Shell-and-Tube Heat Exchangers
Shell-and-tube heat exchangers are the most common type of heat exchanger that are being used in industry today. Heat exchangers are applied in numerous applications such as: chemical processing, heater cooling, condensing and evaporating, and chilling and heating. This type of heat exchanger consists of two main components: a shell and several tubes. The fluid that needs to be either heated or cooled flows through the tube, while another fluid passes around the outside of the tubes and in the shell side. Heat transfer effectively takes place through walls of the tubes, due to their large surface area which results in high rates of heat transfer.
The Shell-and-tube heat exchanger consists of a set of tubes which are fixed in a circular tube sheet, which is then inserted in an outer shell containing the remaining two tube sheets. The arrangement of the tubes can either be a single or a double series. In a single series arrangement, the tubes are arranged directly opposite on the tube sheet while in a double series arrangement, the tubes are arranged in an alternating order. The presence of the tube sheets acts as a support to the tubes in order to keep them in position.
The design of a Shell-and-tube heat exchanger can be further divided into two parts: the tube side and the shell side. The fluid that flows in the outer side of the tubes is referred to as the tube side fluid and the fluid that flows in the inner side of the tubes is referred to as the shell side fluid. To help increase the heat transfer rate, several features such as baffles, louvers and modifiers can be used. The baffles are used to improve turbulence on the shell-side and should be spaced appropriately to ensure the most effective heat transfer rate. The further use of louvers and modifiers in a heat exchanger helps to couple the fluids across the gap of the tube bundle.
Shell-and-tube heat exchangers are commonly used in the chemical and process industries to move heat from one liquid to another, to heat or cool a single component, or to recover waste heat from process streams. They can also be used to provide heat transfer across a large range of process conditions, making them a versatile piece of equipment. These heat exchangers are continually enhanced and modified, making them more efficient, reliable, and easier to use and maintain.
