Emissions and Performance Potential of a Small Stratified Charge 2-Stroke Engine Using Reed Valves

Moeser, Christian M.; Gantert, Jochen; Keck, Ulrich; Raffenberg, Michael; Rieber, Martin; Rosskamp, Heiko

doi:10.4271/2006-32-0058

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…To understand the performance of reed valves, 3D CFD simulations, and 0D-1D models were investigated in previous investigations [15][16][17][18][19][20][21][22]. While the CFD simulations were used to describe the fluid dynamics inside the crankcase and combustion chamber, the 0D and 1D models were mainly focused on calculating the flow boundary conditions through the reed valve at the engine intake.…”

Section: Double Compression Expansion Enginementioning

confidence: 99%

Reed Valve Evaluation and Selection for the Compressor Cylinder in Double Compression Expansion Engine (DCEE) Concept

Cabezas

Goyal

Andersson

et al. 2021

SAE Technical Paper Series

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This paper shows the potential benefits of implementing four configurations of reed valves at the inlet of the two-stroke compressor used in the double compression expansion engine (DCEE) concept or 8-stroke engines over the conventional poppet valves used in 4-stroke internal combustion engines. To model the reed and poppet valve configurations, the discharge coefficient was estimated from RANS computational fluid dynamics simulations using ANSYS Fluent 2020 R1, with a pressure difference up to 0.099 bar. The calculated discharge coefficients for each case were then fed in a zero-one dimension model using GT-Power to understand the valve performance i.e. the volumetric efficiency of the compressor cylinder and the mean indicated pressure during the compression process at 1200 rpm. The results showed that for reed valve configurations, the discharge coefficient and mass flow rate were higher, the pressure drop was lower and the response with negative pressure difference was faster compared to poppet valves. In addition, all the reed valve cases showed improvement in volumetric efficiency and a drop in mean effective pressure than poppet valves. In particular, the optimum reed valve geometry in the present study resulted in a volumetric efficiency improvement of 7.2 percentage points and a mean effective pressure reduction of 3.2 percentage points compared to conventional poppet valves.

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Section: Double Compression Expansion Enginementioning

confidence: 99%

Reed Valve Evaluation and Selection for the Compressor Cylinder in Double Compression Expansion Engine (DCEE) Concept

Cabezas

Goyal

Andersson

et al. 2021

SAE Technical Paper Series

View full text Add to dashboard Cite

show abstract

“…In recent years the increasing R&D efforts have led to a new type of two-stroke engines known as airhead scavenging engine that -along with new vibration damping systemshave led to much better environmental situations and even better customer comfort when operating the chain saws [2].…”

mentioning

confidence: 99%

Energy efficient drive train for a high-performance battery chain saw

Heinzelmann

Liebhard

Rosskamp

2011

2011 1st International Electric Drives Production Conference

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Up to today, smaU two-stroke gasoline engines are the major power source for professional outdoor power equipment such as hedge trimmers, chain saws, blowers, cut-off saws. For a while now, small consumer-like equipment with a battery-based power source is available. But only since 2010 professional grade cordless mobile power chain saws are available. Several break-through innovations in the drive train and safety circuits have been necessary to enable the use of an electric motor fed by battery energy for a premium grade high performance chain saw. This paper highlights the necessity for brush less direct drive technology and strict optimization of all components. Based on a complete system analysis, ways for enhancing energy efficiency are derived. A lithium ion smart battery pack is the basis for continous drain electric power supply for wood cutting. Besides superior performance and good handling characteristics, three items are most important for a professional product for craftsman, carpenters and wood workers: -very robust drive train and especiaUy bearings and drive shaft rigidity -high motor torque at very low weight to enable the user to work also with the whole guide bar engaged in the woods -sufficient cooling of drive train and motor control electronics for continuous work also under elevated summer time temperaturesThe paper presents details to these factors and describes the technology approach.

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Engine-Control Impact on Energy Balances for Two-Stroke Engines for 10–25 kg Remotely Piloted Aircraft

Ausserer

Polanka

Litke

et al. 2018

Journal of Engineering for Gas Turbines and Power

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The rapid expansion of the market for remotely piloted aircraft (RPA) includes a particular interest in 10–25 kg vehicles for monitoring, surveillance, and reconnaissance. Power-plant options for these aircraft are often 10–100 cm3 internal combustion engines (ICEs). The present study builds on a previous study of loss pathways for small, two-stroke engines by quantifying the trade space among energy pathways, combustion stability, and engine controls. The same energy pathways are considered in both studies—brake power, heat transfer from the cylinder, short circuiting, sensible exhaust enthalpy, and incomplete combustion. The engine controls considered in the present study are speed, equivalence ratio, combustion phasing (ignition timing), cooling-air flow rate, and throttle. Several options are identified for improving commercial-off-the-shelf (COTS)-engine efficiency and performance for small, RPA. Shifting from typical operation at an equivalence ratio of 1.1–1.2 to lean operation at an equivalence ratio of 0.8–0.9 results in a 4% (absolute) increase in fuel-conversion efficiency at the expense of a 10% decrease in power. The stock, linear timing maps are excessively retarded below 3000 rpm, and replacing them with custom spark timing improves ease of engine start. Finally, in comparison with conventional-size engines, the fuel-conversion efficiency of the small, two-stroke ICEs improves at throttled conditions by as much as 4–6% (absolute) due primarily to decreased short-circuiting. When no additional short-circuiting mitigation techniques are employed, running a larger engine at partial throttle may lead to an overall weight savings on longer missions. A case study shows that at 6000 rpm, the 3W-55i engine at partial throttle will yield an overall weight saving compared to the 3W-28i engine at wide-open throttle (WOT) for missions exceeding 2.5 h (at a savings of ∼5 g/min).

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Emissions and Performance Potential of a Small Stratified Charge 2-Stroke Engine Using Reed Valves

Cited by 6 publications

References 3 publications

Reed Valve Evaluation and Selection for the Compressor Cylinder in Double Compression Expansion Engine (DCEE) Concept

Reed Valve Evaluation and Selection for the Compressor Cylinder in Double Compression Expansion Engine (DCEE) Concept

Energy efficient drive train for a high-performance battery chain saw

Engine-Control Impact on Energy Balances for Two-Stroke Engines for 10–25 kg Remotely Piloted Aircraft

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