ekadewi handoyo - Academia.edu (original) (raw)

Papers by ekadewi handoyo

Solar Energy, 2016

founded in 1954 and is now incorporated as a non-pro t educational and scienti c institution. Wit... more founded in 1954 and is now incorporated as a non-pro t educational and scienti c institution. With participation encompassing 100 countries, ISES® serves as a centre for information on research and development in solar energy utilisation. Through its publications and its sponsorship of technical conferences, the Society provides a world forum for the active consideration of solar energy.

Rumput laut adalah salah satu hasil alam Indonesia yang sedang berkembang sekarang. Rumput laut b... more Rumput laut adalah salah satu hasil alam Indonesia yang sedang berkembang sekarang. Rumput laut biasa dikeringkan terlebih dahulu guna mengurangi bobot pengiriman dan agar tidak mudah rusak. Rumput laut dikeringkan dengan cara dijemur dibawah sinar matahari. Pengeringan secara tradisional ini memerlukan waktu yang lama untuk mendapatkan rumput laut yang kering dan siap dikirim. Oleh karenanya digunakan ketel uap agar mempercepat proses pengeringan dari rumput laut. Ketel uap yang digunakan adalah ketel uap piapa api, karena tekanan kerja hanya 7 bar (gauge). Ketel uap dirancang untuk menghasilkan uap jenuh sebanyak 500 kg/jam. Ketel berupa alat penukar kalor jenis shell and tube yang dilengkapi dengan cerobong, dengan menggunakan bahan bakar batubara. Dari hasil perancangan didapat kebutuhan bahan bakar sebanyak 82 kg/jam, jumlah pipa sebanyak 268 buah, dengan diameter 52,7 mm, panjang 6 m, dengan susunan pipa berjajar dan jarak antar pipa sebesar 121 mm. sehingga didapat diameter s...

Electricity demand growth in the long run should be satisfied by a matched available power supply... more Electricity demand growth in the long run should be satisfied by a matched available power supply. Several aspects involved in this issue include the proper projection of sectoral end-use electricity demand, appropriate assumpsion on key parameters, available energy resources and power energy delivered into the system. Such energy system can be represented in a long-term electricity supply-demand model. This paper presents a long-term electricity planning model using Longrange Energy Alternatives Planning System (LEAP), an accounting framework bottom-up model tool. A district area sustainable long-term electricity planning taken into account household, business, industry, and public sectors from 2013 to 2025 is modelled with emphasized on the involvement of demand side mitigation scenario to help reduce the need of energy. From the analysis, the Jember-Lumajang district electricity consumption is estimated to be around 2,310.3 Thousand MWh in 2025 with BEU scenario and it would be r...

Jurnal Teknik Mesin

Energi matahari dapat dikonversikan menjadi energi termal dengan menggunakan kolektor surya maupu... more Energi matahari dapat dikonversikan menjadi energi termal dengan menggunakan kolektor surya maupun menjadi energi listrik dengan menggunakan sel surya/photovoltaic. Radiasi matahari bersifat menyebar, sehingga memerlukan pengumpul atau pengarah agar lebih fokus.Ada banyak penelitian yang menggunakan lensa Fresnel untuk mengumpulkan radiasi matahari pada sel surya. Sedang penelitian lensa Fresnel pada kolektor surya masih terbatas sebagai concentrator. Makalah ini membahas perancangan dan pemakaian lensa Fresnel sebagai penutup pada suatu kolektor surya plat datar. Lensa Fresnel komersial hanya memiliki 1 titik fokus, maka langkah pertama penelitian adalah merancang lensa Fresnel dengan enam titik fokus. Jarak focus dirancang agar radiasi matahari jatuh ke plat penyerap pada jarak 90 mm dari lensa Fresnel. Bahan yang digunakan adalah PMMA Polymethyl methacrylate (acrylic) dan pembuatan profil lensa menggunakan proses tekan. Lensa Fresnel yang dihasilkan berhasil memiliki titik fokus ...

IOP Conference Series: Materials Science and Engineering

A passive solar heater can be used to heat air in a room or water for some household needs. Passi... more A passive solar heater can be used to heat air in a room or water for some household needs. Passive solar heater can reduce the energy consumption by converting solar radiation energy to be thermal energy. Basically, a simple passive solar heater consists of absorber plate, thermal insulation, working fluid, cover, and structure to hold everything. This paper will discuss about the effect of Fresnel lens used as the cover and the air gap between cover and absorber plate on a passive solar water heater. The results of the experiment are that the commercial Fresnel lens could not gave the highest water temperature nor efficiency for passive solar water heater. The highest efficiency with glass cover and five-cm air gap was 22.8%. The smaller the air gap, the higher the water temperature in a passive solar water heater. The highest water temperature with glass cover and five-cm air gap was 63.8°C. The result of this experiment gives new challenge for the next research: we do the experi...

