TRAINING ON BUILDING AND TESTING A SOLAR TUNNEL DRYER TO DRY AGRICULTURAL PRODUCTS AT BULU, KARANGMOJO, KARANGMOJO, GUNUNG KIDUL

Bulu Karangmojo village is a known cashew nut producer central in Gunung Kidul. However, cashew nut farmers faced obstacles in the drying process, especially in the rainy season. An affordable yet simple made solar dryer was essential for the drying process. Our team at UKRIM (Universitas Kristen Immanuel) came up with the solution of using a solar tunnel dryer. The solar tunnel dryer was chosen because people do not need fossil fuels to operate it, so it was more economical, environmentally friendly, and most of the material e.g. wood and bamboo were abundantly and locally available in their village. Moreover, solar tunnel dryer construction was simple enough, so that farmers could make it by themself. Solar energy was used for the drying process. The drying process was using a solar absorber to collect the heat of the sun. The heated air will move to the cashew nuts to absorb the humidity, finally, humid air is leaving through a bug-screen to the environment. Eighteen farmers had actively participated in this training. Finally, a solar tunnel dryer of 5 m length and 1 m width connected with a 10-watt solar panel was successfully constructed. The result showed a 50% faster drying time compared to the traditional sun drying and supplied a higher product quality.


INTRODUCTION
Karangmojo The process of drying cashews in Bulu village is done in the traditional methods so that the community often suffers losses due to the non-optimal drying process. In the rainy season, the drying which should last 5 days can become 10 days. From interviews with farmers, it is estimated that 10 percent of cashew nut production is damaged during the drying process. Good quality cashews can be sold at IDR 150,000 per kg. If the drying of cashew nuts is not optimal so the quality is decreased, the price will drop to IDR 90,000 per kg. If the drying process is not optimum, farmers will lose around IDR 30,000,000.00 for every 5 tons CNS they produced.
Instead of cashew, The Bulu area in Karangmojo village also produces various agricultural products such as peanuts, bananas, cassava, ginger, turmeric, ginger, and so on. Therefore, agricultural products need to be dried to preserve agricultural products that are not consumed and increase economic value. In running a business, every process must be done effectively and efficiently. The solar dryer can help the Bulu community in Karangmojo village in maximizing the drying process of existing agricultural products so that the community gets more profit than the previous one.
The drying process is a method of preserving food ingredients without further deterioration of the product which is popular and is often applied in developing countries. Drying is the process of evaporating water contained in food. Drying is first done traditionally in direct sunlight. Some studies state that the performance of the solar tunnel dryer model is very good for drying capsicum varieties grown in Peru [5] and drying cocoa in Indonesia [2]. The capacity of the solar tunnel dryer depends on its size. For a standard size of 2 m wide and 10 m long, it can dry 100 kg for medical plants and 300 kg for pork, apricots, and coffee [6].
Nowadays, UKRIM's renewable energy laboratory has developed two kinds of solar dryers i.e. solar cabinet dryer and solar tunnel dryer modeled by the University of Hohenheim. Of the two types of solar dryers, the solar tunnel dryer was chosen to be implemented in the Bulu village of Karangmojo village.
The solar tunnel dryer has 3 parts, namely solar collector, dryer section, and airflow system.
The air flow is controlled by a fan that uses 10 watts of electricity from the solar panel. Air is pushed into the solar collector by the fan and will be heated by solar radiation. This hot air then flows into the dryer to dry the product. Finally, the humid air is released through vents at the end of the solar dryer.
The expected benefits of community service activities include the community being able to build a solar dryer to dry their agricultural products, the community has experience and understanding that the solar dryer that is built can function well to dry agricultural products. Furthermore, it is hoped that the community will get benefits both economically and environmentally.

METHODS
The target of this activity is the community of farmer groups in Bulu village of Karangmojo, Gunung Kidul Regency. The majority of people who live in Bulu work as farmers and they frequently have to dry agricultural products when the harvest arrives so that these agricultural products can be stored safely and sold at a higher price. taking into account the existing requirements then it was decided to make a solar tunnel dryer because this model has been tested and used in more than 100 countries [3]. where was the best location to build a solar tunnel dryer and determine the best time to do this activity.
The Head of the Bulu area was in charge of socializing this activity with the residents as well as inviting residents to be actively involved in the planned process.

RESULT AND DISCUSSION
From the results of surveys and interviews with Bulu residents, it is known that the problem they often face is the drying of cashew harvests and other agricultural products. During the rainy season, the drying process which was originally 5 days can last up to 10 days. If the agricultural products are not dried immediately, they can be damaged to cause economic losses. From this problem the community development team decided to make a solar tunnel dryer that can be used without the need for fossil fuels so that it is more economical to operate.
The results in Fig. 2

Fig. 2. Comparison of solar drying and traditional drying
A literature study on solar dryer models was conducted. To implement solar drying successfully, solar dryers must be relatively simple to make, the material has to be locally available in Bulu village, easy to maintain, and economical to operate. With these considerations, it was decided to build a solar tunnel dryer. The solar tunnel dryer design is made following the manual "Small solar tunnel dryer" developed by the University of Hohenheim [4] and "Manual training on solar tunnel dryers" developed by the Women Empowerment Program in Nigeria [1]. This solar tunnel dryer has been used in 100 countries to dry various agricultural products [3]. Some parts are adjusted according to available materials, the size of the dryiruang area, the number of fans, and the size of the solar panel.
The solar tunnel dryer scheme is illustrated in Figure 3.

