Simple But Powerful Centrifugal ChillersWritten by Thomas Yoon
Centrifugal chillers are used for cooling large buildings in a centralized air conditioning system. There are other types of chillers using screw compressors and reciprocating compressors. These are usually smaller in size. Today's topic is about centrifugal chillers - ultimate choice for any air conditioning installations higher than 500 RT (refrigeration tons)
Basically, centrifugal chillers use centrifugal fans to move refrigerant within chiller circuit. As with any refrigeration circuit, there must be a compressor, a condenser, an expansion device, and evaporator.
In case of centrifugal chiller, fan is compressor. Rotating at very high speeds, it is capable of pressurizing refrigerant gas so as to increase its temperature. Because pressure is so dependent on efficiency of impeller of compressor, impeller is very carefully designed to match system.
The clearances between impeller and housing at mouth ring (impeller suction) are made very small so as to reduce leaks back to discharge.
Usually inlet vanes that throttle gas control flow of gas, and thus chiller load. The expansion of liquid to gas is usually made through a fixed orifice.
Google Alerts Gets GoingWritten by John Calder
© 2004, John Calder http://www.TheEzine.net
Do a search on Google today, and you may see an offer to "...Get latest web results on (your search) emailed to you with Google Web Alerts." Marketers should be quick to realize this can be a useful way to monitor your own business, your competitors, your markets, and search results for your keywords.
You can set up a Google alert to monitor top 10 Google News stories, top 20 Google web search results, or both. Enter a search term, tell Google type of alert you want, how often you want Google to check for alerts, & your email address. After you confirm your alert by email, you're all set.
Just think - you can use a Google web search alert to monitor search results for your highest-ranking pages, your best-paying keywords, and new markets you're thinking about entering. By signing up for alerts of volatile keywords, you can get a good idea of when a Google dance is occurring. And of course, you can monitor ranking of your own and competitors' business pages as well.