This paper discusses the manufacturing process of rotor radial turbo-expanders for small Organic Rankine Cycle systems using additive manufacturing machine Selective Laser Melting (SLM) machine. The process manufacturing consists of data preparation, build job process, and process finishing product. Data preparations are include material preparations, build data preparation using software 3D design Solidworks, support management with software magics and additive manufacturing software with Autofab for build job process on SLM machine. The results shows rotor with material Aluminum Silicon Powder (AlSi) can be made with either the appropriate geometry design within 5 hours with total cost for the whole processing is up to 11 milion IDR.

This paper discusses measurement of temperature on busbar connection based on contact resistance and plating material in relation to the value of contact resistance. This study is intended to prevent failure when busbar connection is attached. The failure of the electrical connection can occur due to bad contact so that the contact resistance is increased, high losses, overheating, and it can even cause a fire hazard. Thereare three test samples of modeled: copper busbar connection without plating, copper busbar connection with nickel plating and copper busbar connection with silver plating. The contact resistance of each sample was measured at contact pressure of 12 MPa. Subsequently the samples loaded with the current of 350 A and temperature at the connection was measured and simulated until steady state condition reached. The results show that the temperature at the contact area is higher than that of busbar appears caused by the contact resistance. Both measurement and simulation results show that busbar connection with silver plating having lower contact resistance and lower maximum temperature, followed by the connection with the nickel plating and busbar connection without plating.

Pemanfaatan biogas dari kotoran sapi sebagai alternatif bahan bakar pembangkit listrik dilakukan melalui proses anaerobik. Pilot Plant dengan produksi biogas sebesar 7 m 3 /hari telah terpasang di Pesantren Saung Balong. Biogas ini dimanfaatkan untuk keperluan sehari-hari seperti memasak dan penerangan, dan digunakan sebagai bahan bakar pure biogas dengan genset skala 2.500 Watt. Produksi biogas rata-rata sebesar 0,040 m 3 per 30 menit atau 0,080 m 3 /jam. Biogas yang dihasilkan selama pengukuran (450 menit) adalah 0,604 m 3. Dengan data tersebut maka diperkirakan dalam sehari (24 jam) biogas yang dapat dihasilkan adalah sebesar 1,92 m 3. Sementara, konsumsi biogas untuk genset pada beban 1.047 W adalah 0,019 m 3 /menit, genset akan beroperasi selama 101,05 menit atau sekitar 1,68 jam. Dengan demikian listrik yang dapat dihemat adalah 1,759 kWh per-hari atau 52,77 kWh per-bulan dan biaya listrik yang dapat dihemat yaitu sebesar Rp. 40.896/bulan. Kata kunci: biogas, pure biogas, pilot plant, anaerobik.

This paper discussed the influence of tightness or contacts pressure on copper busbar joints to determine changes in the value of the initial contact resistance and the maximum temperature at the joint due to high current load. The test sample was copper busbar 3 x 30 mm with configuration of bolted overlapping joint. Increasing contact pressure at the joint was measured to find out its effect on the value of contact resistance. The applied pressure was 6 to 36 MPa. Procedure of contact resistance measurement refer to the ASTM B539 standard using four-wire method. The sample subsequently loaded with the current of 350 A for 60 minutes and the maximum temperature at the joint was measured. The result showed that increasing contact pressure at the busbar joint will reduce the contact resistance and maximum temperature. The increase of contact pressure from 6 to 30 MPa causes decreasing contact resistance from 16 µΩ to 11 µΩ. Further increasing of contact pressure more than 30 MPa did not affect the contact resistance significantly. The lowest temperatur of busbar joint of 54°C was reached at a contact pressure of 36 Mpa.

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