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Isobaric Combustion at a Low Compression Ratio

King Abdullah University of Science & Technology-Aibolat Dyuisenakhmetov, Harsh Goyal, Moez Ben Houidi, Rafig Babayev, Bengt Johansson
Saudi Aramco-Jihad Badra
  • Technical Paper
  • 2020-01-0797
To be published on 2020-04-14 by SAE International in United States
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…
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Validation of Computational Models for Isobaric Combustion Engines

King Abdullah University of Science & Technology-Hammam H. Aljabri, Rafig Babayev, Xinlei Liu, Bengt Johansson, Hong G. Im
Saudi Aramco-Jihad Badra
  • Technical Paper
  • 2020-01-0806
To be published on 2020-04-14 by SAE International in United States
This study aims to contribute to the development of the isobaric combustion engines by exploring multiple injection strategies, employing computational simulations using a commercial CFD code Converge. As a first attempt to achieve isobaric combustion, a multiple injection strategy using a single injector was explored with up to four consecutive injections. Considering that the computational simulations were unable to reproduce the experimental data due to several uncertainties, the present study attempted to identify the leading causes of the discrepancies through a sensitivity analysis. First, different liquid fuel properties were examined, and it was found that, while the physical properties of the fuels have a notable effect in terms of evaporation and atomization, such variations were not sufficient to reproduce the experimentally observed heat release rate. Next, the effects of the uncertainties in the kinetic mechanisms were assessed by the reaction multiplier, an artificial adjustment of the rate constants, and it was found that the reaction multiplier affected the ignition of the first injection, but not the subsequent injection events. As such, the use of reaction…
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Injection Strategies for Isobaric Combustion

Clean Combustion Research Center (CCRC), King Abdullah Unive-Rafig Babayev, Moez Ben Houidi, VS Bhavani Shankar, Bassam Aljohani, Bengt Johansson
  • Technical Paper
  • 2019-01-2267
Published 2019-12-19 by SAE International in United States
In a previous study, we demonstrated that the isobaric combustion cycle, achieved with a split injection strategy, can be more suitable for the double compression expansion engine concept than the conventional diesel combustion cycle. The present work is focused on understanding the effect of different injection strategies on the heat release, efficiency, and emissions of isobaric combustion at the peak cylinder pressure of 150 bar. In situ injection rate measurements are performed to improve our understanding of the heat release rate shape and pollutant formation. A variation of load is performed to demonstrate the feasibility of the isobaric combustion cycle at higher loads, and the means of achieving them. The thermal efficiency reduces at lower loads because of heat losses. It peaks at a medium load point before reducing again at higher loads because of exhaust losses. The effect of altering the injection strategy on the isobaric combustion cycle is also studied at a constant equivalence ratio. The alteration of injection strategy is proven to have minimal effect on efficiency, loss mechanisms, and emissions when…
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In Situ Injection Rate Measurement to Study Single and Split Injections in a Heavy-Duty Diesel Engine

King Abdullah University of Science & Te-Bassam S. E. Aljohani, Moez Ben Houidi, Rafig Babayev, Khalid Aljohani, Bengt Johansson
Published 2019-09-09 by SAE International in United States
The split injection strategy holds a potential for high pressure combustion engines. One advantage of such strategy is the capability to control the heat release rate, which also implies the use of multiple split-injections with relatively short dwell intervals. Most injection rate measurement techniques require installment of the injector on a dedicated test rig. However, these techniques fail to accurately reproduce real-engine operating conditions. Using the spray impingement method, this paper investigates the injection rate of a high flow-rate solenoid injector while being operated on the engine. The aim is to have an experimental configuration as similar as possible to the real engine in terms of the acoustics and the fuel temperature within the injection system. The assumption of spray force proportional to the spray momentum is used here to measure the injection rate. The spray momentum is measured while the injector is mounted on the Volvo D13 engine and connected to the in-series fuel rail and pump. A high-natural-frequency piezoelectric pressure transducer is mounted perpendicularly at 4 mm from one of the nozzle holes.…
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Should We Walk or Take a Car for Minimum Greenhouse Gas Emissions?

King Abdullah University of Science & Technology-Rafig Babayev, Bengt Johansson
Published 2019-04-02 by SAE International in United States
This paper compares the greenhouse gas (GHG) emissions attributed to driving a popular production vehicle powered by an internal combustion engine (ICE), as well as a hybrid electric vehicle (HEV), with GHG emissions associated with walking, running and bicycling. The purpose of this study is to offer a different perspective on the problem of global warming due to anthropogenic causes, specifically on transportation and eating patterns. In order to accurately estimate emissions, a full life cycle of food has been considered coupled with energy expenditures of the aforementioned activities obtained from several different sources and averaged for more reliable results. The GHG emissions were calculated for Sweden, the UK, and the US. Depending on the availability of certain data, the methodology for different countries was altered slightly. The question whether walking, running or taking a bicycle is better for the environment than driving a car cannot be answered uniquely. This study demonstrates that the answer depends on several factors, such as diet composition, the number of people commuting, vehicle powertrain, as well as the country…
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Isobaric Combustion: A Potential Path to High Efficiency, in Combination with the Double Compression Expansion Engine (DCEE) Concept

King Abdullah University of Science & Technology-Rafig Babayev, Moez Ben Houidi, Bengt Johansson
Volvo Global Truck Tech Powertrain Engineering-Arne Andersson
Published 2019-01-15 by SAE International in United States
The efficiency of an internal combustion engine is highly dependent on the peak pressure at which the engine operates. A new compound engine concept, the double compression expansion engine (DCEE), utilizes a two-stage compression and expansion cycle to reach ultrahigh efficiencies. This engine takes advantage of its high-integrity structure, which is adapted to high pressures, and the peak motored pressure reaches up to 300 bar. However, this makes the use of conventional combustion cycles, such as the Seiliger-Sabathe (mixed) or Otto (isochoric) cycles, not feasible as they involve a further pressure rise due to combustion. This study investigates the concept of isobaric combustion at relatively high peak pressures and compares this concept with traditional diesel combustion cycles in terms of efficiency and emissions. Multiple consecutive injections through a single injector are used for controlling the heat release rate profile to achieve isobaric heat addition. In this study, the intake pressure is varied to enable a comparison between the isobaric cases with different peak pressures, up to 150 bar, and the mixed cycle cases. Tests are…
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