Utilising a high pressure, cross flow, stainless steel fintube heat exchanger for direct steam generation from recovered waste heat

Wipplinger, Karl Paul Martin (2004)

Thesis (MScEng) -- Stellenbosch University, 2004.

Thesis

ENGLISH ABSTRACT: Around the world the implementation of heat recovery systems is playing an increasingly important role in the engineering inqustry. The recovered energy is utilised in the plants and saves companies millions in expenses per year. Not only is this seen on the grand scale of industry, but also in everyday life, where for instance turbochargers are used to boost the performance of automobiles by utilising the wasted energy expelled along with exhaust gasses. The aim of this project is to investigate a small scale waste heat recovery system, and to determine the optimum method by which to convert the recovered energy into electrical energy, which can be used as a secondary energy source. The research contained in this thesis, centres on the main components and theory needed for the construction of a small scale waste heat recovery system. Also included, is a theoretical analysis concerning the design and construction of the system, utilising researched theory and a simulation program of the recovery system. The simulation is control volume-based and generates property data on the fluid and exhaust gas throughout the heat exchanger. The final design included a finite element stress analysis of certain parts of the system to ensure safe testing at high pressures and temperatures. The final design resulted in a high pressure, cross flow, stainless steel fintube heat exchanger that, by using a continuous combustion unit as energy source and water as the working fluid, reached efficiencies of up to 74% in direct steam generation testing. The tube-side of the heat exchanger was designed to withstand pressures of up to 2MPa (20bar), which is imperative for the implementation of the next phase, where a turbocharger will be connected to the heat exchanger. The completion of this part of the project has paved the way for further development and implementation of the heat recovery system.

AFRIKAANSE OPSOMMING: Die herwinning van energie begin 'n toenemend belangrike rol in die ingenieurs industrie speel. Die herwonne energie word in fabrieke ben ut en spaar maatskappye milj oene aan uitgawes per jaar. Hierdie beginsel word nie net in die grootskaalse nywerhede toegepas nie, maar ook in die allerdaagse lewe, soos byvoorbeeld in voertuie waar turbo-aanjaers gebruik word om die energie-uitset van enjins te verhoog deur bloot gebruik te maak van die verlore energie wat saam met die uitlaatgasse in die atmosfeer gepomp word. Die doel van hierdie projek is om 'n kleinskaalse energieherwinningstelsel te ondersoek en die mees effektiewe metode te vind om die herwinde energie na elektriese energie om te skakel wat as 'n sekondere energiebron gebruik kan word. Die navorsing bevat in die tesis, kyk na al die hoofkomponente en teoretiese kennis wat nodig is vir die konstruksie van 'n kleinskaalse hitteherwinningstelsel. Ook ingesluit is 'n teoretiese analise ten opsigte van die ontwerp en konstruksie van die sisteem. Dit behels die gebruik van nagevorsde teorie saam met 'n simulasie program van die herwinnings stelsel. Die simulasie program is op kontrole volumes gebasseet en genereer uitlaatgas- en water eienskappe soos dit deur die hitteruiler vloei. Die finale ontwerp bevat 'n eindige element spannmgs analise van sekere kritiese komponente in die stelsel om die veilige gebruik van die sisteem by hoe drukke en temperature te verseker. Die finale ontwerp was 'n hoedruk, kruisvloei, vlekvrye staal finbuis hitteruiler. Deur 'n konstante verbrandingseenheid as energiebron te gebruik saam met water as werksvloeier, het die hitteruiler effektiwiteite van tot 74% in direkte stoomgenerasie-toetse bereik. Die hitteruiler is ontwerp om hoe drukke van tot 2MPa (20bar) te hanteer wat baie belangrik is vir die implementasie van die volgende fase van die projek waar 'n turbo-aanjaer aan die stelsel gekoppel sal. Die suksesvolle voltooiing van hierdie fase van die projek het die weg gebaan vir die verdere ontwikkeling en implimentasie van die energieherwinningsstelsel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50217
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