Is This Heat Transfer Calculation for a Box with Heated Liquid Correct?

[Robbyj]

Say we have a box made of two materials (a box with an internal lining) and a lid for the box made of a certain material. If I fill the box with a heated liquid and cover a certain percentage with the lid, is the following calculation correct for heat loss in the liquid if you ignore any film or scale effects or am I going about this the wrong way?

delta Q_total = ([A_box*delta T / (d₁/k₁+d₂/k₂)] + [A_lid*delta T / (d_lid/k_lid)] + [h_air* A_air * delta T]) * delta t

The eventual purpose is to calculate the percentage of the box that needs to be covered by the lid in order to allow the liquid to cool to a certain temperature range in a specific amount of time.

 

[Chestermiller]

No. The air resistance is in series with the resistance of the box wall and the lid, not parallel.