Results 1 to 7 of 7

Thread: Economiser

  1. #1
    Join Date
    Mar 2007
    Location
    UAE
    Age
    42
    Posts
    78
    Rep Power
    18

    Thumbs down Economiser



    Hi to all,

    Now a days the refrigeration compressor is designed with economiser.Can i know the fundamendal details of economiser. Especially the functions & applications.

    And also the fundamentals of Pump Vessel.

    Awaiting for your replies.

    Regards,

    TJK



  2. #2
    Join Date
    Apr 2007
    Location
    United States
    Posts
    51
    Rep Power
    17

    Re: Economiser

    An economizer is a pre-cooler used on screw compressors to chill the liquid refrigerant before the expansion device.

    The ones I've seen are a brazed plate type heat exchanger with it's own expansion valve.

    Comparing compressor capacities with and without an economizer is eye opening. I've a small Frascold screw that is rated at 175K Btu/h without an economizer, and 225K Btu/h with one, truly a huge increase in capacity that's basically free.

    I've got to admit, seeing a liquid line frost up on a brine chiller is pretty odd looking! Out of my condenser I get 77°C refrigerant, coming out the economizer the refrigerant is down to -2°C, a 79°K drop. Yes, the system looses a few K Btu/h to cool it's own refrigerant but the capacity gains are well worth both the initial cost to include an economizer and employ it.

    I've never run across a pump vessel, will be interested to read others input on those.

  3. #3
    Join Date
    Aug 2005
    Location
    USA
    Posts
    5,326
    Rep Power
    25

    Re: Economiser

    Quote Originally Posted by dkemper
    ...truly a huge increase in capacity that's basically free.
    Not quite, but close. You still have to pay for compressing the flash gas created in the economizer.

    On the other subject. I'm assuming he means a liquid overfeed system. A pressure vessel is used as a low-pressure receiver to store cold liquid refrigerant. The refrigerant pump pumps the cold liquid out to the various evaporators.

    This is also known as a liquid recirculation system by some.
    If all else fails, ask for help.


  4. #4
    Join Date
    Feb 2007
    Location
    UK
    Age
    55
    Posts
    53
    Rep Power
    18

    Re: Economiser

    Another means of employing a vessel as an economiser is known as a 'Flash Tank'.the system controls flow of liquid in/out of the vessel and the vapour above the liquid goes to the compressor at its indermediate port.This pressure is lower than that of condensing pressure and hence subcools the liquid in the vessel.

  5. #5
    Join Date
    Aug 2005
    Location
    USA
    Posts
    5,326
    Rep Power
    25

    Re: Economiser

    Quote Originally Posted by wkd
    This pressure is lower than that of condensing pressure and hence subcools the liquid in the vessel.
    The liquid is not really subcooled, it's just cold. By definition a subcooled liquid exists at a temperature lower than the saturation temperature of the existing pressure.

    I think it's important to distinguish between subcooling and cold liquid since this leads to a conflict of system analysis.
    If all else fails, ask for help.


  6. #6
    Join Date
    Mar 2007
    Location
    UAE
    Age
    42
    Posts
    78
    Rep Power
    18

    Smile Re: Economiser

    Morning to all,

    The suggetions are quite interesting.Can anybody give me the details for Pump Vessel.

    Thank you,

    Have a nice day.

    TJK

  7. #7
    Join Date
    Aug 2007
    Location
    Adelaide Australia
    Age
    70
    Posts
    567
    Rep Power
    24

    Re: Economiser

    Hi tjk2007
    Go to the first page of this site where all the different sections are listed go to Industrial and click on NH3 there are some good explainations of economisers in the thread titled economisers.

Similar Threads

  1. Economizers and screw compressors
    By US Iceman in forum NH3
    Replies: 56
    Last Post: 05-10-2011, 03:07 AM
  2. Problematic Economiser
    By Kevin Yeo in forum Supermarket Refrigeration
    Replies: 9
    Last Post: 22-07-2005, 04:06 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •