Introduction of Aluminum Brazed Heat Exchanger

Brazed Aluminium Heat Exchangers (BAHX) play a crucial role in cryogenics. This due to their ability to facilitate heat transfer with small temperature differences. They are widely used for olefin, liquefied natural gas (LNG), and gas processing applications, offering high reliability and low energy consumption.

Our BAHX offer exceptional compactness and lightness, with a common surface area per volume around 2,000 m2/m3. That is four to five times as many as conventional exchangers.

Lighter exchangers offer a significantly reduced environmental footprint. In addition, our BAHX work at temperatures as low as 2-3°C, sometimes even lower for special applications. With design pressures of up to 140 bar, our BAHX are available in a wide range of sizes, configurations and fin types.

Benefits of Brazed Aluminum Heat Exchangers

Our team of experts are dedicated to assisting you in choosing the perfect aluminum heat exchanger for your needs.The benefits of our brazed aluminum heat exchangers include:

Cost-effective
Compact
Strength
Low-Temperature capabilities

Features of Aluminum Brazed Heat Exchanger

Compactness

Simple configuration.

Large heat transfer area per unit volume.

Aluminum alloy construction.

Good Economy

Mass production facilitated by standardized components and common work processes.

Reduced installation area and lower construction costs owing to the use of modular fabrication.

Reduced start-up time.

Wide Range of Application

Wide range of heat exchange processes including condensation and vaporization.

Allows the addition or removal of fluid during the heat exchange operation with multifluids.

Efficient extraction of heavy gas component from multigas mixtures.

Strength

Sufficiently strong to withstand repeated stress and thermal shock.

Applicable under high pressures up to 13 MPa.

Low-temperature

Aluminum alloy structure allows operation at a very low temperature of -269°C.

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Main Products Group of Aluminum Brazed Heat Exchanger

Clad tube

Tube products for both welded and folded tube designs supporting the continuing trend for downgauging and incressing demands on corrosion resistance, brazeability and strength.

Clad fin

Clad fin developed for excellent brazeability to withstand core dissolution and high-temperature sagging,and to enable downgauging for lighter heat exchangers.

Unclad fin

The most basic heat exchanger material. Unclad fin comprises only one alloy without clad layers and is used for applications such as radiators, heaters, charge air coolers and evaporators.

Clad plate

Consists of a core alloy clad with braze clad on one or two sides. The rolled product is stamped or shaped by the customer depending on the application and used in most kinds of heat exchanger applications, either for coolant plates or manifolds.

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Inspection Considerations for Aluminum Brazed Heat Exchanger

Consider visual inspection on a routine basis to identify any obvious damage or maintenance issues.

Perform routine leak detection utilizing forward-looking infrared (FLIR) surveys on BAHX reboilers, those in sub-cooler service, and those configured with inter-modular layers. Leak detection should be employed following any notable plant events or operating excursions, including compressor trips, start-ups, shutdowns, dehydrator bed switching, etc.

Periodically perform phased array ultrasonic testing (PAUT) of heat exchanger header welds to identify the presence of crack-like flaws.

Consider inspecting BAHX headers using a borescope or employing dye penetrant examination of welds such as header-to-core welds, nozzle-to-header welds, inter modular core welds etc. (note that this is not an acceptable test method for brazed surfaces).

Why Use Aluminum For Heat Exchangers?

In the HVAC&R sector, copper was becoming obsolete because of its cost, availability and flexibility of use. The market is progressively turning towards ecological options and innovative air conditioning systems. Why use aluminum for heat exchangers?

Performance and efficiency: aluminum has high thermal conductibility, perfect for creating high quality efficient heat exchangers, regardless of their specific field of use. Furthermore, since there are many alloys available, conductibility is variable according to the chemical composition and metallurgic combination, creating a series of new opportunities for different types of systems.
Cost reduction: aluminum costs far less than copper.
Weight and dimensions.
Versatility.

What Material Properties Should You Look for In Heat Exchanger Design?

Thermal Conductivity

Thermal conductivity is the measure of a material's ability to transfer heat. Higher thermal conductivity materials allow more efficient heat transfer, which improves the performance of your design.

Temperature Resistance

Temperature resistance is the measure of a material's ability to withstand high temperatures without deformation or compromising strength.

Density//Weight

Often, heat exchangers are designed for applications that require lightweight parts or where increases in weight decrease fuel efficiency - as with aerospace applications.

