Experimentally investigated the asparagus (Asparagus officinalis L.) drying with flat-plate collector under the natural convection indirect solar dryer

Abstract

In this study, a natural convection indirect solar cabinet dryer has been fabricated to study the drying behavior of Asparagus (Asparagus officinalis L.) in terms of its convective heat transfer coefficient and moisture removing rate (% db). The experiments were conducted during the months of June, July, and August 2016, at College of Engineering, Nanjing Agricultural University, Nanjing (32°3′36.92″ N and 118°47′48.76″ E), China. Linear regression method was applied to the experimental data to evaluate the Nusselt number constant. From the results of the experiments, it was observed that convective heat transfer coefficient decreased with the increasing mass of the samples. Similarly, the progression of drying months with variation from 0.59 to 5.42 W/m² °C for the different mass of samples was noted. Therefore, from the results of the experiment, it was reported that moisture removing rate increased with the increase in mass of asparagus samples and significantly decreased with progression of drying months. Similarly, during experiments, the average collector efficiency was noted to vary from 14.97% to 16.14% under the increasing and decreasing trends of solar irradiations from morning to noon and noon to evening, respectively. For describing the drying behavior of the different mass of Asparagus samples, modified Henderson and Pabis were reported. During experiments, experimental error in terms of percent uncertainty was observed in the range from 29.19% to 46.25%.

In this research work, linear regression method was applied to the experimental data to evaluate the Nusselt number constant. Different drying model was also applied to the dried varieties for describing the drying behavior of the different mass of the dried product.

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