Abstract
This study mainly deals with the evaluation of various degradation mechanisms that heat exchangers are susceptible to with an aim of evaluating future design requirements. A heat exchanger is a heat management system that uses fluids to transfer heat from one medium to the other; the most common types of fluids being air, water, oil or specialised coolant mixtures. As part of this study a failure analysis of heat exchangers was carried out on selected heat exchangers used in both aerospace and automotive sectors. This study was then extended to designing test-rigs supporting two types of heat exchangers. For this study, an air-to-air and an oil-to-air heat exchanger test rigs were designed. Temperature, pressure and flow sensors were introduced in the test rig designs to monitor the flow characteristics in order to determine if degradations occurring as a result of operation have an impact on them. As part of the initial evaluation both visual inspection and pulsed thermography inspection were selected as suitable inspection methods to evaluate their in-service condition. Some heat exchanger units where then subjected to accelerated corrosion tests and their performance was monitored using scanning electron microscopy (SEM) measurements. The outcomes of the study presented in this paper confirm the suitability and adaptability of thermography in detecting degradations occurring in heat exchangers.
Highlights
Heat transfer and fluid management systems are key parameters in the aerospace and automotive industry
This paper presents ongoing work undertaken in the area of degradation assessment of aerospace grade heat exchangers
A pulsed thermography inspection was carried out on the air-to-air heat exchanger unit to determine degradations occurring on its outer shell
Summary
Heat transfer and fluid management systems are key parameters in the aerospace and automotive industry. Despite the wide use of these heat management units, manufacturers still struggle with failures occurring during service They are mainly connected with temperature gradient, fouling and corrosion phenomenon. Corrosion is the gradual and continuous degradation of metals and its alloys due to their exposure to harsh environmental conditions and their relative chemical reactions with some substances. As a result, it may generate pits on the surface, crevices and other localized damages. Sri Addepalli et al / Procedia CIRP 38 (2015) 137 – 142 other NDT techniques remains in the very short inspection and cracks and other mechanical fractures which can result in analysis time.
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