Answer:
a) i) The maximum pressure is approximately 122.37 bar
ii) The thermal efficiency is approximately 56.47%
iii) The mean effective pressure is approximately 20.974 bar
b) (b) Four types of internal combustion engine includes;
1) The diesel engine
2) The Otto engine
3) The Brayton engine
4) The Wankel engine
Explanation:
The parameters of the Otto cycle are;
The heat added, = 2,800 kJ/kg
The compression ratio, r = 8
The beginning compression pressure, P₁ = 1 bar
The beginning compression temperature, T₁ = 300 K
Cp = 1.005 kJ/kg·K
Cv = 0.718 kJ/kg·K
R = 287 kJ/kg·K
K = Cp/Cv = 1.005 kJ/kg·K/(0.718 kJ/kg·K) ≈ 1.4
T₂ = T₁×r^(k - 1)
∴ T₂ = 300 K×8^(1.4 - 1) ≈ 689.219 K
∴ P₂ = 8 × 1 bar × (689.219K)/300 K ≈ 18.379 bar
= m·Cv·(T₃ - T₂)
∴ = 2,800 ≈ 0.718 × (T₃ - 689.219)
T₃ = 2,800/0.718 + 689.219 = 4588.94 K
P₃ = P₂ × (T₃/T₂)
P₃ = 18.379 bar × 4588.94K/(689.219 K) = 122.37 bar
The maximum pressure = P₃ ≈ 122.37 bar
(ii) The thermal efficiency, , is given as follows;
Therefore, we have;
The thermal efficiency, ≈ 0.5647
Therefore, the thermal efficiency ≈ 56.47%
(iii) The mean effective pressure, MEP is given as follows;
Therefore, we get;
The mean effective pressure, MEP ≈ 20.974 bar
(b) Four types of internal combustion engine includes;
1) The diesel engine; Compression heating is the source of the ignition, with constant pressure combustion
2) The Otto engine which is the internal combustion engine found in cars that make use of gasoline as the source of fuel
The Otto engine cycle comprises of five steps; intake, compression, ignition, expansion and exhaust
3) The Brayton engine works on the principle of the steam turbine
4) The Wankel it follows the pattern of the Otto cycle but it does not have piston strokes
