1,720,964 research outputs found
Kajian Eksperimental Mesin Pendingin Adsorpsi Tenaga Surya dengan Menggunakan Adsorben Campuran
Get PDFThe purpose of this study was to obtain the performance of the adsorption refrigerator driven by solar energy using mixed adsorbents. The refrigerant used is methanol with 99% purity. The adsorbent used is a mixture of active carbon-active alumina with mass of 7 kg. The type of active alumina used is molecular sieve 13X and the activated carbon used is the ordinary type of coconut shell with 1-3 mm grain size and is produced in the province of North Sumatra. Note that active alumina and activated carbon tested can absorb methanol in the range of 350 ml/kg and 300 ml/kg with a heat source of about 120oC. The test was carried out in the open field exposed to solar radiation from 08.00 WIB until 08.00 WIB the next day for seven cycles. The average of solar radiation ranges from 107.036-214.44 W/m2, and the duration of radiation varies from 12.03 to 12.28 hours/day during experiments. The test results also show that the use of mixed adsorbents with methanol adsorbate can produce evaporation temperatures up to about 4,16-13,90°C with a heat source from a temperature of 91.32-97.35°C. The efficiency of collector obtained during testing ranges from 60.09 to 62.26% with maximum solar radiation conditions ranging from 799.40 to 882.76 W/m2. The COP value obtained in the range 0.0770-0.1003 with the total daily radiation between 11.245-17.156 MJ/m2
MECHANISM OF WATER DISTRIBUTION ON LEMON FARM LAND
Get PDFPump is mechanical device to increase the pressure energy of a fluid. Generaly pumps are used to lift the water from low level to high level. These are of two types,namely reciprocating pumps and centrifugal pumps. On centrifugal pumps the centrifugal force or variation of pressure due to rotation is responsible for their operation or working.
The program of community services as implementation of sciences and technology intended to introduced and give skill training about water supply units to the community at Desa Sempa jaya ,Kabupaten Deli-Karo. In this area the people have a problem about availibity of water for agricultute, when mountain Sinabung gets eruption the leave of plantation are covered with dust and damaged to citrus plants,in dry season orange plants lack of water even though the success of the harvest is very dependent on water.
The program was carried out by designing, fabricating and erecting the unit of water supply,consist of deepwell pump,piping system, valve,tee,bent,tower tank and panel control.
The result of this community services showed that the capacity of pumps are 6 liter/menit,head are 50-70 meter,power 2 HP,speed 1500 rpm.capacity of tower tank 5400 liter, the pump may supply the water to tower tank until full about 2 hours,and the farmer may use the water from the tower tank by gravitation about 3 days
EFEK BAHAN BAKAR BIODIESEL DARI MINYAK KEDELAI TERHADAP EMISI GAS BUANG DAN TEMPERATUR RUANG BAKAR MESIN DIESEL
Get PDFSaat ini bahan bakar biodiesel yang digunakan untuk mesin diesel umumnya berasal dari CPO (crude palm oil). Penelitian ini menggunakan bahan bakar biodiesel dengan bahan baku minyak kedelai. Tujuan penelitian ini selain untuk mengetahui pengaruhnya terhadap kinerja mesin, diteliti juga efeknya terhadap perubahan temperatur di ruang bakar mesin diesel yang diuji dan emisi gas buang yang dihasilkan. Perlu diketahui bahwa perubahan temperatur di ruang bakar sangat mempengaruhi proses pembakaran yang dihasilkan mesin dan hal masih sangat jarang dikaji oleh para peneliti. Metode penelitian diawali dengan pengujian nilai kalor bahan bakar yaitu B30, B20, B10 dan minyak solar. Untuk pengujian kinerja mesin digunakan mesin diesel empat langkah tanpa modifikasi. Dari hasil eksperimental tampak bahwa terjadi peningkatan nilai pemakaian bahan bakar spesifik yang sesuai dengan meningkatnya komposisi biodiesel minyak kedelai di dalam campuran bahan bakar. Besarnya emisi gas buang CO dan HC mengalami penurunan saat menggunakan bahan bakar B10, B20 dan B30. Data eksperimental menunjukkan bahwa daya maksimum diperoleh 1,26 kW, konsumsi bahan bakar spesifik 373,15 g/kWh dan efisiensi termal maksimum 23,04% saat menggunakan bahan bakar solar. Temperatur maksimum ruang bakar mesin diesel diperoleh saat menggunakan bahan bakar solar sebesar 507,86°C. Data pengujian menunjukkan bahwa temperatur ruang bakar minimum diperoleh saat mesin diesel menggunakan bahan bakar B30 sebesar 388,49°C
Analisa kinerja sistempendingin peltier yang menggunakan sel PVdengan sumber energi radiasi matahari
No full textAbstrak:
