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Exchanger World Europe 2022 Conference Series
Corrosion , scaling , and leaching in BPHE : Best practices for a happy ownership
The Paris agreement is an international treaty on climate change with the goal to limit global warming to well below 2 ° C . To contribute to the Paris agreement different measures have to be undertaken . One way to help lower the carbon footprint is by increasing the efficiency of existing technology .
By Marion Karlsson Faudot , Application Engineer - SWEP
Brazed plate heat exchangers ( BPHE ) have one of the most efficient ways of transferring heat from one medium to another . Additionally , they consist of a minimum of material and require extremely small space compared to other heat exchanger technologies . In BPHE , around 95 % of the material is used for heat transfer , leading to a light and compact product with a low environmental impact . Their plate geometry enables high turbulence implying not only an efficient heat transfer , but also a self-cleaning effect .
The subject of this article was originally presented during the Heat Exchanger World Conference 2022 held in Rotterdam , the Netherlands . Our next European event will be held in 2024 . For more information on future events or to see how our 2022 edition went , check our event website : https :// heat-exchanger-worldeurope . com /
Securing an efficient product Media and material interaction with the heat transfer surface and operating conditions can lead to undesirable outcomes such as corrosion , fouling and scaling , as well as leaching . To enable a BPHE to remain highly efficient , it is important to investigate issues that can arise and impact its performance . Once the risks are detected solutions to counter them can emerge .
Fouling Fouling is the formation of an unwanted layer on heat transfer surfaces . The general effect of fouling is a decreased heat transfer and an increased pressure drop , lowering the product ’ s efficiency . There are different types of fouling that are classified into four categories : biofouling , particulate , scaling , and corrosion . Biofouling is the accumulation of microorganisms , plants , algae on the heat transfer area . It is common in cooling water systems . Particulate is when suspended solids settle ,
Cut-out of BPHE having been exposed to media with major sulphate content and high conductivity in order to trigger copper corrosion . The corrosion is seen from the green tint in the outer circuit .
Portrayal of the importance of a good media and material interaction with the heat transfer surface and operating condition . This cooperative interaction is needed to avoid undesirable outcomes such as corrosion , fouling , scaling and leaching .
this is common in open systems with cooling towers and with surface water . Scaling is the deposit of inorganic salts in the water circuit when temperature of water increases and wall temperature exceeds 65 ° C . This occurs commonly in boilers , hot water heat pump condensers , and desuperheaters . An added layer of corrosion product on the BPHE ’ s surface leads to what is called corrosion fouling . This it is common in all applications and is reduced with the help of a closed water system . Heat transfer surface properties such as structure and geometry have a significant role in whether fouling is likely to happen . Smooth stainless steel minimises the risk of surface adhesion and a BPHE with high chevron angle promotes turbulence and shear stress , reducing the likelihood of fouling . By keeping tabs on the operating conditions such as : flow velocity , temperature , turbulence level but also shear stress , the probability of fouling can be reduced . The last parameter influencing the prospect for unwanted fouling build up is media . The media ’ s properties ( conductivity , hardness , alkalinity and so forth ) interact with the heat transfer surface to promote or demote fouling formation . To mitigate fouling water filtration and water treatment can be utilised . Biocides , corrosion inhibitors , magnet filter , scaling inhibitor and make up water to keep the conductivity and mineral at a good level are all different potential treatments . Widening the view to the system , a strainer in front of key equipment , water flow control and water quality measurement and monitoring can be of aid .
28 Heat Exchanger World February 2023 www . heat-exchanger-world . com