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Module 4 · Diesel Power Plant
Diesel electric stations serve as stand-by plants, peak load plants, mobile units, and emergency supply for cinemas, hospitals, etc. They offer higher thermal efficiency than steam plants but are limited to small power requirements due to high fuel cost.
Uses of Diesel Electric Station
$$\text{1. Stand-by plant} \quad \text{2. Peak load plant} \quad \text{3. Mobile plant} \quad \text{4. Supply: Cinemas, Hospitals}$$
Components of Diesel Electric Plant
$$\text{1. Fuel Supply System} \quad \text{2. Air Intake System} \quad \text{3. Lubrication System}$$
$$\text{4. Exhaust System} \rightarrow \text{Cooling System} \quad \text{5. Diesel Engine} \rightarrow \text{Starting System}$$
$$\text{6. AC or DC Generators}$$
Diesel Cycle Efficiency (Ideal)
$$\boxed{\eta_{Diesel} = 1 - \frac{1}{r^{\gamma-1}} \left[\frac{r_c^{\gamma} - 1}{\gamma(r_c - 1)}\right]}$$
$$r = \frac{V_1}{V_2}\;\text{(compression ratio)} \quad r_c = \frac{V_3}{V_2}\;\text{(cut-off ratio)} \quad \gamma \approx 1.4$$
$$\eta_{diesel,thermal} \approx 35\text{–}45\% \quad \eta_{steam,thermal} \approx 29\text{–}40\%$$
Fuel Consumption
$$\dot{m}_{fuel} = \frac{P_{output}}{\eta_{diesel} \times CV_{diesel}} \quad CV_{diesel} \approx 43{,}000\;\text{kJ/kg}$$
Advantages
$$\text{Simple design} \cdot \text{Portable} \cdot \text{Low initial cost} \cdot \text{Higher }\eta\text{ than coal} \cdot \text{Less staff} \cdot \text{Lower overall cost}$$
Disadvantages
$$\text{High fuel cost} \cdot \text{Small capacity only} \cdot \text{High lubricant cost} \cdot \text{High maintenance} \cdot \text{Poor overload performance}$$
🛢️ Diesel Plant & Cycle Efficiency
DIESEL CYCLE EFFICIENCY
FUEL CONSUMPTION
η COMPARISON
✓ Diesel η > Steam η