دانلود مقاله : Fouling and pressure drop analysis of milk powder deposition on the front of parall

چکیده : 

One method to reduce the energy consumption of industrial milk spray dryers is to recover waste heat

from the exhaust dryer air. A significant challenge associated with this opportunity is the air contains

a small amount of powder that may deposit on the face and surfaces of a recuperator. This paper introduces

a novel lab based test that simulates powder deposition on a bank of parallel plate fins at exhaust

dryer air conditions. The fin bank acts like the face of a typical finned tube row in a recuperator. The aim

of this study is to look at how deposition on the front of fins is affected by the air conditions. Results show

similar characteristics to other milk powder deposition studies that exhibit a dramatic increase in deposition

once critical stickiness levels are reached. As powder deposits on the face of the fins, the pressure

drop across the bank increases until eventually an asymptote occurs, at which point the rates of deposition

and removal are similar. For very sticky conditions, deposition on the face of the fins can cause a rise

in the pressure drop by as much as 65%. The pressure drop has also been successfully related to the percentage

of open frontal area of the fins with and without deposition. Deposition inside and at the rear of

the fin bank was found to be minimal.