This kind of thing should be solvable by Flow Sim, but you need a detailed layout of the piping and the wetted surface inside the electronics unit in order to get a proper CFD model and get reasonably heat transfer rates. This kind of sounds like a school assignment, with the extremely specific temperature and time frame.
Thank you for your input.
Yes We do have FlowSimulation. Its just a block diagram I have shared.
We want to know what is the best steps to follow. Can I split the problem?
What is wetted surface?
For complete tank how can I define 3deg temp water inside it.?
You could define the walls of the tank to have a set temperature, but that might not work if your flow rate is too high. You could cut the tank out of the simulation and specify the water at your boundary condition as having the required temperature when it enters your simulation domain.
"Wetted surface" just means the surface in contact with the fluid.