There are many types of heat exchangers. However, the ones we will be talking about in this article are specifically for heat pumps.
What is a Heat Exchanger
A heat exchanger is a device used to transfer heat between two or more fluids. The fluids can be either liquid or gas, but they must be at different temperatures.
The purpose and function of a heat exchanger is to maintain a fluid at its optimal temperature for use in a heat pump system.
By doing this, the heat exchanger helps to improve the efficiency of the system and prevents damage to the pump itself.
What Types Of Heat Exchanger Are Available?
You have Brazed heat exchangers (BHE), Finned Tube Heat Exchanger, and Air Cooled Heat Exchangers (ACHE).
Brazed heat exchangers (BHE)
European heat pumps frequently install brazed heat exchangers (BHE). They function as condensers, evaporators, and, sometimes, economizers in water-to-water and water-to-brine systems.
Finned Tube Heat Exchanger
A finned tube heat exchanger, also known as an air-cooled heat exchanger, is a type of heat exchanger that uses fins to increase the surface area of the tubes. This allows for more heat to be transferred in a shorter amount of time.
The finned tube heat exchanger is often used in applications where there is a need for high heat transfer rates and where space is limited.
The efficiency of finned tube heat exchangers, ACHEs, coolers, and dryers is dependent on the amount of surface area exposed to the air/gas flow.
The extended surface – the fins – that protrude into the air/gas flow and enhance heat transfer capability is what makes these devices so efficient.
Where Would You Use A Finned Tube Heat Exchanger?
In processes that produce hot gases, finned tube heat exchangers are frequently utilized for heat recovery.
The heat in the gas is transferred to a liquid, usually water or a thermal oil.
The heated liquid may be used in an application where you would previously need to use additional energy to warm it up.
ACHE’s are best suited to chemical processes, petrochemical cooling, steam cooling in textiles processing, grain drying, concrete curing, paper production, and food processing.
Since air is the most frequently used flow process in the world, ACHE applications are very broad.
Shell And Tube Heat Exchanger
Heat exchangers that use shell and tube technology transfer heat through a series of tubes enclosed in a huge metal shell (known as a tube bundle) for example. The counter-flowing hot or cold fluid or gas is pumped into the shell, where the heat transfer occurs.
Where Would You Use A Shell And Tube Heat Exchanger?
These designs are often utilized for high-pressure applications, but they may also be used to meet the demands of a vacuum environment.
A shell and tube heat exchanger is less susceptible to contamination than a finned tube bank, owing to its inbuilt containment features.
The use of the shell and tube heat exchanger in oil, gas, and chemical industries is widespread.
Plate Heat Exchanger Or Gasket Plate Heat Exchanger
Heat exchangers made of plate heat exchangers, usually known as gasket plate heat exchangers, use a series of plates that are compacted together side-by-side to transfer fluids.
Where Would You Use A Plate Heat Exchanger?
Heat exchangers are most often used in liquid to liquid systems, such as hot process water that contains chemicals/contaminants, which need to be heated.
Individual houses may benefit from plate heat exchangers or gasket plate heat exchangers, allowing them to use the right quantity of hot water from a centralized source.
Plate heat exchangers can also be used to cool oils by transferring heat between two liquids that can’t mix.
Air Source Heat Pump Heat Exchangers
An air-source heat pump has two heat exchangers. The first is located outside the unit. It uses the principle of heat transfer to transport thermal energy from the air and pump it into the interior unit by using a coil of refrigerant-filled tubing.
The refrigerant enters the air source heat pump’s interior unit in this form since it is filled with a liquid that is colder than the external air.
Thermal energy is drawn into the coil as a result of this, warming up the refrigerant and causing it to transition to gas.
The refrigerant goes from there into the house via the air source heat pump’s interior device.
The interior unit of a heat pump features a second heat exchanger, which serves as a junction between the warmer interior temperatures inside the heat exchanger coil and the home’s relatively cool environment.
So, the heat energy that has been carried into the house seeks equilibrium and begins to flow from the area with more energy (the heat exchanger coil) to the area with less energy (your home).
When the fan blows in fresh air, it is warmed and pushed into the ductwork. The refrigerant cools and condenses back into a liquid as the fan drives this heat into the ductwork.
After that, the refrigerant goes back to the outside unit to continue the process as needed in order for your home to maintain a comfortable temperature.
Are heat exchangers 100% efficient?
For all practical purposes, heat exchanger thermal efficiency is close to 100 percent. As a result, no improvement is needed.
What are the disadvantages of a heat exchanger?
The major drawbacks of a heat exchanger are the initial expenditures, titanium plates are pricey, and finding leaks is difficult because pressure testing isn’t as simple as tube coolers. The operating temperature of the cooler is limited by bonding material between the plates, and the pressure drop caused by the plate cooler is greater than that of a tube cooler.