Engine Size Research Articles

Biogas upgrading by amine scrubbing: solvent comparison between MDEA and MDEA/MEA blend

Biogas upgrading to biomethane has received particular attention in recent years as a key strategy to produce a natural gas-substitute from biomass. Among the available upgrading technologies, amine-based absorption is an interesting option because of its low electric power consumption and very high methane recovery rates. This paper assesses the energy and economic performance of a biogas upgrading process involving chemical absorption with two different aqueous solvent formulations: 50%w MDEA and a 20%w/20%w MDEA/MEA blend. The process performance is evaluated with Aspen Plus and the optimal process conditions are determined with a multi-objective optimization approach targeting the maximum efficiency and minimum specific equipment cost. In the proposed scheme, to make the system energy-self-sufficient, an internal combustion engine burns a fraction of the raw biogas stream to co-generate both the electric power for the upgrading process and the thermal power required for solvent regeneration.Aqueous MDEA turns out to be more efficient (Pareto dominant curve) and less expensive than the MDEA/MEA blend, as a result of the lower regeneration energy (0.94 kJ/Nm3BM/h vs 1.43 kJ/Nm3BM/h) which yields to lower energy consumptions and smaller engine sizes. Even though the cost estimates are subject to a higher degree of uncertainty, the MDEA option features an expected specific total equipment cost as low as 1,550 €/(Nm3BM/h)) vs. 1,850 €/(Nm3BM/h)) for the MDEA/MEA blend.

An engine size–scaling method for kinetically controlled combustion strategies

A substantial amount of research has recently focused on kinetically controlled combustion strategies such as reactivity-controlled compression ignition combustion. These strategies are promising methods to achieve high efficiency with near-zero NOx and soot emissions; however, despite promising results, very few attempts have been made to develop size-scaling relationships that would allow these results to be generalized to any engine design. Engine design is a long and arduous process that requires a substantial amount of experimental work. Consequently, it is of interest to develop scaling laws that allow results from one engine to be extrapolated to new designs. Several scaling laws have been proposed for diffusion combustion (i.e. mixing limited) that scale parameters such as liquid length and lift-off length. Such parameters have been deemed unimportant for highly premixed low-temperature combustion strategies; thus, a new methodology is needed. The present effort uses a combination of detailed computational fluid dynamics simulations and engine experiments in two engines with different bore sizes to develop a new engine size–scaling methodology for low-temperature kinetically controlled combustion strategies. The effects of pressure, temperature, and turbulence timescales are explored in order to replicate the large-bore engine performance in a small-bore engine. A size-scaling relationship based on the ignition timescale is proposed and used to generalize the results to an arbitrary bore size and fuel combination.

Energetic assessment of an embedded aircraft propulsion: an analytic approach

This paper investigates the energetic advantage of the embedded propulsion compared to a state-of-the-art propulsion of an aircraft. Hereby, the integral method of boundary layer theory together with the potential theory is applied to analyze the boundary layer thickness and the impact of the flow acceleration due to the embedded propulsion. The aircraft body is treated as a flat plate and the engine as a momentum disk. For an embedded propulsion, there is a trade-off of the engine size, since the propulsion efficiency is affected by the boundary layer. On the one hand, the propulsion inlet momentum is noticeably reduced for a small engine size and the viscous friction is reduced due to boundary layer ingestion. On the other hand, a slow jet speed, i.e., a large engine size, increases the propulsion efficiency as known. The outcome of the energetic assessment is the following: the propulsion efficiency is increased and the drag of the aircraft body is reduced by the embedded propulsion compared to a conventional propulsion. The optimized aircraft engine size depending on Reynolds number is given as well as the dimensionless cost function.