Pemanfaatan energi surya secara umum digunakan untuk energi termal dan energi listrik. Salah satu aplikasi dari sistempemanfaatan untuk energi listrik adalah penggunaan fotovoltaik (PV). Tujuan penelitian ini adalah untuk mengetahui kinerjasistem kerja kotak pendingin dengan bantuan sel PV yang menyerap sumber energi matahari. Kelebihan dari dari sistempendinginan ini adalah beroperasi tanpa menggunakan energi listrik serta ramah lingkungan. Penelitian ini menggunakankomponen elektronik peltier untuk pendingin. Komponen peltier dirangkai dengan heat sink dan kipas kecil diletakkan di bagianluar dan kipas yang lain diletakkan di bagian dalam kotak pendingin. Kotak pendingin terbuat dari styrofoam. Data perubahantemperatur sistem kotak pendingin yang diperoleh kemudian dianalisa sehingga dapat diperoleh kinerja sistem kotak pendingintersebut. Pengujian dilakukan di ruangan terbuka yang mengalami paparan radiasi matahari. Proses pengukuran parametercuaca dilakukan dengan menggunakan alat ukur cuaca HOBO dan untuk merekam perubahan temperatur pada setiapkomponen sistem pendingin peltier digunakan data akuisisi. Hasil penelitian menunjukkan bahwa nilai COP maksimum sistempendingin peltier yang dapat dicapai adalah 0,317. Pada penelitian ini, juga diteliti pengaruh kondisi cuaca yang meliputi radiasimatahari, temperatur dan kelembaban udara terhadap kinerja sistem pendingin peltier.Kata kunci: sistem pendingin peltier, kinerja
Abstract:
The utilization of solar energy consist of thermal energy and electrical energy. One application of the system for the utilization ofelectrical energy was photovoltaic (PV). The purpose of this study is to determine the performance of cooler box with PV cellsthat absorb the solar energy. The advantages of this cooling system was operated without using the electrical energy andenvironmentally friendly. This study uses electronic components Peltier for cooling. The peltier component assembled with a heatsink. The small fan that was placed on the outside and the other fan was placed inside the cooler. The cooler system was madeof styrofoam. The changing of temperature in the cooler system was analyzed and obtained the performance of the cooling boxsystem. The experiments were carried out in open space which exposure to solar radiation. The HOBO station was used tomeasure the weather parameter. To record the changing of temperature in the components was used data acquisition. Theresults showed that the maximum COP of peltier cooling system that can be achieved was 0.317. In this research, also wasstudied the effect of weather conditions against the performance of peltier cooling system.Keywords: peltier cooling system, performanc
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Experimental Study of Solar Refrigerator System using Activated Alumina and Methanol Adsorption Pair
Get PDFThis study investigates the performance of a solar adsorption refrigerator using activated alumina and methanol adsorption pair. The experiments were carried out for 24-hour. The refrigeration was completed during seven cycles with varying weather conditions. A flat plate type collector was used with an area of 0.25 m2 and tilt angle of 30o. Theoretical calculations show that, the maximum collector efficiency is 47.15% when the maximum solar radiation obtained is 936.9 W/m2. In this research, the maximum value of the COP is 0.0991 when the total solar energy is 16.485 MJ/m2 and the minimum value obtained is 0.0919 when the total solar energy is 7.609 MJ/m2. The experiment results show that the adsorption pair system can deliver an evaporator temperature of about 9.92°C and the cooling load can be achieved by a heat source with a temperature range of 83.95°C and 95.39oC
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Artificial Neural Network (ANN) Backpropagation to Forecast 100% Renewable Energy in North Sumatra
Get PDFNorth Sumatra possesses abundant natural resources, including renewable energy sources such as water, geothermal, biomass, biogas, waste and solar energy. However, currently, these resources are not optimally utilized for electricity generation, with fossil fuel plants still dominating the energy mix. This research aims to establish an objective function model to optimize the use of renewable energy sources in North Sumatra by phasing out fossil fuel plants. The method employed in this study is a statistical approach based on secondary data from PT. PLN Persero in the North Sumatra region, which was optimized using the Firefly (FA) and Particle Swarm Optimization (PSO) algorithms. Analysis of the results reveals that the lowest absolute value of θ for |FA/RE–Thermal| in 2064 is 335.404192, while the lowest absolute value for |PSO/RE-Thermal| in 2065 is projected to reach 689.475978. A smaller absolute value of θ indicates closer proximity to the optimum value. Therefore, renewable energy optimization using the Firefly algorithm is predicted, using the Backpropagation Neural Network method, to be achievable in 2064, while with the PSO algorithm, it is expected to be realized in 2065, thus eliminating the need for thermal generators. The θ value serves as a parameter for measuring the discrepancy between predicted and actual values, with a smaller θ value indicating closer proximity to the optimum value. In the context of renewable energy optimization, the optimum value represents the level of renewable energy utilization required to supplant thermal generation. This research contributes by predicting that achieving 100% renewable energy utilization in North Sumatra can be attained by 2064 using the Firefly algorithm, based on the Backpropagation Neural Network method, and by 2065 using the PSO algorithm
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