Question Bank • QB_EXP_APE_EMC_003 MSQ • 2 Marks

Section 6: Agricultural Process Engineering

Equilibrium Moisture Content & Sorption Isotherms

Subtopic: Henderson and Chung-Pfost isotherm models

Question Statement:

Which of the following mathematical equations are standard ASAE-recognized models for grain Equilibrium Moisture Content (EMC)?

Options:

  • (A) Modified Henderson equation: $1 - RH = \exp\left[-K (T + C) M_e^N\right]$
  • (B) Modified Chung-Pfost equation: $\ln(RH) = -\frac{A}{T + B} \exp(-C M_e)$
  • (C) Guggenheim-Anderson-de Boer (GAB) three-parameter isotherm model
  • (D) Navier-Stokes equation for incompressible fluid flow

Answer Key:

A, B, C

Step-by-Step Solution & Explanation

1. Modified Henderson and Modified Chung-Pfost are the premier standard ASAE D245 equations for grains (A and B). 2. GAB model is the international food standard across the full range of water activity $0 < a_w < 0.95$ (C). 3. Navier-Stokes models momentum conservation in fluids, completely unrelated to thermodynamic sorption isotherms (D is false).
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