Jurnal Teknik Mesin Indonesia

Pengelasan induksi magnetik adalah proses umum dalam produksi pipa. Impeder yang digunakan dalam ... more Pengelasan induksi magnetik adalah proses umum dalam produksi pipa. Impeder yang digunakan dalam mesin las perlu didinginkan untuk menjaga suhunya di bawah 35oC. Cairan pendingin adalah air dengan 2% cutting oil dan disebut pendingin. Itu harus memasukkan impeder pada 15oC. Laju aliran yang dibutuhkan adalah sebanyak 30 lt / mnt. Untuk memastikan suhu impeder dijaga lebih rendah dari suhu yang dibutuhkan, maka penukar panas harus dirancang untuk mendinginkan pendingin dari 40oC hingga 15oC. Air chiller berpendingin udara tipe UWAP750AY3 digunakan untuk menghasilkan air dingin yang dibutuhkan oleh penukar panas. Pipa tembaga bersirip 5/8-inci digunakan sebagai tabung di penukar panas. Pendingin dibagi dalam empat tabung yang sama dari header. Untuk memenuhi area perpindahan panas yang dibutuhkan, setiap tabung akan ditekuk untuk membuat 10 lintasan (atau baris). Di akhir baris terakhir, empat aliran akan dikumpulkan di header. Kemudian, pendingin akan diedarkan ke impeder dengan suhu...

E3S Web of Conferences

Garden by The Bay in Singapore is the world’s largest coolest conservatories. Although it is loca... more Garden by The Bay in Singapore is the world’s largest coolest conservatories. Although it is located in tropics and uses so many glasses, its electricity consumption is as much as a commercial building. The key to this low consumption is in air cooling technology. Air used for cooling the conservatories is dehumidified first using liquid desiccants before cooled. The same technology was implemented to a single-split air conditioner (AC) that works on a vapor-compression refrigeration cycle. The experiments were conducted in a room with opened and closed door. Instead of using a liquid desiccant, the experiment used a solid desiccant, i.e., silica gel which thickness was 6 mm and 8 mm with density equals to 1.27 gr cm–3. From the experiment, it is found that: (i) the thicker the silica gel, the higher outlet air temperature from silica gel, (ii) less condensate will be produced when the silica gel used is thicker, (iii) silica gel is suitable for reducing humidity of outdoor/fresh ai...

SHS Web of Conferences

Service learning is new for engineering students in PCU. When heat transfer class was adopting se... more Service learning is new for engineering students in PCU. When heat transfer class was adopting service learning methode last year, a small survey was done to know the students’ respond for this new methode. The survey was done via reflection they wrote in the end of the process. The students learn not only heat transfer itself, but they also learn how to apply it to an oven needed by a community in Kebontunggul, a small village in Mojokerto. The students in three groups visited the village, discussed with the villagers, and designed the oven used to dry crackers’ paste made from corn, cassava, and rice flour. Once the design was ready, the students went to workshop to manufacture the ovens. The oven was tested before sent to the village. They learned that it was difficult to make those cheap crackers. They learned a lot from the villagers in social interpersonal, social intrapersonal, emotional, and cognitive process. They are thankful to God for their being and grateful for this Se...

2015 Seventh International Conference on Computational Intelligence, Modelling and Simulation (CIMSim), 2015

This paper reports the application of new developed "Tool for Electricity Energy Planning" (TEEP)... more This paper reports the application of new developed "Tool for Electricity Energy Planning" (TEEP), an accounting framework based bottom-up model to simulate long-term electricity supply-demand planning. The simulation is carried out using electricity sector data of Banyuwangi regency in East Java province, Indonesia. The projection of electricity demand and supply which consider fossil fuel as well as renewable energy potential is taken into account in the simulation to find the resources allocation implications and generation costs. The total electricity demand would increase up to 2,027.5 GWh from the initial value of 783.4 GWh. In the case of generation mix, the total generation costs of coal fired power plant could be reduced by 450 Million US$ and potential coal saving would be 4.375 thousand ton, among other findings.

