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  1. #1
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    Air cool condenser in humid climate



    Dear Friends,

    As you know air-cool condenser works better in humid climate.

    1 - It is as result of vaporizing water drops on surface of fin ?

    Or

    2 - It is as result of higher mass flow of air (in humid climate instead dry climate) that pass form fins ?

    Which answer is correct ?

    Sincerely yours.



  2. #2
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    Re: Air cool condenser in humid climate

    Non, humidity does not affect condensers.

  3. #3
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    Re: Air cool condenser in humid climate

    Quote Originally Posted by chemi-cool View Post
    Non, humidity does not affect condensers.
    Dear Chemi-Cool,

    Be sure and I promise you humidity effects on working of air-cool condensers.

    Sincerely yours.

  4. #4
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    Re: Air cool condenser in humid climate

    Hi Mortezania
    Can you explain how an increase in humidity will improve the performance of an air cooled condenser and what percentage performance increase would be achieved.
    Regards
    Paul
    Born to fish, forced to work

  5. #5
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    Re: Air cool condenser in humid climate

    Quote Originally Posted by A.Mortezania View Post
    Dear Friends,

    As you know air-cool condenser works better in humid climate.

    1 - It is as result of vaporizing water drops on surface of fin ?

    Or

    2 - It is as result of higher mass flow of air (in humid climate instead dry climate) that pass form fins ?

    Which answer is correct ?

    Sincerely yours.
    It is presumed that the air pressure and dry bulb temperature is a constant and the only change is RH (moisture content)

    1,no,the H2O is already in vapour form

    2 Incorrect, density decrease with increase in RH (lower mass flow), however specific heat capacity raises slightly, so calculation is neutral. (well within the normal range of accuracy and fouling factor)

  6. #6
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    Re: Air cool condenser in humid climate

    Quote Originally Posted by mad fridgie View Post
    It is presumed that the air pressure and dry bulb temperature is a constant and the only change is RH (moisture content)

    1,no,the H2O is already in vapour form

    2 Incorrect, density decrease with increase in RH (lower mass flow), however specific heat capacity raises slightly, so calculation is neutral. (well within the normal range of accuracy and fouling factor)
    Dear Fridgie,
    Thanks for your reply.

    I searched internet, Yes , You are right. By increasing RH , Density of air decrease !!! and in this case I made big mistake.

    Please do me a favor and help to understand this matter better :
    We have 2 cities :

    City 1 : Avg. temp = 35 C , Altitude = 1200 m , humidity = 30%
    City 2 : Avg. temp = 35 C , Altitude = 50 m , Humidity = 85%

    We have 2 cities in our countries above, Temperature is almost same, But I saw it by my eyes that condenser in city with 85% humidity works much more better instead city with humidity 30% and discharge pressure is lower at same system.

    Yes, It is true that by increasing humidity, Density decreases, By this fact, What really change between these 2 cities ???
    Altitude changes ? Dry bulb changes ? Wet bulb changes ? Specific of air changes ? What really changes that help condenser to works better in city with higher humidity ?

    Thanks for your help in advance.

    Sincerely yours.

  7. #7
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    Re: Air cool condenser in humid climate

    Quote Originally Posted by A.Mortezania View Post
    Dear Fridgie,
    Thanks for your reply.

    I searched internet, Yes , You are right. By increasing RH , Density of air decrease !!! and in this case I made big mistake.

    Please do me a favor and help to understand this matter better :
    We have 2 cities :

    City 1 : Avg. temp = 35 C , Altitude = 1200 m , humidity = 30%
    City 2 : Avg. temp = 35 C , Altitude = 50 m , Humidity = 85%

    We have 2 cities in our countries above, Temperature is almost same, But I saw it by my eyes that condenser in city with 85% humidity works much more better instead city with humidity 30% and discharge pressure is lower at same system.

    Yes, It is true that by increasing humidity, Density decreases, By this fact, What really change between these 2 cities ???
    Altitude changes ? Dry bulb changes ? Wet bulb changes ? Specific of air changes ? What really changes that help condenser to works better in city with higher humidity ?

    Thanks for your help in advance.

    Sincerely yours.
    Altitude!
    Air heat exchangers are de-rated for altitude. Reduced Mass Flow!

  8. #8
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    Re: Air cool condenser in humid climate

    Quote Originally Posted by mad fridgie View Post
    Altitude!
    Air heat exchangers are de-rated for altitude. Reduced Mass Flow!
    ِ
    Dear Fridgie,
    Thanks for your reply.

    Ok, Altitude is good subject that influences air density.

    Regarding increasing humidity and decreasing density, As I told you before, Yes, You are right but density changing around air temp : 20C ~ 40C is not high ! (See my diagram below)

    1 - I saw that by increasing humidity enthalpy of air change. It will not help us ?

    2 - What about C parameter in Q = M.C.(T2 – T1) , My mean specific heat ?
    If we increase humidity on air, Twice specific heat would be constant ???
    Do you have any chart or document to prove this ? I didn't find anything on internet.


    Density_Humidity.jpg



    Sincerely yours.
    Last edited by A.Mortezania; 09-02-2017 at 08:26 AM.

  9. #9
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    Re: Air cool condenser in humid climate

    Change in specific heat is also minimal (not twice) at working temperatures, balances with reduction in density, so calculation in neutral, in practice. Fin coil has a design tolerance, so these small changes are within the standard production performance tolerances. Do not worry about it. Move on.

  10. #10
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    Re: Air cool condenser in humid climate

    Hi
    You better check your indoor (evaporating unit) performance and relate it to the condenser performance,
    the way you are trying to relate things will not lead to any useful answer.

    Same units, same indoor conditions, same load , different outdoor humidity,than you can have a peer to peer comparison.

    Indoor load will directly affect the condenser performance.

    regards
    Engineering, sciences, math, physics and my brain will generate "not responding " soon

  11. #11
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    Re: Air cool condenser in humid climate

    I am not quite sure about it.
    Last edited by douglas8; 17-09-2017 at 01:54 PM.

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