[f_rojas]

Hello, I have a question regarding the modeling of an evaporation-condensation problem on a heat exchanger with countercurrent flow.

The setup is the following, as it's seen in Img1 and Img2, I have three rectangular channels, in the middle one enters a hot mixture of air and water vapor(80[C] or 353.15[K]), which I've modeledd using the Species model. And in the lower and upper ones have enters cold water(53[C] or 326.15[K]). The idea is for the air-vapor mixture to lower it's temperature so the vapor can condensate into liquid water, to allow this I've used the multiphase model with surface tension and allowed the mass transfer mechanicsm option with the 'evaporation condensation' option and set the saturation temperature to 353.15[K](100[C]).

Using the coupled scheme I'm able to get a solution that converges, looks reasonable, and matches the resuts found on the literature for heat transfer and condensed water. The only problem I have appears when I plot the temperature distribution, as it shows on the 'Result' image, the maximum temperature of the humid air is greater than 353.15[C], which I found very confusing as this problem doesn´t have any heat source.

Does anyone have any idea as to why the humid air flow increases its temperature? This is a very simple case with a proper mesh, so I would imagine it has something to do with the modelling of the problem rather than the mesh, but so far I've failed to see what's the problem.

If you could give me a hand I'd very much appreciate it.

[schnafkid]

Dude. You confused Celsius and Kelvin: 80°C = 353.15 K.