Medium Load Research Articles

Effects of diesel from direct and indirect coal liquefaction on combustion and emissions in a six-cylinder turbocharged diesel engine

The aim of this study is to evaluate the effects of diesel from direct coal liquefaction (DDCL) and diesel from indirect coal liquefaction (DICL) on combustion and emissions. A six-cylinder turbocharged diesel engine fueled with DDCL, DICL, petroleum diesel (PD), 58% DDCL, and 42% DICL blended by volume (BD58) is used. The experiments are carried out at 1400 and 2300rpm engine speeds and various engine loads (10%, 25%, 50%, 75%, and 90% of the full-load). The results show that the brake thermal efficiency (BTE) of PD was higher than that of CTL (the maximum difference was 2%) at medium and high loads. At 10% load of 1400 rpm, the CO, HC and formaldehyde emissions of DDCL are 88.9%, 44.3% and 26.5% higher than those of PD respectively, and the CO, HC, and formaldehyde emissions of DICL are 30.1%, 15.3%, and 15.2% lower than those of PD. The differences among four fuels decrease rapidly with the increase of load. The NOX emissions of PD are the highest due to high nitrogen content (102.3 μg/g) and low hydrogen-carbon (H/C) ratio. The fuel with higher cetane number has less formaldehyde emission at low loads, while the fuel with lower H/C has less formaldehyde emission at high loads. The particle size distribution shows a bimodal shape at different loads and the peak particle size of accumulation mode and nucleation mode all increases with the increase of load. The particulate emission of different fuels from high to low is the order of PD > DDCL > BD58 > DICL. In addition, the emissions of polycyclic aromatic hydrocarbons (PAHs) and toxicity equivalent (TE) of PD are highest at all loads. The proportion of soluble organic fractions (SOF) from DDCL, DICL, and BD58 is higher than that of PD.

Effects of high-pressure and donor-cylinder exhaust gas recirculation on fuel economy and emissions of marine diesel engines

With the increasingly stringent emission legislation for marine diesel engines, a higher exhaust gas recirculation (EGR) rate is used to reduce NOx. However, a high EGR rate deteriorates brake specific fuel consumption (BSFC). Therefore, a suitable EGR pattern is critical to balancing NOx and BSFC. In this study, high-pressure EGR (HP-EGR) and donor-cylinder EGR (DC-EGR) were separately established by GT-Power, and NOx and BSFC comprehensive optimization was conducted by adaptive particle swarm optimization. The effect of the EGR-coupled high-pressure turbine on NOx and BSFC for HP-EGR and the effect of the EGR-coupled throttle valve on the inhomogeneity of different cylinders for DC-EGR were studied. Comparisons of two EGR patterns show that the achievable maximum EGR rate for HP-EGR is more sensitive to engine loads than DC-EGR. DC-EGR can achieve a higher EGR rate and lower NOx at low and medium loads. Under the same NOx, the required EGR rate, λ, boost pressure and exhaust pressure of DC-EGR are lower. However, the BSFC of DC-EGR is slightly higher at a 25% load. As the turbine flow characteristic of HP-EGR is insufficiently adjusted with loads, DC-EGR is more inclined to achieve comprehensive optimization of NOx and BSFC under full loads.

Effect of Aluminium Oxide Nano Additive on Diesel along with Gasoline Fumigation in Single Cylinder Diesel Engine

The present investigation mainly focuses on overcoming the limitations of gasoline fumigation (GF) in diesel engines by adding up nano fuel additives. Experiments are conducted to ascertain the engine working characteristics in a single-cylinder, four-stroke diesel engine using aluminum oxide (Al2O3) nano additives blended diesel as the main injection fuel along with GF as an inducted fuel. GF was achieved by controlling the electronic injector fitted at the intake manifold using open ECU software. Fuel map for GF was determined based on experiments with three divergent fumigation rates of 10%, 20%, and 30% based on energy consumption and optimized using the design of experiments. The optimization results showed 10% fumigation resulted in better performance and emission characteristics and it is selected for this present investigation. Fumigation results showed a decrease in brake thermal efficiency (BTE) at low and medium loads; increase at high loads.The two different mass fractions of 25 ppm and 50 ppm Al2O3 nano liquid are blended with diesel. Compared to GF with diesel, GF along with 25 and 50ppm Al2O3 nano additives blended diesel showed an increased BTE, maximum in-cylinder pressure, cumulative heat release rate; and reduced smoke opacity, CO, and unburned HC emissions at overall operating conditions. As the dosage level of Al2O3 increases from 25 to 50 ppm results in further enhancement of all working parameters except NOx emission. Finally, the addition of an Al2O3 nano additive is a suitable solution to overcome the limitations of GF in the CI engine.

