The interaction
effects of impinging jets from both directions may reduce the
turbulence created on the product surface, and hence lower the
heat transfer coefficients as compared to those for the modified
impingement dryer. Although the drying times for the impingement
dryer were longer than for the modified impingement dryer
(2.37 vs 2.15 h) at 107 C, the difference was not statistically
significant. The modified impingement dryer had a significantly
shorter drying time than the unmodified impingement dryer (4.58
vs 5.37 h) at 85 C.