Showing papers by "Bengt Johansson published in 2020"

IJER editorial: The future of the internal combustion engine:

Abstract: Internal combustion (IC) engines operating on fossil fuel oil provide about 25% of the world’s power (about 3000 out of 13,000 million tons oil equivalent per year—see Figure 1), and in doing so, they produce about 10% of the world’s greenhouse gas (GHG) emissions (Figure 2). Reducing fuel consumption and emissions has been the goal of engine researchers and manufacturers for years, as can be seen in the two decades of ground-breaking peer-reviewed articles published in this International Journal of Engine Research (IJER). Indeed, major advances have been made, making today’s IC engine a technological marvel. However, recently, the reputation of IC engines has been dealt a severe blow by emission scandals that threaten the ability of this technology to make significant and further contributions to the reduction of transportation sector emissions. In response, there have been proposals to replace vehicle IC engines with electric-drives with the intended goals of further reducing fuel consumption and emissions, and to decrease vehicle GHG emissions. Indeed, some potential students and researchers are being dissuaded from seeking careers in IC engine research due to disparaging statements made in the popular press and elsewhere that disproportionately blame IC engines for increasing atmospheric GHGs. Without a continuous influx of enthusiastic, welltrained engineers into the profession, the potential further benefits that improved IC engines can still provide will not be realized. As responsible automotive engineers and as stewards of the environment for future generations, it is up to our community to make an honest assessment of the progress made in the development of IC engines over the past century, with their almost universal adoption to meet the world’s mobility and power generation needs. Considering that the maturity of IC engine technology is something that many other technologies/possibilities do not have, we also need to assess the potential for future progress, as well as to assess the benefits offered by competitor technologies, in order to make responsible recommendations for future directions. Factors impacting that future are discussed in this editorial and include the following:

Association of FADS1/2 Locus Variants and Polyunsaturated Fatty Acids With Aortic Stenosis

Abstract: Importance: Aortic stenosis (AS) has no approved medical treatment. Identifying etiological pathways for AS could identify pharmacological targets.Objective: To identify novel genetic loci and path ...

Effect of Pre-chamber Enrichment on Lean Burn Pre-chamber Spark Ignition Combustion Concept with a Narrow-throat Geometry

Abstract: The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01. FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and KAUST intended to address the fundamental aspects of hydrocarbon fuel combustion in engines, and develop fuel/engine design tools suitable for advanced combustion modes. The author would like to thank King Abdullah University of Science and Technology (KAUST) and the Clean Combustion Research Center (CCRC) for lab facilities and research support. Last but not least, the authors would like to convey gratitude towards the IC Engine Lab Safety Supervisor Adrian I. Ichim and the lab technician Riyad H. Jambi for their kind input and assistance in performing the experiments.

Effects of Geometry on Passive Pre-Chamber Combustion Characteristics

Abstract: The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01. FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and KAUST intended to address the fundamental aspects of hydrocarbon fuel combustion in engines, and develop fuel/engine design tools suitable for advanced combustion modes. The computational simulations utilized the Shaheen supercomputer at KAUST Supercomputing Laboratory. The authors thank Convergent Science Inc. for providing the CONVERGE license.

Health behaviours reported by adults with congenital heart disease across 15 countries

Abstract: BackgroundHealth behaviours are essential to maintain optimal health and reduce the risk of cardiovascular complications in adults with congenital heart disease. This study aimed to describe health...

Simultaneous Negative PLIF and OH* Chemiluminescence Imaging of the Gas Exchange and Flame Jet from a Narrow Throat Pre-Chamber

