For a glass plate transitivity and reflectivity are specified as $$0.86$$ and $$0.08$$ respectively, the absorptivity of the glass plate is

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.

In the design of shafts made of ductile materials subjected to twisting moment and bending moment, the recommended theory of failure is

For full depth of involute spur gears, minimum number of teeth of pinion to avoid interference depends upon