Effects of Vertical Temperature Gradient on Heavy Gas Dispersion in Build up Area

Abstract

ewline"> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Dispersion of heavy gases is considered to be more hazardous than the passive ones</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>because it takes place more slowly. When the gas is accidentally released at ground</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>level or where there are many obstacles in the area it is considered to be a heavy gas.</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In this paper, based on the extensive experimental work of McQuid and Hanna, the</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>model was tested against two types of experiments: A simple experiment “Thorney</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Island" and a complex experiment “Kit Fox" in order to validate CFD code. In order</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>to accomplish this validation the multiphase approach was employed. Also, the vertical</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>temperature gradient in the atmosphere was investigated. The investigation of wind</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>speed was done taking factors such as time, height and direction into consideration. In</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>order to reduce the number of elements in the computational domain, a combination of</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>2D and 3D geometry was utilized. The results showed that the wind inlet correction, as</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>well as the temperature gradient, had a significant influence on gas concentration</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>records.</em></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>