Expansion heat release and thermal efficiency of acetone-butanol-ethanol-diesel blended fuel (ABE20) combustion in piston engine

The intermediate product of the butanol production process, acetone-butanol-ethanol (ABE) mixture, is a promising alternative fuel for diesel engine as its physical properties are resemble to diesel fuel. This study explores heat release pattern and thermal efficiency as a consequence of combustion of the 20% v/v ABE blended with diesel (ABE20) in a stock single-cylinder diesel engine. All parameters were studied in steady-state condition of medium and full loads at a constant engine speed of 1400 rpm. ABE20 presents a slightly lower thermal efficiency with comparable energy consumption compared to diesel fuel. A longer ignition delay was observed for ABE20 and the diffusion combustion regime was shortened in duration. The cylinder pressure-derived heat release in the expansion stroke discloses a different specific heat ratio during ABE20 combustion.

Effects of nano-Al2O3 and PTFE fillers on tribological property of basalt fabric-reinforced epoxy composites

ABSTRACT Effects of nano-Al2O3 and PTFE fillers on tribological behaviour of basalt fabric reinforced epoxy composite (BFRC) produced with a combination of molding and mixing method were studied by Taguchi L9 design. Microstructures and worn surfaces of composites were investigated by scanning electron microscopy. Regression equations were also developed for predicting wear and coefficient of friction. The results indicated that specific wear rate increased with increasing load and decreasing speed, but friction coefficient decreased with increasing speed, PTFE addition and medium load. In addition, wear rate of nano-PTFE was lower than that of nano-Al2O3 because of its microstructure. PTFE decreased the friction about 17%. Load was effective on the wear rate while speed was dominant on the friction. Moreover, multiple fiber fractures and large numbers of debris were dominated for BFRC while fiber debondings, fiber removals and debris agglomerations were effective for Al2O3, but fiber fractures and flake types of debris were responsible for PTFE.

CoFe2O4 nanoparticles@N-doped carbon coupled with N-doped graphene toward efficient electrochemical water oxidation

Developing high-performance nonprecious-metal electrocatalysts for the oxygen evolution reaction (OER) is crucial for efficient water splitting. Therefore, the reasonable design principle of catalyst, leading to high activity catalytic center and improving the accessibility of active sites, is undoubtedly crucial. Here, we used a kind of Prussian blue analogue (CoFe-PBA) nanoparticles to anchor the nitrogen-carbon doped CoFe 2 O 4 (CoFe 2 O 4 @NC) species to reduced graphene oxide aerogels as OER catalysts. The strong interaction between nanosized CoFe 2 O 4 @NC and the graphitic carbon shell led to synergistic effects in the OER, and the protection of the carbon shell guaranteed stability of the catalyst. As a result, the aerogel electrocatalyst exhibits more excellent activity and stability than the most advanced RuO 2 catalyst in OER under the same mass load in alkaline medium. It shows smaller overpotential of 250 mV to afford a current density of 10 mA cm −2 in a continuous working time of more than 70 hours. • The catalyst has highly exposed active surface, multi-dimensional mass transfer pathway and good charge transfer ability. • The in-situ formation of nitrogen-carbon doped structure can greatly improve the catalytic activity and stability. • The binary active sites on the conductive GA network reduce the interfacial resistance and enhance catalytic activity. • The "Plum Pudding Model" structure integrates multiple requirements for catalyst design strategies.

