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"Cooling systems in tropical countries consume a large portion of the overall energy usage in a building, especially in tropical climates, where there is an especially high demand on cooling systems throughout the year. This paper presents a simulation of the effect of zeolite adsorbent granular size on a zeolite-water solar adsorption chiller for Universitas Indonesia. The adsorption chiller is being mathematically modeled and calculated numerically, using MATLAB®. The mathematical modeling is based on heat transfer principles inside the system for the water inlet and outlet of the system. The adsorption chiller is based on the most recent chiller developed by Shanghai Jiao Tong University (SJTU). The simulation results generally demonstrated the running characteristics of the chiller under a range of different values of granular size. The average granular sizes used in the simulation ranged from 0.5 mm to 1.5 mm. Furthermore, the simulation results showed in detail that the smaller the average granular size of zeolites, the faster the time needed to reach the maximum hot water temperature and the balance state of chilled water outlet temperature."

"Cooling systems in tropical countries consume a large part of energy usage in a building, especially in a tropical climate, which places a high demand on cooling systems throughout the year. This paper presents a simulation of a two-bed silica gel-water adsorption chiller, utilizing solar energy based in the tropical climate of Indonesia. The adsorption chiller is being mathematically modelled and calculated numerically using MATLAB®. The simulation is used to show the performance of the chiller during the working hours, based on maximum and minimum inputs of solar irradiation in Indonesia Furthermore, mass recovery and heat recovery is also applied in the adsorption cycle in order to increase the cooling capacity. The adsorption chiller is based on the most recent chiller developed by Shanghai Jiao Tong University (SJTU). The simulation results generally demonstrated the running characteristics of the chiller under a range of different values of solar radiation. Furthermore, the simulation results in detail showed that during the maximum value of irradiation, the average value of COP can reach 0.26, while during the minimum value of irradiation the COP is 0.15. At the same time, the cooling capacity is also varied which can reach up to the maximum value of 37.8 kW, whereas in the minimum range of irradiation values, the cooling capacity dropped to 5.3 kW."

"ABSTRAKSistem pendingin mengkonsumsi bagian yang besar dari keseluruhan konsumsi energi pada sebuah gedung, terutama di daerah tropis seperti di Indonesia yang mempunyai permintaan sistem pendingin yang besar sepanjang tahun. Naskah ini mempresentasikan simulasi chiller sistem adsorpsi dengan 2 buah adsorber yang memanfaatkan tenaga matahari sesuai iklim di Indonesia. Chiller adsorpsi dimodelkan dan dikalkulasi secara matematika menggunakan perangkat lunak MATLAB®. Simulasi dilakukan secara transien selama jam kerja sehingga mendapatkan nilai temperatur pada titik-titik tertentu pada chiller. Selain itu, sistem mass recovery dan heat recovery juga diaplikasikan dalam sistem untuk memaksimalkan efisiensi. Chiller yang dimanfaatkan berdasarkan pada chiller terbaru yang dikembangkan oleh SJTU. Simulasi dijalankan pada beberapa variasi, yaitu pada input air panas temperatur 60oC dan 90oC untuk mendapatkan range performa chiller, kemudian dilakukan simulasi pada input sesuai radiasi. Selain itu, variasi juga dilakukan dengan penambahan PCM pada tangki air panas untuk meningkatkan efisiensi. Hasil simulasi menunjukkan range performa chiller berada pada COP 0,043-0,342. Secara umum, performa chiller apabila memanfaatkan energi matahari mencapai COP 0,282 dengan kapasitas pendinginan 17 kW, serta dengan adanya PCM mampu meningkatkan performa chiller.

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ABSTRACTCooling system consumes a large part of energy consumption in a building, especially tropical area like Indonesia which has a high demand of cooling system along the year. This paper presented a simulation of two bed silica gel-water adsorption chiller utilizing solar energy based on Indonesia climate. The adsorption chiller is being mathematically modelled and calculated numerically using MATLAB®. The simulation is run transiently at working hours to achieve temperature in some points in the system. Furthermore, mass recovery and heat recovery is also applied in the adsorption cycle in order to increase the efficiency. The adsorption chiller is based on the most recent development by SJTU. Simulation is being run in some variations, for the stable hot water temperature in 60oC and 90oC in order to get the range of chiller performance. Then simulation is run using the radiation data as input energy. Another variation using PCM is also added to the hot water tank in order to increase the efficiency. The simulation results demonstrated the running characteristic of the chiller with the range of COP 0.043-0.342. In general, the chiller performance can reach COP 0.282 with 19 kW cooling capacity when utilize the solar radiation as input energy. Moreover, Adding PCM in hot water tank also can improve the chiller’s performance."

