This experim ental project aims to describe the influencing factors in the vacuum
boiling o f w ater in w ater vapour refrigeration system s Testing was conducted using a
2 kW three-stage steam je t ejector system, w ith barom etric condensers, as the
com pression device. Three direct-contact evaporators were used to investigate the
boiling phenom ena. T hese were : a through-flow evaporator w here heal and mass
transfer rates were established for boiling m echanism s at various positions within the
evaporator; a vertical cylinder where small quantities o f w ater were subjected to rapid
decom pression and the effects m easured, and a sim ple channel for photographic
studies o f the process.
Boiling in direct-contact water vapour systems is described herein The vacuum
boiling proo ss was found to be controlled by a com bination o f the w ater surface
tem perature and the hydrostatic pressure gradient, these being governed by the w ater
vapour flow geometry between the w ater surface and ejector suction and convective
heat transfer below the boiling region. The contributions o f the various boiling
regim es to the total heat transfer are discussed. Heat and mass transfer coefficients
and their applicability to evaporator design are presented
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/14725 |
| Date | 30 May 2014 |
| Creators | Mitchley, Stephen Ronald |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
Page generated in 0.0024 seconds