Second order analyses methods for stirling engine design

[摘要] ENGLISH ABSTRACT:In the midst of the current non-renewable energy crises specifically with regard to fossil fuel, variousresearch institutions across the world have turned their focus to renewable and sustainable development.Using our available non.renewable resources as efficiently as possible has been a focal point the pastdecades and will certainly be as long as these resources exist Various means to utilize the world'sabundant and freely available renewable energy has been studied and some even introduced andinstalled as sustainable energy sources, Electricity generation by means of wind powered turbines,photo-voltaic cells, and tidal and wave energy are but a few examples.Modern photo-voltaic cells are known to have a solar to electricity conversion efficiency of 12% (VanHeerden, 2003) while wind turbines have an approximate wind to electricity conversion efficiency of 50%(Twele et aI., 2002). This low solar to electricity conversion efficiency together with the fact thatrenewable energy research is a relatively modern development, lead to the investigation into methodscapable of higher solar to electricity conversion efficiencies. One such method could be to use therelatively old technology of the Stirling cycle developed in the early 1800's (solar to electricity conversionefficiency in the range of 20.24 % according Van Heerden, 2003). The Stirling cycle provides a methodfor converting thermal energy to mechanical power which can be used to generate electricity, One of themain advantages of Stirling machines is that they are capable of using any form of heat source rangingfrom solar to biomass and waste heat.This document provides a discussion of some of the available methods for the analysis of Stirlingmachines. The six (6) different methods considered include: the method of Beale, West, mean-pressurepower-formula (MPPF), Schmidt, idea! adiabatic and the simple analysis methods. The first three (3) areknown to be good back-of-the-envelope methods specifically for application as synthesis tools duringinitialisation of design procedures, while the latter three (3) are analysis tools finding application duringStirling engine design and analysis procedures. These analysis methods are based on the work done byBerchowitz and Urieli (1984) and form the centre of this document. Sections to follow provide adiscussion of the mathematical model as well as the MATlAB implementation thereof. Experimental testswere conducted on the Heinrici engine to provide verification of the simulated resutls. Shortcomings ofthese analyses methods are also discussed in the sections to follow. Recommendations regardingimprovements of the simulation program, possible fields of application for Stirling technology, as well asfuture fields of study are made in the final chapter of this document. A review of relevanl literatureregarding modern applications of Stirling technology and listings of companies currently manufacturingand developing Stirling machines and findings of research done at various other institutions are provided.

[发布机构] Stellenbosch University