Solar panel Charge controler Baterai
Voltage regulator Fan

Fig. 3 Solar tunnel dryer scheme
The tools needed to build a solar tunnel dryer are hammers, saws, tape measure, drills, brushes, and screwdrivers. Materials needed to make one unit of solar tunnel dryer with the size of (1 x 5) m are shown in Table 1 Stepdown regulator 3 A 1 The drying area of the solar tunnel dryer is shown in Fig.4. It was divided into two main parts namely the collector area and the area for drying. From the total area of (5x1) m, the collector area was (1,7 x 1) m and the rest of the area was for the drying material area. This collector area was important because if all of the drying area is covered by material, the result of the drying process will not be uniform. A battery was used to store energy, so the dryer would be able to work at night. The design of the solar tunnel dryer roof is shown in Fig. 5. The length of the base follows the width of the solar tunnel dryer that was built. The way these solar tunnel dryers work is that a part of the collector that is painted black will convert sunlight into heat. Furthermore, the hot air becomes relatively dry and then moves to the dryer, where the material is dried to take away the moisture of the dried material. In addition to the hot air collector, the sun's rays on the dried material also help evaporate the water content of the material. The air that has taken moisture from the material then flows out through the ventilation area. Fan power is obtained from electricity produced by solar panels so that the temperature in the solar tunnel dryer is stable. If the intensity of the sun light is strong enough, then the space in the dryer will get hot quickly. The ventilator also serves to drain hot air quickly out to avoid overheating in the drying chamber avoiding lower product quality. Conversely, if the intensity of the sun is weak, electricity from the solar panel will be smaller so that the fan will move more slowly so that the hot air will stay in the drying chamber for longer [4].
During the discussion on the supply of tools and materials, the management of RUAS farmers group that was targeted by workshop, participated proactively to provide the tools and materials that could be obtained in the area, while the tools and materials not available on site were provided by the community development team. The materials provided by the community include metal sheets, wood, plywood, paint, nails, screws, bolts, and gauze. Electronic components such as solar modules, batteries, charge controllers, cables, step-down regulators, and fans were provided by the community development team. The total amount of funds to buy materials to make 1 unit of solar tunnel dryer is Rp. 3,000,000. If the wood and bamboo are already owned by the community, the costs can be reduced to Rp. 2,500,000. To reduce the cost of manufacturing, it can be done by using a solar tunnel dryer without batteries so that if the community uses their wood and bamboo and does not use batteries, the amount of capital needed will be Rp. 2,000,000.00. Solar tunnel dryers without batteries can function only during the day when there is sunlight.
Presentations on drying agricultural products and how to build a solar tunnel dryer were actively followed by the community. This presentation took place with active participation. The participants enthusiastically expressed their opinions and asked questions if they did not understand something. The community learned about the theory and methods of the solar tunnel dryer and the community development team learned about the daily challenges faced by the community in drying agricultural products and the potentials of the local area. Besides, the community development team also learned that there is great potential for renewable energy technology to be applied in the village.
We learned that technology implemented in the village should not be sophisticated and difficult to apply but instead the technology should be simple so that the community can learn and make it independently by them self after the workshop is finished. does not just fund, but also the knowledge that can be used to solve everyday problems that she encounters. Fig.6 shows the building process of the solar tunnel dryer with the participants. In this workshop we learned that this activity can work well with the open communication between our team and the target community and equal relations between us. The success of a program is largely determined by the process of a comprehensive approach in recognizing the problems faced by the community. If the communication process goes well, the community can be actively involved in the activity and feel the real benefits of this activity.

CONCLUSION
A solar dryer for drying cashew nuts and other agricultural products is needed by farmers in Bulu Karangmojo. A solar tunnel dryer was chosen because its construction is simple, does not require fuel to operate because it uses renewable and environmentally friendly solar energy, and has been proven to have a good performance to dry agricultural products in around 100 countries. This solar dryer uses a 10 W solar panel and a battery to store electricity so that the solar dryer can still work at night.
The solar tunnel dryer has a size of 1 x 5 m, with 1x 1.7 m being a solar energy collector area. The comparison of the second workshop showed that the solar dryer was performing around 50% faster than traditional sun drying and supplies a higher product quality.
Bulu farmer community has been able to make their own solar tunnel dryers. During the training, they actively participated in the building process. They are motivated that they want to have it in their own homes to dry their agricultural products but were still constrained by funds. The community development team explained that the they provide training on how solar dryers are built and used, but could not yet provide funds to build more solar tunnel dryers. Finally, the community understood that the workshops were contributing the value of knowledge instead of funds. They also realized that this is an important solution for solving their problems regarding drying their agricultural products, especially cashew nuts. Good communication and knowledge transfer in this activity can occur because there was sincerity that both parties meet on eye level and learn from each.
To Improve outcome in further community development programs, a good business model should be introduced so that participants can understand the additional value of the solar dryer.