Assessment of an exhaust thermoelectric generator incorporating thermal control applied to a heavy duty vehicle

The road transport industry faces the need to develop its fleet for lower energy consumption, pollutants and CO2 emissions. Waste heat recovery systems with Thermoelectric Generators (TEGs) can directly convert the exhaust heat into electric energy, aiding the electrical needs of the vehicle, thus reducing its dependency on fuel energy. The present work assesses the optimisation and evaluation of a temperature-controlled thermoelectric generator (TCTG) concept to be used in a commercial heavy-duty vehicle (HDV). The system consists of a heat exchanger with wavy fins (WFs) embedded in an aluminium matrix along with vapour chambers (VCs), machined directly into the matrix, that grant the thermal control based on the spreading of local excess heat by phase change, as proposed by the authors in previous publications and patents. The TCTG concept behaviour was analysed under realistic driving conditions. An HDV with a 16 L Diesel engine was simulated in AVL Cruise to obtain the exhaust gas temperature and mass flow rate for each point of two cycle runs. A model proposed in previous publications was adapted to the new fin geometry and vapour chamber configuration and used the AVL Cruise data as input. It was possible to predict the thermal and thermoelectric performance of the TCTG along the corresponding driving cycles. The developed system proved to have a good capacity for applications with highly variable thermal loads since it was able to uncouple the maximisation of heat absorption from the regulation of the thermal level at the hot face of the TEG modules, avoiding both thermal dilution and overheating. This was achieved by the controlled phase change temperature of the heat spreader, that would ensure the spreading of the excess heat from overheated to underheated areas of the generator instead of wasting excess heat. A maximum average electrical production of 2.4 kW was predicted, which resulted in fuel savings of about 2% and CO2 emissions reduction of around 37 g/km.This article was partially supported by projects COOLSPOT PTDC/EME-TED/7801/2020, UIDB/00481/2020 and UIDP/00481/2020 (Centre for Mechanical Technology and Automation—TEMA) and UIDB/04077/2020 (MEchanical Engineering and Resource Sustainability Center—MEtRICs)— Fundação para a Ciência e a Tecnologia (FCT); CENTRO-01-0145-FEDER-022083 (Centro2020), Norte2020, Compete2020, under the PORTUGAL 2020 Partnership Agreement, through Portuguese national funds of FCT/MCTES (PIDDAC) and the European Regional Development Fund

Experimental study on steam oxidation resistance at 600 °C of Inconel 625 coatings deposited by HVOF and laser cladding

Inconel 625 (IN625) coatings were deposited by High-Velocity Oxy-fuel (HVOF) and laser cladding, on a 10.50–12%Cr steel to improve its oxidation resistance. Both as-deposited coatings exhibited a γ-Ni-Cr matrix and two protective oxides (Cr2O3 and NiCr2O4). In addition, laser cladding as-deposited coatings also presented precipitates A2B-type Laves phases due to the dilution effect from laser cladding technique. Coated and uncoated steel were oxidized under isothermal conditions at 600 ◦C for 2000 h and subsequently analyzed using gravimetry, SEM-EDS and XRD techniques. The application of IN625 coatings revealed a weight gain ten times lower than that registered for the uncoated steel, this improvement being mainly due to the presence of protective and stable Cr2O3 and NiCr2O4 oxides. Additionally, the XRD analysis showed that the initial Laves phases present in the laser cladding coating, were re-dissolved and transformed in δ-Ni3Nb compound suggesting that that the temperature and exposure time are enough to induce this transformation

Spatial distribution of bivalves in relation to environmental conditions (middle Danube catchment, Hungary)

The spatial distribution of bivalves in relation to environmental conditions was studied along a second- and third order stream – medium-sized river (River Ipoly) – large river (River Danube) continuum in the Hungarian Danube River system. Quantitative samples were collected four times in 2007 and a total of 1662 specimens, belonging to 22 bivalve species were identified. Among these species, two are endangered (Pseudanodonta complanata, Unio crassus) and five are invasive (Dreissena polymorpha, D. rostriformis bugensis, Corbicula fluminea, C. fluminalis, Anodonta woodiana) in Hungary. The higher density presented by Pisidium subtruncatum, P. supinum, P. henslowanum and C. fluminea suggests that these species may have a key role in this ecosystem. Three different faunal groups were distinguished but no significant temporal change was detected. The lowest density and diversity with two species (P. casertanum and P. personatum) occurred in streams. The highest density and diversity was found in the River Ipoly, in the side arms of the Danube and in the main arm of the Danube with sand and silt substrate, being dominated by P. subtruncatum and P. henslowanum. Moderate density and species richness were observed in the main arm of the Danube with pebble and stone substrate, being dominated by C. fluminea and S. rivicola. Ten environmental variables were found to have significant influence on the distribution of bivalves, the strongest explanatory factors being substrate types, current velocity and sedimentological characteristics.The project was financially supported by the Hungarian Scientific Research Fund under the contract No. OTKA T/046180. Special thanks to the DanubeIpoly National Park for the help in field work.info:eu-repo/semantics/publishedVersio

Species richness and functional structure of fish assemblages in three freshwater habitats:effects of environmental factors and management

