Accuracy of 2D modeling approach for performance simulation of noncircular single- and dual-layer monolithic catalysts: a case study

Author(s):  
Behnam Mozaffari
Author(s):  
Behnam Mozaffari

This study aims to evaluate the accuracy of widely applied approach of modeling noncircular channels and washcoats of monolithic catalysts with equivalent circular geometrical shapes. For this purpose, catalytic performance of equivalent circular and square channel cross-sectional shapes with single-layer Pt/Al2O3 and dual-layer Fe-ZSM-5+Pt/Al2O3 washcoats are investigated. For the noncircular cross-sections, three-dimensional computational fluid dynamics models that consider species gases convection inside the channel bulk flow region, and reaction and diffusion of species inside the washcoat layer(s) are utilized to simulate the performance of one channel of the monolithic catalytic converters. In addition, in order to investigate the amount of inaccuracy of 2D modeling approach for noncircular channels, 2D models are applied to simulate the equivalent monolithic catalysts with circular cross-sections, and the results of the 2D and 3D models are compared together, and also, with the experimental and 1D+1D modeling technique results available in the literature.


2020 ◽  
Vol 6 ◽  
pp. 699-704 ◽  
Author(s):  
S. Mahmoud ◽  
M. Fahmy ◽  
M. Mahdy ◽  
I. Elwy ◽  
M. Abdelalim

2021 ◽  
Vol 11 (8) ◽  
pp. 3487
Author(s):  
Helge Nordal ◽  
Idriss El-Thalji

The introduction of Industry 4.0 is expected to revolutionize current maintenance practices by reaching new levels of predictive (detection, diagnosis, and prognosis processes) and prescriptive maintenance analytics. In general, the new maintenance paradigms (predictive and prescriptive) are often difficult to justify because of their multiple inherent trade-offs and hidden systems causalities. The prediction models, in the literature, can be considered as a “black box” that is missing the links between input data, analysis, and final predictions, which makes the industrial adaptability to such models almost impossible. It is also missing enable modeling deterioration based on loading, or considering technical specifications related to detection, diagnosis, and prognosis, which are all decisive for intelligent maintenance purposes. The purpose and scientific contribution of this paper is to present a novel simulation model that enables estimating the lifetime benefits of an industrial asset when an intelligent maintenance management system is utilized as mixed maintenance strategies and the predictive maintenance (PdM) is leveraged into opportunistic intervals. The multi-method simulation modeling approach combining agent-based modeling with system dynamics is applied with a purposefully selected case study to conceptualize and validate the simulation model. Three maintenance strategies (preventive, corrective, and intelligent) and five different scenarios (case study data, manipulated case study data, offshore and onshore reliability data handbook (OREDA) database, physics-based data, and hybrid) are modeled and simulated for a time period of 20 years (175,200 h). Intelligent maintenance is defined as PdM leveraged in opportunistic maintenance intervals. The results clearly demonstrate the possible lifetime benefits of implementing an intelligent maintenance system into the case study as it enhanced the operational availability by 0.268% and reduced corrective maintenance workload by 459 h or 11%. The multi-method simulation model leverages and shows the effect of the physics-based data (deterioration curves), loading profiles, and detection and prediction levels. It is concluded that implementing intelligent maintenance without an effective predictive horizon of the associated PdM and effective frequency of opportunistic maintenance intervals, does not guarantee the gain of its lifetime benefits. Moreover, the case study maintenance data shall be collected in a complete (no missing data) and more accurate manner (use hours instead of date only) and used to continuously upgrade the failure rates and maintenance times.


Author(s):  
A. Rodriguez

In three-dimensional models of urban historical reconstruction, missed contextual architecture faces difficulties because it does not have much written references in contrast to the most important monuments. This is the case of Merida, Yucatan, Mexico during the Colonial Era (1542-1810), which has lost much of its heritage. An alternative to offer a hypothetical view of these elements is a typological - parametric definition that allows a 3D modeling approach to the most common features of this heritage evidence.


Author(s):  
Ruá María José ◽  
Huedo Patricia ◽  
Cabeza Manuel ◽  
Saez Beatriz ◽  
Civera Vicente

In the urban context, buildings play a key role as they are energy consumers. In well-established cities with a high percentage of aged building stock, the focus should lie on sensitive urban areas where the weakest population sectors and the worst physico-economic conditions are usually encountered. In this work, the energy refurbishment of social housing is proposed. A block of municipally owned buildings is selected as a case study to consider that public buildings play an exemplary role according to Directive 2012/27/EU. The group is formed by 12 buildings, which account for 120 dwellings.This study is grounded on two levels. First the urban level. The building is located in a prioritised urban Area of Rehabilitation, Renovation and Urban Regeneration (ARRU), according to the new local Land Plan. This area presents multidimensional vulnerability and considers urban, building, socio-demographic and socio-economic features. Second, the building presents very low energy performance. It was built in 1959 when a high demand of dwellings and the economic resources then available led to low-quality buildings that are far from meeting today’s standards.Some proposals are made, having in mind the specific features of the urban context. The energy refurbishment of the building is proposed, selecting the optimal solution, considering technical, environmental and economic criteria. The energy performance simulation shows a remarkable improvement of the energy performance, resulting in an improvement of the thermal comfort of the dwellers. Besides, a reduction in the energy consumption is reached, which would reduce the energy bills and, on the other hand, a reduction of the carbon emissions to the atmosphere, contributing to a better environment quality. Having in mind that the building is intended for social housing, energy poverty situations could be avoided, as dwellings are inhabited by low-income dwellers.


Author(s):  
A. Buda ◽  
S. Mauri

<p><strong>Abstract.</strong> Historic buildings are fragile systems to be managed and protected during time: in the task of heritage restoration, efficiency improvement interventions should enable a more sustainable building conservation and use. Such measures might be defined within the combination of building survey and energy performance simulation. A good knowledge of materials and physics characteristics is fundamental to weigh correctly any improvement intervention. This can be supported also by documentary research and diagnostics, to detect existing resources and conservation issues. However, how to match all collected qualitative and quantitative data with a building energy model is still an open question. Energy simulation alone gives a partial vision of heritage needs, excluding information which do not affect the thermal performance of the model; on the contrary, a whole building approach is necessary for defining restoration interventions. With the aim of suggesting a methodology to combine both fields of investigation, a case study has been chosen to our purpose: Giuseppe Terragni’s Casa del Fascio (1936). A multidisciplinary process with the combination of building survey, monitoring campaign, on-site investigation and energy modelling has been functional to the understanding of the real building needs and the definition of interventions. Furthermore, the analysis has given to the rediscover of Terragni’s microclimatic control system (not more existing), leading to the choice of reinventing - in a modern way – the existing devices (as curtains), well-balanced on building needs.</p>


2014 ◽  
Vol 95 (8) ◽  
pp. 1757-1763 ◽  
Author(s):  
Cosimo Taiti ◽  
Corrado Costa ◽  
Paolo Menesatti ◽  
Diego Comparini ◽  
Nadia Bazihizina ◽  
...  
Keyword(s):  

2019 ◽  
Author(s):  
Hoang Gia Diem ◽  
Duong Tan Da ◽  
Nguyen Do Ngoc Nhi ◽  
Nguyen Tien Thanh
Keyword(s):  

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