3.5 Economic evaluation of solar dryer
3.5.1Sizing of dryer
Following procedure has been adopted for calculating collector area required for a particular amount of
Nylon-6 using solar dryer. Detailed calculation of collector area requirement to dry 1 kg/hr of Nylon-6 is given below.
Procedure for sizing of solar dryer:
1) Find out the quantum of moisture to be removed from plastic pellets.
2) Plot the entire drying process on the Psychometric chart [10] by plotting temperature readings defining
processes sensible heating, while air is passing through the solar collector. Allowed by its passage through
the drying of plastic pellets in drying chamber. Note down relative humidity of air at the start of drying. Also,
note down the absolute humidity at all the state points.
3) Find out the amount of moisture to be removed per kg of drying material.
4) Referring the moisture absorption-desorption isotherm find out the value of water activity for Nylon-6at the
corresponding relative humidity of air. Assume water activity 1 for absorption and find the average of water
activity at absorption and desorption as per the calculation.
5) Find out volumetric air flow rate and the total enthalpy required over the entire drying process.
6) Collector area required for drying of Nylon pellets can be calculated by using dying efficiency and thermal
efficiency obtained from the reported experimental results in this work.
The drying process starts at average temperature of pellets and not the temperature of surrounding in the
drying chamber. This means the drying of pellets start only when pellets are heated and moisture becomes free. And