Comparing Heat Exchangers for Boiler

Water/High Temperature Water Heaters

WATER HEATERSTM

HEAT EXCHANGERS

What Are They?

A heat exchanger is a device that allows thermal energy (heat) from a liquid or gas to pass another fluid without the two fluids mixing. It transfers the heat without transferring the fluid that carries the heat. Therefore, just the heat is exchanged from one fluid to another. This type of heat transfer is utilized with many applications including water heating, sewage treatment, heating and air conditioning, and refrigeration.

There are several different types of heat exchangers, each with their own design that work to heat up water. Next we will break down some of the key features of commonly used heat exchangers and the differences between them.

Plate:

A plate heat exchanger consists of a series of metal plates, typically stainless steel, that are joined together with a small amount of space between the face of the plates. The bottom of the plates create a small gutter or channel in between each plate which helps to keep water flowing. The thinner the channel, the more efficient the plates will be at transferring heat to the water because smaller amounts of water can be heated up faster. Plate heat exchangers have a large surface area, so as fluid flows in between these plates, it extracts heat from the plates rather quickly. This design is available as a brazed plate or gasketed design and can be configured as single or double wall.

Electric/Coil:

An electric heat exchanger is probably what most people think of when they think “electric heat” It is a simple coil wire that gives off heat like a light bulb in a lamp, and when electricity flows through it, it converts the energy passing through into heat. These electric coil heat exchangers are highly efficient, while their simple design allows for low maintenance.

Gas-Fired Heat Exchanger:

Gas fired heat exchangers are modular units that consist of multiple tubes that are bundled together. It heats water by firing into a chamber which creates natural exhaust gas. This exhaust goes into the tubes which condenses and transfers heat to the water. Condensing is when the moisture in the exhaust gas is cooled enough to change into a liquid. During this process, heat is given off without adding any more energy to the system. If this extra heat can be trapped inside the heat exchanger and used to heat the coils, then a much higher efficiency can be achieved without additional operating costs. This process happens when the water temperature is below 140°F. This increased heating has allowed boiler companies to achieve efficiencies into the high 90% range rather than the 86% range achieved by non-condensing designs.

Tube Bundle/Shell&Tube:

A shell and tube heat exchanger consists of a series of tubes that are bundled and encompassed by a baffle which directs the fluid across the bundle. The tubes run parallel to each other, with fluid from the tubes transferring energy to the water flowing through. This type of heat exchanger can work for a wide variety of applications

because tube diameter, thickness, length, and layout is available in a range of sizes that can be customized for your specific needs.

In Conclusion:

We have illustrated numerous unique designs suitable for a wide array of applications. Despite their design differences, all heat exchangers serve the same purpose, transferring energy from one source to another.