Salah satu alat penukar kalor yang penting di negara tropis seperti Indonesia adalah kolektor sur... more Salah satu alat penukar kalor yang penting di negara tropis seperti Indonesia adalah kolektor surya yang dapat digunakan untuk memanaskan air atau udara. Problem terbesar yang dihadapi kolektor surya pemanas udara adalah rendahnya koefisien perpindahan kalor konveksi antara permukaan plat penyerap dengan udara yang mengalir di sebelah atas atau bawahnya. Koefisien perpindahan kalor konveksi gas jauh lebih rendah dari cairan, baik untuk konveksi jenis alami ataupun jenis paksa. Hal ini mendorong banyak peneliti berupaya untuk meningkatkan efisiensi kolektor surya pemanas udara. Berbagai upaya yang telah dilakukan peneliti terdahulu adalah menggunakan plat absorber yang dicat hitam atau diberi lapisan yang mempunyai absorptance tinggi dan emittance rendah, memasang honeycomb untuk mengurangi kalor yang hilang ke lingkungan, membuat aliran menjadi dua laluan, meningkatkan koefisien konveksi udara dengan plat absorber dengan mempersempit saluran sehingga aliran menjadi turbulen, dan menggunakan v-corrugated absorber plate sehingga membentuk saluran dengan penampang segitiga. Kolektor surya pemanas udara yang menggunakan saluran dengan penampang segitiga mempunyai kinerja lebih baik dibandingkan dengan saluran plat datar. Namun, belum ada simulasi numerik untuk aliran dalam saluran dengan penampang segitiga ini. Oleh karenanya, makalah ini akan membahas simulasi numerik aliran tersebut dan kemudian dibandingkan dengan hasil eksperimen. Simulasi diawali dengan pembuatan mesh dan evaluasi grid independency. Dengan konfigurasi mesh yang terpilih, tahap selanjutnya adalah memilih model viscous yang tepat untuk masalah yang diteliti. Model viscous steady state yang dibandingkan adalah SKE, RNGKE, RKE, SKW, dan STTKW. Pemilihan model dilakukan dengan mengacu pada hasil eksperimen. Mesh dengan jumlah node 540.000 dan jumlah cell 566.401 merupakan konfigurasi yang terbaik dan memenuhi grid independency, sehingga konfigurasi ini yang digunakan dalam studi numerik berikutnya. Sedangkan model viscous yang memberikan hasil simulasi paling mendekati hasil ekperimen terjadi pada model viscous RKE. Perbedaan hasil simulasi numerik terhadap hasil eksperimen untuk kenaikan temperatur udara mencapai 15.56 dan untuk penurunan tekanan mencapai 17.15.

Wire drawing die wear is measured by the dilatation of die gap diameter. Many factors that contri... more Wire drawing die wear is measured by the dilatation of die gap diameter. Many factors that contribute to wire drawing die wear, one of them is temperature of the wire during drawing process. Therefore, die cooling system have to be considered to reduce die wear. Water that is cooled by cooling tower is usually used as die coolant. If the heat is not transferred well to the coolant, then the die wear will happen faster and the die needs replacement more often. ASM International gives suggestion to maintain the die gap or the wire’s temperature at 137°C during drawing process. At this temperature, die wear will be 0.01 mm for 500 km of drawing wire that contains 0.08 % Carbon. In a wire company that produces AISI 1010, wire was drawn from diameter 5.5 mm to 4.75 mm and die wear was 0.05 mm for 332.1 km of drawing wire. This die wear showed the existing die cooling system was not enough. Assessment of existing cooling system and numerical simulation were conducted to find solution. From the assessment, the cooling tower’s average effectiveness was only 25.9%. Numerical simulation using Gambit, ANSYS Workbench, and ANSYS Fluent was conducted to obtain die gap surface temperature and some improvement of the cooling system. The mesh used in simulation is 0.7 mm interval and Standard K-Epsilon (SKE) is chosen as the viscous model. From the simulation, die gap or wire temperature was found 159.3°C. This value is much higher than 137°C that is recommended by ASM International. Some improvement proposed to the existing cooling system are: 1) Replacing the cooling tower or using water chiller to produce water flowing into die box at rate of at least 0.332 l/s and maximum temperature of 25°C; 2) Changing the die box shape into cylindrical shape.Wire drawing die wear is measured by the dilatation of die gap diameter. Many factors that contribute to wire drawing die wear, one of them is temperature of the wire during drawing process. Therefore, die cooling system have to be considered to reduce die wear. Water that is cooled by cooling tower is usually used as die coolant. If the heat is not transferred well to the coolant, then the die wear will happen faster and the die needs replacement more often. ASM International gives suggestion to maintain the die gap or the wire’s temperature at 137°C during drawing process. At this temperature, die wear will be 0.01 mm for 500 km of drawing wire that contains 0.08 % Carbon. In a wire company that produces AISI 1010, wire was drawn from diameter 5.5 mm to 4.75 mm and die wear was 0.05 mm for 332.1 km of drawing wire. This die wear showed the existing die cooling system was not enough. Assessment of existing cooling system and numerical simulation were conducted to find solution. From the assessment, the c...

