An on-line method for monitoring of relative humidity using thermal sensors

Relative humidity is an important process variable in many agro-based and food processing industries and continuous monitoring and control of it becomes necessary. There are a numbers of direct reading type measuring techniques using variable parameter sensors. Many attempts have also been made to measure relative humidity on-line with the classical concept of wet and dry bulb psychrometer. With this concept, the design of a robust technique by piecewise linearization of the psychrometric chart over a working temperature range and using thermal sensors, can be formulated. This paper illustrates the methodology applicable to a working temperature range in the tea industry