الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Evaporation is commonly used by various processing industries as a method of concentrating aqueous liquid streams by vaporizing the water component. the use of evaporator in the concentration of date juice )30%( to produce date juice concentrate of )60%( was economically analyzed and comparing schemes of evaporation were evaluated, three schemes are single effect evaporator, mechanical compression of vapor, and thermal compression of vapor. Mathematical models were formulated for the three schemes used. The results indicated that steam jet ejector scheme has the minimum annual total cost compared with other investigated schemes and hence it is recommended to use such evaporation scheme to concentrate date juice from 30% to 60%.
Also, was dedicated to studying the rheological properties of date juice during evaporation, pumping and mixing. The rheological properties of date juice were studied using a Brookfield viscometer at various temperatures of 30, 40, 50, 60, °C and at different concentrations of 30, 40, 50, 60% by wt, and shear rates (9.3 to 93 s-1). The results showed that, all samples exhibit non-Newtonian pseudoplastic behavior. Friction factors-Reynold’s number of pseudoplastic fluids was necessary to predict the optimum economic pipe diameter which was found to be 0.038m. An impeller mixer was used to predict the power number, blend number and pumping number as a function of Reynolds number at different impeller to tank diameter ratios at 60% concentration.
Key words:
Date juice, evaporation, rheological properties, mixing