Eksperimentalno ispitivanje svojstava crvene banane tijekom sušenja u solarnoj sušari s jednostrukim nagibom i prirodnom ili prisilnom konvekcijom

Research background. Traditionally, open sun drying method serves to dry the products for long time preservation. Solar drying is also employed to minimise the drying time to achieve the required moisture content. This method inherently contains complex heat and mass transfer mechanisms, which makes difficult to describe drying kinetics at the micro level. Experimental approach. In this paper, research is carried out to investigate the drying of 5 mm thick slices of red banana (Musa acuminata ’Red Dacca’) in a single slope solar dryer based on natural and forced convection. Based on the experiments, a new semi-empirical thin layer drying kinetics is proposed and compared with other existing models. The proposed model with the correlation coefficient (R2) of 0.997 is in very good agreement with other well-known models. Based on the model, we calculated the moisture diffusivity and activation energy of the red banana drying process. Results and conclusions. It was found that the moisture diffusivity of the red banana samples was in the range 0.87-1.56·10-9 m2/s for natural convection solar drying and 0.84-2.61·10-8 m2/s for forced convection solar drying. The activation energy of the red banana varied from 24.58 to 45.20 kJ/mol for passive and 22.56 to 35.49 kJ/mol for active drying. Besides, we carried out energy and exergy analyses of red banana in the dryers and found that the average exergy losses in the forced and natural convections were 16.1 and 6.63 kJ/kg and the average exergic efficiency of the natural and forced convection dryers was 57.7 and 70.9%, respectively. Novelty and scientific contribution. A single slope direct solar dryer was designed and built to maintain the desired temperature for a specified period in both natural and forced convection mode. A novel drying kinetics model with higher correlation coefficient (R2) than the other drying kinetic models is proposed for the preservation of red bananas.Pozadina istraživanja. Sušenje na suncu se tradicionalno primjenjuje za dugotrajno očuvanje prehrambenih proizvoda. Također se koristi za postizanje željenog udjela vlage u proizvodu u što kraćem vremenu. Ova metoda neizostavno obuhvaća složene mehanizme prijenosa temperature i mase, zbog čega je teško opisati kinetiku sušenja u samom uzorku. Eksperimentalni pristup. U ovom je radu ispitano sušenje kriški crvene banane (Musa acuminata „Red Dacca“) debljine 5 mm u solarnoj sušari s jednostrukim nagibom i prisilnom ili prirodnom konvekcijom. Na osnovi rezultata pokusa predložen je novi, djelomično empirijski model za opisivanje kinetike sušenja u tankom sloju uzorka, te je uspoređen s postojećim modelima. Predloženi je model, s koeficijentom korelacije (R2) od 0.997, bio u skladu s drugim dobro poznatim modelima. Na osnovi novog modela izračunali smo efektivnu difuzivnost vlage i energiju aktivacije sušenja uzoraka crvene banane. Rezultati i zaključci. Rezultati pokazuju da je efektivna difuzivnost vlage u uzorcima crvene banane sušenim prirodnom konvekcijom bila 0,87−1,56·10-9 m2/s, a onih sušenih prisilnom konvekcijom 0,84−2,61·10-8 m2/s. Energija aktivacije varirala je od 24,58 do 45,20 kJ/mol tjekom pasivnog, te od 22,56 do 35,49 kJ/mol tijekom aktivnog sušenja. Osim toga, utvrđeno je da je prosječni eksergijski gubitak tijekom sušenja crvene banane u solarnoj sušari prisilnom konvekcijom bio 16,1 kJ/kg, a prirodnom konvekcijom 6,63 kJ/kg, dok je prosječni eksergijski učinak bio 57,7 %, odnosno 70,9 %. Novina i znanstveni doprinos. Solarna sušara s jednostrukim nagibom dizajnirana je s ciljem da zadrži željenu temperaturu tijekom definiranog perioda u oba načina sušenja: prirodnom ili prisilnom konvekcijom. Predložen je novi kinetički model sušenja s većim koeficijentom korelacije (R2) nego u ostalim modelima sušenja, a sa svrhom produljenja trajnosti crvenih banana

Assessment of Solar Dryer Performance for Drying Different Food Materials: A Comprehensive Review

Studying crucial drying parameters, such as activation energy and moisture diffusivity, offers valuable insights for optimizing food safety. Accurate predictions and simulations through mathematical thin-layer models aid in designing, controlling, and optimizing drying operations for various food items. Solar drying presents a viable and eco-friendly solution for food preservation. This chapter critically evaluates solar drying performance for various vegetables, fruits, marine products, and other commodities, providing comprehensive insights into its efficiency. According to the literature, the moisture diffusivity (m2/s) for vegetables has been reported to be within the range of 2.01 × 10−10–1.935 × 10−8. For fruits, the moisture diffusivity varies between 1.33 × 10−10 and 6.98 × 10−9. In the case of marine food products, the range is found to be 2.8 × 10−8–3.408 × 10−7, while for other commodities, it falls between 1.79 × 10−9 and 1.061 × 10−7. The activation energy (kJ/mol) for vegetables has been observed to fall within the range of 24.81–47.19. Similarly, for fruits, the activation energy varies between 2.56 and 45.20. Notably, Ginger demonstrates an activation energy of 35.675 kJ/mol. Experimental results showed that lower activation energy and higher moisture diffusivity accelerate dehydration

Harnessing nature’s ingenuity: A comprehensive exploration of nanocellulose from production to cutting-edge applications in engineering and sciences

Primary material supply is the heart of engineering and sciences. The depletion of natural resources and an increase in the human population by a billion in 13 to 15 years pose a critical concern regarding the sustainability of these materials; therefore, functionalizing renewable materials, such as nanocellulose, by possibly exploiting their properties for various practical applications, has been undertaken worldwide. Nanocellulose has emerged as a dominant green natural material with attractive and tailorable physicochemical properties, is renewable and sustainable, and shows biocompatibility and tunable surface properties. Nanocellulose is derived from cellulose, the most abundant polymer in nature with the remarkable properties of nanomaterials. This article provides a comprehensive overview of the methods used for nanocellulose preparation, structure–property and structure–property correlations, and the application of nanocellulose and its nanocomposite materials. This article differentiates the classification of nanocellulose, provides a brief account of the production methods that have been developed for isolating nanocellulose, highlights a range of unique properties of nanocellulose that have been extracted from different kinds of experiments and studies, and elaborates on nanocellulose potential applications in various areas. The present review is anticipated to provide the readers with the progress and knowledge related to nanocellulose. Pushing the boundaries of nanocellulose further into cutting-edge applications will be of particular interest in the future, especially as cost-effective commercial sources of nanocellulose continue to emerge