Abstract: Pre-chamber combustion (PCC) is a promising engine combustion concept capable of extending the lean limit at part load. The engine experiments in the literature showed that the PCC could achieve higher engine thermal efficiency and much lower NOx emission than the spark-ignition engine. Improved understanding of the detailed flow and combustion physics of PCC is important for optimizing the PCC combustion. In this study, we investigated the gas exchange and flame jet from a narrow throat pre-chamber (PC) by only fueling the PC with methane in an optical engine. Simultaneous negative acetone planar laser-induced fluorescence (PLIF) imaging and OH* chemiluminescence imaging were applied to visualize the PC jet and flame jet from the PC, respectively. Results indicate a delay of the PC gas exchange relative to the built-up of the pressure difference (△P) between PC and the main chamber (MC). This should be due to the gas inertia inside the PC and the resistance of the PC nozzle. The PC jet can be either continuous or intermittent depending on the △P and pressure fluctuation amplitude. Distinct PC jet with low speed is witnessed after 15° CA ATDC, which could account for the postcombustion of the PCC engine in the literature. The probability distribution analysis of the PLIF and OH* images presents a much longer penetration length of the PC jet than that of the flame jet. This means that the flame jet resides in an atmosphere of the unburned gas mixture from the PC when it appears in the MC. The flame jet and PC jet show longer penetration length and become more stable with the enriching of the prechamber charge from lean to stoichiometric. However, the overall PC jet characteristics regarding the penetration length and probability distribution become less sensitive to the PC global excess air ratio (λ) when the PC charge is close to stoichiometry.

Isobaric Combustion at a Low Compression Ratio

Abstract: In a previous study, it was shown that isobaric combustion cycle, achieved by multiple injection strategy, is more favorable than conventional diesel cycle for the double compression expansion engine (DCEE) concept. In spite of lower effective expansion ratio, the indicated efficiencies of isobaric cycles were approximately equal to those of a conventional diesel cycle. Isobaric cycles had lower heat transfer losses and higher exhaust losses which are advantageous for DCEE since additional exhaust energy can be converted into useful work in the expander. In this study, the performance of low-pressure isobaric combustion (IsoL) and high-pressure isobaric combustion (IsoH) in terms of gross indicated efficiency, energy flow distribution and engine-out emissions is compared to the conventional diesel combustion (CDC) but at a relatively lower compression ratio of 11.5. The experiments are conducted in a Volvo D13C500 single-cylinder heavy-duty engine using standard EU diesel fuel. The current study consists of two sets of experiments. In the first set, the effect of exhaust gas recirculation (EGR) is studied at different combustion modes using the same air-fuel ratio obtained from the preceding work. In the second set of experiments, different injection strategies are investigated for IsoL and IsoH combustion at constant and varying load conditions. From the results, it is found that isobaric combustion has similar or higher gross indicated efficiency than those of CDC. The exhaust losses are higher while the heat transfer losses are lower than CDC, which could be beneficial for DCEE concept. For isobaric cases, the NOx emissions were lower with higher uHC/CO/Soot emissions compared to CDC. From the injection strategy study, it was found that the gross indicated efficiency is highest with three injections i.e. at medium load. The efficiency is lower for both low and high load conditions due to increased exhaust and heat transfer losses, respectively. Also, the gross indicated efficiency is largely unchanged when more than one injection event is executed; however the IsoL yields higher overall emissions as compared to IsoH combustion. Introduction Compression ignition engines operated with conventional diesel fuel are widely used in stationary and transportation energy sectors due to high engine efficiency and reliability advantages. However, attaining the strict emission regulations of nitrogen oxides (NOx), particulate matter (PM), fuel economy and subsequently greenhouse gas (GHG) emissions while retaining high engine efficiency is a challenging task for the engine manufacturers. Around the world, heavy-duty vehicles is largely fueled with diesel fuel and accounts for very high transportcarbon emissions. For example, in the current European automobile market, heavy-duty diesel vehicles constitute for 25% of the CO2 emissions [1] and with predicted 45% increased demand by 2040, this percentage would likely escalate [2]. In recent years, it is well understood from the existing literature that there are not enough engine efficiency improvements of heavy-duty diesel vehicles. This is potentially due to the lack of major technological breakthrough [3,4]. Advanced combustion concepts such as low-temperature combustion (LTC) diesel [5,6], homogeneous charge compression ignition (HCCI) [7,8], reactivity controlled compression ignition (RCCI) [9,10] and partially premixed charge combustion (PPC) [11–17] has been investigated in detail to improve the thermodynamic efficiency due to reduced heat transfer losses and increased effective expansion ratio. However, the thermodynamic efficiency is not fully converted to brake thermal efficiency (BTE) because of the losses incurred during different cycle components of combustion, gas exchange, and mechanical efficiencies. To optimize the individual efficiencies, a wide variety of splitcycle engine concept has been investigated ranging from the “series XIV-engine” [18], the compact compression ignition (CCI) engine [19], the Scuderi engine [20], the “CryoPower” engine [21] and the double compression expansion engine (DCEE) [22]. The series XIV-engine comprises of two conventional combustion cylinders and one large low-pressure cylinder. Due to substantial heat losses, the engine efficiency was lower compared to conventional diesel engines. The CCI engine has an intake cylinder, a combustion cylinder and an exhaust cylinder. The simulations suggested that this concept can result in higher engine efficiency and lower heat transfer losses but the

