Working principle of plate heat exchanger

Plate Heat Exchanger (PHE) is widely used in various industrial fields due to its high efficiency, compact design and easy maintenance. Its production, installation and working principle involve multiple technical links, which are described in detail below.You can also refer to my other articles to learn moreHow to manufacture a plate heat exchanger？  How work a plate heat exchanger?

1. Production of plate heat exchanger

1. 1.Material selection

1.1.1.Plate: The main components of the plate heat exchanger are composed of metal plates, which are usually made of corrosion-resistant and thermally conductive materials. Common materials include stainless steel, titanium alloy, aluminum alloy and nickel-based alloy. The specific choice depends on the working environment and the properties of the fluid medium.

Stainless steel (such as 304 and 316 stainless steel) is widely used in the food, chemical and pharmaceutical industries.

Titanium alloy is suitable for highly corrosive fluids.

1.1.2.Gasket: Gaskets are used to seal between plates, and gaskets are usually made of rubber, silicone or polytetrafluoroethylene (PTFE) and other materials. These gaskets need to have good high temperature resistance and corrosion resistance.

Frame and support: To ensure the stability and firmness of the plate heat exchanger, a support frame is required. This frame is usually made of corrosion-resistant steel or aluminum alloy.

1.2.Plate processing

1.2.1.Stamping: The metal plates used to make plate heat exchangers are usually formed by stamping, pressing, welding and other processes. Each plate surface is designed to have a concave and convex pattern. The pattern is designed to enhance the turbulence effect of fluid flow, thereby improving heat exchange efficiency.

1.2.2.Pattern design: The design of the plate surface pattern is crucial. Common patterns include: flat plate, fish scale, corrugated, etc. The shape of the pattern determines the flow pattern of the fluid, helps to increase the turbulence of the fluid and improve the heat transfer efficiency.

1.3. Assembly of plate heat exchanger

Stack multiple metal plates together, use gaskets to seal the gaps between adjacent plates, and fix the plates together through support structures. Two independent channels are formed between each pair of adjacent plates through gaskets, one for hot fluid and the other for cold fluid.

Gaskets need to be installed on the four edges of each plate to ensure that the hot fluid and the cold fluid do not mix.

1.4. Sealing and testing

During the assembly process of the plate heat exchanger, it is necessary to ensure the sealing of each gasket to prevent fluid leakage. It is usually necessary to pressure test the final assembled heat exchanger to ensure that there will be no leakage problems under actual operating conditions.

2. Installation of plate heat exchangers

2.1. Selection of installation location

2.1.1.Space requirements: Plate heat exchangers are more compact than traditional tube heat exchangers, so it is necessary to select a suitable installation space. The installation location needs to consider the inlet and outlet pipes of the fluid and the maintenance and cleaning space of the heat exchanger.

2.1.2.Pipeline interface: The water inlet and outlet, inlet and outlet of the heat exchanger need to be connected to the system pipeline. When connecting the pipeline, it is necessary to ensure that the pipeline interface is completely matched with the heat exchanger interface and has good sealing.

2.2. Horizontal or vertical installation

Plate heat exchangers can generally be installed horizontally or vertically. The specific installation method depends on the layout and space conditions of the system.

Horizontal installation: suitable for situations with more spacious space, which can be easily installed and maintained.

Vertical installation: suitable for situations where the space is small and the floor space needs to be saved. Vertical installation is usually used for compact heat exchangers.

2.3. Pipe connection

During installation, the inlet and outlet pipes of the cold fluid and the hot fluid need to be connected to the inlet and outlet interfaces of the plate heat exchanger to ensure good sealing at the connection. Common connection methods include flange connection, threaded connection and welding connection.

Pipeline flow direction: When connecting the pipeline, you need to pay attention to the flow direction of the fluid. The hot fluid and the cold fluid need to flow to the relative channels of the plate heat exchanger to maximize the heat exchange efficiency.

2.4. Inspection and testing

After the installation is completed, pressure testing, leakage testing and flow testing are required to ensure the normal operation of the equipment. Through these tests, potential installation problems can be troubleshooted and the reliability of the plate heat exchanger can be ensured.

3. Working principle of plate heat exchanger

The working principle of plate heat exchanger is mainly to achieve heat transfer through the heat conduction of metal plates. The specific process is as follows:

3.1. Fluid flow

In the plate heat exchanger, the hot fluid and the cold fluid flow through different channels. The direction of the two fluid flows can be convection, parallel flow or cross flow.

3.1.1.Convection: The hot fluid and the cold fluid flow in opposite directions. This is the most common flow mode and the most efficient flow mode.

3.1.2.Parallel flow: The hot fluid and the cold fluid flow in the same direction. Although the flow time is longer, the efficiency is lower.

3.1.3.Cross flow: The flow directions of the two fluids are arranged in a cross pattern. This method is often used in situations where efficient heat exchange is not required.

3.2. Heat exchange

The hot fluid flows through the channel of the plate heat exchanger and transfers heat to the cold fluid through the heat conduction of the plate surface. After the cold fluid absorbs heat, the temperature rises, while the temperature of the hot fluid decreases.

The speed and efficiency of heat transfer depend on factors such as the flow rate of the fluid, the temperature difference, the thermal conductivity of the fluid, and the design of the plate pattern.

3.3. Turbulence enhances heat exchange

The plate pattern of the plate heat exchanger is very complex. The turbulent flow is formed by the corrugated or concave-convex design, so that the flow of the fluid between the plates is no longer a simple laminar flow, but has turbulent properties. Turbulence can enhance the mixing of the fluid, thereby improving the heat exchange efficiency.

The emergence of turbulence allows the fluid to contact more plate surfaces in the same time, thereby accelerating the transfer of heat.

3.4. Separation of hot and cold fluids

To prevent the hot and cold fluids from mixing, the plate heat exchanger uses sealing gaskets to separate the channels of different fluids. The sealing gaskets between each plate ensure that the hot and cold fluids do not cross-mix when passing through the heat exchanger.

3.5. Energy efficiency

The plate heat exchanger can efficiently recover waste heat and use waste heat to heat the cold fluid to improve energy efficiency. Therefore, it is often used in energy-saving renovation and green building projects.

4.Summary

The plate heat exchanger is an efficient, compact and energy-saving heat exchange device. It achieves efficient heat exchange through the heat conduction between multiple metal plates and the flow mode enhanced by turbulence. In the production process, it is necessary to select suitable materials, accurately process the plate surface pattern, and ensure the sealing of the equipment. When installing, it is necessary to pay attention to details such as pipe connection, installation location and fluid flow direction. Through reasonable working principles and optimized designs, plate heat exchangers are widely used in industries, food processing, air conditioning, energy recovery and other fields.

 

Maintenance manual of plate heat exchanger link

How to manufacture a plate heat exchanger？