Shell and tube heat exchangers and brazed plate heat exchangers have the following differences:

Construction and Design

Shell and Tube: Consists of a cylindrical shell with a bundle of tubes inside. Tubes can be straight, U-shaped, or in other configurations. Baffles are often used in the shell to direct fluid flow and enhance heat transfer.

Brazed Plate: Comprises multiple corrugated metal plates that are brazed together. The plates create a series of channels for the fluids to flow through, with alternating channels for the different fluids to ensure heat exchange.

Heat Transfer Efficiency

Brazed Plate: Generally offers higher heat transfer efficiency. The corrugated plates provide a large surface area and the close spacing between plates promotes turbulent flow, resulting in efficient heat transfer. It can achieve a higher heat transfer coefficient compared to shell and tube heat exchangers in many applications.

Shell and Tube: Can also provide good heat transfer, but typically not as efficient as brazed plate heat exchangers in terms of heat transfer per unit volume. However, it can handle higher pressures and temperatures in some cases.

Pressure and Temperature Limits

Shell and Tube: Can handle higher pressures and temperatures. It is suitable for applications with extreme operating conditions and is often used in industrial processes where high pressure and temperature requirements are common.

Brazed Plate: Usually has lower pressure and temperature limits compared to shell and tube heat exchangers. The brazed joints and the materials used may limit the maximum allowable pressure and temperature. However, there are advanced brazed plate designs that can handle relatively higher pressures and temperatures.

Fouling and Cleaning

Brazed Plate: Prone to fouling due to the small flow channels between the plates. Fouling can reduce the heat transfer efficiency and may require more frequent cleaning. Cleaning can be challenging as the channels are narrow and may not be easily accessible. Chemical cleaning or using specialized cleaning agents is often necessary.

Shell and Tube: Also susceptible to fouling, especially on the shell side. However, cleaning is relatively easier compared to brazed plate heat exchangers. Methods such as mechanical cleaning or chemical cleaning can be used, and in some cases, the tubes can be removed for cleaning.

Size and Space Requirements

Brazed Plate: Compact design and requires less space compared to shell and tube heat exchangers. The small size and high heat transfer efficiency make it suitable for applications where space is limited.

Shell and Tube: Larger in size and requires more floor space. However, it can be designed for vertical or horizontal installation depending on the available space.

Cost

Brazed Plate: Generally has a higher initial cost compared to shell and tube heat exchangers. The complex manufacturing process of brazing the plates and the use of high-quality materials contribute to the higher cost.

Shell and Tube: Lower initial cost due to the more common and established design. However, maintenance costs may be higher in some cases depending on the application and fouling tendencies.

In conclusion, the choice between shell and tube and brazed plate heat exchangers depends on the specific requirements of the application, including heat transfer needs, pressure and temperature limits, fouling potential, space availability, and cost considerations. Brazed plate heat exchangers are favored for their high efficiency and compact size in certain applications, while shell and tube heat exchangers are often chosen for their ability to handle higher pressures and temperatures and for more demanding industrial processes.