Drying kinematics of cabinet type solar dryer for aloe vera and biomethanation study of aloe vera waste

Abstract

The economic and social progress of developing countries like India, energy is one of most important key factor. India s total installed capacity of renewable energy has reached to of 14.8 per cent of total energy. Aloe vera barbadensis miller is considered as best type of aloe vera species which has 95 per cent of medicinal properties. In present investigation aloe vera gel was dried in solar cabinet dryer and it was compared for its quality with open sun dried sample. The time required for reduction of aloe vera gel moisture content from 98.45 per cent (wb) to 8.82 per cent (wb) in solar cabinet dryer is two days while in open sun is three days. The average drying rate in open sun drying and solar cabinet drying of aloe vera was found 1.47, 1.34 and 1.19 g/100g dm/ h in OSD1 OSD2 OSD3 and 3.96, 2.7 and 2 g/100g dm/ h in CSD1, CSD2 and CSD3 respectively. The moisture diffusivity varied in the range of 1.59×10-9 m²/s to 1.54×10-9 m2/s for open sun drying and 1.88×10-9 m2/s to 2.56×10-9 m2/s for solar cabinet drying of aloe vera. The best ranked thin layer drying model applicable to the variation of moisture ratio with drying time of aloe vera samples in open sun drying was two term model where as in cabinet drying were diffusion approach model. The dried sample was analyzed for protein, fat, ash, carbohydrate and fibre content. The results obtained were 6.5, 1.76, 16.45, 59.78 and 15.48 g/100 g in solar cabinet drying and 5.8, 1.6, 16.45, 50.64 and 15.48 g/100 g in open sun drying for protein, fat, ash, carbohydrate and fibre respectively. The ascorbic acid content of fresh aloe vera 129.75 mg/100 g which was highly reduced in drying process. Ascorbic acid obtained was 37.6275 mg/100 g in solar cabinet dryer and 28.545 mg/100 g sun drying. Contd....