How Shell and Tube Heat Exchanger Work

Shell and Tube Heat Exchanger is a common heat exchange equipment widely used in petroleum, chemical, electric power, food, pharmaceutical and other industries. Its main function is to achieve heating or cooling through heat exchange between two fluids. Here is a brief description of its working principle:

1. Structure

Shell and Tube Heat Exchanger mainly consists of three parts:

1.1.Shell: The outer shell, usually a cylindrical container, and the fluid flows inside the shell.

1.2.Tube Bundle: A group of arranged tubes, usually slender metal tubes, and the internal and external fluids flow inside and outside these tubes respectively.

1.3.Inlet/Outlet Nozzles:

The inlet and outlet pipes of the shell and tube heat exchanger are usually installed at both ends of the shell and connected to the outside world through the end caps.

Hot fluid (such as oil, water, etc.) enters from one end, flows through the tube, exchanges heat with the cold fluid, and is discharged from the other end.

The cold fluid flows in the shell, absorbs the heat of the fluid in the tube, and then is discharged from the outlet. The inlet and outlet positions of the cold fluid can be flexibly adjusted according to the design requirements.

2. Working principle

The working principle of the shell and tube heat exchanger is based on the principles of heat conduction and convection heat transfer. The specific process is as follows:

2.1 Fluid flow

Hot fluid: usually the fluid that needs to be cooled (such as water, oil, etc.), flows through the inside of the tube bundle.

Cold fluid: usually the fluid that needs to be heated (such as water, air, etc.), flows through the shell space and surrounds the outside of the tube bundle.

2.2 Heat exchange process

The hot fluid flows through the tube and transfers heat to the tube wall.

The cold fluid in the shell flows through the outside of the tube and absorbs this heat.

In the process of the hot fluid passing through the tube wall, the heat is transferred to the cold fluid through the heat conduction of the tube wall to complete the heat exchange.

2.3 Convection and conduction

Convection heat transfer: heat is transferred between the fluid in the tube and the tube wall by convection; similarly, heat is transferred between the fluid in the shell and the outer wall of the tube by convection.

Heat conduction: heat is transferred between the two fluids through the metal tube wall. The thermal conductivity of metal is an important factor in heat exchange efficiency.

2.4 Temperature difference drive

Heat is always transferred from high-temperature fluid to low-temperature fluid, so the temperature difference between the fluids is the driving force for heat exchange. The heat exchange efficiency can be improved by designing different flow modes (such as parallel flow, countercurrent flow, crossflow, etc.).

3. Flow mode

Shell and tube heat exchangers can be divided into several types according to the flow mode of the fluid:

3.1.Parallel flow: hot fluid and cold fluid flow in the same direction.

3.2.Countercurrent flow: hot fluid and cold fluid flow in opposite directions, which usually has higher heat exchange efficiency.

3.3.Crossflow: cold fluid passes through the tube bundle horizontally, and hot fluid flows along the tube bundle longitudinally.

4. Heat transfer efficiency

The heat transfer efficiency is affected by the following factors:

4.1.Temperature difference: The greater the temperature difference between the fluids, the higher the heat transfer efficiency.

4.2.Fluid flow rate: Increasing the fluid flow rate can increase turbulence and enhance the heat transfer effect.

4.3.Tube wall material: The thermal conductivity of the tube wall will directly affect the heat transfer efficiency. Common materials include stainless steel, copper, copper alloy, etc.

 

5. Application

Shell and tube heat exchangers are widely used in industrial processes that require efficient heat exchange, such as:

5.1.Petrochemical: such as cooling of crude oil, heating of chemical reaction products, etc.

5.2.Power plants: such as cooling and heat exchange of boilers, etc.

5.3.Food industry: such as heating and cooling liquid food, etc.

6.Summary

Shell and tube heat exchangers achieve temperature regulation of two fluids through heat exchange between internal tubes and external shells. Its structural design can adapt to harsh working environments such as high pressure and high temperature, and has strong application flexibility and efficient heat transfer performance.

 

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