"ABSTRAKSolar Thermal Cooling System with its absorption cycle is expected toreplace the conventional air conditioning system with vapor compression cyclebecause it is more efficient in terms of cost and energy. However, due to the heatof the sun is not always stable, the system needs to be equipped with a backupenergy source, one of which is CNG. In the Manufacturing Research Centerbuilding, the lack of facilities that support availability of CNG causes largeoperating costs. Therefore, Optimization efforts with the aim to reduce operatingcosts are needed. Simulation and optimization performed with EnergyPlus andGenOpt. The conclusion is that the installation of 100 kW electric heater tanklesshot water storage tank is able to reduce total operating costs by 34.95% comparedto the use of a combination of solar thermal and CNG and 49.92% compared withthe full use of CNG.

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ABSTRACTSolar Thermal Cooling System with its absorption cycle is expected toreplace the conventional air conditioning system with vapor compression cyclebecause it is more efficient in terms of cost and energy. However, due to the heatof the sun is not always stable, the system needs to be equipped with a backupenergy source, one of which is CNG. In the Manufacturing Research Centerbuilding, the lack of facilities that support availability of CNG causes largeoperating costs. Therefore, Optimization efforts with the aim to reduce operatingcosts are needed. Simulation and optimization performed with EnergyPlus andGenOpt. The conclusion is that the installation of 100 kW electric heater tanklesshot water storage tank is able to reduce total operating costs by 34.95% comparedto the use of a combination of solar thermal and CNG and 49.92% compared withthe full use of CNG."

"Penggunaan energi yang tidak terbarukan seperti minyak bumi dan batu bara secara perlahan telah membawa dunia ini ke dalam krisis energi, sehingga diperlukan upaya penghematan energi. Isu dunia mengenai penghematan energi tersebut sangat berkaitan erat dengan industri otomotif. Industri otomotif dituntut untuk menghasilkan produk dengan emisi kendaraan yang rendah dan kendaraan yang hemat bahan bakar. Material TWDI (thin wall ductile iron) yang dapat dilakukan pemrosesan lanjut menjadi TWADI (thin wall austempered ductile iron) menjadi kandidat yang paling menarik karena sifat mekanisnya yang baik serta biaya yang lebih murah jika dibandingkan dengan aluminium. Tantangan yang dihadapi pada proses pembuatan material TWDI saat ini yaitu kecenderungan terbentuknya lapisan kulit (skin effect) pada permukaan logam hasil pengecoran yang dapat menurunkan sifat mekanis.Penelitian ini dilakukan untuk mendapatkan pengaruh penggunaan isolator berupa glasswool, kayu, dan rockwool dengan ketebalan 40 mm terhadap kecepatan pendinginan. Pengujian yang dilakukan adalah pengujian komposisi kimia, pengamatan makro, pengamatan struktur mikro, dan pengujian tarik. Pengamatan struktur mikro dilakukan secara kualitatif dan kuantitatif, dengan bantuan program image analysis. Sedangkan analisis kecepatan pendinginan didapatkan secara kualitatif.Hasil dari penelitian ini diketahui bahwa kecepatan pendinginan merupakan fungsi dari jumlah nodul, karbida, nodularitas, dan diameter rata-rata nodul. Kecepatan pendinginan tercepat hingga terlambat yaitu pada penggunaan isolator rockwool (P9M1), kayu (P8M1), dan glasswool (P6M1). Untuk ketebalan lapisan kulit rata-rata terbesar hingga terkecil yaitu P8M1 32,58 μm, P9M1 25,59 μm, dan P6M1 25,45 μm. Dari karakteristik nodul, P8M1 memiliki nodularitas tertinggi sebesar 81% lalu diikuti P6M1 sebesar 79% dan P9M1 sebesar 76%. P6M1 memiliki 1605 nodul/mm2, P9M1 1274 nodul/mm2 dan P8M1 1141 nodul/mm2. Sedangkan, diameter nodul P6M1 10,20 μm, P8M1 9,71 μm, dan P9M1 9,09 μm. Matriks yang didapatkan adalah ferit dan karbida dengan tingkat keparahan karbida tertinggi hingga terendah yaitu P9M1, P8M1, dan P6M1. Nilai kekuatan tarik P6M1 367 MPa, P9M1 329 MPa, dan P8M1 146 MPa. Sedangkan elongasi P6M1 2%, P9M1 1,1%, dan P8M1 1%. Sifat mekanis yang didapatkan masih berada di bawah nilai standar.