A method to analyze and optimize hybrid electric architectures applied to unmanned aerial vehicles

PurposeThis paper addressed some critical issues in the development of hybrid electric powertrains for aircraft and propose a design methodology based on multi-objective optimization algorithms and mission-based simulations.Design/methodology/approachScalable models were used for the main components of the powertrain, namely, the (two stroke diesel) engine, the (lithium) batteries and the (permanent magnet) motor. The optimization was performed with the NSGA-II genetic algorithm coupled with an in-house MATLAB tool. The input parameters were the size of engine, the hybridization degree and the specification of the battery (typology, nominal capacity, bus voltage, etc.). The outputs were electric endurance, additional volume, performance parameters and fuel consumption over a specified mission.FindingsElectric endurance was below 30 min in the two test cases (unmanned aerial vehicles [UAVs]) but, thanks to the recharging of the batteries on-board, the total electric time was higher. Fuel consumption was very high for the largest UAV, while an improvement of 11 per cent with respect to a conventional configuration was obtained for the smallest one.Research limitations/implicationsThe research used a simplified approach for flight mechanics. Some components were not sized in the proposed test cases.Practical implicationsThe results of the test cases stressed the importance of improving energy density and power density of the electric path.Social implicationsThe proposed methodology is aimed at minimizing the environmental impact of aircraft.Originality/valueThe proposed methodology was obtained from the automotive field with several original contributions to account for the aircraft application.

Status of the large-scale commercial trawl fisheries in southern Lake Malawi

A study to assess the status of the large scale commercial fisheries operating in southern Lake Malawi was conducted using generalised linear modelling and Principles of Precautionary Approach. The generalised linear modelling analysis was used to standardise catch per unit of effort data from 1976 to 2009 and to determine the effects of fishing vessel characteristics such as engine size and hydro-acoustic devices on fish catch rates. The Precautionary Approach, through reference points like Bmax (reference point corresponding to period of relatively high fish catch rate), Bpa (reference point at which precautionary management action should be undertaken), Blim (limit reference point beyond which a fishery is considered seriously depleted) and Bcur (reference point corresponding to current fish catch rate), was used to assess the status of fish stocks using standardised fish catch rate which approximated fish biomass or stock size. Results of the assessment indicated that the current fish biomass level in all three categories, bottom pair trawl, stern bottom trawl and stern mid-water trawl fisheries, is well above Blim, but is 9–12% above Bpa, which is very close suggesting that the fishery is fully exploited and precautionary management measures are required. Suggested measures included introduction of fishing closed season for the large scale commercial fisheries which will be dependent on the biology of the most important target fish stocks, relocation or reduction of fishing effort in the current fishing grounds and intensification of patrols to reduce incidences of illegal, unreported and unregulated fishing activities.

Webometrics: Some Critical Issues of WWW Size Estimation Methods

The number of webpages in the Internet has increased tremendously over the last two decades however only a part of it is indexed by various search engines. This small portion is the indexable web of the Internet and can be usually reachable from a Search Engine. Search engines play a big role in making the World Wide Web accessible to the end user, and how much of the World Wide Web is accessible on the size of the search engine’s index. Researchers have proposed several ways to estimate this size of the indexable web using search engines with and without privileged access to the search engine’s database. Our report provides a summary of methods used in the last two decades to estimate the size of the World Wide Web, as well as describe how this knowledge can be used in other aspects/tasks concerning the World Wide Web.

Whole-Day Driving Prediction Control Strategy: Analysis on Real-World Drive Cycles

The Whole-Day Driving Prediction (WDDP) concept is a unique plug-in hybrid electric vehicle (PHEV) control strategy that uses the day’s planned travels to determine if a small range-extending engine should be turned on at the start of each day. This control strategy allows for the use of a very small engine, in contrast to commercially available PHEVs, which generally have engines large enough to propel the vehicle. This paper presents modeling and simulation results for WDDP vehicles on the real-world logged driving cycles of 100 drivers who were each logged for between 2 and 6 weeks. The simulation results show that with an engine size between 5 and 7 kW, the WDDP vehicle with a 35-kWh battery has similar range capabilities to a pure EV with a 60-kWh battery. The consequence is that purchase price can be decreased while keeping similar range performance, encouraging a higher market penetration of plug-in vehicles. The results of this paper show that the WDDP concept is viable for real-world use, and has the potential to reduce plug-in vehicle costs while achieving driving ranges similar to the new long-range EVs recently introduced to the market.

