Can anyone help me in the following question How to increase

Solution

An enhanced heat transfer process whereby solid particles are heated, dried, or cooled by a gas: Particles are repeatedly lifted and dropped as, for example, in flighted rotary drums. By forced recirculation, gas is passed through showering particles generally perpendicular to their plane of fall. Examples show gas forced to contact particles in this manner imparts an overall volumetric heat transfer coefficient to a rotary drum superior to that expected from classical literature or presently operating rotary drum heat exchangers. Disclosure teaches gas temperature adjustment between forced recirculations. Technique usage will reduce exchanger captial cost, increase energy efficiency, and reduce pollution problems. Also, prewetting of the particles in certain instances can be utilized to effect substantially increased pseudo volumetric heat transfer coefficients when cooling non-hygroscopic materials.