Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The performance of wet cooling towers can be improved by installing spray nozzles that distribute the cooling water uniformly onto the fill whilst operating at a low pressure head. In this thesis, three commercial spray nozzles are experimentally evaluated in terms of flow and pressure loss characteristics as well as water distribution patterns. The results of the evaluation process highlight the need for spray nozzles with enhanced performance characteristics. The theory required to implement the results of the evaluation process in the design of a cooling tower is presented and discussed. A systematic approach to enhance the performance of a spray nozzle through minor alterations is applied to one of the commercial spray nozzles that was evaluated. The fluid dynamics of an orifice nozzle, such as the effect of a change in pressure head, spray angle, spray height, orifice diameter and wall thickness on drop diameter and spray distance, is experimentally investigated and a model with which a spray nozzle can be designed is finally presented. Two prototype spray nozzles show that it is possible to enhance the performance of spray nozzles and thus wet cooling towers by means of the methods presented. / AFRIKAANSE OPSOMMING: Die werkverrigting van natkoeltorings kan verbeter word deur sproeiers te installeer wat die verkoelingswater uniform versprei op die pakking teen 'n lae pomp drukhoogte. In hierdie tesis word drie kommersiële sproeiers eksperimenteel geëvalueer in terme van vloei en drukverlies eienskappe sowel as water verdelings patrone. Die resultate van die evaluasie proses beklemtoon die behoefte aan sproeiers met verbeterde werkverrigtingseienskappe. Die teorie wat benodig word om die resultate van die evaluasie proses te implementeer in die ontwerp van 'n natkoeltoring word bespreek. 'n Stelselmatige benadering om die werkverrigtings van 'n sproeier te verhoog deur klein veranderinge aan die ontwerp aan te bring, word toegepas op een van die sproeiers wat getoets is. Die vloeidinamika van 'n plaatmondstuk, soos die effek van 'n verandering in drukhoogte, sproeihoek, sproeihoogte, gatdiameter en wanddikte op druppel diameter en sproeiafstand, is eksperimenteel ondersoek en 'n model word aangebied waarmee 'n sproeier ontwerp kan word. Twee prototipe sproeiers wys dat dit moontlik is om die werkverrigting van sproeiers, en dus ook natkoeltorings, te verbeter deur die metodes wat in die tesis aangebied word, toe te pas.