Computational Fluid Dynamics Simulation Approach for Scrubber Wash Water pH Modelling

In the current article, we will use a CFD approach for the scrubber wash water dilution simulation, by considering the current MEPC (Marine Environment Protection Committee, a subsidiary of IMO—International Maritime Organization) regulations that are in force. The necessity for scrubber wash water pH modelling and its importance in the current environmental framework is emphasized. The presented 3D model is considered as a 400 mm hydraulic diameter fluid domain with two outlets and a discharge water flow rate of 3050 m3/h for the considered pH value of 3, obtained within a state-of-the-art exhaust gas scrubber solution developed by a major EGCS (Exhaust Gas Cleaning Systems) supplier. The CFD study was developed by considering a k-ε turbulence model. In order to achieve accurate results, a structured mesh with two levels of refinement volumes was realized. Based on the obtained data and the various parameters discussed, the paper presents a way to investigate the optimal results for further analytical research of the scrubber washwater dilution process within the exhaust gas cleaning system

Optimal Sizing of the Evaporation Chamber in the Low-Flow Aerothermopressor for a Combustion Engine

Konovalov, D. Optimal Sizing of the Evaporation Chamber in the Low-Flow Aerothermopressor for a Combustion Engine. In: , et al. Advanced Manufacturing Processes II . InterPartner 2020. Lecture Notes in Mechanical Engineering. Springer, Cham. – P. 654–663. –https://doi.org/10.1007/978-3-030-68014-5_63The efficiency of gas turbine plants will be improved by cooling the cyclic air with an aerothermopressor. Constructive and technological factors affecting the aerothermopressor work were considered in this paper. CFD simulation and calculation of the water evaporation process in the evaporation chamber (working chamber) of the aerothermopressor was carried out. The Eulerian–Lagrangian approach was used to simulate the interaction of water droplets injected and airflow. The developed software was used in order to determine the characteristics of the aerothermopressor workflow. It is based on the methods of calculating thermogasdynamic compression and pressure losses due to the aerodynamic resistance of the two-phase flow in the aerothermopressor flow part. An empirical equation has been determined for calculating the optimal relative length of the aerothermopressor evaporation chamber depending on the initial droplet diameter at the inlet and the mass water concentration in the airflow. Analytical determination of the optimal relative length of the aerothermopressor evaporation chamber allows determining the length section of the evaporation chamber in order to obtain the maximum value of pressure increase, as a result of thermogasdynamic compression

Determination of hydraulic resistance of the aerothermopressor for gas turbine cyclic air cooling

One of the promising trends to increase the fuel and energy efficiency of gas turbines is contact cooling of cyclic air by using a twophase jet apparatus – an aerothermopressor. The rational parameters of work processes of the aerothermopressor were studied. The experimental setup was designed to simulate the aerothermopressor operation in the cooling air cycle of the gas turbine and to determine pressure losses in the aerothermopressor flow part. Based on the obtained experimental data, an empirical equation was proposed to determine the hydraulic resistance coefficient of the aerothermopressor flow part, depending on the initial pressure and the amount of water injected. The deviation of the calculated hydraulic resistance coefficient from the experimental ones is ± 25 %. The obtained results can be used in the practice of designing the aerothermopressor for gas turbine cyclic air cooling

Numerical and analytical study of seismic response of structural systems with new formulation using energy and impact methods

This paper presents two simple and robust technique for response estimating of single-degree-of-freedom (SDOF) structural systems. The impulse method, because it is formulated based on the fundamentals of dynamics; especially, the linear impulse concept, and also the energy method, because the main idea of this method is inspired by energy conservation principles. These methods can strongly cope with linear damped systems for which damping ratio ζ is greater than 0.01. Assessment of SDOF dynamic systems under any arbitrary excitations is easily possible through the proposed methods. There is no error propagation through the solving process. The numerical example reveals the simplicity and robustness of the new technique compared to Duhamel’s integral and similar techniques. Finally, a numerical example is investigated to demonstrate the efficiency of the algorithms. The most famous record of El Centro ground motion is applied to the systems. The obtained results show that the new algorithm works exactly enough to compete with a conventional method such as the Duhamel integration method and the Newmark-β method. A comparison between the results of this method with the solution methods used by other researchers is shown to be a good match

Considerations regarding the anti-icing system for the ship propulsion plant with gas turbine

Vessels that have navigation routes in areas with ambient temperatures that can drop below + 5 [°C], with a relative humidity of over 65%, will have implemented technical solutions for monitoring and combating ice accumulations in the intake routes of gas turbine power plants. Because gas turbines are not designed and built to allow the admission of foreign objects (in this case - ice), it is necessary to avoid the accumulation of ice through anti-icing systems and not to melt ice through defrost systems. Naval anti-icing systems may have as a source of energy flow compressed air, supersaturated steam, exhaust gases, electricity or a combination of those listed. The monitoring and optimization of the operation of the anti-icing system gives the gas turbine power plant an operation as close as possible to the normal regimes stipulated in the ship's construction or retrofit specification