Applied Mechanics and Materials, 2014

A solar air heater (SAH) is a simple heater using solar radiation that is useful for drying or sp... more A solar air heater (SAH) is a simple heater using solar radiation that is useful for drying or space heating. Unfortunately, heat transfer from the absorber plate to the air inside the solar air heater is low. Some researchers reported that obstacles are able to improve the heat transfer in a flat plate solar air collector and others found that a v-corrugated absorber plate gives better heat transfer than a flat plate. Yet, no work of combining these two findings is found.This paper describes the result of experimental study on a SAH with v-corrugated absorber plate and obstacles bent vertically started from 80o to 0o with interval 10o on its bottom plate. Experiments were conducted indoor at five different Reynolds numbers (1447 Re 7237) and three different radiation intensities (430, 573, and 716 W/m2).It is found that the obstacles improve SAH performance. Both the air temperature rise and efficiency increase with inserting obstacles bent at any angle vertically. Unfortunately, t...

A refrigerator mostly operates on vapor-compression refrigeration cycle needs a lot of energy (us... more A refrigerator mostly operates on vapor-compression refrigeration cycle needs a lot of energy (usually electricity) as an input. An attempt to wire the capillary tube to line suction will be analyzed in this article to find its effect to the refrigerator's performance. The experiment is carried on a freezer. The performance analyzed is its COP and time needed to cool down 1Co brine from 6oC to 5oC and so on until -3oC. From the experiment, it is found that wiring capillary tube could increase the freezer's COP, yet the time needed to cool the brine is not much effected. Abstract in Bahasa Indonesia : Mesin pendingin yang kebanyakan bekerja dengan dasar siklus pendingin kompresi uap membutuhkan energi input (umumnya listrik) dalam jumlah cukup besar. Dalam artikel ini dibahas pengaruh usaha melilitkan pipa kapiler pada line suction terhadap performansi suatu mesin pendingin, dalam eksperimen ini digunakan freezer. Performansi yang diamati adalah COP dan waktu pendinginan. Wak...

Ilmu tanpa pengenalan akan Pencipta akan menghasilkan kehampaan dan menjadi sia-sia. Itu sebabnya... more Ilmu tanpa pengenalan akan Pencipta akan menghasilkan kehampaan dan menjadi sia-sia. Itu sebabnya ilmu yang dipelajari perlu diintegrasi dengan iman percaya kepada Tuhan Pencipta. Dalam makalah ini akan dibahas beberapa fenomena yang terjadi di alam yang terkait dengan ilmu bidang termal, yaitu Termodinamika dan Perpindahan Kalor. Fenomena yang dibahas adalah anomali air, tekanan dan temperatur saturasi air, tekanan atmosfir, konductivitas bahan, angin di laut, dan radiasi dari matahari. Ilmu yang dipahami sebagai wahyu dari Pencipta dapat menghantarkan manusia mengagumi, menyembah dan memuji Penciptanya.

Shell-and-tube heat exchanger is a device commonly used to transfer heat. To enhance the heat tra... more Shell-and-tube heat exchanger is a device commonly used to transfer heat. To enhance the heat transfer occurred and to support the tubes inside the shell, baffles are installed. Better heat transfer is obviously expected in a heat exchanger. A research is done to find out the effect of baffle used toward the effectiveness and pressure drop in heat exchanger. The result is that the effectiveness increases when the baffles are installed. Effectiveness increases as the spacing between the baffles is smaller until certain spacing, and then it decreases. Abstract in Bahasa Indonesia : Shell-and-tube heat exchanger merupakan jenis alat penukar panas yang banyak digunakan. Untuk membuat perpindahan panas lebih baik dan untuk menyangga tube yang ada di dalam shell, maka sering dipasang baffle. Perpindahan panas yang lebih baik sangat diharapkan dalam suatu heat exchanger. Penelitian dilakukan untuk mengetahui pengaruh penggunaan baffle terhadap efektifitas dan penurunan tekanan dalam heat e...

In a heat exchanger, there is heat transferred either from the surrounding or to the surrounding,... more In a heat exchanger, there is heat transferred either from the surrounding or to the surrounding, which is not expected. A thermal insulator is used to reduce this heat transfer. The effectiveness of a heat exchanger will increase if the heat loss to surrounding can be reduced. Theoretically, the thicker the insulator the smaller the heat loss in a plate heat exchanger. A research is carried on to study the effect of an insulator thickness on heat exchanger effectiveness. The insulators used are glasswool and rockwool. It turns out that the effectiveness is increasing until a maximum point, and then decreasing when the thickness of the insulator is increasing. Abstract in Bahasa Indonesia : Dalam suatu heat exchanger selalu terjadi perpindahan panas ke atau dari lingkungan yang tidak diharapkan. Untuk mengurangi perpindahan panas ini digunakan isolator termal. Efektivitas heat exchanger akan meningkat jika panas yang hilang ke atau dari lingkungan dapat dikurangi. Secara teoritis un...