The role of engineering laboratories in the establishment of a quality culture in higher education in Greece

An academic legislative reform of the public university sector was recently initiated in Greece (since 2005). It was designed to respond to the requirements of convergence to a common frame of the European Space of Higher Education. This reform found significant resistance from university personnel and students, resulting in a very slow degree of implementation. A careful examination of possible causes for the slow pace of reform usually points to the reluctance of a significant part of the academic and administrative personnel (tenured public service employees), to follow quality assurance procedures and undergo performance evaluation. Engineering schools, on the other hand, are more apt to adopt such principles, since they are taught in engineering curricula and widely applied in industry and services sectors. In this paper, the authors comparatively describe their experience in applying basic quality principles and practices to the university laboratory environment, motivated by cooperation with industry. The comparative discussion adds insight to the reasons for the resistance of the public higher education sector to quality assurance procedures and indicates specific directions to enhance the dissemination of quality culture in engineering faculties. After two decades of experience with the application and introduction of quality structures in the university and industry, the authors believe that engineering laboratories are a valuable tool in initiating and establishing a quality culture in the Greek higher education system

Experience gained from the application of basic quality assurance procedures in a Greek university engineering department

During the last decade, significant funding has become available to Greek public universities to support the convergence to the common European space of higher education. In a number of departments, this funding was wisely invested in the development of a quality culture, covering not only the educational process, but also the services offered by the department's administration and technical support staff. This paper presents the design and implementation of a quality-oriented studies' reform plan in the Mechanical Engineering Department, University of Thessaly in the period 2002-2008. Based on the successful experience from its application, a significant part of the personnel and students have become acquainted with basic quality assurance procedures and performance evaluation. Experience and lessons learnt from this effort are reported and discussed in this paper. © 2010 SEFI

Overview of Diesel particulate filter systems sizing approaches

Although application of Diesel particulate filters in modern automotive Diesel engines is commonplace, their introduction to large Diesels as locomotive or marine engines is moving at a slower pace. One important reason for this delay is the large volume of filter required which is not easy to accommodate in this type of equipment. Thus, rational sizing of the filters becomes essential in these applications. It is observed that DPF systems for large Diesel engines are usually oversized. Possible reasons are discussed in this paper. With the present status of technology and the concern for compact and cost-optimized exhaust treatment systems a new design methodology is needed. This paper summarizes progress in the specific fields of application and attempts to formulate a filter sizing methodology that would lead to feasible solutions with regard to space requirements and backpressure penalty. © 2017 Elsevier Lt

Thermogravimetric analysis of soot emitted by a modern diesel engine run on catalyst-doped fuel

Understanding the mechanisms that affect catalytic activity in porous ceramic diesel particulate filters (DPF) at the temperature range 200 to 400degreesC is important for the successful modeling of the initiation and evolution of catalytic regeneration by use of fuel additives. This refers not only to the dry carbon particulate, but also to the volatile hydrocarbons adsorbed on it. In this paper, a detailed analysis of the hydrocarbon adsorption-desorption and oxidation behavior of diesel particulate emitted by a modern diesel engine and collected on a SiC diesel filter is performed by use of thermogravimetric and differential scanning calorimetry analysis (TGA-DSC). Non-isothermal tests were performed with samples collected directly from a ceramic filter connected to the exhaust system of the diesel engine running under low and medium speed and load operating conditions with and without fuel additive. Fuel additive concentration was varied to investigate its effect on the soot oxidation behavior. Based on the TGA data, the kinetic parameters of the soot oxidation reaction were calculated. The effect of volatile adsorbed hydrocarbons on the soot oxidation reaction was evaluated by comparing the calculated activation energies for samples collected from the center and the periphery of the filter at various exhaust temperatures prevailing at filter loading phase. In particular it was seen that the catalytic activity of the fuel additive is enhanced by the presence of the volatile organic components. (C) 2003 The Combustion Institute. All rights reserved

Mow maldistribution measurements in wall-flow diesel filters

Understanding the flow maldistribution phenomena inside porous ceramic diesel particulate filters and their effects on the pressure drop and regeneration characteristics is important for the successful design and modelling of this class of exhaust aftertreatment system. In this paper the results from an experimental study of flow distribution in wall-flow diesel filters are presented. The experiments were performed on a specially designed cold flow test rig, under steady state flow conditions. The flow distribution at the exit of cordierite and SIC filters were measured with a hot film velocity sensor under low and medium mass flowrate conditions. The system configuration was varied to incorporate tests with and without the installation of an oxidation catalyst before the filter in order to investigate the effect of the catalyst honeycomb structure to the measured flow distribution. Flow distribution in filters loaded with various levels of particulate mass was also measured using the same device. The filters were loaded in a modern diesel engine run on catalyst-doped fuel up to different backpressure levels. A flow uniformity index was adopted in order to quantify the measured flow maldistribution by a single number for each case. The velocity distribution at the exit of the filters is found to be significantly affected by certain design and operating parameters of the system: diffuser-catalyst-filter. The results of this work aim to give a better assessment of the magnitude of flow maldistribution in diesel filters, which severely distort their pressure drop characteristics and affect the distribution of collected soot mass. In this way, a previously neglected aspect of the complex three-dimensional filter regeneration behaviour is better understood

Modelling three-way catalytic converters: an effort to predict the effect of precious metal loading

The need to deliver ultra-low emitting vehicles at a reasonable cost is driving the automotive industry to invest significant manpower in computer aided design and optimization of exhaust treatment systems. The significant fluctuations in the stock exchange market values of the precious metals employed in the manufacture of automotive catalytic converters has increased interest in the possibility of assisting precious metal loading optimization by means of mathematical modelling. Currently employed models of real world performance of catalytic converters cannot predict this effect. Recent improvements in the core chemical reaction modelling of the CATRAN code, reported in this paper, allow a good correlation to be made of precious metal loading with apparent kinetics, at least in the case of Pt-Rh catalysts. This may open new frontiers to the use of mathematical modelling in automotive exhaust after-treatment system optimization

Flow distribution effects in the loading and catalytic regeneration of wall-flow diesel particulate filters

The study of catalytic regeneration characteristics of porous ceramic diesel particulate filters (DPFs) is of growing interest to industry as diesel soot emissions are limited by legislation to levels below 0.01 g/km (for passenger cars). More specifically, pressure drop computations and correlations are important factors employed in the design and control of diesel filter systems. However, in numerous cases, computations and models fail to match the experimentally observed evolution of soot combustion in the filter. In this paper, the role of flow maldistribution in this issue is investigated, by means of full-scale tests of the loading and regeneration behaviour of a particulate filter installed on a modern diesel engine run on catalyst-doped fuel. Loading tests were performed at three characteristic engine operation points with markedly different levels of engine exhaust gas mass flowrate. In these tests, it becomes apparent that complex flow maldistribution phenomena exist during the loading phase, which are not directly reflected by the behaviour of the pressure drop versus time curve. However, these phenomena are shown to affect the distribution of collected soot mass in the different channels of the filter and, consequently, the regeneration behaviour. The evolution of flow maldistribution was also studied in a number of regeneration experiments. It was confirmed that the variation of the volatile organic fraction in the filter and the associated partial catalytic regenerations at low temperatures interact with flow and soot maldistribution in a complex way. The conclusions from this study set the scene for future, more detailed investigations that are expected to improve understanding and modelling of diesel filter pressure drop and regeneration characteristics