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  1. chillin

    Ammonia Mass Flow Meter?

    Most compressor manufacturers have computer simulation programs, or at the very least capacity tables with correction factors, for their products. The data provided by the programs/tables is backed up by the factory's own R&D lab tests. If you doubt the accuracy of the data, you can always...
  2. chillin

    Ammonia Mass Flow Meter?

    I've not seen anyone in the ammonia industry attempt to measure flow. Most energy analysis is done by monitoring compressor performance (i.e. temp in/out, press in/out and motor current). The most effective and simplest way to cut energy costs is to float head pressure based on wet-bulb...
  3. chillin

    Is this possible in AutoCAD? Pls, help!

    ASCII (American Standard Code for Information Interchange) is built into all PC's. The only way a recipient would not get "see" the symbols is if they didn't have the base font to begin with. Visit http://www.asciitable.com/ for some more info...the samples I listed are...
  4. chillin

    Is this possible in AutoCAD? Pls, help!

    A much speedier solution is to use ASCII characters. They won't work with all fonts, but they work with most (esp. standard fonts). Depending on your OS, you can verify the Alt-key sequence using Start|Programs|Accessories|System Tools|Character Map. Press and hold the "Alt key" and...
  5. chillin

    Selection of Controls for Hot gas defrosting

    By controls, I'm guessing you mean control valves, not necessarily control sequence or logic. To properly defrost a freezer evaporator you will need sufficient hot gas, as veekrish has stated. Providing you don't try to defrost more than 1/3 of your total system capacity, you should have...
  6. chillin

    single stage vs 2 stage ammonia systems

    Stoecker (Industrial Refrigeration, ISBN 0-912524-42-1) suggests that two stage compression should seriously considered for evaporator temperatures below about -20°C (-4°F). In practice, the decision to utilize 2-stage compression has alot to do with the load at both suction temperatures. If...
  7. chillin

    Pipe sizing exercise

    I would recommend a discharge line pressure drop of 2-5 psi/100ft at normal condensing temperature, as it should not greatly effect the operating efficiency of your system. For the liquid line between the condenser and receiver (or high-side float), I would use a velocity of 75 fpm for small...

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