Optical Study on the Fuel Spray Characteristics of the Four-Consecutive-Injections Strategy Used in High-Pressure Isobaric Combustion

Abstract: High-pressure isobaric combustion used in the double compression expansion engine (DCEE) concept was proposed to obtain higher engine brake thermal efficiency than the conventional diesel engine. Experiments on the metal engines showed that four consecutive injections delivered by a single injector can achieve isobaric combustion. Improved understanding of the detailed fuel-air mixing with multiple consecutive injections is needed to optimize the isobaric combustion and reduce engine emissions. In this study, we explored the fuel spray characteristics of the four-consecutiveinjections strategy using high-speed imaging with background illumination and fuel-tracer planar laser-induced fluorescence (PLIF) imaging in a heavy-duty optical engine under non-reactive conditions. Toluene of 2% by volume was added to the n-heptane and served as the tracer. The fourth harmonic of a 10 Hz Nd:YAG laser was applied for the excitation of toluene. The PLIF image distortion caused by the side window curvature and the optical piston was mitigated using a correction lens and corrected with a grid mapping technique. The effects of hydraulic delay and injection dwell on the in-cylinder liquid-phase fuel penetration and vapor-phase fuel distribution were evaluated under different combinations of the four direct injections. The high-speed imaging of the liquid-phase spray shows that a short injection dwell reduces the hydraulic delay of the injector, resulting in an increase in both the peak liquid-phase penetration length and the injection duration. The fuel-tracer PLIF imaging clarifies the spatial fuel distribution of the four consecutive injections involved with the interaction between the vapor-phase spray and the piston bowl wall and the squish region. The intensity distribution in the PLIF images confirms that a longer injector hydraulic delay leads to a shorter peak vapor-phase spray penetration length and a reduced flow rate.

Isobaric Combustion for High Efficiency in an Optical Diesel Engine

Abstract: Isobaric combustion has been proven a promising strategy for high efficiency as well as low nitrogen oxides emissions, particularly in heavy-duty Diesel engines. Previous single-cylinder research engine experiments have, however, shown high soot levels when operating isobaric combustion. The combustion itself and the emissions formation with this combustion mode are not well understood due to the complexity of multiple injections strategy. Therefore, experiments with an equivalent heavy-duty Diesel optical engine were performed in this study. Three different cases were compared, an isochoric heat release case and two isobaric heat release cases. One of the isobaric cases was boosted to reach the maximum in-cylinder pressure of the isochoric one. The second isobaric case kept the same boost levels as the isochoric case. Results showed that in the isobaric cases, liquid fuel was injected into burning gases. This resulted in shorter ignition delays and thus a poor mixing level. The lack of fuel/air mixing was clearly the main contributor to the high soot emissions observed in isobaric combustion. The lower heat losses of the isobaric strategy were further explained by tracking the chemiluminescence. Unlike a long single injection, multiple injections helped to contain the hot gases away from the walls. However, the opposite effects were also found from the high thermal radiation caused by the extensive soot formation. Highpressure fluctuations from the rapid heat release of the isochoric case were further seen. Finally, better mixing for improved air utilization was deemed needed when utilizing isobaric heat release.

Healthcare system inputs and patient-reported outcomes: a study in adults with congenital heart defect from 15 countries

