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| == '''[[Industrial cooling tower]]''' ==
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| {{Image|TVA Cooling Towers.jpg|right|200px|Figure 1: Power plant counterflow cooling tower (note water vapor plumes)}} | | ==Footnotes== |
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| {{Image|Crossflow Cooling Tower.jpg|right|200px|Figure 2: Process plant crossflow cooling tower (offstream for maintenance, no water vapor plume)}} | |
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| '''Industrial cooling towers''' are heat rejection systems used primarily to provide circulating cooling water in large industrial facilities. The circulating cooling water absorbs heat by cooling and/or condensing the hot process streams or by cooling hot rotating machinery and other hot equipment within the industrial facilities. The cooling towers then reject that absorbed heat by transferring it to the [[atmosphere]].
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| === How a cooling tower works ===
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| Basically, a cooling tower intimately contacts a flow of warm water with a flow of ambient air which is not saturated with water vapor (i.e, air which contains less water vapor than it is capable of containing). That causes part of the warm water to evaporate and the air absorbs that evaporated water. The heat required to evaporate part of the water is derived from the water itself and thus causes the water to cool. This process is known as [[evaporative cooling]].<ref>{{cite book|author=Larry Drbal, Kayla Westra and Pat Boston|title=Power Plant Engineering|edition=1st Edition |publisher=Springer|year=1996|id=ISBN 0-412-06401-4}}</ref><ref>{{cite book|author=Robert H. Perry (deceased), Don W. Green and James O. Maloney (Editors)|title=[[Perry's Chemical Engineers' Handbook]]|edition=6th Edition|publisher=McGraw-Hill|year=1984 |id=ISBN 0-07-049479-7}}</ref> The net result is that the air leaving the tower is saturated with water vapor and the unevaporated water leaving the cooling tower has been cooled.
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| An evaporative cooling tower is referred to as a ''wet cooling tower'' or simply a ''cooling tower''. Such towers can cool water to a temperature that approaches the [[wet-bulb temperature]] of the ambient air. The average ambient air wet-bulb temperature chosen as the design basis essentially determines the size of the cooling tower, and the size of a cooling tower is inversely proportional to the design wet-bulb temperature.
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| ''[[Industrial cooling tower|.... (read more)]]''
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| ! style="text-align: center;" | [[Industrial cooling tower#References|notes]]
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| {{reflist|2}} | | {{reflist|2}} |
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Latest revision as of 09:19, 11 September 2020
The Mathare Valley slum near Nairobi, Kenya, in 2009.
Poverty is deprivation based on lack of material resources. The concept is value-based and political. Hence its definition, causes and remedies (and the possibility of remedies) are highly contentious.[1] The word poverty may also be used figuratively to indicate a lack, instead of material goods or money, of any kind of quality, as in a poverty of imagination.
Definitions
Primary and secondary poverty
The use of the terms primary and secondary poverty dates back to Seebohm Rowntree, who conducted the second British survey to calculate the extent of poverty. This was carried out in York and was published in 1899. He defined primary poverty as having insufficient income to “obtain the minimum necessaries for the maintenance of merely physical efficiency”. In secondary poverty, the income “would be sufficient for the maintenance of merely physical efficiency were it not that some portion of it is absorbed by some other expenditure.” Even with these rigorous criteria he found that 9.9% of the population was in primary poverty and a further 17.9% in secondary.[2]
Absolute and comparative poverty
More recent definitions tend to use the terms absolute and comparative poverty. Absolute is in line with Rowntree's primary poverty, but comparative poverty is usually expressed in terms of ability to play a part in the society in which a person lives. Comparative poverty will thus vary from one country to another.[3] The difficulty of definition is illustrated by the fact that a recession can actually reduce "poverty".
Causes of poverty
The causes of poverty most often considered are:
- Character defects
- An established “culture of poverty”, with low expectations handed down from one generation to another
- Unemployment
- Irregular employment, and/or low pay
- Position in the life cycle (see below) and household size
- Disability
- Structural inequality, both within countries and between countries. (R H Tawney: “What thoughtful rich people call the problem of poverty, thoughtful poor people call with equal justice a problem of riches”)[4]
As noted above, most of these, or the extent to which they can be, or should be changed, are matters of heated controversy.
- ↑ Alcock, P. Understanding poverty. Macmillan. 1997. ch 1.
- ↑ Harris, B. The origins of the British welfare state. Palgrave Macmillan. 2004. Also, Oxford Dictionary of National Biography.
- ↑ Alcock, Pt II
- ↑ Alcock, Preface to 1st edition and pt III.
