Seal trap performance in high-rise drainage systems

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Seal trap performance in high-rise drainage systems

 

Author: Fu, Chen
Title: Seal trap performance in high-rise drainage systems
Degree: M.Eng.
Year: 2010
Subject: Hong Kong Polytechnic University -- Dissertations
Plumbing
Evaporation (Meteorology)
Department: Dept. of Building Services Engineering
Pages: xiv, 83 leaves : ill. ; 31 cm.
InnoPac Record: http://library.polyu.edu.hk/record=b2356328
URI: http://theses.lib.polyu.edu.hk/handle/200/5811
Abstract: It is well known, evaporation is the process by which water is converted from its liquid form to its vapor form and thus transferred from land and water masses to the atmosphere. Evaporation from the oceans accounts for 80% of the water delivered as precipitation, with the balance occurring on land, inland waters and plant surfaces. The rate of evaporation depends upon: 1. Wind speed: the higher the wind speed, the more evaporation 2. Temperature: the higher the temperature, the more evaporation 3. Humidity; the lower the humidity, the more evaporation. Shows that the evaporation of water is a complex process. Many factors will affect the evaporation of water. Many previous researches showed the evaporation, rate of water from free surface to the ambient air. The differences of evaporations rates between free surface and wetted surface also were found. Many applications require calculation of water losses from water bodies to the ambient air. Examples are swimming ponds, lakes, dames, solar stills, management of liquid wastes, and passive evaporate cooing of buildings. There were numerous experimental and theoretical expressions aimed at predicting water evaporation rates from a free water surface to still air, or to ambient air. Some expressions included not only the effects of airflow above the water temperature and the differences between surface water temperature and the ambient air temperature and relative humidity. These expressions were based on measurements made on indoor or outdoor water bodies in the specific experimental sites under narrow range of climatic conditions, or derived based on the analogy between mass and heat transfer.
The environment of drainage system was simulated in my experiment. Mass loss of water body in the water seal trap was measured. But the evaporation of water is a slow process. After the experiment, many data were collected, such as temperatures of different parts, humidity and mass loss. After calculation, the results of experiment and our prior assumptions are consistent. Relationship between evaporation rate and vapor pressure was found in seal trap. When the vapor pressure increases with temperature, the evaporation rate will be increased. The evaporation rate of water bodies from seal trap is slower than the evaporation rate from free surface. Two cases were studied in my experiment. One was control case with sealing of glass glue. The other one was normal case. Evaporation rate of control case is faster than the evaporation rate normal case. It is well known tempemtute is able to affect evaporation rate of water bodies. But the extent of this impact is different at free surface or at seal trap. The affect of temperature is bigger to evaporation rate from a free surface. Based on the above data and the experimental results, it can easily calculate the duration of liquid seal failure. These can be well applied in the construction industry.

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