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This study aims to design and test the citronella leaf distillation tool by conducting experiments and testing the tools and test results. The parameters observed were heat transfer in the citronella leaf distillery produced by the tool, the results of the conduction heat transfer research in the distillation tank were 1,032.61 J/s (Joules per second) and heat transfer by natural convection in the distillation tank was 3,761.16 J/s (Joules per second) with an initial water temperature of 28°C to a specified temperature of 98°C. The distillation time of more than 5 hours will reduce the quality of the yield which is not up to standard. The effect of the part of lemongrass which produces a high yield percentage is on the leaves, while the high quality of citronella oil is on the leaves. % citronella citronella on fresh leaves was 67.36%, withered leaves were 44.92%.

Dusun Tangsi Jaya Gunung Halu merupakan desa binaan Universitas Darma Persada dimana di dusun tersebut terdapat Unit Pengolahan Kopi yang di kelola oleh Koperasi Rimba Lestri bantuan dari Mitsui Jepang dan Unsada. Saat ini unit pengolahan kopi tersebut dapat berfungsi dengan baik, kendala yang saat ini dihadapi oleh pengelola Koperasi adalah, tidak berfungsinya mesin pengering kopi dikarenakan sistem pemanasan yang telah rusak. Menjawab permasalahan tersebut melalui skema Teknologi Tepat Guna dibuatlah mesin oven pengering hybrid ( Solar Thermal dan biomassa) yang cara penggunaan dan perawatannya lebih mudah serta kapasitas pengeringan yang lebih besar. Oven Pengering Hybrid untuk kopi ini memanfaatkan cahaya matahari dan pembakaran dari kayu untuk pemanasannya, pembuatan oven pengering hybrid dengan melibatkan petani kopi yang tergabung dalam Koperasi Rimba Lestari, ukuran dari oven pengering hybrid ini adalah panjang 8m, lebar 3m dan tinggi 2,4 m, tungku biomassa dengan dimensi panjang 1,2 m, lebar 1,2 m dan tinggi 1,3 m, kapasitas pengeringan 300 kg sekali proses.

Urban in Indonesia, is no longer limited as a center of community settlement. Now the city also functions as a center of government, a central hierarchy, and a center of economic growth. As a logical consequence of the role of cities as a center of growth and economy, urban contributions to national economic growth are increasing. To overcome this problem, a portable conveyor of solar-energized drying system was designed. With the portable conveyor of solar-energized drying system, the dryer will be easily moved and flexible to use. The advantage of portable conveyor of solar-energized drying system is the drying process could be done continuously with a little human power. Therefore, this portable conveyor of solar-energized drying system is designed to use renewable energy sources. To examine the portable conveyor of solar-energized drying system, the foodstuff was used for a testing of ingredients. The portable conveyor of solar-energized drying system testing show that the amount of water content in the foodstuff reduced, the drying rate accelerate. In addition, the amount of heat energy needed for the drying process also reduced. Hence process of drying foodstuff more efficienct.

A novel recirculation type ICDC solar dryer has been designed, constructed and tested. The solar dryer was comprised of a feed hopper, centrifugal blower, pneumatic conveyor and a transparent structure acting as drying chamber containing a hopper with vortex at the top. Test with 104 kg of rough rice indicated that the drying time required to reduce the moisture content of rough rice from 28.4% wet basis (wb) to the final moisture of 14.3%wb was 5 hrs. During the test the drying temperature was kept constant at 50.1°C and relative humidity (RH) of 21.73%. The required power for the pneumatic conveyor was 581 W with total energy input of 210.7 MJ including LPG and solar radiation. The resulting drying efficiency was 22.4% with specific energy of 15.2 MJ/kg of water evaporated. Another test using 200 kg with initial moisture content (m.c.) of 27.6%wb.of rough rice have shown that the required drying time to achieve the final moisture of 14.3% was 8 hrs. During the test the drying temperature was kept at 46.9 C, and RH of 21.7%. The drying efficiency was 31.7% with specific energy of 10.7 MJ/kg water evaporated.

A novel recirculation-type integrated solar collector drying chamber solar dryer has been designed, constructed, and tested. The solar dryer comprises a feed hopper, a centrifugal blower, a pneumatic conveyor, and a transparent structure acting as drying chamber containing a hopper with a vortex at the top. The transparent structure has a dimension of 3 m in diameter and height of 3 m. The blower used has a capacity of maximum 1 kW, 220 V, and a supplying air velocity of 30.3/s. A series of tests were conducted outdoors where solar radiation was available. A test with 104 kg of rough rice indicated that the drying time required to reduce the moisture content (m.c.) of rough rice from 28.4 % wb to the final m.c. of 14.3 % wb was 5 h. During the test, the drying temperature was kept constant at 50.1 °C and the relative humidity (RH) was 21.73 %. The required power for the pneumatic conveyor was 581 W, with a total energy input of 210.7 MJ, including LPG and solar radiation. The resulting drying efficiency was 22.4 % with specific energy of 15.2 MJ/kg of water evaporated. Another test using 200 kg with initial m.c. of 27.6 % wb of rough rice has shown that the required drying time to achieve the final m.c. of 14.3 % was 8 h. During the test, the drying temperature was kept constant at 46.9 °C, and the RH was 21.7 %. The drying efficiency was 31.7 % with specific energy of 10.7 MJ/kg of water evaporated. By knowing the amount of rough rice retained in the receiving hopper and the rate of recirculation, it was possible to measure the drying time of each cycle until the drying process completed. By using the sphere model, we were able to estimate the drying curve, where it was found that a good agreement exists between the theoretical and experimental data using the value of drying constant k = 2.75 (1/hr) and M e of 7 % db. As the drying time increased toward the end of drying process, it was observed that the variation in rough rice m.c. became smaller and smaller and was better than that found in the previous study.

The coventional flat bed dryer has the demerit of having nonhomogeneous drying results. Therefore, to obtain nonhomogeneous drying result recirculating type solar dryer with pneumatic conveyor as the recirculating equipment will be. As the grains transported within the penumatic conveyor rapid heat and mass transfer occur resulting in even drying process and make the final results of the drying process homogene. The complete solar dryer was comprised of a feed hopper, centrifugal blower, pneumatic conveyor and a transparent structure acting as drying chamber containing a hopper with vortex at the top. Pneumatic conveyor was used to make recirculation of the grain and to perform continuous drying process. Spherical model was used to predict the drying time.Test with 104 kg of rough rice indicated that the drying time required to reduce the moisture content of rough rice from 28.4% w.b to the final moisture of 14.3% w.b was 5 h. During the test the drying temperature was kept constant at 50.1 oC and RH of 21.73%. The required power for the pneumatic conveyor was 581 W with total energy input of 210.7 MJ including LPG and solar radiation. The resulting drying efficiency was 22.4% with specific energy of 15.2 MJ · kg–1 water evaporated.