Relative humidity is an important process variable in manyagro-based and food processing industries and continuous monitoring andcontrol of it becomes necessary. There are a numbers of direct readingtype measuring techniques using variable parameter sensors. Manyattempts have also been made to measure relative humidity on-line withthe classical concept of wet and dry bulb psychrometer. With thisconcept, the design of a robust technique by piecewise linearization ofthe psychrometric chart over a working temperature range and usingthermal sensors, can be formulated. This paper illustrates themethodology applicable to a working temperature range in the teaindustry
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