Question

Classify hydropower plants on the basis of water head and state the turbine used for them.

Answer 1

Hydropower plants can be classified based on the water head, which is the height difference between the water source and the turbines. The water head affects the type of turbine used and the overall efficiency of the power generation. Here’s a detailed classification:

### 1. **Low-Head Hydropower Plants**
   - **Water Head:** Typically less than 10 meters (33 feet).
   - **Turbine Used:** **Kaplan Turbine** or **Propeller Turbine**.
     - **Kaplan Turbine:** This is a type of axial-flow turbine with adjustable blades that can handle low heads efficiently. It is commonly used in low-head situations where the height of the water source is not significant.
     - **Propeller Turbine:** Similar to the Kaplan turbine but generally used for even lower heads. It has a propeller-like design and is effective in situations where the water flow rate is high, but the head is low.

### 2. **Medium-Head Hydropower Plants**
   - **Water Head:** Ranges from 10 to 100 meters (33 to 328 feet).
   - **Turbine Used:** **Francis Turbine**.
     - **Francis Turbine:** This is a mixed-flow turbine that operates well in medium-head conditions. It has a design that allows water to flow radially inward through the turbine, making it efficient for medium heads where there is a balance between flow rate and head height.

### 3. **High-Head Hydropower Plants**
   - **Water Head:** Greater than 100 meters (328 feet).
   - **Turbine Used:** **Pelton Wheel**.
     - **Pelton Wheel:** This is a type of impulse turbine that is highly efficient for high-head applications. It works by directing high-pressure water jets onto spoon-shaped buckets attached to a wheel. The design of the Pelton wheel makes it ideal for situations where there is a significant height difference, resulting in high kinetic energy.

### Summary of Turbines Based on Head

- **Kaplan and Propeller Turbines:** Used for low-head conditions.
- **Francis Turbines:** Used for medium-head conditions.
- **Pelton Wheels:** Used for high-head conditions.

Each type of turbine is optimized for different head ranges, ensuring that the hydropower plant operates efficiently according to the specific conditions of the water source.

Answer 2

Hydropower plants can be classified based on the water head, which refers to the vertical distance the water falls. The classification affects the type of turbine used in the plant. Here's a detailed classification:

### 1. **Low-Head Hydropower Plants**

- **Water Head:** Typically less than 30 meters (about 100 feet).
- **Characteristics:** Low-head plants are usually found in river environments with moderate flow rates. They are often used in run-of-the-river systems.
- **Turbine Type:** **Kaplan Turbine** or **Propeller Turbine**. Kaplan turbines are adjustable and suitable for low heads with high flow rates. Propeller turbines are similar but usually have fixed blades.

### 2. **Medium-Head Hydropower Plants**

- **Water Head:** Between 30 meters (100 feet) and 300 meters (1,000 feet).
- **Characteristics:** These plants are often built on rivers with moderate flow and elevation differences. They balance the need for both head and flow.
- **Turbine Type:** **Francis Turbine**. Francis turbines are versatile and can handle a range of heads and flow rates, making them suitable for medium-head applications.

### 3. **High-Head Hydropower Plants**

- **Water Head:** Greater than 300 meters (1,000 feet).
- **Characteristics:** High-head plants are usually located in mountainous regions where the elevation difference can be significant. They generate more power with a smaller flow rate due to the high head.
- **Turbine Type:** **Pelton Turbine**. Pelton turbines are impulse turbines designed for high heads and low flow rates. They use the kinetic energy of the falling water to turn the turbine.

### Summary of Turbines

1. **Kaplan Turbine:**
   - **Type:** Reaction Turbine
   - **Head Range:** Low
   - **Operation:** Water flows through the turbine, causing it to spin. The blades can be adjusted to accommodate different flow rates.

2. **Francis Turbine:**
   - **Type:** Reaction Turbine
   - **Head Range:** Medium
   - **Operation:** Water flows radially inward, passing through the turbine’s blades, which spin and generate power.

3. **Pelton Turbine:**
   - **Type:** Impulse Turbine
   - **Head Range:** High
   - **Operation:** Water is directed into high-speed jets that strike buckets attached to the turbine, causing it to spin.

Each type of turbine is optimized for specific conditions of water head and flow, ensuring efficient energy conversion in different hydropower settings.