Selection of Main Engines for Hopper Suction Dredgers with the Use of Probability Models

Abstract This paper presents a new original method of selection of main engines for hopper suction dredgers with regard to probabilistic models. It was proposed to use the normal distribution to describe the operational loads of the main receivers. The principles for determination of parameters of load distribution and design power of the main engines were formulated. Lastly, the principles of selection of the size and number of main engines has been proposed.

Emission measurement of diesel vehicles in Hong Kong through on-road remote sensing: Performance review and identification of high-emitters

A two-year remote sensing measurement program was carried out in Hong Kong to obtain a large dataset of on-road diesel vehicle emissions. Analysis was performed to evaluate the effect of vehicle manufacture year (1949–2015) and engine size (0.4–20 L) on the emission rates and high-emitters. The results showed that CO emission rates of larger engine size vehicles were higher than those of small vehicles during the study period, while HC and NO were higher before manufacture year 2006 and then became similar levels between manufacture years 2006 and 2015. CO, HC and NO of all vehicles showed an unexpectedly increasing trend during 1998–2004, in particular ≥6001 cc vehicles. However, they all decreased steadily in the last decade (2005–2015), except for NO of ≥6001 cc vehicles during 2013–2015. The distributions of CO and HC emission rates were highly skewed as the dirtiest 10% vehicles emitted much higher emissions than all the other vehicles. Moreover, this skewness became more significant for larger engine size or newer vehicles. The results indicated that remote sensing technology would be very effective to screen the CO and HC high-emitters and thus control the on-road vehicle emissions, but less effective for controlling NO emissions. No clear correlation was observed between the manufacture year and percentage of high-emitters for ≤3000 cc vehicles. However, the percentage of high-emitters decreased with newer manufacture year for larger vehicles. In addition, high-emitters of different pollutants were relatively independent, in particular NO emissions, indicating that high-emitter screening criteria should be defined on a CO-or-HC-or-NO basis, rather than a CO-and-HC-and-NO basis.

Analysis of the Relative Velocity and Its Influence on the Process Results in Unguided Vibratory Finishing

The relative velocity between workpiece and media has a strong effect on the material removal rate in vibratory finishing. Due to this fact, a measurement system in the form of a camera-integrated workpiece is presented in this paper, which is capable of measuring the relative velocity between the workpiece and the media in an unguided vibratory finishing process. The unique feature of this measurement system is the completely wireless construction, so that the results are not influenced by wires for the data transfers and the electrical power supply of the light-emitting diodes of the camera system. Furthermore, the influence of the media size and adjustments of the imbalance engine like rotational speed, mass distribution between the upper and the lower imbalance weights, and offset angle between the imbalance weights were investigated. The evaluation of the results has shown that the media size and the rotational speed of the imbalance engine are the major influence factors on the relative velocity between workpiece and media.

Mathematical modeling of mini-CHP based on biomass

One of the promising directions of small-scale distributed power generation for Russia is the use of biomass. The present work is devoted to studies of an mini-CHP based on multi-stage biomass gasification. Mathematical models of elements and mini-CHP in general based on technological schemes were constructed. The mathematical models were constructed with the software developed at Melentiev Energy Systems Institute of Siberian Branch of the Russian Academy of Sciences. The calculations were made for two sizes of internal combustion engines. Thus, we obtained the values of flow rates, temperatures of heat carriers at various points of flow charts of the plants.

The advisability of using combustion chambers with a toroidal recirculation-mixing zone in small-sized gas turbine engines

The interrelations between the size of the gas turbine engine (GTE) and the size and workflow of the combustion chamber (CC) were considered. On the base of analysis of workflow organization the design of CC with toroidal recirculation mixing zone was proposed. The theoretical justification of chosen design was carried out on the base of comparison of combustion volumes, which formed in traditional CC with swirlers and in proposed CC. The comparison of combustion volumes, schematic display of combustion zones with a discrete flame and a combined combustion zone were given.

