ^γ − 1) / [γ(ρ − 1)]
- = 1 − [1/3.17767] × 1.63902 ÷ 1.4
- = 0.631578
Diesel Cycle Formula
η = 1 − [1/r^(γ−1)] × (ρ^γ − 1)/[γ(ρ − 1)]
r compression ratio, ρ = V₃/V₂ cut-off ratio
Worked Example
r = 18, cut-off ratio 2, γ = 1.4, intake 300 K and 100 kPa:
- η = 1 − [1/r^(γ−1)] × (ρ^γ − 1) / [γ(ρ − 1)]
- = 1 − [1/3.17767] × 1.63902 ÷ 1.4
- = 0.631578
p₂ = p₃: 5719.81 kPa · T₃ at cut-off: 1906.6 K · T₄ after expansion: 791.705 K · Heat added qin = cp(T₃ − T₂): 957.591 kJ/kg · Net work w: 604.793 kJ/kg · Mean effective pressure: 743.751 kPa
More Thermodynamics Calculators
-
Otto Cycle Calculator
η = 1 − 1/r^(γ−1)
r compression ratio, γ = cp/cv
Example: r = 8, γ = 1.4, intake 300 K and 100 kPa, peak 2000 K: Air-standard efficiency η = 56.4725 %.
-
Brayton Cycle Calculator
η = 1 − 1/rp^((γ−1)/γ)
rp pressure ratio; optimum rp = (T₃/T₁)^(γ/2(γ−1)) for maximum work
Example: rp = 10, T₁ = 300 K, T₃ = 1200 K, ideal compressor and turbine: Thermal efficiency η = 48.2053 %.
-
Carnot Efficiency Calculator
η = 1 − TL/TH
COPR = TL/(TH − TL), COPHP = TH/(TH − TL), absolute temperatures
Example: An engine between 600 K and 300 K: Carnot efficiency η = 50 %.
-
Polytropic Process Calculator
W = (p₁V₁ − p₂V₂)/(n − 1), Q = W(γ − n)/(γ − 1)
pVⁿ = constant; n = 1 isothermal W = p₁V₁ ln(V₂/V₁)
Example: Air compressed from 100 kPa, 0.1 m³, 300 K to 800 kPa with n = 1.3: Work done by the gas W = -20.5289 kJ.
Frequently asked questions
Is the Diesel cycle less efficient than Otto?
At the same compression ratio, yes; but diesels run much higher ratios, so they are more efficient in practice.
What is the dual cycle?
A cycle with heat added partly at constant volume and partly at constant pressure; Otto and Diesel are its limiting cases.
Sources
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Diesel Cycle Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/diesel-cycle-calculator/
IEEE
Scientific Converters, "Diesel Cycle Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/diesel-cycle-calculator/