Abstract: The relationship between healthcare system inputs (e.g., human resources and infrastructure) and mortality has been extensively studied. However, the association between healthcare system inputs and patient-reported outcomes remains unclear. Hence, we explored the predictive value of human resources and infrastructures of the countries’ healthcare system on patient-reported outcomes in adults with congenital heart disease. This cross-sectional study included 3588 patients with congenital heart disease (median age = 31y; IQR = 16.0; 52% women; 26% simple, 49% moderate, and 25% complex defects) from 15 countries. The following patient-reported outcomes were measured: perceived physical and mental health, psychological distress, health behaviors, and quality of life. The assessed inputs of the healthcare system were: (i) human resources (i.e., density of physicians and nurses, both per 1000 people) and (ii) infrastructure (i.e., density of hospital beds per 10,000 people). Univariable, multivariable, and sensitivity analyses using general linear mixed models were conducted, adjusting for patient-specific variables and unmeasured country differences. Sensitivity analyses showed that higher density of physicians was significantly associated with better self-reported physical and mental health, less psychological distress, and better quality of life. A greater number of nurses was significantly associated with better self-reported physical health, less psychological distress, and less risky health behavior. No associations between a higher density of hospital beds and patient-reported outcomes were observed. This explorative study suggests that density of human resources for health, measured on country level, are associated with patient-reported outcomes in adults with congenital heart disease. More research needs to be conducted before firm conclusions about the relationships observed can be drawn. ClinicalTrials.gov: NCT02150603. Registered 30 May 2014,

A Study on the Performance and Emissions of HCCI Oxy-Fuel Combustion in a CFR Engine with Recirculated Carbon Dioxide

Abstract: Stringent emission regulations and the anticipated climate change call for a paradigm shift in the design of the conventional internal combustion engines. One way to combat this problem is oxy-fuel combustion in which the combustion products are mainly water vapor and carbon dioxide. Water vapor can be easily separated by condensation and carbon dioxide is then easily captured and stored. However, many technical challenges are associated with this mode of combustion. There are many challenges facing oxy-fuel combustion before it find its way to commercial production especially for internal combustion engines. One such challenge is the relatively high temperature of the oxy-fuel combustion. A solution to this problem is the recirculation of the generated CO2 to moderate the in-cylinder temperature. Therefore, careful study of the effect of recirculating the CO2 back to combustion chamber is needed before the implementation of such a concept. This study is a continuation of a previous work published by the authors. In the previous study, the performance and emissions of an oxy-fuel HCCI engine were investigated. The in-cylinder temperature was moderated by supplying the engine with fresh CO2 from gas cylinders. In this present work the performance of the same oxy-fuel HCCI engine is investigated but the difference is that the in-cylinder temperature is regulated by recirculating the generated CO2. The experiments were conducted in a variable compression CFR engine that was modified to operate in oxy-fuel mode with recycled carbon dioxide. The emissions were also measured using an FTIR exhaust analyzer. The results showed that the implementation of this concept is possible. However, the indicated thermal efficiency deteriorates due to lower combustion and gas exchange efficiencies. Also, the CO2 recirculation resulted in higher CO and unburned hydrocarbon (UHC) emissions.

A European industrial development policy for prosperity and zero emissions

Abstract: The objective of this paper is to outline and discuss the key elements of an EU industrial development policy consistent with the Paris Agreement. We also assess the current EU Industrial Strategy proposal against these elements. The “well below 2 °C” target sets a clear limit for future global greenhouse gas emissions and thus strict boundaries for the development of future material demand, industrial processes and the sourcing of feedstock; industry must evolve to zero emissions or pay for expensive negative emissions elsewhere. An industrial policy for transformation to net-zero emissions must include attention to directed technological and economic structural change, the demand for emissions intensive products and services, energy and material efficiency, circular economy, electrification and other net-zero fuel switching, and carbon capture and use or storage (CCUS). It may also entail geographical relocation of key basic materials industries to regions endowed with renewable energy. In this paper we review recent trends in green industrial policy. We find that it has generally focused on promoting new green technologies (e.g., PVs, batteries, fuel cells and biorefineries) rather than on decarbonizing the emissions intensive basic materials industries, or strategies for handling the phase-out or repurposing of sunset industries (e.g., replacing fossil fuel feedstocks for chemicals). Based on knowledge about industry and potential mitigation options, and insights from economics, governance and innovation studies, we propose a framework for the purpose of developing and evaluating industrial policy for net-zero emissions. This framework recognizes the need for: directionality; innovation; creating lead markets for green materials and reshaping existing markets; building capacity for governance and change; coherence with the international climate policy regime; and finally the need for a just transition. We find the announced EU Industrial Strategy to be strong on most elements, but weak on transition governance approaches, the need for capacity building, and creating lead markets. (Less)

Troponin T but not C reactive protein is associated with future surgery for aortic stenosis: a population-based nested case-referent study.

