Shell and tube heat exchangers: types, components, and working principle

A shell and tube heat exchanger is a type of heat exchanger that is widely used in industrial applications for transferring heat between two fluids. One fluid flows through the tubes, while the other fluid flows around the tubes within a shell. This design allows efficient heat transfer between the two fluids without mixing them.

Handbook of heat exchangers

Components of a Shell and Tube Heat Exchanger:

1. Shell:

- The outer cylindrical vessel that houses the tube bundle.

- One fluid flows through the shell, passing over the tubes.

2. Tube Bundle:

- A set of tubes housed inside the shell.

- The second fluid flows through these tubes.

- Tubes can be arranged in various patterns (e.g., triangular, square) to maximize heat transfer.

Fundamentals of heat exchanger design handbook

3. Tube Sheets:

- Plates at the ends of the heat exchanger that hold the tubes in place.

- The tube sheets are perforated to allow the tubes to pass through and are welded or fixed to the shell.

4. Baffles:

- Metal plates inside the shell that guide the fluid flowing through the shell side.

- They help in improving heat transfer by inducing turbulence and ensuring uniform fluid distribution.

5. Front and Rear End Headers:

- The front header (also called the stationary head) allows the entry of the tube-side fluid and provides a place for tube maintenance.

Heat exchanger design handbook

- The rear header allows the fluid to exit and can also provide access for tube cleaning.

6. Nozzles:

- Inlet and outlet connections for both shell-side and tube-side fluids.

Types of Shell and Tube Heat Exchangers:

1. Fixed Tube Sheet Heat Exchanger:

- The tube sheets are fixed to the shell, and the tube bundle cannot be removed.

- Suitable for applications where both fluids are clean.

2. U-Tube Heat Exchanger:

- The tubes are bent in a U-shape, allowing for expansion and contraction.

- Only one tube sheet is fixed, allowing the bundle to be removed for maintenance.

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3. Floating Head Heat Exchanger:

- One end of the tube bundle is fixed to the shell, while the other end can move (floating head).

- This allows for thermal expansion of the tubes and easier cleaning.

Working Principle of a Shell and Tube Heat Exchanger:

1. Fluid Flow:

- One fluid flows through the tubes (tube-side fluid).

- The other fluid flows over the tubes, inside the shell (shell-side fluid).

2. Heat Transfer:

- Heat is transferred from the hotter fluid to the cooler fluid through the tube walls.

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- The heat exchanger can be designed for either counterflow (fluids flow in opposite directions) or parallel flow (fluids flow in the same direction).

3. Turbulence:

- Baffles inside the shell induce turbulence in the shell-side fluid, which enhances heat transfer by disrupting the boundary layer around the tubes.

Applications of Shell and Tube Heat Exchangers:

- Oil Refining: Used for cooling or heating petroleum products.

- Power Plants: In steam generation systems and condensers.

- Chemical Processing: Heat exchangers are essential in chemical reactions where precise temperature control is required.

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- HVAC: Used in air conditioning and refrigeration systems for cooling water or refrigerant.

- Marine Applications: Used in ships to cool engine oil, water, and other fluids.

Advantages of Shell and Tube Heat Exchangers:

- High Efficiency: Offers a large surface area for heat exchange, leading to efficient thermal transfer.

- Versatility: Can handle a wide range of temperatures and pressures.

- Durability: Robust design capable of handling high pressures.

- Ease of Maintenance: U-tube and floating head designs allow for easy cleaning of the tube bundle.

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Disadvantages:

- Large Footprint: Can be bulky and take up considerable space.

- Cost: Depending on the design, they can be expensive to manufacture and maintain.

- Potential for Fouling: If the fluids contain particulates or contaminants, fouling on the tube or shell surfaces can reduce heat transfer efficiency.

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