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Abstrak :
[ABSTRAK
Selain tantangan untuk mereduksi penggunaan energi tak terbarukan yang menyebabkan pemanasan global, potensi besar Indonesia dalam menerima panas dari matahari harus dioptimumkan. Pemanfaatan energi panas dari matahari masih rendah, oleh karena itu solar kolektor bertipe tabung vakum merupakan solusi yang bijak untuk memanfaatkan panas tersebut. Dengan menggunakan heat pipe sebagai media penghantar panas yang pasif, solar kolektor dapat bekerja tanpa konsumsi energi tambahan. Karakterisasi dibawah sinar matahari dan dengan menggunakan lampu halogen beserta voltage regulator dilakukan untuk mengetahui panas yang diserap oleh prototipe. Pada eksperimen ini, kotak insulasi yang dibuat dari styrofoam dan kayu digunakan untuk mengetahui kerugian panas. Untuk meningkatkan jumlah panas yang diserap, plat penyerap panas yang diberi lapisan coating digunakan pada heat pipe. Optimasi performa thermal dilakukan dengan memvariasikan fluida kerja, wick, dan aplikasi sudut kemiringan, dimana air suling, nanofluida Al2O3-air dengan konsentrasi volumetris sebesar 5% dan 0,3% digunakan sebagai fluida kerja, stainless steel screen mesh dengan skala mesh 200, 250, dan 300 digunakan sebagai wick, dan sudut aplikasi divariasikan pada sudut 0o – 60o dengan 15o perubahan sudut kemiringan. Hasil eksperimen dan analisis lanjutan menunjukan bahwa performa thermal terbaik dari prototipe solar kolektor didapatkan dengan penggunaan nanofluida Al2O3-air dengan konsentrasi volumetris 0,3% dan wick dengan skala mesh 300 dan sudut kemiringan sebesar 60o. Resistansi thermal terbaik diketahui sebesar 0,592 oC/W dengan efisiensi sistem yang mencapai 76,53%.

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ABSTRACT
Beside the challenges to reduce the consumption of nonrenewable energy that causes global warming, Indonesia great potential in receiving heat from the sun must be optimized. Since the utilization of thermal energy from the sun is still low, vacuum tube solar collector will be a well applicable solution to utilize the heat. Using heat pipes as passive heat transfer device, this research was conducted to optimize the thermal performance of solar collector without using extra energy. Characterization under the sun, and using halogen lamp with voltage regulator was done in order to predict the heat absorbed by the designed prototype. In this experiment, insulation box, which made of Styrofoam and wood was made to calculate heat losses. To increase heat absorbed, coating fin is applied at heat pipe. Optimization of thermal performance of solar collector was done with varied working fluid, wick of heat pipe, and inclination angle of prototype application, where condensed water, Al2O3-water nanofluid with 5% and 0.3% volumetric concentration were used as varied working fluid, stainless steen screen mesh with 200, 250, and 300 mesh scale were used as wick, and inclination angle was varied from 0o – 60o with 15o inclination angle differences. Experimental result and further analysis shows that the best thermal performance of solar collector prototype by using 0.3% volumetric ratio of Al2O3-water nanofluid as working fluid, stainless steel screen mesh with 300 mesh scale as wick inside heat pipe, and 60o inclination angle for prototype application. The thermal resistance is as high as 0.592 oC/W and the system efficiency is as high as 76.53%., Beside the challenges to reduce the consumption of nonrenewable energy that causes global warming, Indonesia great potential in receiving heat from the sun must be optimized. Since the utilization of thermal energy from the sun is still low, vacuum tube solar collector will be a well applicable solution to utilize the heat. Using heat pipes as passive heat transfer device, this research was conducted to optimize the thermal performance of solar collector without using extra energy. Characterization under the sun, and using halogen lamp with voltage regulator was done in order to predict the heat absorbed by the designed prototype. In this experiment, insulation box, which made of Styrofoam and wood was made to calculate heat losses. To increase heat absorbed, coating fin is applied at heat pipe. Optimization of thermal performance of solar collector was done with varied working fluid, wick of heat pipe, and inclination angle of prototype application, where condensed water, Al2O3-water nanofluid with 5% and 0.3% volumetric concentration were used as varied working fluid, stainless steen screen mesh with 200, 250, and 300 mesh scale were used as wick, and inclination angle was varied from 0o – 60o with 15o inclination angle differences. Experimental result and further analysis shows that the best thermal performance of solar collector prototype by using 0.3% volumetric ratio of Al2O3-water nanofluid as working fluid, stainless steel screen mesh with 300 mesh scale as wick inside heat pipe, and 60o inclination angle for prototype application. The thermal resistance is as high as 0.592 oC/W and the system efficiency is as high as 76.53%.]