To improve the performance of a variable geometry turbocharged SI engine by porous material application

• The fuel economy of the turbocharged gasoline engine was improved by using porous material. • The reduced exhaust temperature by using porous material expanded the equivalent ratio combustion range of the engine. • The porous material enhanced the high-temperature stability and durability of the variable geometry turbocharger (VGT). • The peak torque of the engine was improved by using porous material. As an effective method to improve engine performance at low engine speed, and reduce fuel consumption, VGT has been widely used in diesel engines. However, due to the higher exhaust temperature of the gasoline engines, it still has challenges of application in the turbocharged gasoline engines. As the high temperature of exhaust gas could damage the components of the complex variable structure in VGT, which may result in being deteriorated after long-term use of VGT. To improve the durability of VGT, researchers have been considering enhancing the high-temperature stability and durability by new components of the variable structure or advanced material for VGT production. In this study, a kind of porous material was installed before the turbine to study the effects on VGT application in a 4-cylinder turbocharged gasoline engine. As a result, using porous material, under the steady condition of medium load at 3200 RPM, a fuel economy improvement of about 1% was obtained due to the higher turbine efficiency and less pumping loss, and a 33 ℃ turbine inlet temperature decrease occurred due to the extra heat loss by adding porous material. In addition, under a high load of 4000 RPM, due to the decreased turbine inlet temperature by using of porous material, the stoichiometric combustion range of the engine was expanded, and peak torque was increased by a 25 ℃ lower turbine inlet temperature with porous material than the highest turbine inlet temperature limit. As a result, porous Si-SiC material could improve the fuel economy, high-temperature durability, and peak torque of the VGT engines.

Investigating the Use and Performance of a Three-wheeler used in Inner City Transportation in Sub-Saharan Africa

The dominance of three-wheelers in inner city transportation cannot be overrated, because it is presumed to be safer compared to two-wheel drives. It is an intermediary between the motor cycles and taxis, as it is efficient for both passengers and goods transportation. However, as manufacturers introduce newer brands into the market, the impact relating to mechanical functioning is usually overlooked. This study was designed to evaluate the performance of the transmission system of the three-wheeler. In order to gather background information on the three-wheeler and its users, a questionnaire was administered to thirty (30) drivers. A Bajaj engine was selected because of the orientation of the output shaft and mounted on a test-rig equipped with a dynamometer. Output speed (OS), output torque (OT), fuel consumed and time taken under five loading conditions namely; No Load, 120W, 800W, 920W and 1600W corresponding to idle, downhill, level ground and overload/uphill conditions were recorded. However, it was discovered that 60% of the drivers were less than 40 years old, while the remaining 40% were adults. The output speed and torque for No-load and downhill, likewise medium load and level ground are similar, but the uphill was different. The results showed that Bajaj and TVS brands are used, Bajaj being the oldest. Also, there is significant variation in engine output with loading and terrain navigation with associated noise as load increases. The manual transmission fitted with the engine seems unable to properly transmit engine output from the shafts. A better transmission is therefore recommended. Keywords— Dynamometer, Output speed, output torque, three-wheeler

MECHANICAL BEHAVIOR OF BANANA REINFORCED EPOXY COMPOSITE BY FINITE ELEMENT METHOD

In the recent years, there is a shift in interest of engineers and researchers to natural fibres from synthetic fibres. Natural fibres have high strength, are light weight and are also inexpensive than the traditional synthetic fibres. In addition, the fibres obtained naturally are biodegradability and eco-friendly in nature. Banana fibre is a derived product by cultivation of banana fruit and thus plentiful in environment. Banana fibre is classified among the strongest naturally obtained fibre and therefore when reinforced with other few binding resins can be utilized for different applications. Epoxy resin are suitable matrix for composite creation since they have outstanding binding characteristics. The (FEA) Finite Element Analysis of epoxy-banana composite shows that the maximum value of impact, flexural and tensile load that the composite can bear is 1000 N, 900 N and 2100 N respectively. According to this investigation it can be concluded that because of their outstanding load bearing characteristics epoxy-banana composite can be utilized for several medium load industrial uses to high load industrial uses. It is observed that the composite with least volume percent of epoxy has better mechanical strength and can bear higher deformation under higher load for tensile and flexural tests and for the impact strength results, the increase in fibre % results in lower impact strength. Also, the increase in higher vol. % of epoxy results in lower stiffness and higher deflection in the specimens, except for the specimen with 40% vol. of epoxy which obtained the most optimal results.

