Aluminum is a cornerstone material in microchannel heat exchangers, valued for its lightweight and corrosion-resistant characteristics. However, safeguarding its longevity is crucial. This is where advanced nanoscale coating technology, newly deployed by Kaltra, emerges as a groundbreaking solution, providing unparalleled protection and extending heat exchangers’ performance life.
Protective coatings, being widely used for protection against unfavorable environmental exposure of heat exchangers, have raised many questions concerning their influence on thermal performance of coils and increased air resistance.
Amid the global shift towards carbon neutrality, air-source heat pumps (ASHP) have emerged as efficient and environmentally beneficial to traditional boilers, attracting substantial attention in recent years. Contrary to the cooling process, where the condenser is inside, the heating process uses an indoor condenser and an outdoor evaporator in ASHPs.
Electrocoating—also known as e-coating, electro-deposition, or electrophoretic deposition—is a high-performance finishing process in which metal parts are immersed in a paint bath and coated through the application of electrical current.
In the context of microchannel heat exchangers, e-coating is primarily used to apply a uniform, corrosion-resistant epoxy layer to aluminum components.
Condensation management is essential for ensuring the efficient function of heat exchangers and is critical for the correct operation of evaporators.
Hydrophilic topcoats, or water-resistant surfaces, are effective in environments with excessive condensation, as they enable water to flow easily off the heat exchanger surface based on the lowered surface tension, thereby enhancing heat transfer performance in wet and frost conditions. At the same time, hydrophilic coatings protect heat exchangers from the corrosive effect of water and provide excellent protection in salty environments.
Surface coatings play an important role in increasing the service life of heat exchangers and, consequently, HVAC equipment’s lifespan. Surface coatings may also positively impact heat transfer efficiency – but this potential remained unfulfilled until now.
Brazed all-aluminum microchannel coils perform superior heat transfer efficiency and capacity at the compact size compared with the conventional tube-fin heat exchangers. Another important factor of growing of microchannel heat exchanger popularity is the high corrosion resistance of aluminum, which is, however, achievable through the careful selection of aluminum alloys, surface treatments, and other protective measures.
Kaltra advances in creating protective treatments for microchannel heat exchangers and introduces new anti-corrosion coating for dry (fluid) coils to apply to inner surfaces. The new coating enables for an expanded range of process water pH value, a measure of how acidic/basic water is.
Although modern microchannel heat exchangers made from highly corrosion-resistant alloys and able to withstand any type of corrosion, be it galvanic, formicary, or other types, even without any protective coating, there are some harsh conditions under which additional treatment may extend their service life and guarantee trouble-free HVAC equipment operation.
Corrosion is the deterioration of metals arising from the chemical reactions between a metal and the surrounding environment. In HVAC equipment, such as air-cooled chillers, condensers, and dry coolers, corrosion of the heat exchangers may lead to performance and efficiency losses, as well as to equipment failures.
In order to avoid unwanted corrosion, microchannel heat exchangers and chilled water system, in general, must be properly protected based on environmental conditions.