Effect of Aging Heat Treatment on the Mechanical Properties of SiC Reinforced 7075 Al-Alloy Composites Manufactured by Vortex Casting Method

Nowadays, light part production by the strategies of performance improving known as 'Engine Downsizing' by decreasing the engine size is popular. Al-Zn-Mg alloyed composites reinforced by SiC particle are mostly produced by powder metallurgy. In fact, Liquid mixing casting technique alternatively developed against the powder metallurgy has more than advantageous when taking into the consideration of its production capacity, production cost and part production similar to the definitive form. In this study, the hardness variation of SiC particle reinforced composites manufactured by the method of affordable 'Vortex Casting' and in different amounts by weight and 7075 alloy after aging process in different times at 140℃ and 230℃ was reviewed and their microstructure analyses were made accordingly. After 16 hours aging of 7075 alloy and the composites reinforced by 5% SiC at 140℃ and 12 hours aging in the composites reinforced by 3% SiC, at 230℃, after 9 hours aging in all materials, the maximum hardness value was measured. In higher aging temperature, due to the fact that max hardness was achieved in shorter period, in lower aging temperature, higher hardness was achieved.

Efficient Reconfigurable Architecture for Pricing Exotic Options

This article presents a new method for Monte Carlo (MC) option pricing using field-programmable gate arrays (FPGAs), which use a discrete-space random walk over a binomial lattice, rather than the continuous space-walks used by existing approaches. The underlying hypothesis is that the discrete-space walk will significantly reduce the area needed for each MC engine, and the resulting increase in parallelisation and raw performance outweighs any accuracy losses introduced by the discretisation. Experimental results support this hypothesis, showing that for a given MC simulation size, there is no significant loss in accuracy by using a discrete space model for the path-dependent exotic financial options. Analysis of the binomial simulation model shows that only limited-precision fixed-point arithmetic is needed, and also shows that pairs of MC kernels are able to share RAM resources. When using realistic constraints on pricing problems, it was found that the size of a discrete-space MC engine can be kept to 370 Flip-Flops and 233 Lookup Tables, allowing up to 3,000 variance-reduced MC cores in one FPGA. The combination of a highly parallelisable architecture and model-specific optimisations means that the binomial pricing technique allows for a 50× improvement in throughput compared to existing FPGA approaches, without any reduction in accuracy.

Socio-economic, technological and environmental drivers of spatio-temporal changes in fishing pressure

As part of an ecosystem based approach to fisheries management (EBFM), the heterogeneity of biological communities, key ecological processes and human uses must be understood. Although fishing effort distribution and marine habitat distribution and use are increasingly well understood, little research has quantified spatio-temporal changes in fishing effort or investigated drivers of these changes. Here, a holistic approach was taken to investigate socio-economic, environmental and technological drivers of change in fishing effort distribution of the Northumberland pot-fishery (2004–2014) using Bayesian Belief Network (BBN) analyses. BBNs were populated using large-scale high resolution spatial and temporal fisheries monitoring data, quantitative and qualitative interviews with fishers and expert opinion. Increases in fishing effort over time were explained by a combination of changes in fleet composition and fishers’ behaviour. Increasing vessel and engine sizes, combined with an increased uptake of improved fishing technology have resulted in a greater ability for vessels to fish a greater number of pots. This increase in vessel and fishing capability has resulted in fishers’ increased ability to fish in harsher weather conditions, as well as target specific areas or habitats quickly and opportunistically. Non-technological factors, such as declines in stocks of finfish and nephrops and the increasing operational costs of participating in these fisheries may have resulted in fishers solely fishing in the less regulated pot-fishery, targeting high value European lobster on a full-time basis. Increasing costs of pot-fishing in Northumberland coupled with stagnating crab and lobster landings prices may have resulted in increased fishing effort to maintain profitability.

Wing and Engine Sizing by Using the Matching Plot Technique

Abstract The research focuses on the development of an Unmanned Aircraft System. For design purposes, a rather new design method called Systems Engineering Approach is used. Development of the whole system takes much time and effort. This paper contains a concise description of the research on the preliminary development phase of Unmanned Aircraft System air vehicle. The method was first introduced by NASA and later developed by authors of books on aircraft design used for information purposes for design and are mentioned in references. The obtained results are rather realistic and promising for further design process. The method is simple and understandable, and it should be used more often to make it more steady and reliable.

Exploring the Effect of Frictional Heat on Rate of Fuel Combustion by ICE through Modeling and Simulation with Reference to ICE Parameters.

