Selection of the heat dissipation coefficient

Buildings are generally flat, while pipes are round; there seems to be some discrepancy here. This may also involve the issues of natural convection and forced convection. No wind indoors seems to be natural convection, while wind outdoors is forced convection. Also, what value should be used for the atmospheric temperature? It’s really quite troublesome. Waiting for a professional to answer.

This heat transfer model should be similar to that of heat transfer in optical tubes; you can refer to the calculations for cylindrical walls in Section 2-3 of Chapter 2 on heat transfer. Since this is a single tube, the calculation should be straightforward. It is also necessary to determine the thermal conductivity of the tube, which depends on its material. Whether the tube is sealed or not is important as well; if it is sealed, the properties of the fluid inside the tube are relevant, while if it isn’t sealed, it’s simply a case of heat dissipation. If the flow velocity of the surrounding gas is low, it’s natural convection heat transfer, whereas a higher flow velocity results in forced convection heat transfer—both of which are covered in the theory of heat transfer. For the calculation formulas, refer to the table provided for selecting appropriate thermal conductivity values, and finally draw a conclusion