Large Two-Stroke Marine Diesel Engine Operation with a High-Pressure SCR System in Heavy Weather Conditions

Abstract The transient performance of a direct-drive large two-stroke marine diesel engine, installed in a vessel operating in a seaway with heavy weather, is investigated via simulation. The main engine of the ship is equipped with a selective catalytic reduction (SCR) aftertreatment system for compliance with the latest International Maritime Organization (IMO) rules for NOx reduction, IMO Tier III. Because of limitations of exhaust gas temperature at the inlet of SCR systems and the low temperature exhaust gases produced by marine diesel engines, in marine applications, the SCR system is installed on the high-pressure side of the turbine. When a ship sails in heavy weather, it experiences a resistance increase, wave-induced motions, and a time-varying flow field in the propeller, induced by ship motions. This results in a fluctuation of the propeller torque demand and, thus, a fluctuation in engine power and exhaust gas temperature, which can affect engine and SCR performance. To investigate this phenomenon and take into account the engine–propeller interaction, the entire propulsion plant was modeled, namely, the slow-speed diesel propulsion engine, the high-pressure SCR system, the directly driven propeller, and the ship’s hull. To simulate the transient propeller torque demand, a propeller model was used, and torque variations due to ship motions were taken into account. Ship motions in waves and wave-added resistance were calculated for regular and irregular waves using a 3D panel code. The coupled model was validated against available measured data from a shipboard propulsion system in good weather conditions. The model was then used to simulate the behavior of a Tier III marine propulsion plant during acceleration from low to medium load, in the presence of regular and irregular waves. The effect of the time-varying propeller demand on the engine and the SCR system was investigated. Introduction The effect of waves on a marine propulsion system is a complex phenomenon involving interactions between different subsystems of the propulsion plant, i.e., the prime mover, the propeller, and the ship’s hull. Ships sailing in heavy weather conditions experience a resistance increase, wave-induced motions, and a time-varying flow field in the propeller. This leads to a fluctuation of the propeller torque demand which results in a fluctuation in engine-produced power and exhaust gas temperature.

ДОСЛІДЖЕННЯ РЕЖИМУ НАПРУГИ В ДАЛЬНІХ ЛІНІЯХ ЕЛЕКТРОПЕРЕДАЧІ ЗМІННОГО СТРУМУ

The charging currents of EHV transmission lines cause the Ferranti effect, which causes an increase in voltage at intermediate points transmission line. The work aims to study the laws of the voltage distribution along the line route and to develop a method for determining the coordinates of a point with extreme voltage. Methodology. Mathematical modeling of long-distance transmission lines in Wolfram Mathematica allowed to form the laws of the voltage distribution along the line and determine the coordinate of the extreme point on the voltage. Results. It is shown that the application of the traditional model of idealized power transmission causes high modeling accuracy only in the modes of unloaded line and low loads. In the range of medium and high loads, the simulation error reaches unacceptably large values. The paper proposes more accurate models for determining the coordinate of an extreme voltage point: linearized and second- and third-order models. It is shown that the proposed models are characterized by higher accuracy in a wide range of loads. Increasing the degree of the model results in higher accuracy, but is associated with an increase in the cumbersomeness of the mathematical model. It is shown that first and second-order models provide sufficient accuracy for typical designs of 750 kV power transmission lines. It is shown that neglecting the losses on the corona has almost no effect on the accuracy of calculating the coordinates of the extreme point on the voltage, which simplifies the linear calculation model and models of the second and third-order. Originality. Mathematical models of the first, second and third orders have been developed for high-precision determination of the coordinate of a voltage-extreme point along a long-distance transmission line. Practical significance. The offered mathematical models are intended for application in problems of regulation and adjustment of parameters of flexible power transmissions. Ref. 12, figure, tables 4.

