The development of a small diesel engine test bench employing an electric dynamometer

Thesis (MEng)--Stellenbosch University, 2017.ENGLISH ABSTRACT: Global efforts to combat climate change, reduce greenhouse gas emissions and increase energy security has led to renewed interest in the use of biofuels as an alternative to fossil fuels. Therefore, it has become increasingly important to understand the effects that the use of biofuel has on the performance and emissions of internal combustion engines. The subject of this report is the development of a small diesel engine test bench employing an electric dynamometer. The purpose of the project is to establish an engine testing platform which can be used to test small quantities of biofuel, as well as to expand the testing capabilities of the Biofuel Test Facility at Stellenbosch University. In this report, a review of the literature surrounding various aspects of engine performance testing and engine indicating testing is presented. In addition, literature research regarding the different types of dynamometers available is also presented. A thorough evaluation of the various dynamometer options is performed and a suitable electric dynamometer system is selected for the development of the test bench. Further aspects surrounding the development of the test bench covered in this report include integrating the dynamometer with a small test bench employing a single-cylinder, compression-ignition engine, designing a driveshaft to couple the dynamometer to the test engine, as well as instrumenting the test bench. In addition, this report also details the instrumentation of the test engine with a fibre-optic pressure transducer to measure in-cylinder pressure data, as well as the development of software which is used to measure and record all engine indicating data. The obtained engine indicating data is then used to construct a zero-dimensional, single-zone heat release model. Calibration of the dynamometer system is performed and it is concluded that the dynamometer’s signal output exhibits excellent repeatability and displays very little hysteresis. Engine tests are also performed during which it is found that the developed test bench produces accurate and repeatable results, both during engine performance testing and engine indicating testing. It is also concluded that the test setup is sensitive enough to detect small changes in engine performance and engine particulate emissions when switching from petroleum diesel to B10 biodiesel.AFRIKAANSE OPSOMMING: Globale pogings om klimaatsverandering te bestry, vrystelling van kweekhuisgasse te verminder en energie sekuriteit te verhoog, het gelei tot hernude belangstelling in die gebruik van biobrandstowwe as 'n alternatief vir fossielbrandstowwe. Gevolglik het dit al hoe belangriker geword om die effek wat die gebruik van biobrandstof op die werkverrigting en uitlaatgasse van binnebrandenjins het te verstaan. Die onderwerp van hierdie verslag is die ontwikkeling van 'n klein dieselenjin toetsbank wat gebruik maak van 'n elektriese enjin rem. Die doel van hierdie projek is om 'n enjin toets platform te ontwikkel wat gebruik kan word om klein hoeveelhede biobrandstof te toets, asook om die toets vermoë van die Biobrandstof Toetsfasiliteit by die Universiteit van Stellenbosch uit te brei. Hierdie verslag verskaf ‘n oorsig van die literatuur wat handel oor die verskeie aspekte van enjin prestasietoetsing, sowel as oor die meting van druk binne die silinder van ‘n enjin. Daarbenewens word literatuurnavorsing oor verskillende tipes enjin remme ook aangebied. 'n Deeglike evaluering van die verskillende enjin rem opsies word gedoen en die mees geskikte elektriese enjin rem stelsel word gekies vir implementering met die toetsbank. Addisionele aspekte rakende die ontwikkeling van die toets bank wat in hierdie verslag aangespreek word sluit in die integrasie van die enjin rem met ‘n beskikbare klein toets bank wat gebruik maak van ‘n enkel-silinder, kompressie-ontstekingsenjin, die ontwerp van 'n dryfas om die enjin rem aan die toets enjin te koppel, sowel as die instrumenting van die toets bank. Verder word besonderhede ook verskaf rondom die instrumentering van die toets enjin met 'n optiese-vesel druk sensor om gevolglik die druk binne die enjin silinder te meet. Die ontwikkeling van die sagteware, wat gebruik word om hierdie gemete druk waardes te stoor, word ook bespreek. Die druk waardes gemeet binne die silinder van die enjin word dan gebruik om 'n nul-dimensionele, enkel-area numeriese model te ontwikkel wat beskryf hoe hitte binne die enjin vrygestel word. Kalibrasie van die enjin rem stelsel word uitgevoer waartydens daar gevind word dat die uittree sein vanaf die enjin rem uitstekende herhaalbaarheid en baie min histerese toon. Enjin toetse word ook uitgevoer waartydens daar bevind word dat die ontwikkelde toets bank baie akkurate en herhaalbare resultate oplewer tydens beide die enjin prestasie toetse sowel as tydens die meet van die silinder druk. Daar word ook tot die gevolgtrekking gekom dat die toets opstelling sensitief genoeg is om klein veranderinge in enjin werkverrigting en enjin uitlaatgasse te identifiseer, wanneer daar vanaf petroleum diesel na B10 biodiesel oorgeskakel word