In this study, the inverted trophic hypothesis was tested in the freshwater fish communities of a reservoir. The distribution of fish species in three freshwater habitats in the Jurumirim Reservoir, Brazil, was examined using both species richness and the relative proportions of different trophic groups. These groups were used as a proxy for functional structure in an attempt to test the ability of these measures to assess fish diversity. Assemblage structures were first described using non‐metric multidimensional scaling (NMDS). The influence of environmental conditions for multiple fish assemblage response variables (richness, total abundance and abundance per trophic group) was tested using generalised linear mixed models (GLMM). The metric typically employed to describe diversity; that is, species richness, was not related to environmental conditions. However, absolute species abundance was relatively well explained with up to 54% of the variation in the observed data accounted for. Differences in the dominance of trophic groups were most apparent in response to the presence of introduced fish species: the iliophagous and piscivorous trophic groups were positively associated, while detritivores and herbivores were negatively associated, with the alien species. This suggests that monitoring functional diversity might be more valuable than species diversity for assessing effects of disturbances and managements policies on the fish community

Prevalence and predictors of coronary artery disease in patients with a calcium score of zero

The absence of coronary calcification is associated with an excellent prognosis. However, a calcium score of zero does not exclude the presence of coronary artery disease (CAD) or the possibility of future cardiovascular events. Our aim was to study the prevalence and predictors of coronary artery disease in patients with a calcium score of zero. Prospective registry consisted of 3,012 consecutive patients that underwent cardiac CT (dual source CT). Stable patients referred for evaluation of possible CAD that had a calcium score of zero (n = 864) were selected for this analysis. The variables that were statistically significant were included in a multivariable logistic regression model. From 864 patients with a calcium score of zero, 107 (12.4 %) had coronary plaques on the contrast CT (10.8 %, n = 93 with nonobstructive CAD and 1.6 %, n = 14 with obstructive CAD). By logistic regression analysis, the independent predictors of CAD in this population were age >55 years [odds ratio (OR) 1.63 (1.05-2.52)], hypertension [OR 1.64 (1.05-2.56)] and dyslipidemia [OR 1.54 (1.00-2.36)]. In the presence of these 3 variables, the probability of having coronary plaques was 21 %. The absence of coronary artery calcification does not exclude the presence of coron

Diabetes as an independent predictor of high atherosclerotic burden assessed by coronary computed tomography angiography: The coronary artery disease equivalent revisited

(1) To study the prevalence and severity of coronary artery disease (CAD) in diabetic patients. (2) To provide a detailed characterization of the coronary atherosclerotic burden, including the localization, degree of stenosis and plaque composition by coronary computed tomography angiography (CCTA). Single center prospective registry including a total of 581 consecutive stable patients (April 2011-March 2012) undergoing CCTA (Dual-source CT) for the evaluation of suspected CAD without previous myocardial infarction or revascularization procedures. Different coronary plaque burden indexes and plaque type and distribution patterns were compared between patients with (n = 85) and without diabetes (n = 496). The prevalence of CAD (any plaque; 74.1 vs. 56 %; p = 0.002) and obstructive CAD (≥50 % stenosis; 31.8 vs. 10.3 %; p<0.001) were significantly higher in diabetic patients. The remaining coronary atherosclerotic burden indexes evaluated (plaque in LM-3v-2v with prox. LAD; SIS; SSS; CT-LeSc) were also significantly higher in diabetic patients. In the per segment analysis, diabetics had a higher percentage of segments with plaque in every vessel (2.6/13.1/7.5/10.5 % for diabetics vs. 1.4/7.1/3.3/4.4 % for nondiabetics for LM, LAD, LCx, RCA respectively; p<0.001 for all) and of both calcified (19.3 vs. 9.2 %, p<0.001) and noncalcified or mixed types (14.4 vs. 7.0 %; p<0.001); the ratio of proximal-to-distal relative plaque distribution (calculated as LM/proximal vs. mid/distal/branches) was lower for diabetics (0.75 vs. 1.04; p = 0.009). Diabetes was an independent predictor of CAD and was also associated with more advanced CAD, evaluated by indexes of coronary atherosclerotic burden. Diabetics had a significantly higher prevalence of plaques in every anatomical subset and for the different plaque composition. In this report, the relative geographic distribution of the plaques within each subgroup, favored a more mid-to-distal localization in the diabetic patients

Decrease of CD68 Synovial Macrophages in Celastrol Treated Arthritic Rats

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disease characterized by cellular infiltration into the joints, hyperproliferation of synovial cells and bone damage. Available treatments for RA only induce remission in around 30% of the patients, have important adverse effects and its use is limited by their high cost. Therefore, compounds that can control arthritis, with an acceptable safety profile and low production costs are still an unmet need. We have shown, in vitro, that celastrol inhibits both IL-1β and TNF, which play an important role in RA, and, in vivo, that celastrol has significant anti-inflammatory properties. Our main goal in this work was to test the effect of celastrol in the number of sublining CD68 macrophages (a biomarker of therapeutic response for novel RA treatments) and on the overall synovial tissue cellularity and joint structure in the adjuvant-induced rat model of arthritis (AIA).FCT fellowship: (SFRH/BPD/92860/2013)