The fundamentals of two-phase flow in wet domestic central heating systems
type: CreativeWork
description: An emerging trend in the building services industry is the installation of passive deaerators on the flow line of domestic wet central heating systems. To date, no data and theoretical models predicting the two-phase flow characteristics in domestic wet central heating systems are available in the open literature. This gap in literature has prevented essential design improvements to passive deaerators thus impeding the efficiency enhancement of such devices. Hence, the current study is aimed at assisting designers of deaeration devices by providing fundamental data and model correlations with respect to the two-phase flow characteristics typical in a wet domestic central heating system. For this purpose an experimental research project was adopted and several studies were carried out, including; (1) a comprehensive review to understand the background of the phenomena, (2) the design and construction of an experimental test rig to conduct the necessary investigations into the phenomenon of two-phase flow in domestic wet central heating systems, (3) the development of a reliable image capture and analysis technique, (4) the completion of a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. This research has, for the first time, provided an in depth analysis into two-phase flow characteristics in wet domestic central heating systems through the use of a high speed camera and image analysis techniques. The two-phase phenomenon finds its origins in high dissolved gas concentrations present in the water flowing through the closed loop system, thus resulting in super saturation conditions at the primary heat exchange wall conditions. Bubble sizes at the boiler flow line were found to be dependent on the bulk fluid velocity, heat flux and…
abstract: An emerging trend in the building services industry is the installation of passive deaerators on the flow line of domestic wet central heating systems. To date, no data and theoretical models predicting the two-phase flow characteristics in domestic wet central heating systems are available in the open literature. This gap in literature has prevented essential design improvements to passive deaerators thus impeding the efficiency enhancement of such devices. Hence, the current study is aimed at assisting designers of deaeration devices by providing fundamental data and model correlations with respect to the two-phase flow characteristics typical in a wet domestic central heating system. For this purpose an experimental research project was adopted and several studies were carried out, including; (1) a comprehensive review to understand the background of the phenomena, (2) the design and construction of an experimental test rig to conduct the necessary investigations into the phenomenon of two-phase flow in domestic wet central heating systems, (3) the development of a reliable image capture and analysis technique, (4) the completion of a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. This research has, for the first time, provided an in depth analysis into two-phase flow characteristics in wet domestic central heating systems through the use of a high speed camera and image analysis techniques. The two-phase phenomenon finds its origins in high dissolved gas concentrations present in the water flowing through the closed loop system, thus resulting in super saturation conditions at the primary heat exchange wall conditions. Bubble sizes at the boiler flow line were found to be dependent on the bulk fluid velocity, heat flux and…
author: Fsadni, A.M.
language: en
keywords: H200 - Civil engineering, H220 - Environmental engineering, H300 - Mechanical engineering
date published: 2012-04
date modified: 2026-07-24T01:35:46Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Brunel University