Abstrak :
ABSTRAK
Seluruh kegiatan manusia tak lepas akan kebutuhannya atas energi. Pemanfaatan sumber energi tak terbarukan secara berlebihan dan meningkatnya kebutuhan manusia akan energi membuat beberapa isu global menjadi marak diperbincangkan. Salah satu pemanfaatan energi terbarukan adalah dengan menggunakan energi matahari melalui solar water heater. Solar water heater terbagi menjadi dua komponen utama, yaitu solar kolektor dan tangki penyimpanan. Pada paper ini akan dibahas pengujian melalui prototipe tabung vakum solar kolektor berbasis heat pipe ganda sebagai instrumen yang melakukan ekstrkasi panas. Panas dari matahari akan disimulasikan dengan menggunakan lampu halogen dengan daya 150 Watt. Prototipe solar kolektor yang digunakan didesain dengan memanfaatkan satu buah sirip yang menghubungkan kedua buah heat pipe. Pengujian dilakukan dengan menggunakan dinding isolatif dengan menggunakan styrofoam dan tripleks untuk mengurangi pengaruh perpindahan panas dari lingkungan akibat perbedaan temperatur. Variasi yang dilakukan dan diamati pada eksperimen ini adalah pengaruh panjang wick terhadap performa heat pipe dan solar kolektor dimana wick akan mempengaruhi dinamika fluida kerja dan resistansi thermal dari pada heat pipe. Melalui pengujian ini didapatkan bahwa heat pipe dengan wick yang memanjang pada adiabatic zone dan seluruh evaporating zone memiliki resistansi termal yang paling rendah dibandingkan penggunaan heat pipe dengan wick yang menutupi setengah evaporator dan tiga perempat evaporator, yaitu sebesar 0,37 K/W dengan efisiensi sistem tertinggi yaitu sebesar 34,95% sehingga memiliki performa terbaik dibandingkan yang lain.

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ABSTRACT
Every human activity needs energy. The increasing number of non-renewable energy and the rising need of energy caused some global issue. It always be interesting to discuss how human being could create and improve an instrument that can extract energy from renewable energy resources which is clean and applicable. One of the instrument that can extract energy from the sun is solar water heater. Solar water heater is consist of two main component. The first component is called storage tank, and the other is called solar collector. This paper will discuss the experimental result of evacuated tube solar collector based on dual heat pipes as an heat extractor from the sun. The experiment goes with a 150 Watt halogen lamp as a simulator of the sun.The solar collector prototype which is used in this experiment designed with a fin. A copper fin is being used to collect heat from the sun and trasfer the heat to heat pipes. Adibatic walls made from styrofoam and plywood are used in this experiment to prevent any heat transfer from the environment due temperature difference. Wick length inside heat pipe is the variation that being investigated in this research. The flow characteristic inside the heat pipe depend on the wick length, and thermal resistance of heat pipe will be changed as a result of wick length variation. The experiment result conclude that the full length wick heat pipe has the best performace with 0.37 K/W thermal resistantion and the efficiency of the system reach 34,95%. This is the highest value compared to the half length and three quarter length wick heat pipe.