Browsing by Author "Dreyer, Andre Alexis"

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    Analysis of evaporative coolers and condensers
    (Stellenbosch : Stellenbosch University, 1988) Dreyer, Andre Alexis; Erens, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: In this report various mathematical models for the thermal evaluation of evaporative coolers and condensers are presented. These models range from the exact model based on the work by Poppe [84P01] to the simplified logarithmic models based on the work of McAdams [54Mcl] and Mizushina et al. [67MI1], [68MI1]. Various computer programs were written to perform rating and selection calculations on cross-flow and counterflow evaporative coolers and condensers. Experimental tests were conducted on a cross-flow evaporative cooler to determine the governing heat and mass transfer coefficients. The experimentally determined coefficients were cqrrelated and these correlations are compared to the existing correlations. The two-phase pressure drop across the tube bundle was also measured and a correlation for two-phase pressure drop across a tube bundle is presented.
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    Modelling of cooling tower splash pack
    (Stellenbosch : Stellenbosch University, 1994) Dreyer, Andre Alexis; Erens, P. J.; Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic Engineering.
    AFRIKAANSE OPSOMMING: 'n Wiskundige model en 'n rekenaar simulasie program is ontwikkel om die vertoning van teenvloei koeltoring spat-pakking ("splash pack") te voorspel. Die een-dimensionele model gebruik basiese lugdinamiese, hidrodinamiese en warmte/massa-oordrag data om die vertoning te voorspel sander om van gemete koeltoring toetsdata gebruik te maak. Sekere basiese eksperimentele werk is gedoen om die volgende aspekte meer duidelik te maak: die massa water wat spat vanaf die nat latte, die grootte-verdeling van die spat druppels en die grootte-verdeling van die druppels wat afdrup vanaf die latte. Toetse is ook gedoen op twaalf verskillende pakkings om verwysingsdata te genereer waarteen die akkuraatheid van die simulasie-program getoets kon word. Die gemete oordrags-karakteristieke en drukval data is vergelyk met die voorspelde data wat met die program gegenereer is. Daar is gevind data die model die korrekte tendense in drukval en oordrags-karakteristieke voorspel. Die program het die oordrags-karakteristieke en die drukval oor die pakking oor-voorspel en moontlike redes hiervoor word bespreek. Die simulasie program is gebruik om ontwerpsriglyne te genereer vir die optimum pakkingsmateriaal uitleg. Met behulp van die program was dit ook moontlik om die effek van verlaagde oppervlakspanning (en gevolglik kleiner druppels) op die termiese vertoning van pakkingsmateriaal te ondersoek. Verskeie voorstelle vir verdere werk word gemaak.