Degradation study of heat exchangers

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

Terminal Weaning or Immediate Extubation for Withdrawing Mechanical Ventilation in Critically Ill Patients (the ARREVE Observational Study)

International audiencePURPOSE: The relative merits of immediate extubation versus terminal weaning for mechanical ventilation withdrawal are controversial, particularly regarding the experience of patients and relatives. METHODS: This prospective observational multicentre study (ARREVE) was done in 43 French ICUs to compare terminal weaning and immediate extubation, as chosen by the ICU team. Terminal weaning was a gradual decrease in the amount of ventilatory assistance and immediate extubation was extubation without any previous decrease in ventilatory assistance. The primary outcome was posttraumatic stress symptoms (Impact of Event Scale Revised, IES-R) in relatives 3~months after the death. Secondary outcomes were complicated grief, anxiety, and depression symptoms in relatives; comfort of patients during the dying process; and job strain in staff. RESULTS: We enrolled 212 (85.5%) relatives of 248 patients with terminal weaning and 190 relatives (90.5%) of 210 patients with immediate extubation. Immediate extubation was associated with airway obstruction and a higher mean Behavioural Pain Scale score compared to terminal weaning. In relatives, IES-R scores after 3~months were not significantly different between groups (31.9~±~18.1 versus 30.5~±~16.2, respectively; adjusted difference, -1.9; 95% confidence interval, -5.9 to 2.1; p~=~0.36); neither were there any differences in complicated grief, anxiety, or depression scores. Assistant nurses had lower job strain scores in the immediate extubation group. CONCLUSIONS: Compared to terminal weaning, immediate extubation was not associated with differences in psychological welfare of relatives when each method constituted standard practice in the ICU where it was applied. Patients had more airway obstruction and gasps with immediate extubation. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01818895

“You helped me keep my head above water”—experience of bereavement research after loss of a loved one in the ICU: insights from the ARREVE study

International audienc

Correction to: Terminal Weaning or Immediate Extubation for Withdrawing Mechanical Ventilation in Critically Ill Patients (the ARREVE Observational Study)

International audienceCorrection to: Intensive Care Med (2017) DOI 10.1007/s00134-017-4891-0

ICU physicians’ and nurses’ perceptions of terminal extubation and terminal weaning: a self-questionnaire study

International audienc