Development of Light Weight Solar Dryer and Optimization of Drying Process for Bottle Gourd

Abstract

The light weight solar dryer has been designed and fabricated to align with the atmospheric conditions of Kashmir valley. The experimental studies titled as “ Development of a light weight solar dryer and optimization of drying process for bottle gourd ” were conducted at the Sher-e –Kashmir University of Agricultural science and Technology , Shalimar, Srinagar J&K , in the northern part of India, during summer season of 2023. The solar dryer consists of drying chamber, drying tray, air inlet , exhaust fan for cross ventilation , temperature humidity controller module, solar panel, battery and solar charge controller. The dryer harnesses solar energy for the drying process and holds substantial promise for drying fruits, vegetables , herbs with medicinal properties and a variety of other products. The dryer has dimension of( length=36? , width=24?, front height=30?, back height 40? and a slope for attaining maximum sunlight intensity. This dryer has an average capacity of 4-5kg of the food product for drying. In this experiment tray is loaded with untreated and treated bottle gourd slices. In two separate trials drying completed in 20 and 32 hours for treated and untreated sample respectively . The temperature inside the dryer increased up to 60? and relative humidity was reduced upto 27%. The moisture content in %d.b( dry basis) of untreated bottle gourd is reduced to 9.8% while as in pre-treated bottle gourd , moisture content is reduced to 8.8%.

Introduction

I. INTRODUCTION

Preservation of agricultural produce is one of the central problems faced by developing countries. And as time goes on, these problems will be aggravated by the growing dietary needs of the ever increasing population of these countries( Hauser et al. 1997).  In numerous developing nations, substantial amounts of fruits and vegetables go to waste because of insufficient infrastructure, limited processing capabilities, and increasing challenges in marketing due to heightened competition in global agricultural markets. Drying these items can offer a solution to these issues while simultaneously playing a vital role in enhancing people’s income and the availability of these products. Kashmir valley is under temperate climate and there is severe scarcity of local fruits and vegetables from November to April. During this season, cultivation of fruits and vegetables is not possible because of severe cold & snow (Kumar et al .2005). Therefore there is high market for dried fruits and vegetables under hygienic conditions so as to extend their availability during off season and fetch good money& enhances shelf life of products.

Bottle gourd is one of the excellent vegetable gifted by the nature to human beings having composition of all the essential constituents that are required for normal and good human health. It is extensively cultivated throughout the world. It is grown throughout India and is available in the market throughout the year. More than 80% of most fruits and vegetables contain water (GEPC, 2005). Microorganisms obtain nutrients and water for their growth from the crop in which they grow. Hence, the fruit must be dried in order to stop the multiplication of microorganism and store it for longer period.  Drying  is  one  of  the primordial  and  rampant  techniques  for  safeguarding  food  quoted  by  numerous people  like  Lima  (2002)  and Ratti(1997). The quality of the solar dried bottle gourd on the basis of moisture content, water activity, colour attributes, vitamin C retention and rehydration ratio determines that the solar dried products are significantly good as indicated by the T- test ( Rehman et al. 2022). The samples are dried in hygienic conditions and drying time has reduced significantly. During solar drying there is very less chance of samples being exposed to rain, birds and are prevented from the direct exposure to the Sunlight which prevents the UV- exposure and make dried vegetables safe for consumption. Further there is an acute crises of electric power and other forms of fuel like wood, kerosene oil and coal in the Kashmir valley. Moreover, energy sources like wood, kerosene oil and coal have a serious impact on environment. As most of the Indian farmers are poor and unable to afford these energy resources, so there is a need   of utilizing cheaper , easily available, non-conventional sources of energy like solar energy. A light weight solar dryer is one of the way to utilise solar energy in a controlled environment.

II. DRYER DESIGN

While designing a dryer , various factors need to be taken into account to ensure that the resulting dryer is suitable for a specific purpose. It is essential to incorporate a suitable design for a solar dryer to succesfully meet its intented goals. The  dryer  consists  of  a  drying  chamber  having one  tray  for  loading vegetables. The dimensions of dryer are: length=36? , width=24?, front height=30 ?, back height 40? and  a slope surface is giving to dryer for attaining maximum sunlight intensity. The drying tray is kept at a height of  12? from the bottom . The dryer is covered with a transparent UV stabilized polyethylene cover of 0.2 mm thickness which is not affected by the atmospheric  conditions  and  has  transmissivity  of  92%  for  visible  radiation  and thus  traps  the  solar  energy  leading  to  the  greenhouse  effect  and  enhance  the temperature  inside  the  dryer  to  maintain  it  at  optimum  level  for  drying  of vegetables.  The  top  surface  of  the   drying  chamber  have  been designed  in  a  sloping shape  in  order  to  increase  the  area  for  radiation.  The advantage of slope is to maximize utilization of  solar  radiation  inside  the  dryer.  The  shape  and  orientation  plays  an important role in the dryer (Odesola, 2012). The dryer is provided with an air inlet and exhaust fan   The exhaust fan is on the upper side to remove hot air and inlet vents are placed at the bottom of the dryer for better cross ventilation. The dryer is made from the PPR pipes which is very light in weight  and  thus  can  be  easily  handled. Temperature and humidity is being controlled by temperature and humidity controller module. An exhaust fan works when temperature reaches 60?  and the heat accumulated inside dryer is removed . when the temperature drops to 55?  fan stops working. Meanwhile for operating temperature humidity controller , a 12 V , 7 Ah battery is used which gets charged by solar panel .The actual photograph,  three dimensional and two dimensional view of  the dryer is shown in figure 1a, 1b and 1c respectively.

Conclusion

The study involved a two-fold investigation, focusing on both the drying process itself and the efficacy of the solar dryer in facilitating this process. The initial phase of the research involved the assessment of bottle gourd drying characteristics. Through experimental trials, the moisture content and drying rate are tracked at regular intervals during the drying process. The study revealed valuable insights into the drying behaviour of bottle gourd, shedding light on its moisture reduction patterns and the interplay of various process variables. It is observed that temperature inside the dryer increased upto 60? and relative humidity is reduced upto 27%, The treated bottle gourd took 35.48% less time to dry compared to the untreated bottle gourd. The moisture content in %d.b of untreated bottle gourd is reduced to 9.8% while as in pre-treated bottle gourd , moisture content is reduced to 8.8%. Cost of the dryer can further be reduced as there is no need of battery during daytime and the whole system can function directly from solar panel.

References

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Copyright

Copyright © 2023 A A Balkhi, G M Mir, Arbin Lateef, Riyaz Ashraf. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.