Aluminum heat exchanger, corrosion, thermal performance.
This paper shows the impact of the external corrosion generated by SWAAT tests on the thermal performance of the aluminum heat exchangers. The SWAAT tests were designed to evaluate the durability of metallic materials, it could be further utilized to evaluate the effect of corrosion on the thermal and hydraulic performances. The accelerated corrosion test leaves a large amount of salt and corrosion products on the heat exchanger surface. These deposits do not usually occur in operating conditions (some fouling does), they could mislead the understanding of the real effect of corrosion on heat exchanger performance. This paper presents experiments with two identical brazed aluminum HXs being exposed to a series of salt spray corrosion tests (SWAAT): the airside pressure drop, the heat exchanger heat transfer characteristics, and the weight of the heat exchangers were examined periodically after the salt spray test. One heat exchanger is cleaned periodically to remove the deposit. The thermal performances are evaluated both before and after cleaning. The other heat exchanger is evaluated without cleaning and removal of the deposits. The uncleaned heat exchanger shows much worse performance than the cleaned heat exchanger: a significant increase in the airside pressure drop and weight, also a decrease of the heat transfer coefficient have been identified. Our experimental results show a linear trend of thermal performance degradation vs. corrosion testing time. Data also suggests that the periodical cleaning of the heat exchanger may further accelerate the corrosion, indicated by the faster decrease of thermal performance and drop of HX weight.