Trying to explain what a heat exchanger is to someone not in the food industry can be a little more involved than simply saying “Well, it exchanges heat?” There’s a better way of telling people what heat exchangers in your industry do, and we’re going to give you a solid description of what a heat exchanger is to help bridge that gap.
The most basic definition of a heat exchanger is a specialized device assisting in the transfer of heat from one fluid to the other. There may be a solid wall keeping the liquids separate, the fluids may be in direct contact with each other in others. In the most efficient heat exchangers, the surface area of the wall between the fluids is maximized while fluid flow resistance is minimized.
You can use common appliances as basic examples of heat exchangers; air conditioners, refrigerators, and space heaters all apply. The likely most commonly known heat exchanger is a car radiator, which cools hot radiator fluid by use of airflow over the surface of the radiator.
There are multiple primary flow arrangements used with heat exchangers. In the counter-flow exchanger, the fluids enter the exchanger from opposite sides. It transfers the greatest amount of heat, making it the most efficient design. In the parallel-flow version, the fluids come in from the same end and move parallel to each other as they flow to the other side. The cross-flow heat exchanger moves the fluids in a perpendicular fashion.
There are also four different designs of heat exchangers. The most typical type is the shell and tube design, with multiple finned tubes. One of the fluids runs through the tubes while the other fluid runs over them, causing it to be heated or cooled. In the plate heat exchanger, the fluid flows through baffles, causing the fluids to be separated by plates with a large surface area. This type of exchanger is typically more efficient than the shell and tube design. The regenerative heat exchanger uses the shell and tube or plate designs to take advantage of the heat from a specific process in order to heat the fluid used in the same process. Finally, the intermediate fluid or solid heat exchanger uses the fluids or solids within it to hold heat and move it to the other side in order to be released. This method is used to cool gases while removing impurities at the same time.