6. Conclusions
Based on indoor experimental investigations on mixed- mode solar dryer with potato for 16 different test conditions, dimensionless parameter referred as dryer performance index (DPI) has been identified to evaluate the performance of a given dryer. It is concluded that the proposed parameter, DPI is found to be more or less inde- pendent of different operating conditions and food product characteristics. Further, highly consistent values of DPI obtained for all test conditions permits to use it as a suit- able test parameter for performance comparison between various dryer designs on equitable basis. Moreover, a close agreement between DPI results for indoor and real climatic conditions as well as variety of food products has validated the concept of proposed test method.
This kind of approach is found to be interesting because it facilitate comparison of experimental results for 16 differ- ent test conditions in terms of single generalized drying curve. The proposed testing method can therefore be con- sidered as the most rational among all existing methods and thus, it would further prove to be an effective tool for research institutions, standardizing agencies to rate var- ious solar dryer designs in a meaningful manner.