Heat exchangers work by passing a hot and a cold fluid across opposite sides of a metal plate. As a result, the heat from one fluid passes across the metal (which is thermally conductive) and into the other fluid without the fluids coming into contact. Heat transfer is more efficient when there is high fluid velocity, turbulence, a large surface area and a large temperature differential. Depending on the application, different designs are more efficient than others.
In industry, shell-and-tube heat exchangers are probably the most common. Many types of HVAC equipment use them. Shell and tube heat exchangers are named appropriately - the main components are a tube pack (above, right) and a shell that encloses the tubes. Two fluids flow through the tubes, and one through the larger shell, surrounding the tubes.
Plate heat exchangers consist of a series of plates attached to a large frame. The inputs and outputs alternate between two liquids (hot, cold, hot, cold, etc., as shown above, right). Heat transfer efficiency is very high in this design because of the large surface area - much higher than a shell and tube heat exchanger taking up the same space.
Although its market share is much less than that of the previous two categories, dimple plate/plate coil technology is the best solution for applications where one of the fluids isn’t moving. It’s also useful in retrofit applications, such as waste heat recovery that wasn’t accounted for in the initial blueprints. Gasketed plate heat exchanger can also be a beer tank or dairy tank) where refrigeration or heating would otherwise be expensive.
Although its market share is much less than that of the previous two categories, dimple plate/plate coil technology is the best solution for applications where one of the fluids isn’t moving. It’s also useful in retrofit applications, such as waste heat recovery that wasn’t accounted for in the initial blueprints. Gasketed plate heat exchanger can also be a beer tank or dairy tank) where refrigeration or heating would otherwise be expensive.
Two steel sheets are spot-welded together, then inflated to create channels between the plates for fluid to flow. Dimple plate/plate coil technology can be customised to fit any particular application because of its simplicity and low cost. Most commonly, dimple plates are used to make tank jackets for beer and dairy tanks, but they can also be cut to fit inside tanks and submerged in liquid for efficient heat transfer. Dimple plate/plate coils combine the best features of both above types of heat exchangers – they are cheap, customizable, and compact, but can withstand high pressures and temperatures due to their design and materials. In many industrial processes, it can be incorporated as an afterthought, most notably to reduce energy costs or comply with environmental regulations.