Vehicle level health assessment through integrated operational scalable prognostic reasoners

Today’s aircraft are very complex in design and need constant monitoring of the systems to establish the overall health status. Integrated Vehicle Health Management (IVHM) is a major component in a new future asset management paradigm where a conscious effort is made to shift asset maintenance from a scheduled based approach to a more proactive and predictive approach. Its goal is to maximize asset operational availability while minimising downtime and the logistics footprint through monitoring deterioration of component conditions. IVHM involves data processing which comprehensively consists of capturing data related to assets, monitoring parameters, assessing current or future health conditions through prognostics and diagnostics engine and providing recommended maintenance actions. The data driven prognostics methods usually use a large amount of data to learn the degradation pattern (nominal model) and predict the future health. Usually the data which is run-to-failure used are accelerated data produced in lab environments, which is hardly the case in real life. Therefore, the nominal model is far from the present condition of the vehicle, hence the predictions will not be very accurate. The prediction model will try to follow the nominal models which mean more errors in the prediction, this is a major drawback of the data driven techniques. This research primarily presents the two novel techniques of adaptive data driven prognostics to capture the vehicle operational scalability degradation. Secondary the degradation information has been used as a Health index and in the Vehicle Level Reasoning System (VLRS). Novel VLRS are also presented in this research study. The research described here proposes a condition adaptive prognostics reasoning along with VLRS

Analysis of electric propulsion electrical power conditioning component technology. Volume 1 - Data bank Final report

Analysis of electric propulsion electric power conditioning component technology - data revie

Towards system-level prognostics : Modeling, uncertainty propagation and system remaining useful life prediction

Prognostics is the process of predicting the remaining useful life (RUL) of components, subsystems, or systems. However, until now, the prognostics has often been approached from a component view without considering interactions between components and effects of the environment, leading to a misprediction of the complex systems failure time. In this work, a prognostics approach to system-level is proposed. This approach is based on a new modeling framework: the inoperability input-output model (IIM), which allows tackling the issue related to the interactions between components and the mission profile effects and can be applied for heterogeneous systems. Then, a new methodology for online joint system RUL (SRUL) prediction and model parameter estimation is developed based on particle filtering (PF) and gradient descent (GD). In detail, the state of health of system components is estimated and predicted in a probabilistic manner using PF. In the case of consecutive discrepancy between the prior and posterior estimates of the system health state, the proposed estimation method is used to correct and to adapt the IIM parameters. Finally, the developed methodology is verified on a realistic industrial system: The Tennessee Eastman Process. The obtained results highlighted its effectiveness in predicting the SRUL in reasonable computing time

Enhancing fuel cell lifetime performance through effective health management

Hydrogen fuel cells, and notably the polymer electrolyte fuel cell (PEFC), present an important opportunity to reduce greenhouse gas emissions within a range of sectors of society, particularly for transportation and portable products. Despite several decades of research and development, there exist three main hurdles to full commercialisation; namely infrastructure, costs, and durability. This thesis considers the latter of these. The lifetime target for an automotive fuel cell power plant is to survive 5000 hours of usage before significant performance loss; current demonstration projects have only accomplished half of this target, often due to PEFC stack component degradation. Health management techniques have been identified as an opportunity to overcome the durability limitations. By monitoring the PEFC for faulty operation, it is hoped that control actions can be made to restore or maintain performance, and achieve the desired lifetime durability. This thesis presents fault detection and diagnosis approaches with the goal of isolating a range of component degradation modes from within the PEFC construction. Fault detection is achieved through residual analysis against an electrochemical model of healthy stack condition. An expert knowledge-based diagnostic approach is developed for fault isolation. This analysis is enabled through fuzzy logic calculations, which allows for computational reasoning against linguistic terminology and expert understanding of degradation phenomena. An experimental test bench has been utilised to test the health management processes, and demonstrate functionality. Through different steady-state and dynamic loading conditions, including a simulation of automotive application, diagnosis results can be observed for PEFC degradation cases. This research contributes to the areas of reliability analysis and health management of PEFC fuel cells. Established PEFC models have been updated to represent more accurately an application PEFC. The fuzzy logic knowledge-based diagnostic is the greatest novel contribution, with no examples of this application in the literature

30th International Conference on Condition Monitoring and Diagnostic Engineering Management (COMADEM 2017)