Effect of diesel injection strategy on performance and emissions of CH4/diesel dual-fuel engine

Methane/diesel dual-fuel combustion technology has the potential to reduce emissions of nitrogen oxides (NOx) and particulate matter (PM). However, this combustion mode still suffers from low thermal efficiency, high levels of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions under low-load conditions. In the current study, experimental research was conducted to investigate the effect of diesel injection strategy, including single and split injections, on the performance and emissions of a methane/diesel dual-fuel engine. The experimental tests were carried out on a single-cylinder diesel engine at 1500 rpm under different engine load conditions. The results revealed that split injection strategy has a significant impact on the combustion of the dual-fuel engine. Moreover, the brake thermal efficiency increased by an average of 25.6 % compared to the single injection strategy at low load. Brake specific fuel consumption decreased by 20.4% with a pre-injection timing of 11°bTDC at 20% engine load. Further, the pre-injection strategy contributed to the simultaneous reduction of NOx and combustion noise with a slight reduction of HC emissions. Finally, the inclusion of early post-injection resulted in improved brake thermal efficiency. NOx emissions decreased slightly, by delaying the post-injection timing for low to medium loads.

Towards the Use of 2D Video-Based Markerless Motion Capture to Measure and Parameterize Movement During Functional Capacity Evaluation.

Purpose The objective of this study was to determine the agreement of kinematic parameters calculated from motion data collected via a 2D video-based pose-estimation (markerless motion capture) approach and a laboratory-based 3D motion capture approach during a floor-to-waist height functional lifting test. Method Twenty healthy participants each performed three floor-to-waist height lifts. Participants' lifts were captured simultaneously using 2D video (camcorder) in the sagittal plane and 3D motion capture (Vicon, Oxford, UK). The three lifts were representative of a perceived light, medium, and heavy load. Post-collection, video data were processed through a pose-estimation software (i.e., markerless motion capture). Motion data from 3D motion capture and video-based markerless motion capture were each used to calculate objective measures of interest relevant to a functional capacity evaluation (i.e., posture, balance, distance of the load from the body, and coordination). Bland-Altman analyses were used to calculate agreement between the two methods. Results Bland-Altman analysis revealed that mean differences ranged from 1.9° to 22.1° for posture and coordination-based metrics calculated using markerless and 3D motion capture, respectively. Limits of agreement for most posture and coordination measures were approximately + 20°. Conclusions 2D video-based pose estimation offers a strategy to objectively measure movement and subsequently calculated metrics of interest within an FCE context and setting, but at present the agreement between metrics calculated using 2D video-based methods and 3D motion capture is insufficient. Therefore, continued effort is required to improve the accuracy of 2D-video based pose estimation prior to inclusion into functional testing paradigms.

Effect on the performance and emissions of methanol/diesel dual-fuel engine with different methanol injection positions

In methanol/diesel combined injection mode engines, the high latent heat of vaporization of methanol reduces the combustion temperature. It effectively reduced NOx emissions, which led to the deterioration of combustion under high blending ratio conditions. This study attempted to improve the adverse effect of high latent heat vaporization on combustion by changing the methanol injection positions. The experiment was carried out on a Yunnei D30 inline 4-cylinder turbocharged and intercooled common rail diesel engine. Methanol that used five kinds of methanol substitution rates (0%, 10%, 20%, 30%, 40%) was injected at three positions, namely pre-intercooler, post-intercooler, and intake manifold under three load conditions (100 N.m, 200 N.m, 300 N.m) with four engine speeds of 1200 rpm, 1400 rpm, 1800 rpm and 2000 rpm, respectively. The results showed that under medium and low load conditions, regardless of the injection position, the methanol substitution rate increased, the maximum explosion pressure in the cylinder decreased, the peak heat release rate shifted backward, the ignition delay prolonged, and total energy consumption increased, HC and CO emissions increased, and NOx emissions reduced. Under high load conditions, with the methanol substitution rate increasing, maximum explosion pressure first increased and then decreased. The total energy consumption first decreased and then increased, while the HC and CO emissions slightly increased and the NOx emissions decreased. Under medium and low load conditions, varying methanol injection positions could lessen the adverse effects of methanol blending combustion. Methanol injected into the pre-intercooler, which utilized the high temperature of intake air after pressurization, vaporized effectively, shortened ignition delay and combustion duration, and reduced HC and CO emissions. At post-intercooler, HC emissions slightly increased under low load conditions, ignition delay was shortened under medium load conditions, and cylinder pressure was restored to the level of pure diesel. Under high-speed and high-load conditions, due to higher cylinder temperature, HC and CO emissions decreased, and NOx emissions increased. At the intake manifold, the lowest in-cylinder pressure and slowest heat release rate were found at low-load conditions, but NOx emissions were reduced the most at high speed and high load conditions.

