Page 3 of 3 FirstFirst 123
Results 27 to 32 of 32
  1. #27
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    400
    Quote Originally Posted by IRBH View Post
    Barbar... I saw that 10C!
    N of 49?
    Sorry, Barbar... I was just wondering if you were Canadian, with the celsius.

  2. #28
    Join Date
    Jan 2010
    Posts
    6,228
    Quote Originally Posted by IRBH View Post
    "WASH HIS BEARINGS OUT!!

    Where to start? First of all, refrigerant migrated into the crankcase of his semi-hermetic has NOTHING to do with washed out bearings!! It's past the bearings, next stop blown valves/head gaskets!

    For goodness sakes read the OP's above post!
    Are you a hvac tech, or still in schooling (excellent for you).
    http://www.danfoss.com/North_America...AF9EAFE0D.html
    The more you speak the more you show your ignorance. Keep talking the world is watching.
    Looks like you've got the crankcase heater part down now further your education and geography. New Zealand is in the southern hemisphere.
    Last edited by VTP99; 08-18-2013 at 10:32 PM.

  3. #29
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,395
    Quote Originally Posted by IRBH View Post
    "WASH HIS BEARINGS OUT!!

    Where to start? First of all, refrigerant migrated into the crankcase of his semi-hermetic has NOTHING to do with washed out bearings!! It's past the bearings, next stop blown valves/head gaskets!
    Refrigerant in the crankcase has EVERYTHING to do with washed out bearings. Not sure what you mean that its past the bearings. The bearings are in the crankcase.

  4. #30
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,103
    If you plot a system with a SLHX on a PE diagram, and compare it against the same system without the HX, the increase in NRE is less than the extra superheat gained after the evap. Adding this to the pressure drop across the HX, a large penalty can be seen against the ideal operation of the system.

    As was mentioned before, there's no such thing as a free lunch, a classic application of the 2nd law.

  5. #31
    Join Date
    Dec 2011
    Location
    New Zealand
    Posts
    2,181
    Quote Originally Posted by syndicated View Post
    If you plot a system with a SLHX on a PE diagram, and compare it against the same system without the HX, the increase in NRE is less than the extra superheat gained after the evap. Adding this to the pressure drop across the HX, a large penalty can be seen against the ideal operation of the system.

    As was mentioned before, there's no such thing as a free lunch, a classic application of the 2nd law.
    it is somewhat more complicated than that.

    I will give an example (not real figures)

    lets luck at the suction, 6 sh at the evap 21 at the comp, so we could we have 15 of non useful superheat, lets say 100btu for this 15

    so we add SLHE, at the evap but after the bulb as in the OP question, we now add the 15 extra superheat by the heat exchange process "useful", because the suction line is warmer it will not absorb the 15 non useful but only a smaller fraction say 5 "33BTU", so at this stage we get a net benifit of 66BTU, but the increased superheat reduces the mass flow through the comp, therefore HOR reduces slightly, dropping the head pressure, reducing power draw.
    So when plotting on a PH diagram you need to consider that the evap and cond are fixed surface areas, thus allowance has to be made for this on your plotting data.
    Remember that that refrigeration is a "circular" so any change in part of the system, effects all other parts.
    The vapour fraction after the TXV is not a free lunch, it is a lunch paid for and not eaten.

  6. #32
    Join Date
    May 2003
    Location
    Utah
    Posts
    719
    Quote Originally Posted by IRBH View Post
    I'm still mulling this over.
    Your facts are correct - higher suction temp, less dense vapor.
    But the enthalpy of the return gas would be higher and that would mean more btu are being pumped .
    Not good for discharge temp though.
    Well, plotting the system on a ph diagram and doing all of the system calculations will show it.

Page 3 of 3 FirstFirst 123

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event