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## Homework Statement

Hello. First of all sorry about this question, it has to do a little with heat transfer from engineering. This situation is not real, I was working in a proyect and this doubt came to me.

I have a heat exchanger of parallel tubes. Water flows in a tube and oil flows in another one. The initial conditions are shown in the picture. I will write them here:

Water

To= 18°C

Tf= 26°C

m=0.25 kg/s

cp= 4.18 kJ/kg°C

Oil

To: 0°C

m= 0.1 kg/s

Cp= 1.79 kJ/kg°C

## Homework Equations

Q= m.cp (Tf-to)

## The Attempt at a Solution

I found the heat transfer from the water to the oil

Qw= (0.25)(4.18)(26-18)=8.36

This is the same heat that comes in to the oil.

So

8.36=(0.1)(1.79)(Tf-0)

Tf= 46.7°C

This result does not make sense to me, because I find impossible that the oil has increased its temperature more than water. I thought that the maximum possible temperature than the oil can reach is the same 26°C of water ( Assuming an infinite length in the heat exchanger)

In the picture I put a axis with the temperatures.

Could anyone explain me why, according with the calculations, I got Tf= 46.7°C for the oil?