Carnot, Otto, Diesel and Joule Cycles
Pressure Volume (PV) and Temperature Entropy (TS) diagrams for the Carnot, Otto, Diesel and Joule cycles.
The Carnot, Otto, Diesel and Joule cycles describes the processes common in combustion displacement and gas turbine engines.
Carnot Cycle
The Carnot cycle is the ideal cycle with the best possible efficiency for a machine operating between two temperature levels Tmax and Tmin.
Heat addition and heat rejection occur isothermally in the cycle between point 1 and 2, and 3 and 4.
The efficiency can be calculated as
μ = 1 - Tmin / Tmax (1)
where
μ = efficiency (0.. 1)
Tmin = min. temperature (K)
Tmax = max. temperature (K)
Otto Cycle
The Otto cycle is a contant-volume cycle where addition of heat or combustion takes place isochorically.
Heat addition and heat rejection occur isothermally in the cycle between point 2 and 3, and 4 and 1.
The efficiency of the Otto cycle can be calculated as
μ = 1 - ε(1 - κ) (2)
where
μ = efficiency (0.. 1)
ε = compression ratio
κ = isentropic exponent
Diesel Cycle
The Diesel cycle is a constant-pressure cycle where the addition of heat and combustion takes place isobaric.
Heat addition and heat rejection occur isothermic in the cycle between point 2 and 3, and 4 and 1.
The efficiency of the Diesel cycle can be calculated as
μ = 1 - (Φκ - 1) / (ε(κ - 1) κ (Φ - 1) ) (3)
where
μ = efficiency (0.. 1)
ε = compression ratio
κ = isentropic exponent
Φ = injection ratio
Joule Cycle
The Joule cycle is a comparison cycle for gas turbines with continuous flow.
The efficiency can be calculated as
η = 1 - T1 / T2 (4)
