Plate heat exchangers are cooling devices used to cool liquid and air using the principle of convection. This process uses buoyancy forces between the warm surface and the cold outside air or liquid. A plate heat exchanger is a special type of air-cooled metal plate where in liquid or water flows through it. The flow of the liquid or water cools through the exchanger plate through metal fins. The plate used for this cooling process is generally made out of steel or aluminium.
As the name suggests, a plate heat exchanger operates on plate metal; its surface area is much higher than that of conventional free-standing heat exchangers. This enables the heat exchanger to more effectively transfer heat to the liquid being cooled. These types of heat exchangers can be found in many different industries such as electronics, food processing, chemical processing and the oil and gas industry. These modern day heat exchangers are also used in the construction of power generation plants and medical imaging equipment.
The process of cooling using plate heat exchangers is similar to that of air conditioners or refrigerators. The plates move with the heat of the process being accelerated or slowed down. The plate heat exchanger is therefore a very effective way to cool liquid because it is able to change the heat input to the incoming liquid.
There are several different types of plate heat exchangers available in the market. These include the direct plate heat exchanger, which is the cheapest but also the most inefficient. The indirect plate heat exchangers are cost effective but not as efficient as the direct ones. The indirect ones also require a cooling coil which is placed in another part of the machine instead of on the heat absorbing plate itself.
Plate heat exchangers also vary in size. The biggest and most efficient ones are called thermal expansion heat exchangers (THE) and have a cooling capacity of nearly twelve KVA. Smaller ones, however, can cool just as well if not better than THEs and their efficiency depends only on the size and the capacity of the cooling coil.
Although there are many benefits to using a plate heat exchanger, this type of heat exchange unit is not ideal for some applications. For example, they may work best in industrial applications in which the temperature to be cooled is very high. Also, it is important to ensure that the size of the plate heat exchanger is proportional to the size of the machine, to overheating occur. It is also advisable to have a qualified electrician inspect your heat exchanger after purchase to ensure that it meets safety standards.