Given temperature inlet for water is 25.28C, temperature outlet for water is 80C and mass flow rate of water is 1.122kg/s.
You have to convert to kg/s to C.
With heat exchangers you have two inlets and two outlets. In your case both fluids are water, so the given information are not specified for what fluid.
There is not sufficient information given. For any heat exchanger calculations you need the surface area of the exchanger, the over all heat transfer coefficient as well as the log mean temperature difference. With this information you can calculate the amount of heat transferred. Since you can calculate the amount of heat transferred you could calculate the log mean temperature difference and therefore the temperature of the steam but only if you have the other variables.