Corrosion Resistance

Corrosion resistance is the measure of a material's ability to resist corrosion from chemical and environmental conditions and is especially critical if a heat exchanger will be subjected to harsh conditions.

Strength

Strength is the measure of a material's ability to resist mechanical forces. Increased mechanical strength is required for applications that contain fluids at high pressure or will be subjected to heavier loads.

Cost and Availability

Cost and availability are self explanatory - you always want the best functional materials at the lowest cost.

FAQ

Q: 1.What is aluminum brazing?

A: Aluminum brazing is a joining process that connects two aluminum parts using a filler metal with a lower melting point than the base material. The filler metal is heated until it melts and flows into the joint, where it solidifies and forms a bond between the two parts.

Q: 2.How does a brazed heat exchanger work?

A: A brazed plate heat exchanger consists of corrugated plates that combine to create channels through which a hot medium and a cold medium (typically water) can be distributed.

Q: 3.Are aluminium heat exchangers any good?

A: Aluminium has a very high thermal conductivity (237W/m²/K). In layperson's terms, that means that they warm up very quickly and allow heat to pass through them efficiently. In other words, you're not wasting heat by warming up the heat exchanger for a long time.

Q: 4.What is brazing temperature for aluminium?

A: The aluminium brazing temperature range is normally 580-620°C. As a consequence, high strength aluminium alloys of the Al-Cu and the Al-Zn-Mg-Cu systems (which generally have lower liquidus temperatures) are generally not joined by brazing.

Q: 5.What is the difference between brazed and welded heat exchangers?

A: Brazed Plate heat exchangers are efficient and compact, making them an excellent economic choice. Welded plate heat exchangers are similar to Gasketed plate heat exchangers, but instead the plates are welded together.

Q: 6.What is the main purpose of heat exchanger?

A: Heat exchangers are used to transfer heat from one medium to another. These media may be a gas, liquid, or a combination of both. The media may be separated by a solid wall to prevent mixing or may be in direct contact. Heat exchangers are required to provide heating and/or cooling to meet a process requirement.

Q: 7.How long do aluminum heat exchangers last?

A: In the past, heat exchangers were often built with heavy metals, such as cast iron. These exchangers can last as long as 30 or 40 years, much longer than the steel exchangers most manufacturers build today. Modern stainless or aluminized steel heat exchangers typically have a life span of 15 to 25 years.

Q: 8.Why is aluminium used in heat exchangers?

A: Performance and efficiency: aluminum has high thermal conductibility, perfect for creating high quality efficient heat exchangers, regardless of their specific field of use.

Q: 9.Is aluminium brazing strong?

A: While it's true that welding typically provides a stronger bond, brazing can create joints that are strong enough for many applications. The strength of a brazed joint is often adequate for non-structural components, especially where flexibility and thermal conductivity are crucial.

Q: 10.What material is used to braze aluminum?

A: Aluminum brazing alloys are used to join brazeable aluminum base metals. Silicon and copper are typically added to pure aluminum to lower melting range and provide a suitable joining material. Magnesium can also be added to aluminum to assist in the facilitation of oxide dispersion in vacuum brazing.

Q: 11.Is an aluminium heat exchanger better than stainless steel?

A: In comparison to stainless steel, it is also cheaper, lighter and arguably more effective at resisting corrosion. However, it should be noted that an aluminium heat exchanger is more likely to suffer damage if it is not maintained regularly.

Q: 12.What is the difference between copper and aluminum heat exchangers?

A: Copper heats up faster than aluminum but also cools down faster. Aluminum heats up slower than copper but also cools down slower. This means that copper is better suited for applications that require fast heat transfer, while aluminum is better suited for applications that require gradual heat transfer.

Q: 13.Are aluminum heat exchangers good?

A: Cast aluminium heat exchangers are generally less expensive, lightweight, and corrosion-resistant, but they can be prone to cracking and have a limited lifespan.

Q: 14.How do you clean a brazed plate heat exchanger?

A: Use a tank with weak acid, 5% phosphoric acid or, if the exchanger is frequently cleaned, 5% oxalic acid. Pump the cleaning liquid through the exchanger. For optimum cleaning, the cleaning solution flow rate should be a minimum of 1.5 times the normal flow rate, preferably in a back-flush mode.

Q: 15.What is brazed heat exchanger?

A: The Brazed heat exchanger is constructed by a package of thin corrugated metal plates, surrounded by two thicker stabilizing plates. A thin copper foil placed between each of the thin metal plates melts and seals the brazed plate heat exchanger during a vacuum brazing process.

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