If you create a shared topology you won't get the nonconformal interface. That simplifies the heat transfer as you'll have a coupled wall between the hot fluid & pipe and pipe & cold fluid assuming the pipe is a solid. If the pipe isn't a solid (modelled as a volume) you'll just see a coupled wall between the two fluids and will need to give it a thickness. Have a look in the tutorials, focus on conjugate heat transfer, and also look at some of the electronics cooling examples as the heat sink is a similar set up.

Mr. Rob, I have created two fluids one is air and other is Licl solution. Both of them are stacked to each other having same dimensions. I want to insert a membrane (PVDF Solid) between two. For this I made a geometry in Design moudular,then in meshing option I deleted the Automatic contact zones and name manually (like Airinterface , Licl interface, inlte and outlet etc). In set up option, I used the mesh interface option, by using air_interface and licl_interface zone i make a coupled wall and named it a membrane and has given a thickness. Now in post processing option, I want to see the heat transfer on membrane, the message is, Zone surface cannot create from sliding interface zone. Creating empty surface.nI want to observe the effect on wall ( which is termed as membrane).nPlease let me know that I have been something wrong? What i have to do for observing the effect on membrane.nThanks in advance.nRegards,n