Dahlander, Petter

Zander, Lennarth

English

Chalmers Research

Title SlideLicentiate-Presentation: ”A Two-Stroke Range Extender Engine for Heavy Duty Battery Electric vehicleapplications”Lennarth Zander Mechanical and Maritime Science, ChalmersTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-102Boom!Agenda:• Introduction• The idea• Research questions• Methodology• Results• Conclusions• Further work• AknowledgementTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-103Boom!IntroductionBoom!Pure-BEV Fuel Cell-BEVREX-BEVTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-104Boom!IntroductionTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-105The ideaTwo-Stroke Back Up REX-BEVTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-106+The ideaTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-107Boom!• Back-up Range Extender• Develop a (turbo) charging system for a single cylinder crank case scavenged two-stroke SI-engine• Charging system interaction with the two-stroke gas exchange• Turbocharger fundamentals and selection of concept• Model- and experimental results for the final conceptResearch questionsTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-108Two-stroke gas exchange basicsCA at tuned speedBDCSpOSpCEpCEpOAssumed center of rarefactionwave reflectionAssumed center ofcompressionwave reflectionDistanceSpeed12Exhaust PrimaryPipeResidencePressureWavesSuperpositioned pressure tracedownstream exhaust portTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-109Methodology: Experimental engine and dyno testing and 1D engine simulationEngine experiments were utilized to calibratea 1D engine model equiped with variablepressure boundaries to simulate different supercharger and turbocharger systemA single cylinder motorbike engine at 125cc swept volume and 30 [HP] was used in the engine dyno experimentsTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1010Boom!ResultsTitle and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1011Exploring the optimum boost- and exhaust pressures for the two-stroke engine with the help of 1D engine simulationsEngine simulations were carried out with a boost pressure of 2.0 [bar a] and the exhaust pressure was variedbetween 1.0-2.4 [bar a]. The pressures were applied independent of engine speed.A boost pressure of 2.0 [bar a] in combination with an exhaust pressure of 2.0-2.2 [bar a] was considered to optimize the gas exchange.This pressure balance will not be achieved with a mechanical driven compressor (supercharger) but can be achieved with an optimized turbocharger system.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1012Turbocharging challenges to obtain the desired pressure balanceCompressorEngineTurbineWastegatePower equilibrium over the turbocharger and isentropic assumptions can be utilized to express the turbine pressureratio as a function of the boost pressure.The different efficiencies, wastegate-ratio and exhaust temperature have a strong impact.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1013Turbocharging supported by an afterburner system (EBK)The two-stroke engine is exhaust temperature limited because of the piston controling the exhaust port and great heat losses over the large tuned exhaust pipe. But the exhaust gases contain both air- and unburned fuel(HC) which can be converted to heat upstream the turbine using an oxidation catalyst hereby aso namedafterburner.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1014The 1D engine simulation is expanded…The 1D engine model is now developed withturbocharger- and heater object to come closerto a real afterburner assisted turbocharger system. Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1015Prove of conceptOnce the heat release model was calibratedusing cylinder pressure traces the correlationwas acceptable to indicate that the conceptworks. Also exhaust pressure traces wascollected to calibrate the tuned effects from the exhaust pipe.The power level is increased from 22 [kW] to 50 [kW] or 400 [kW/L]Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1016Prove of conceptThe afterburner assisted turbocharger system makes it possible to ”over scavenge” the engine to lower the exhaust port temperature while the pre turbine temperature can be maintained at a decent 800 degCtemperature. Not bad for an engine putting out around 50 [kW].The turbocharger needs to be selected based on the turbine swallow capacity. Since the turbocharger used in the experiments was intended for a four-stroke engine in combination with larger wastegate-ratios, the compressor is operated to close to the surge line.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1017Prove of conceptOnly a fraction of the available air and HC needs to be utilized in the afterburner system to obtain the desiredexhaust temperatures into the turbine.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1018Conclusion• A single cylinder two-stroke engine is small enough to install directly onto the existingelectric mahine in a heavy duty battery electric vehicle as a back up range extender.• This thesis have shows that an afterburner assisted turbocharger system can be optimized to increase the specific power to 400 [kW/L] indicating that a 400-425 [cc] engine can deliverthe 150 [kW] needed to recharge the batteries on a heavy duty battery electric vehicle.• A supercharger is not a good charging system for a two-stroke engine.• The afterburner turbocharging system will create lower exhaust port temperatures in combination with higher exhaust temperatures upstream the turbine which will be a benefit for the engine structural stresses.• The afterburner system will also reduce the HC exhaust emissions.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1019Further work• A simulation study can be carried out on a scaled-up engine with 400-425 [cc] swept volumeto reach the desired 150 [kW].• A scaled up engine shall use direct injection (DI) and not port injection (PI) as the experimental engine in this thesis. • The DI technology will create lower HC emissions and a higher conversion catalystrate can be used for improved exhaust emissions and improved control of the afterburner.• The turbocharger system can also be optimized to suit the two-stroke engine better.Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1020Aknowledgement• Thanks to CERC for financial support!• Thanks to Scania for making it possible to combine work and studies!Title and ContentLennarth Zander Scania CV-Chalmers Department of Mechanical and Maritime Science 20-12-1021Thanks for your kind attention!The turbocharged Rotax 122 engine in the dyno

A Two-Stroke Range Extender Engine for Heavy Duty Battery Electric vehicle applications

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A Two-Stroke Range Extender Engine for Heavy Duty Battery Electric vehicle applications

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