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  1. #1
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    Heat transfer coefficient for car



    Hi all,
    i'm trying to calculate the cooling load capacity for a parked car. In order to find heat load due to conduction transfer, I need the heat transfer co-efficients of various car body such as roof, doors, bottom and glass etc. Even after extensive search I was not able to find any info..In one of texts I found that they have taken conductance value(when moving) to be 80W/deg C and they multiplied it with temp difference and obtained heat load(80*28=2240W).
    What would be the value if vehicle is parked?
    If I know the individual heat transfer coefficients, I can calculate it seperately using the formula Q=U*A*(Tamb-Tint). My problem here is how to find the U value?

    Appereciate your time.



  2. #2
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    hookster is offline Veteran Poster I am starting to push the Mods: of RE
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    Re: Heat transfer coefficient for car

    I would assume that this is required for a question/problem in your studies?
    You are going to have to make your calculation for a steady state energy balance, there will be too many variables otherwise. Just think on the changes of solar gain over the period of the parked car!The mass of varying car makes and styles? Does it have a sun roof etc.

    You will need to work back from your conductance value of vehicle in motion and determine the R(total)
    then estimate the surface area of your other components ie glass, insulation and car body.
    Tabulate your total R components, don't forget your air film internal and external. Allow for air leakage losses.

    Now my old brain is starting to hurt but you get the gist of my mumbling!

    have fun
    I love the smell of Ammonia in the morning!

  3. #3
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    Re: Heat transfer coefficient for car

    Hi,
    You will need to work back from your conductance value of vehicle in motion and determine the R(total)
    then estimate the surface area of your other components ie glass, insulation and car body.
    This is exactly my problem!! How can I find the conductance values of various car parts? For glass its fine but what about body top, doors and floor? Any ideas how I can start?
    I have attached a snapshot from a pdf which gives heat transfer coefficient for parked and moving state. Can I use a constant value of 9.5W/m2 K for all parts?(as denoted in the pdf?)
    Capture.JPG

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