Abstract

South Africa generates 77% of its electricity in coal-fired power stations, with the remaining 23% from the smaller hydropower and Koeberg nuclear stations (Eskom, 2010). Secure electricity supply continues to be a significant factor in the economic Development and performance investigation of a novel solar chimney power generation system Abstract South Africa has limited reserve electricity resources and many parts of the country have limited access to electricity. Predictions suggest South Africa will have a serious electricity allocation problem in the very near future, and current rolling blackouts in many of our cities can attest to the looming problem. The energy crisis in South Africa has highlighted the need to increase electricity generation capacity and to search for alternative energy sources.Solar chimney plants could form part of the solution in the near future in South Africa to create additional power. Solar radiation energy is abundant in South Africa, while wind sources are limited mainly to coastal regions. Presently, wind turbine technology is more efficient than solar voltaic cells. This study develops a wind generation system in areas where wind is absent. A solar chimney power plant is expected to provide remote areas in South Africa with electric power, or complement the current electricity grid. Solar energy and the psychometric state of the air are important to encourage the full development of a solar chimney power plant for the thermal and electrical production of energy for various uses. A solar chimney power plant consists of a greenhouse roof collector, and the chimney is located at the centre. The chimney is used to direct and vent the low density air through a wind turbine which in turn converts the air enthalpy into mechanical energy. The main advantage of a solar chimney system lies in its low maintenance cost, the simplicity to operate and the durability of the system.Research of a design within the South African context and particularly on increasing the effectiveness of the solar chimney power plant technology is lacking. Several simulations were performed to find the optimum design configuration to focus the research. The results from the simulations were used to design the best configuration for a pilot plant.

Die artikel gee ’n uiteensetting van die resultate van navorsing wat gedoen is om te bepaal of die gebruik van chroom-karbied (CK) oorlegde voeringplate as ’n alternatief vir slytvaste (SV) plate aanbeveel kan word ter verlenging van die produksiesiklus van hidrouliese voorlaaiers in platinummyne. Navorsing toon dat slegs 53% van die RH340 voorlaaiers wat in die myn gebruik word ’n diensperiode van 3 500 uur in produksie haal alvorens meganiese herstelwerk genoodsaak word. ’n Alternatiewe voeringplaat met langer diensperiodes kan die produktiwiteit van die meganiese voorlaaierkomponente verhoog terwyl produksie-uitsette en hoë vlakke van doeltreffendheid gehandhaaf word. Die slytvastheid van saamgestelde CK- en standaard SV-plate is vergelyk deur twee RH340 voorlaaierbakke toe te rus met die onderskeie materiale, waarna die werkverrigting van die twee tipes plate onder normale produksietoestande gemonitor en gedokumenteer is tydens gereelde velddiensinspeksies. Die geldigheid van die navorsing is eerstens ondersteun deur ’n vergelykende literatuuroorsig van beide materiale. Tweedens is ’n reeks metallurgiese toetse uitgevoer op die twee materiale nà vergelykbare periodes in produksie, insluitend ’n vergelykende slytanalise. Die evaluering het aangedui dat saamgestelde CK-slytplate duurder is en dat die wagperiode van bestelling tot aflewering langer is, maar dat die CK-slytplaat minder weeg as die SV-slytplate. Die SV-slytplaat in hierdie studie het 3 283 ure in produksie voltooi, en die CK-slytplaat 4 803 ure. Die bevindinge van hierdie studie is van toepassing op komponente wat in platinummyne gebruik word, aangesien die slytasietempo van laaibakvoerings beïnvloed word deur die geologiese eienskappe van die las wat dit moet skuif. Die studieresultate ondersteun die aanbeveling van CK as ’n alternatief tot SV voerings. Verdere navorsing behoort gedoen te word om die plasing en oriëntasie van die CK-plate te optimaliseer.