A critical evaluation and refinement of the performance prediction of wet-cooling towers
Date
2003-12
Authors
Kloppers, Johannes Christiaan
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
The thermal performance prediction of wet-cooling towers is critically analyzed and refined. Natural draft
counterflow towers and mechanical draft counterflow and crossflow towers are considered. The Merkel,
Poppe and e-NTU heat and mass transfer methods of analysis are derived from first principles, as these
methods form the cornerstone of wet-cooling tower performance evaluation. The critical differences
between these methods, when applied to fill performance analyses and cooling tower performance
evaluations, are highlighted. The reasons for these differences are discussed with the aid of psychrometric
charts. A new extended empirical relation for the loss coefficient of fills is proposed where the viscous
and form drag effects are accounted for as well as the buoyancy, momentum and fill height effects. The
empirical equation for the transfer characteristic of fills is extended to include the effects of fill height and
the inlet water temperature. Empirical equations to predict the temperature inversion profile, height of the
temperature inversion and the height from which air is drawn into the cooling tower are developed. The
influence of temperature and humidity inversions on the performance of wet-cooling towers is
subsequently investigated. A comprehensive analytical computer program is developed to predict and
optimize the performance of wet-cooling towers. Computer programs are also developed to generate
cooling tower performance curves, analyze fill performance test data and plot psychrometric charts.
Description
Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2003.
Keywords
Wet-cooling tower, Merkel, Poppe, e-NTU, Natural draft, Mechanical draft, Fill, Temperature inversion, Cooling towers, Dissertations -- Mechanical engineering, Theses -- Mechanical engineering