The design specifications for shell and tube heat exchangers are available in three main varieties: parallel-flow heat exchangers, counter-flow heat exchangers and cross-flow heat exchangers. The distinctive designs and there purposes can easily be explained.
A pair of fluids which enter the heat exchanger at the same time from one side of the tube and travels parallel to the other down the length of the tube and then exiting out the other end is how a parrallel-flow heat exchanger is put together. The counter-flow heat exchanger in contrast works conversely to the parallel flow design, where the fluids are sent into the heat exchange from opposite ends. If compared to the other two, this design has the ability to work more efficiently since the greatest amount of heat can be transmitted due to the difference in temperature between the pair of tubes is far greater. In a cross-flow heat exchanger arrangement, the fluids in the heat exchanger travel perpendicular to one another.
All heat exchangers are constructed in order to take the most advantage of the area of the wall’s surface between the fluids while reducing the resistant against the fluids moving through the tubes regardless of the design configuration. To raise the surface area of the exchangers, fins can be added to better channel the fluid thereby creating a lot less turbulence.
One particularly powerful heat exchanger is the shell and tube heat exchanger. Using a series of tubes, this design configuration requires one set of tubes filled with fluid needing to be heated or cooled. Cooling and heating the fluid is possible when a second fluid moves across the tubes. They are constructed several ways as an example, in a plain layout, longitudinally or can be finned. They work well when it comes to applications where the pressure exceeds 30 bar regardless of how they are put together.
Designers of shell and tube heat exchangers need to consider how to best utilize the tube’s diameter, thickness and length to create optimum performance. While they could breakdown quicker than larger sized ones, a smaller tube may be far more compact and economical. An expensive heat exchanger is dependent on the pitch which is also significant as the greater the pitch the larger the overall diameter of the shell. The general performance of the heat transfer can be improved when a tube is corrugated, where more turbulence is generated.
The layout of the tubes must also be configured by the engineer. Tubes are usually arranged in a triangular design or a square pattern. Triangular layouts create a greater heat transfer because of the increased turbulence whereas square patterns will be more efficient for applications where cleaning is regular.
In shells and tube heat exchangers, baffles is yet another layout consideration. Baffles direct liquid across the tubes. While keeping them from drooping and vibrating, baffles are secured while running perpendicular to the shell. The spacing of a baffle is very important when designing the heat exchanger as the conversion of heat transfer and pressure drop must be dealt with. The tubes might sag if the baffles are placed too far apart potentially enabling them to suffer from cool spots.
Significant amount of time is taken when planning and designing top quality shell and tube heat exchangers. If you are looking to buy one, it is important to balance the cost savings of a cheaper variety to the top of the line products.
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