Proceedings of COMADEM 201

District Cooling – Towards Improved Substation Performance

The global cooling demand in buildings is rapidly increasing and to supply this demand, district cooling is one solution. However, many district cooling systems suffer from low delta-Ts (receiving low return temperatures from the buildings connected to the system). The low delta-Ts cause an increased water flow rate, congested distribution networks, require more chiller to operate and reduce the amount of free cooling possible to use. Ultimately, the costs increase, and energy is being wasted. The problem with low delta-Ts has previously mainly been investigated in district cooling systems without heat exchangers in the substation separating the system and the buildings. The purpose of this thesis is therefore to contribute with such knowledge with the aim to develop a systematic approach on how to evaluate and improve the performance of district cooling substations with heat exchangers, to achieve high delta-Ts.The work was done by analyzing data from both sides of the heat exchanger of approximately 40 substations of buildings connected to an actual district cooling system. The results show a majority of the investigated substations perform poorly. The reasons to this are many but some examples include incompatibility with the district cooling system and limited or lacking follow-up and optimizations of the buildings’ systems and substations. Low delta-Ts, high overflows and flow in the saturation zone are primary side performance indicators, developed and tested to evaluate the substation’s performance. The performance indicators showed improvements can be done to almost all investigated substations. Three additional performance indicators were developed including data from the secondary side. These showed further reasons to poor substation performance can be explained by the heat exchanger’s temperature approaches. Moreover, high primary flow rates in relation to the secondary flow rates were also shown to cause low delta-Ts. Two control strategies were identified as potential solutions to resolve some low delta-Ts. These control strategies were field tested in four buildings and shown to successfully increase delta-T and eliminate the flow in the saturation zone.To achieve improved performance, it is recommended to employ a systematic method to follow up the substations on a regular basis. This can be done by using the developed performance indicators together with a ranking system as support for decision-making on which substations to address first. Moreover, a systematic follow-up method can be used for collaboration between the utility company and the customers, or it can be used by the property owners as part of their optimization work. Lastly, incentives for improved substation efficiency can be strengthened by adding a temperature component to the price model

Study of the automated bioliogical laboratory project definition. Volume III - System engineering studies Final report, 10 Aug. 1964 - 10 Aug. 1965

Systems engineering studies for automated biological laboratory for exploration of life on Mar

Chromium Poisoning:The Needle in the SOFC Stack

This thesis focuses on Cr-poisoning in solid oxide fuel cells (SOFC), which currently presents a key challenge for the development of this technology. By the implementation of dedicated experimental tools, this work offers a new access to, and comprehension of, electrochemical performance degradation caused by Cr contamination accumulation. An experimental setup for the in situ assessment of Cr vapor concentrations within the hot air flux of an SOFC system inlet gives direct proof, and a measure of severity, of the Cr contamination issue. An energy-dispersive X-ray spectroscopy (EDX) based Cr quantification methodology leads this work to objective and therefore comparable data from post-test observations performed by scanning electron microscopy (SEM).Moreover, the developed methods are time-efficient. To understand Cr-poisoning, in particular the deposition mechanisms of Cr gVI to CrsIII , electronic conducting cathode materials such as (La,Sr)MnO3 as well as mixed ionic electronic conductors (MIEC) such as (La,Sr)CoO3, (La,Sr)(Co,Fe)O3, (La,Sr)MnO3-(Y,Zr)O2 and Nd1.95NiO4+δ are investigated during and after medium- to long-term electrochemical testing involving deliberate exposure to Cr contamination in button cell and stack test arrangements. The deposition rate of both chemically-driven and electrochemically-driven cathode mechanisms related to Cr-poisoning depends on the material, its operating conditions as well as on superimposed degradation phenomena, such as sulfur-poisoning. Investigation and subsequent results at the SOFC stack level combine the different aspects of Cr contamination encountered within this work. The severity of Cr-poisoning of a cathode, depending on the electrode overpotential, guides the development of less-sensitive materials towards high performing cathodes, in particular MIEC electrode materials at lower temperature. The crucial role of electrode proximal layers within the cathodic half-cell, such as current collectors and protective coatings of metallic interconnects (MIC) is found to be adequately dispatched by present SOFC technology. Their role is to lower the concentration of Cr vapor species reaching electrochemically active cathode regions both by diffusion resistance and reactive trapping. In contrary, sealing materials do not achieve satisfactory tightness to hydrogen diffusion into the cathode compartment, causing aggravated Cr-poisoning by local steam generation and hence increased Cr-evaporation. As the protection against Cr evaporation of the entire balance-of-plant (BoP) of a real SOFC system, or its construction with non-emitting components regarding Cr evaporation, is not practicable, a Cr-getter-based air filter, developed within this work and validated in situ, offers a suitable solution for BoP-caused Cr pollution