Otto cycle operations of ICEs have relatively higher capacities and efficiency. Factors of efficiency, emission, fuel consumption and output power are considered during design and construction of ICEs. Engine size, engine weight, number of pistons, swept volume, cylinder arrangement and number of valves all differs in accordance to type of ICE. Fundamental principle of ICE is burning of air – fuel mixture of appropriate proportions in air tight chamber to produce heat energy for motion. Fossil fuel of diesel and gasoline obtained from underground are the main fuels used by ICEs. The engine block houses cylinders, pistons rings, connecting rods and pistons. At top seals of cylinders are located inlet valves, outlet valves and channels. Crankcase houses crankshaft and bearings whiles the sump serves as reservoir for lubrication oil. Lubrication oil also known as lubricant reduces friction between moving surfaces in ICEs through piston ring grooves. Connecting rod is the linkage between crankshaft and piston. Gudgeon – pin transmits combustion force from piston to connecting rod then to crankshaft. Thus, crankshaft converts reciprocating motion of piston to cyclic motion. During operations of ICEs, friction occurs between pistons with piston rings collectively and inner walls of cylinder. Frictional effects account for about thirty five percent (35%) of total heat generated in ICEs. The methodology adopted by this article is modeling and simulating frictional models by previous authors. These models were incorporated with ICE parameters before modeling and simulation again. Objectively, graphical results show reduction in heat generation due to friction.

Eco-economic excavator configuration method

Abstract Excavating processes performed frequently in building, civil and infrastructure projects are critical and costly. To define a cost-effective excavator configuration, an earthwork planner depends mostly on experience and intuition. This intuitive reasoning is often error-prone, and highly experience based. This paper presents a computational method called the Eco-Economic Excavator Configuration (E3C), which selects the most favorable configuration of a heavy duty excavator according to the earthwork package and its job conditions. E3C obtains the input data from external databases, derives the formulae involved in computing the process performance (e.g., production rate, process completion time, and profit), and instructs the earthwork manager in the best-fit excavator configuration (e.g., maximum digging depth, engine size in HP, and bucket size) for profitable operation by considering the implicit constraints and conditions exhaustively. The method identifies the best-fit PDFs of the process completion time and that of the total profit, given an excavator configuration. A test case, which was performed at a building basement excavating project, confirmed the usability and validity of the method.

Simulation of hybrid propulsion system using LSRG and single cylinder engine

Nowadays, more and more people are beginning to use hybrid vehicles (HVs). The drive system of HVs needs to produce the electric energy with the electric generator and gearbox powered by an engine. Therefore, the structure becomes complex and the cost is high. To solve this issue, this research proposes a new drive system design that combines the engine and a linear switched reluctance generator (LSRG). When the engine is operating, the LSRG can simultaneously assist the engine’s mechanical output or can generate power to charge the battery. In this research, three research steps are executed. In the first step, the LSRG is designed according to the size of normal engine. Then, finite element analysis is used to get the data of flux linkage and calculate the inductance and translator force. Finally, Simulink models of control system are constructed to verify the performance of LSRG.

Selection of chipper engine size based on business scale and optimised cost of chipping and transportation

ABSTRACTThe best chipper engine size was obtained by optimising the chipping operation according to business scale and transportation cost. The total chip supply cost could be reduced by improving the rate of machine utilisation of chippers. From regression analysis, the engine power of chippers expressed well the chipping and transportation costs, and the trade-off relationship between these costs was proved by the model supply chain in Iwate Prefecture, Japan. The chipper with a middle-sized engine, with an engine power of 200–400 kW, was the best choice in the perspective of economy and transportation management while the business scale needed to be at least 20,000 solid m3 year−1. The total supply cost by a chipper with a smaller engine was not the best but it could be recommended to attract small-scale companies that produce less than 10,000 solid m3 year−1. Chippers with a larger engine could be introduced if the business scale was about 50,000 solid m3 year−1. However, even if the chipping cost could be reduced, the supply chain would require larger trucks or trailers on such a large business scale. The shuttle transportation system needs to be improved to reduce the unloading time that occupies one-fifth to one-fourth of a cycle time and empty drives.