Table of Contents

Fabrication of Solar Dryer Report Download – Mechanical projects

Introduction

Drying is one of the methods used to preserve food products for longer periods. The heat from the sun coupled with the wind has been used to dry food for preservation for several years.
Drying is the oldest preservation technique of agricultural products and it is an energy intensive process. High prices and shortages of fossil fuels have increased the emphasis on using alternative renewable energy resources. Drying of agricultural products using renewable energy such as solar energy is environmental friendly and has less environmental impact.
Different types of solar dryers have been designed, developed and tested in the different regions of the tropics and subtropics. The major two categories of the dryers are natural convection solar dryers and forced convection solar dryers. In the natural convection solar dryers the airflow is established by buoyancy induced airflow while in forced convection solar dryers the airflow is provided by using fan operated either by electricity/solar module or fossil fuel.
Solar thermal technology is a technology that is rapidly gaining acceptance as an energy saving measure in agriculture application. It is preferred to other alternative sources of energy such as wind and shale, because it is abundant, inexhaustible, and non-polluting. Solar air heaters are simple devices to heat air by utilizing solar energy and it is employed in many applications requiring low to moderate temperature below 80°C, such as crop drying and space heating.

Problem Statement

Food scientists have found that by reducing the moisture content of food to between 10 and 20%, bacteria, yeast, mold and enzymes are prevented from spoiling it. The flavor and most of the nutritional value is preserved and concentrated.
Drying and preservation of agricultural products have been one of the oldest uses of solar energy. The traditional method, still widely used throughout the world, is open sun drying where diverse crops, such as fruits, vegetables, cereals, grains, tobacco, etc. are spread on the ground and turned regularly until sufficiently dried so that they can be stored safely. However, there exist many problems associated with open sun drying. It has been seen that open sun drying has the following disadvantages. It requires both large amount of space and long drying time. The disadvantages of open sun drying need an appropriate technology that can help in improving the quality of the dried products and in reducing the wastage. This led to the application of various types of drying devices like solar dryer, electric dryers, wood fuel driers and oil-burned driers. However, the high cost of oil and electricity and their scarcity in the rural areas of most third world countries have made some of these driers very unattractive. Therefore interest has been focused mainly on the development of solar driers.

The orientation of the Solar Collector:

The flat-plate solar collector is always tilted and oriented in such a way that it receives maximum solar radiation during the desired season of used. The best stationary orientation is due south in the northern hemisphere and due north in southern hemisphere. Therefore, solar collector in this work is oriented facing south and tilted at 45 to the horizontal. This inclination is also to allow easy run off of water and enhance air circulation.

Materials required for making the solar dryer:

The materials which are used to make the solar dryer are used in our everyday life .And they are found easily near our locality.
1) Plywood
2) Hammer
3) Nail And Glue
4) Wired Mess
5) Glass
6) Thermometer
7) Black Paint

Conclusion

From the test carried out, the following conclusions were made. The solar dryer can raise the ambient air temperature to a considerable high value for increasing the drying rate of agricultural crops. The product inside the dryer requires less attentions, like attack of the product by rain or pest (both human and animals), compared with those in the open sun drying. Although the dryer was used to dry Potato, it can be used to dry other crops like yams, cassava, maize and plantain etc. There is ease in monitoring when compared to the natural sun drying technique. The capital cost involved in the construction of a solar dryer is much lower to that of a mechanical dryer. Also from the test carried out, the simple and inexpensive solar dryer was designed and constructed using locally sourced materials. . In this experiment we find that how much moisture removed from the sample which is present in solar dryer and the sample which is present in ordinary air and we compare both of them by mathematical calculation. In this paper we took green chili, some of the chili we put inside the dryer and some in the ordinary air and then compare their moisture removed with respect to time and temperature. We find that temperature inside the dryer is two times outside the temperature. As per our experiment the maximum peak temperature inside the drying chamber is 75°C during mid-day(3pm) and in an average approximately 60°C-62°C in a full sunny day(10:00 AM to 03:00 PM). In 6 hours continuous drying in one full sunny day under the same climatic condition and in same time the solar dryer removed a maximum of 30- 40% moisture content from drying chamber for drying of low moisture content food products.