Which one is true for a throttling process?

Pick out the wrong statement?

A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of________?

Make up water is supplied during cooling tower operation to compensate for water losses due to________?

Common salt is produced from sea water in India generally by the ________ method?

With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will________?