MOISTURE CONTENT AND DRYING RATE CALCULATIONS

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Materi Pengering

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  • MOISTURE CONTENT AND DRYING RATE CALCULATIONSSOLIDS

  • MOISTURE CONTENT RELATIONSHIPSMOISTURE/SOLID EQUILIBRIUM RELATIONSHIPSFIGURES 9.4-1 AND 9.4-2 FOR SEVERAL TYPES OF SYSTEMSDEFINED ON THE BASIS OF RELATIVE HUMIDITY AT A SPECIFIC TEMPERATUREEQUILIBRIUM AMOUNT OF MOISTURE TENDS TO DECREASE WITH INCREASING TEMPERATURE

  • MOISTURE CONTENT VARIABLESBASED ON THE MASS OF MOISTURE RELATIVE TO THE MASS BONE DRY SOLID

  • DRYING RATE CURVESDEPEND ON WHETHER HEAT OR MASS TRANSFER CONTROLSFREE MOISTURE VS. TIMEDRYING RATE VS. MOISTURE CONTENThttp://www.ias.ac.in/sadhana/Pdf2005Oct/PE1280.pdf

  • DRYING REGIMESCONSTANT RATE - NO LIMIT TO MASS TRANSFER IN SOLID PHASE SURFACE MOISTURETRANSFER NEAR SURFACEFALLING RATE MOISTURE FLUX THROUGH THE SOLID IS HINDERED CRITICAL POINTS OCCURBETWEEN CONSTANT RATE AND FALLING RATEWITH A CHANGE IN THE FALLING RATE DRYING MECHANISM

  • DRYING MODELSRATES FROM EMPIRICAL DATA

    CONSTANT RATE DRYINGCONTROLLED BY HEAT TRANSFER TO VAPORIZE THE MOISTURE OR MASS TRANSFER

  • HEAT TRANSFER CORRELATIONSTO PREDICT CONSTANT RATE DRYING

    RADIATION CAN ALSO BE A FACTOR

  • FACTORS THAT AFFECT h

    AIR VELOCITY (G)GAS HUMIDITY (T TW) AND (HW-H)GAS TEMPERATURE (T TW) AND (HW-H)SOLID THICKNESS - NO EFFECT ON RATE FOR SURFACE MOISTUREMATERIALS SURFACE FINISH OR ANY CONDITION THAT STIMULATES TURBULENCE J. E. SUGARMAN & T. J. VITALE, OBSERVATIONS ON THE DRYING OF PAPER: FIVE DRYING METHODS AND THE DRYING PROCESS Journal of the American Institute for Conservation , 1992, Volume 31, Number 2, Article 3 (pp. 175 to 197) http://www.jstor.org/stable/3179491?seq=1

  • CONSTANT RATE DRYING TIMEDRYING TIME CAN BE CALCULATED BY INTEGRATING (9.5.-3)LOWER VALUE OF X > XC (CRITICAL POINT)

  • FALLING RATE DRYINGCONTROLLED BYGAS PHASE MASS TRANSFER FROM SOLIDOR HEAT TRANSFER INTO THE SOLID TO VAPORIZE THE MOISTURE.GENERAL FORM OF THE EQUATION:X1 < XC

  • FALLING RATE DRYINGNUMERICAL CALCULATION FOR COMPLEX SYSTEMS SEE EXAMPLE (9.7-1) FOR NUMERICAL INTEGRATIONSIMPLIFICATIONS FOR LINEAR RELATIONSHIPS: R(X) = aX + b

    FOR b = 0, LINEAR THRU ORIGIN

  • FALLING RATE EXAMPLEShibata, H.; Iwao, Y., Vacuum Drying of Sintered Spheres of Glass Beads, Ind. Eng. Chem. Res.; 1999; 38(9); 3535-3542

  • FALLING RATE EXAMPLECarmen Rossello, Jaime Canellas, Susana Simal, Angel Berna, Simple mathematical model to predict the drying rates of potatoes, J. Agric. Food Chem.; 1992; 40(12); 2374-2378.

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