COVID-19 Inflammatory Markers and Vitamin D Relationship in Pediatric Patients

Background: Biomarkers play an important role in COVID-19, and more research in this regard is needed, especially in the case of children. This study aimed to look for a link between the C reactive protein (CRP), lactate dehydrogenase (LDH), creatine kinase (CK), vitamin D and COVID-19 in pediatric patients. Methods: This is a retrospective cohort study, performed on children diagnosed positively with COVID-19 at a children’s hospital in western Romania. Available CRP, LDH, CK vitamin D and clinical severity were recorded. For each biomarker, groups were formed by patients’ age. Mean/median group differences were assessed using Student’s t test or Mann–Whitney and Kruskal–Wallis with Dunn’s post hoc tests. Association was assessed using the chi2 test, while correlation was assessed using Spearman’s rank correlation. Results: 181 positive children were studied between 1 August 2021 and 1 February 2022. Average age was 8.76 years (SD = 3.93). There were 94 (51.93%) males and 87 (48.07%) females. The cases were: 62 asymptomatic (34.25%), 107 mild (59.12%), 9 moderate (4.97%), 3 severe (1.66%). Regarding CRP, a significant difference between older and younger patients was observed (p = 0.0034). Clinical severity was associated with CRP (p = 0.0281), LDH (p = 0.0410) and vitamin D (p = 0.0444). Regarding CK, no differences or associations proved significant. Correlation testing was conducted for CRP, LDH, vitamin D and clinical signs. With the exception of LDH-CRP and LDH-vitamin D, all relationships proved statistically significant. Conclusions: CRP, LDH and vitamin D levels are important biomarkers for COVID-19-positive pediatric patients, while CK was mostly within normal ranges

Safety of primary anastomosis following emergency left sided colorectal resection: an international, multi-centre prospective audit.

This is the peer reviewed version of the following article: group, T. E. S. o. C. c. (2018). "Safety of primary anastomosis following emergency left sided colorectal resection: an international, multi-centre prospective audit." Colorectal Disease 20(S6): 47-57., which has been published in final form at https://doi.org/10.1111/codi.1437. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsINTRODUCTION: Some evidence suggests that primary anastomosis following left sided colorectal resection in the emergency setting may be safe in selected patients, and confer favourable outcomes to permanent enterostomy. The aim of this study was to compare the major postoperative complication rate in patients undergoing end stoma vs primary anastomosis following emergency left sided colorectal resection. METHODS: A pre-planned analysis of the European Society of Coloproctology 2017 audit. Adult patients (> 16 years) who underwent emergency (unplanned, within 24 h of hospital admission) left sided colonic or rectal resection were included. The primary endpoint was the 30-day major complication rate (Clavien-Dindo grade 3 to 5). RESULTS: From 591 patients, 455 (77%) received an end stoma, 103 a primary anastomosis (17%) and 33 primary anastomosis with defunctioning stoma (6%). In multivariable models, anastomosis was associated with a similar major complication rate to end stoma (adjusted odds ratio for end stoma 1.52, 95%CI 0.83-2.79, P = 0.173). Although a defunctioning stoma was not associated with reduced anastomotic leak (12% defunctioned [4/33] vs 13% not defunctioned [13/97], adjusted odds ratio 2.19, 95%CI 0.43-11.02, P = 0.343), it was associated with less severe complications (75% [3/4] with defunctioning stoma, 86.7% anastomosis only [13/15]), a lower mortality rate (0% [0/4] vs 20% [3/15]), and fewer reoperations (50% [2/4] vs 73% [11/15]) when a leak did occur. CONCLUSIONS: Primary anastomosis in selected patients appears safe after left sided emergency colorectal resection. A defunctioning stoma might mitigate against risk of subsequent complications

The impact of conversion on the risk of major complication following laparoscopic colonic surgery: an international, multicentre prospective audit.

This is the peer reviewed version of the following article: The and E. S. o. C. c. groups (2018). "The impact of conversion on the risk of major complication following laparoscopic colonic surgery: an international, multicentre prospective audit." Colorectal Disease 20(S6): 69-89., which has been published in final form at https://doi.org/10.1111/codi.14371. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.BACKGROUND: Laparoscopy has now been implemented as a standard of care for elective colonic resection around the world. During the adoption period, studies showed that conversion may be detrimental to patients, with poorer outcomes than both laparoscopic completed or planned open surgery. The primary aim of this study was to determine whether laparoscopic conversion was associated with a higher major complication rate than planned open surgery in contemporary, international practice. METHODS: Combined analysis of the European Society of Coloproctology 2017 and 2015 audits. Patients were included if they underwent elective resection of a colonic segment from the caecum to the rectosigmoid junction with primary anastomosis. The primary outcome measure was the 30-day major complication rate, defined as Clavien-Dindo grade III-V. RESULTS: Of 3980 patients, 64% (2561/3980) underwent laparoscopic surgery and a laparoscopic conversion rate of 14% (359/2561). The major complication rate was highest after open surgery (laparoscopic 7.4%, converted 9.7%, open 11.6%, P < 0.001). After case mix adjustment in a multilevel model, only planned open (and not laparoscopic converted) surgery was associated with increased major complications in comparison to laparoscopic surgery (OR 1.64, 1.27-2.11, P < 0.001). CONCLUSIONS: Appropriate laparoscopic conversion should not be considered a treatment failure in modern practice. Conversion does not appear to place patients at increased risk of complications vs planned open surgery, supporting broadening of selection criteria for attempted laparoscopy in elective colonic resection