CUED Publications database

Ventilation effectiveness measures based on heat removal: Part 1. Definitions

Coffey, CJ and Hunt, GR (2007) Ventilation effectiveness measures based on heat removal: Part 1. Definitions. Building and Environment, 42. pp. 2241-2248. ISSN 0360-1323

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Abstract

The effectiveness of ventilation flows is considered from the perspective of buoyancy (or heat) removal from a space. This perspective is distinct from the standard in which the effectiveness is based on the concentrations of a neutrally buoyant contaminant/passive tracer. Three new measures of effectiveness are proposed based on the ability of a flow to flush buoyancy from a ventilated space. These measures provide estimates of instantaneous and time-averaged effectiveness for the entire space, and local effectiveness at any height of interest. From a generalisation of the latter, a vertical profile of effectiveness is defined. These measures enable quantitative comparisons to be made between different flows and they are applicable when there is a difference in density (as is typical due to temperature differences) between the interior environment and the replacement air. Applications, therefore, include natural ventilation, hybrid ventilation and a range of forced ventilation flows. Finally, we demonstrate how the ventilation effectiveness of a room may be assessed from simple traces of temperature versus time. © 2006 Elsevier Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: Buoyancy removal Effectiveness profile Forced Hybrid Natural Transient flows Ventilation effectiveness
Subjects: UNSPECIFIED
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:29
Last Modified: 08 Dec 2014 02:27
DOI: 10.1016/j.buildenv.2006.03.016