A Simple Two-Stage AC-AC Circuit Topology Employed as High-Frequency Controller for Domestic Induction Heating System

The induction heating process at a domestic level is getting attention nowadays as this power converting topology ensures clean, reliable, flexible, and fast operation. The low input frequency is converted to required regulated high output frequency with indirect and direct power converting approaches. The circuit and control complexity and high conversion losses associated with indirect power converting approaches lower their uses for domestic induction systems. The direct ac-ac power conversion approach is one of the viable solutions for low and medium power level loads, especially for domestic induction heating loads. The circuit complexity, cost, and conversion losses of the direct power converting systems depend on the number of the controlled switching devices as each controlled switch requires one gate driving circuit and one isolated dc supply. Simplified pulse width modulation (PWM) switching control also lower their control effort. Therefore, in this article, a simplified direct ac-ac power converting approach is introduced for a high-frequency domestic induction heating system. Here, the regulation of the high output frequency is achieved by simply cascading the single-phase full-bridge rectifier with a full-bridge inverter with a simple control strategy. The characteristics of the developed topology are validated through simulation results of the Simulink-based platform and practical results of the developed practical setup.

Fatigue behavior of fine-grained magnesium under tension-tension loading at 0 °C

This study investigated low-temperature fatigue behavior of fine-grained magnesium through tension–tension fatigue testing at the temperature of 0 °C. The applied stress profiles of fatigue testing were selected to cover a wide range of loading conditions including low, medium, and high loading stresses. Even when the maximum applied stress of fatigue testing was as high as 88% of the ultimate tensile strength of the material, the corresponding fatigue life was long, i.e., 3973 cycles. Deformation accumulation per loading cycle reduced with the progression of fatigue testing for all studied loading conditions. Fatigue life analyses were performed using both Smith-Watson-Topper (SWT) model and Jahed-Varvani energy-based (JV) model. The fatigue life predictions through both models agree well with the experimental data.

Association of the extent of return to fasting state 2-hours after a glucose challenge with incident prediabetes and type 2 diabetes: The CARDIA study

AimTo evaluate whether the extent of return to fasting state 2-hours after a glucose challenge among normoglycemic individuals is associated with lower risk of incident prediabetes/ type 2 diabetes in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort study. MethodsWe evaluated this association among 1879 normoglycemic adults who were categorized into three groups: ‘Low post load’ (2hPG < FPG); ‘Medium post load’ (2hPG ≥ FPG and < 75th percentile of the difference); and ‘High post load’ (2hPG > FPG and ≥ 75th percentile of the difference). We used Cox proportional hazards regression to evaluate the association of the difference in 2hPG and FPG with incident diabetes/prediabetes after adjustment for demographic and clinical covariates. ResultsDuring 20 years of follow-up, 8% developed type 2 diabetes and 35% developed prediabetes. Compared to those with ‘Low post load’, the risk of type 2 diabetes was higher for participants with ‘High post load’ [HR: 1.56, 95% CI (1.03, 2.37)] and similar for participants with ‘Medium post load’ [HR: 0.99, 95% CI (0.64, 1.52)]. However, HRs for incident prediabetes among participants with ‘High post load’ [HR = 1.2, 95 %CI = (0.98, 1.46)] was not significantly different compared to participants with ‘Low post load’. ConclusionAmong normoglycemic individuals, a difference between 2hPG and FPG concentration > 0.9 mmol/L can be used to stratify individuals at higher risk for developing type 2 diabetes.

