THE PERIODIC FLOW COOLING TOWER: A DESIGN ANALYSIS.
Abstract
The rate equations describing heat transfer, mass transfer, and energy transfer by combined heat and mass transfer are developed for the special case of unity Lewis Number. These equations are then combined with energy and mass conservation equations in developing an analysis of the performance of indirect transfer, periodic-flow, counter-flow energy exchangers suitable for use as water cooling units. Compared to the steady-flow, direct transfer exchanger, the periodic flow units have higher effectiveness per unit volume of exchanger core but require larger frontal areas and shorter flow lengths for the same inlet states, flow rates, and installed fan-horsepower. Cooling effectiveness of 0.870 for 0.25 fan-horsepower is predicted for a periodic-flow exchanger with 6.25 cu ft core volume, handling 3600 lbm/hr (7.2 gpm) of water at 85 F on a 60 F (wet bulb) day. A steady-flow, direct transfer unit of conventional design described in the literature displayed a cooling effectiveness of 0.71 for the same fan-horsepower water flow rate and inlet conditions, while requiring a core volume of 43.7 cu ft.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1966
- Accession Number
- AD0489822
Entities
People
- Robert John Moffat
Organizations
- Stanford University