A double pipe counter flow heat exchanger is to be designed to cool $$12000$$ $$kg/hr$$ of an oil of specific heat $$1.95$$ $$kJ/kgK$$ from $$\,85{}^ \circ C$$ to $$\,55{}^ \circ C$$ by water entering the heat exchanger at $$\,30{}^ \circ C$$ and leaving at $$\,45{}^ \circ C$$. If the $$OHTC$$ of heat exchanger is $$400$$ $$\,W/{m^2}K.\,$$ Calculate the $$LMTD$$ and the surface area of the heat exchanger

A shell and tube heat exchanger is to be designed for heating pressurized water by means of hot gasses which get cooled the data are as follows
Temp of water at the inlet $$ = \,80{}^ \circ C$$
Temp of the water at the outlet $$ = \,140{}^ \circ C$$
Temp of hot gasses at the inlet $$ = \,340{}^ \circ C$$
Temp of hot gasses at the outlet $$ = \,180{}^ \circ C$$
Mass flow rate of water $$=12$$ $$kg/s,$$ Specific heat of water $$=4.2kJ/kgK$$
$$OHTC=30$$ $$W/{m^2}K$$,
Correction factor for $$LMTD$$ based on counter flow conditions $$=0.9$$
Calculate the tube surface area required in the heat exchanger and the effectiveness of the heat exchanger.