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Thread: need help with heat transfer problem. urgent

  1. #1
    Associate Engineer
    Join Date
    Feb 2013
    Posts
    5

    need help with heat transfer problem. urgent

    I am not really a heat transfer guy so I hope someone here can help me out here. I would like to know the formula to get this.

    Here is what I have:

    I have a mandrel (basically a piece of cylindrical H-11 steel). It has OD of 3.5 inches and 37 in length. It has a core hole of about 7/8 Dia and 37 length. Water pumped into the core hole at 10 GPM thru a 3/4 dia pipe. The H-11 steel has .110 BTU/lb specific heat capacity. Water enter at 70 deg and not sure the exist temperature.
    I want to be able to lower the temp of the mandrel from 850 to 200 deg F. How much water do I need?

    Please help.

  2. #2
    Associate Engineer
    Join Date
    Feb 2013
    Posts
    5
    Quote Originally Posted by whlock View Post
    I am not really a heat transfer guy so I hope someone here can help me out here. I would like to know the formula to get this.

    Here is what I have:

    I have a mandrel (basically a piece of cylindrical H-11 steel). It has OD of 3.5 inches and 37 in length. It has a core hole of about 7/8 Dia and 37 length. Water pumped into the core hole at 10 GPM thru a 3/4 dia pipe. The H-11 steel has .110 BTU/lb specific heat capacity. Water enter at 70 deg and not sure the exist temperature.
    I want to be able to lower the temp of the mandrel from 850 to 200 deg F. How much water do I need?

    Please help.
    Additional info. It is a closed system where water circulate back into a tank. I need to know how much water I need in the tank.

    My take on the problem is like this.
    Q = m* Cp * T
    Mandrel about 94 lbs
    Q = 94 x 0.11 x 650 = 6721 BTU

    Water has 1 BTU/lb capcity.

    so 6721 BTU will give me 806 gallon of water since 1 lb = 8.33 gallon. Is that correct?

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