The 'lumped-capacitance' model of transient heat transfer

kkanadekkanade Forum Coordinator
Hello, how do I know if I can use the 'lumped-capacitance' model of transient heat transfer for a particular problem?


  • Hello @kkanade , you can use Biot number to quickly check if the lumped-capacitance assumption is valid or not for a particular problem. Biot Number is the ratio of conduction resistance to convective resistance. It is mathematically defined as:

    Bi = h*L / k


    h = heat transfer coefficient [W/(m^2-K)]

    L = conduction length scale [m],

    k = thermal conductivity [W/(m-K)]

    For Smaller values of Biot number the heat conduction inside the body is faster than the heat convection at its outer surfaces, and therefore the temperature gradients inside the body can be neglected. Bi in the range of <0.1 typically leads to an error of <5% if lumped-capacitance model is used.

  • kkanadekkanade Forum Coordinator
    Hi @Kremella
    thank you for the response. I really appreciate it. 
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