When I would like to find total convection heat flux with COMSOL for a channel that fluid is flowing in it, what boundaries or domains for evaluation must be select?
Must the fluid domain, exterior walls boundaries that they are in contact with the fluid, or all solid and fluid domains be selected?
Dear Kourosh Vaferi ,
The convection heat transfer coefficient is defined in the fluid and solid wall interface. You need to obtain the fluid bulk temperature and the wall temperature and then obtain this coefficient.
Dear Kourosh Vaferi ,
The convection heat transfer coefficient is defined in the fluid and solid wall interface. You need to obtain the fluid bulk temperature and the wall temperature and then obtain this coefficient.
Dr. Farhad Sadegh Moghanlou, I would like to find convection heat flux, then with using of q''w= hc (Tw-Tin) equation find heat transfer coefficient (h). For calculating Colburn factor, the heat transfer coefficient is needed.
Kourosh Vaferi
You can easily find it. If your goal is to find mean convective heat flux, do the following steps:
- select the surface average sub-domain of derived values in Comsol, select the all internal solid surfaces which are in contact with fluid and calculate the temperature. it gives you (Tw)
- Go to volume averaged values sub-domain of derived values, select the fluid domain and then calculate temperature. Tb
- using the q''w= hc (Tw-Tb) obtain convective heat transfer coefficient.
If your goal is to obtain local convective coefficient, follow theses steps:
- Define different planes along the channel length.
- in each plane obtain the averaged temperature( averaged surface). Tb
- in each plane, obtain the avreged solid wall temperature( averaged line), Tw
- using the q''w= hc (Tw-Tb) obtain convective heat transfer coefficient.
There is another way using Comsol operators, however i suggest you, at first, to try this method.
Dr. Farhad Sadegh Moghanlou thank for your help.
In my research, Tw=constant and it can be found by effectiveness equation, Tb=Tin, and I just need heat flux (q") for the heat transfer coefficient calculation. Can q= ṁcp(Tout-Tin) be used to calculate the heat transfer rate (q) and find the heat flux by dividing it on the area of surfaces which is in contact with the fluid?
- Badges
- Science topic