In many industries and processes, heat exchangers are of vital importance as they are used to transfer heat from one fluid to another. These fluids can be corrosive to heat exchangers, which are usually made of metallic materials. This paper illustrates that corrosion is an important problem in the operation of heat exchangers in many environments, for which no straightforward answer exists. Corrosion failures of heat exchangers are common, and corrosion often involves high maintenance or repair costs. In this review, an overview is given of what is known on corrosion in heat exchangers. The different types of corrosion encountered in heat exchangers and the susceptible places in the devices are discussed first. This is combined with an overview of failure analyses for each type of corrosion. Next, the effect of heat transfer on corrosion and the influence of corrosion on the thermohydraulic performances are discussed. Finally, the prevention and control of corrosion is tackled. Prevention goes from general design considerations and operation guidelines to the use of cathodic and anodic protection.

https://biblio.ugent.be/publication/8612428/file/8620828.pdf

Corrosion and corrosion prevention in heat exchangers

Fouling was for long considered by many to be an ‘act of God’. The simple theological implications of this view are that fouling is (a) beneficial, and (b) unavoidable, while the legal implications suggest that since no mortal can be held responsible, no damages can be sought as a result of losses attributable to fouling. No apology is therefore required for introducing the devil at this stage. Fouling, treated as an unwanted deposition of materials on surfaces, is not beneficial, and although it may not be completely avoidable, both it and its effects can be reduced.

The Economics of Fouling

The effect of tubeside maldistribution on the thermal performance of condensers used in multistage flash distillation plants

A dual-circulation testing system was constructed to study the effect of heat flux density (q, −22.28 ∼ +22.54 kW m-2) on the corrosion of an Al–Cu–Mg–Mn alloy in 0.5 M H2SO4 at a constant metal surface temperature (50°C) under different controlling heat transfer states. Their heat transfer parameters were determined quantitatively by COMSOL simulation to keep them except q in constant, highlighting the influence of q on metal corrosion. Compared with the q = 0 condition, the positive heat flux (q > 0) improved the surface layer performance of the Al alloy to inhibit its anodic corrosion process, decreasing its corrosion current density (icorr) by 56% with increasing q to 22.54 kW m-2. While q < 0, the opposite effect occurred, increasing its icorr by 52% at q = −22.28 kW m-2. Heat flux also changed the corrosion reaction’s apparent effective activation energy (Ea) and pre-factor, and Ea played a dominating role in changing icorr. 

Effect of heat flux on metal corrosion in non-boiling media: testing system, heat transfer simulations, and corrosion study on Al alloy

ABSTRACT A dual-circulation testing system was constructed to study the effect of heat flux density (q, −22.28 ∼ +22.54 kW m-2) on the corrosion of an Al–Cu–Mg–Mn alloy in 0.5 M H2SO4 at a constant metal surface temperature (50°C) under different controlling heat transfer states. Their heat transfer parameters were determined quantitatively by COMSOL simulation to keep them except q in constant, highlighting the influence of q on metal corrosion. Compared with the q = 0 condition, the positive heat flux (q > 0) improved the surface layer performance of the Al alloy to inhibit its anodic corrosion process, decreasing its corrosion current density (i corr) by 56% with increasing q to 22.54 kW m-2. While q < 0, the opposite effect occurred, increasing its i corr by 52% at q = −22.28 kW m-2. Heat flux also changed the corrosion reaction’s apparent effective activation energy (E a) and pre-factor, and E a played a dominating role in changing i corr.

https://figshare.com/articles/journal_contribution/Effect_of_heat_flux_on_metal_corrosion_in_non-boiling_media_testing_system_heat_transfer_simulations_and_corrosion_study_on_Al_alloy/21197684

In its simplest form, a heat exchanger consists of a bundle of tubes arranged between two thick perforated tube plates and enclosed by an outer shell Covers over the tube plates allow one fluid to pass inside the tubes while a second hotter or cooler fluid is introduced via openings in the shell Since they contain no moving parts it might be expected that heat exchangers would be highly reliable pieces of equipment However, everyday experience with small domestic and automotive heaters and coolers suggests this is not always the case In the case of mass-produced items such as these, replacement of a defective component is usually relatively straightforward and inexpensive However, for the much larger heat exchangers used in the process chemical and power industries, a single failure may result in significant financial losses

J. G. Collier

Papers

Reliability Problems of Heat Transfer Equipment