Abstract: AIMS High-sensitivity troponin T (hs-TnT) and high-sensitivity C reactive protein (hs-CRP) may convey prognostic information in patients with aortic stenosis (AS). This study evaluated if hs-TnT and hs-CRP associate with myocardial mass, and risk of future surgery for AS. METHODS In total, 336 patients (48% women) with surgery for AS with previous participation in large population surveys were identified. Preoperatively, myocardial mass and the presence of coronary artery disease (CAD) were assessed. Two matched referents were allocated for each case, and hs-TnT and hs-CRP were determined in stored plasma from the baseline survey. Conditional logistic regression analysis was used to estimate the risk (OR (95% CI)) related to one (natural logarithm) SD increase in hs-TnT and hs-CRP. Kaplan-Mayer and Cox regression analyses were used to evaluate time to surgery. RESULTS Median age (IQR) was 59.8 (10.3) years at survey, and median time between survey and surgery was 10.9 (9.3) years. Hs-TnT was independently associated with surgery for AS (1.24 (1.06-1.44)) irrespective of CAD, whereas Hs-CRP was not (1.05 (0.90-1.22)). Elevated hs-TnT levels at survey associated with shorter time to surgery (p<0.001), and with increased myocardial mass (p=0.002). Hs-CRP did not associate with time to surgery or with myocardial mass. CONCLUSIONS Hs-TnT-but not hs-CRP-was associated with increased risk of-and shorter time to-future surgery for AS. Hs-TnT associated with myocardial mass at surgery which indicates that hs-TnT could be a potential biomarker for determining intervention.

Assessing Low Carbon Transitions: A Conceptual Model

Abstract: The present report presents a conceptual assessment model or framework for policy relevant analysis of low carbon transitions. The aim of the study is not to present specific guidelines for how to design assessments of low carbon transitions, but rather to give food for thought on aspects that should be regarded in the design process. The exact design would then depend on the purpose of the assessment, the scope and priorities set for the assessment, and the resources (personal and financial) available for the assessments.We find that there are at least three elements of an assessment model that are important to provide policy relevant knowledge: i) monitoring, ii) policy evaluation, and iii) domain knowledge building processes, including research. Monitoring is here understood as a process that is intended to inform whether society is on track on meeting set-up political priorities. Policy evaluation concentrates on the effects of low carbon transition policies and effects of other policies. Domain knowledge building through research and other processes is important both for identifying relevant assessment criteria and designing monitoring systems, as well as for policy evaluations. A domain knowledge base can include knowledge of i) drivers and barriers for low carbon transitions, ii) the sustainability of various technologies, policies and practices, iii) previous policy experiences, and iv) contextual knowledge of the market, actors, mitigation technologies and pathways, etc. in various sectors. This information and background knowledge will help inform how policies can be redesigned for overcoming the barriers and enable change in various contexts while safeguarding that the changes are not in conflict with other key societal goals and sustainability aspects. Monitoring can cover direct outcomes such as greenhouse gas emissions or diffusion of low carbon technologies. But with a long-term transitions perspective it is also important to look into the preparedness for change with regard to existence of factors such as visions and expectations, knowledge, feasible policies and policy instruments (taking into account stringency as well as coverage and policy coherence), societal norms, innovation networks, or the readiness of key technologies.Evaluation of policies can in turn cover several aspects beyond policy relevance and effectiveness including synergies and conflicts with other objectives. It could also evaluate the consistency of targets with overarching objectives as well as specific strategies, policy instruments or policy packages. In the conceptual assessment model, policy adjustments are expected to be informed by the monitoring process regarding what is needed and by policy evaluation with regard to what works. Together these processes can inform on how both the stringency and the design of policies could be developed over time. (Less)

Computational Fluid Dynamics Investigation on Multiple Injector Concepts at Different Swirl Ratios in a Heavy Duty Engine

Abstract: This work was sponsored by King Abdullah University of Science and Technology (KAUST). The simulations in this work were performed with the computing resources at the KAUST Supercomputing Laboratories. The authors would like to thank Dr. Georgios Markomanolis at KAUST Supercomputing Laboratory for helpful guidance in post-processing, and Mr. Nhut Lam at Lund University for providing the experimental data for model validation.

Effect of medical treatment in patients with systemic right ventricle

Abstract: Objective: Congenitally corrected and surgical atrial redirected transposition of the great arteries (TGA) represents states where the morphological right ventricle serves as a systemic ventricle (...