A Study of the Impact of Methanol, Ethanol and the Miller Cycle on a Gasoline Engine

This paper focuses on the investigation and optimisation of the Miller cycle, methanol, ethanol and turbocharging when applied to a high-performance gasoline engine. These technologies have been applied both individually and concurrently to test for potential compounding effects. Improvements have been targeted with regards to both emission output and performance. Also assessed is the capability of the engine to operate when exclusively powered by biofuels. This has been carried out numerically using the 1D gas dynamics tool ‘WAVE’, a 1D Navier–Stokes equation solver. These technologies have been implemented within the McLaren M838T 3.8L twin-turbo engine. The Miller cycle early intake valve close (EIVC) improved peak efficiency by 0.17% and increased power output at low and medium loads by 11%. Reductions of 6% for both NOx and CO were also found at rated speed. The biofuels achieved NOx and CO reductions of 60% and 96% respectively, alongside an efficiency increase of 2.5%. Exclusive biofuel use was found to be feasible with a minimum 35% power penalty. Applied cooperatively, the Miller cycle and biofuels were not detrimental to each other, compounding effects of a further 0.05% efficiency and 2% NOx improvements were achieved.

Experimental investigation on combustion and emission characteristics of butanol/biodiesel under blend fuel mode, dual fuel RCCI and ICCI modes

Based on the United Nations (UN) Sustainable Development Goals (SDG), oxygenated biofuels have become one of the research focuses of engines. Past research has concentrated on the high temperature combustion mode (blend fuel), and low temperature combustion modes (RCCI and ICCI). However, the combined investigations of blend fuel, RCCI and ICCI modes to compare engine combustion and emission characteristics has not been reported. Therefore, the present work focus on the comparison of engine combustion and emission characteristics of the three different combustion modes in a diesel engine at different engine loads, energy ratio and EGR rates using butanol and biodiesel. Results show that blend fuel has higher indicated thermal efficiency than ICCI and RCCI modes at low load, while RCCI and ICCI modes exhibit better engine performance at medium load, which is more suitable for using of ICCI and RCCI modes under practical engine. Significantly higher load of ICCI mode can be operated is another important finding of this study, which demonstrates that ICCI mode has greater potential to expand the engine load than RCCI mode and blend fuel, in which RCCI mode cannot be operated at higher load due to the unacceptable combustion noise. Nitrogen oxides emissions of RCCI and ICCI modes reduced 92% to 95% than blend fuel using EGR, but emits higher incomplete combustion products. In addition, properly increasing the butanol energy ratio increase the combustion efficiency for the three combustion modes, it will reduce the thermal efficiency and increase pollutant emissions at higher butanol energy ratio.

Bacterial bioburden of wounds: influence of debridement and negative-pressure wound therapy (NPWT).

To clarify the role of microbiological swabs in surgical decision-making, we investigated the effect of negative-pressure wound therapy (NPWT) and serial surgical debridement on bacterial bioburden in hard-to-heal wounds and ultimately correlated them with the success of surgical closure. All patients were treated with surgical debridement, jet lavage and NPWT before their wounds were finally closed. The treatment effect was assessed by correlating microbiological swabs obtained immediately after intervention with those obtained after removal of the dressings during the following surgical procedures. The result of the last microbiological swab taken before definitive surgical closure was correlated with the requirement for revision surgery. We included the results of 704 microbiological swabs from 97 patients in 110 wound localisations in this monocentric, retrospective study. NPWT did not improve bacterial bioburden in 77% of cases and the duration of NPWT did not affect the result. Furthermore, no significant effect of NPWT could be found for either anaerobic (p=0.96) or aerobic bacteria (p=0.43). In contrast, surgical debridement decreased bacterial load in approximately 60% of cases. If sterile wound swabs could be obtained at all, it was during the first four surgical debridements in 60% of patients; after that only 10% became sterile. Sterile microbiological wound swabs before surgical closure were associated with lower rates of revision surgery, while low or medium bacterial loads did not increase revision rates.