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Nowadays, the use of unsustainable energy such as petroleum and coal subsequently has brought us to the energy crisis. So that the effort of saving energy is crucial. World issues regarding energy savings is very closely related to the automotive industry. The automotive industry is required to produce products with lower emissions and fuel-efficient vehicles. TWDI (thin wall ductile iron) which can be processed to TWADI (thin wall austemperd ductile iron) became the best candidate due to good mechanical properties and lower cost comparing to aluminum. The challenge confronted in the process of TWDI making is the tendency of skin formation on the surface of the metal casting reduced its mechanical properties.

This research is conducted to obtain the effect of insulators utilization such as glasswool, wood, and rockwool with the thickness of 40 mm towards the cooling rate. Methods performed are chemical composition, visual observation, microstructure observation, and tensile testing. While, microstructure observation is conducted qualitatively and quantitatively using image analysis program, the analysis of the cooling rate is obtained qualitatively.

The cooling rate, from the fastest to the slowest, is rockwool (P9M1), wood (P8M1), and glasswool (P6M1). Where as, for the average skin thickness, from the biggest to the smallest, is P8M1 32.58 μm, P9M1 25.59 μm, and P6M1 25.45 μm. For nodule characteristics, P8M1 has the 81% nodularity and then followed by P6M1 with 79% and P9M1 with 76%. While, P6M1 has 1605 nodule/mm2, P9M1 and P8M1 has 1274 and 1141 nodul/mm2, respectively. While, the biggest nodule diameter is P6M1 with 10.20 μm, the next is P8M1 with 9.71 μm and then P9M1 with 9.09 μm. Ferrite and carbide is found in the matrix. The severity level of carbide, from the highest to the lowest, is P9M1, P8M1 and P6M1. From mechanical aspects, the highest ultimate tensile strength is obtained by P6M1 with 367 MPa, then followed by P9M1 with 329 MPa and P8M1 with 146 MPa. Where as, for the elongation, P6M1 is 2%, P9M1 is 1.1% and P8M1 is 1%. The mechanical properties obtained don't fulfill the standardfollowed by P6M1 with 79 and P9M1 with 76 While P6M1 has 1605 nodule mm2 P9M1 and P8M1 has 1274 and 1141 nodul mm2 respectively While the biggest nodule diameter is P6M1 with 10 20 m the next is P8M1 with 9 71 m and then P9M1 with 9 09 m Ferrite and carbide is found in the matrix The severity level of carbide from the highest to the lowest is P9M1 P8M1 and P6M1 From mechanical aspects the highest ultimate tensile strength is obtained by P6M1 with 367 MPa then followed by P9M1 with 329 MPa and P8M1 with 146 MPa Where as for the elongation P6M1 is 2 P9M1 is 1 1 and P8M1 is 1 The mechanical properties obtained don rsquo t fulfill the standard."

"Seperti kita ketahui, Indonesia memiliki banyak sumber energi yang dapat dimanfaatkan sebagai bahan bakar pembangkit listrik, antara lain Energi Air, Energi Surya, Energi Angin, Energi Panas Bumi dan Energi Gas. Pembangkit listrik tenaga gas memiliki banyak keunggulan dari energi yang laiinnya karena tidak bergntung pada kondisi cuaca seperti angin, intensitas cahaya atau laju aliran air. Potensi gas alam indonesia sebagai sumber bahan bakar Pembangkit Listrik Tenaga Gas (PLTG) sangat melimpah. Menurut studi badan geologi kementerian Energi dan Sumber Daya Alam (ESDM), potensi gas alam yang ada di Indonesia pada tahun 2008 saja mencapai 170 TSCF, dengan komposisi tersebut Indonesia memiliki reserve to production (R/P) mencapai 59 tahun ke depan. Pembangkit listrik tenaga gas memiliki efisiensi yang cukup rendah akibat temperatur gas buang yang masih tinggi. Efisiensi dapat ditingkatkan dengan memanfaatkan sistem pendingin untuk menaikkan efisiensi kerjanya. Namun apabila pembangkit tersebut telah dibuat dengan siklus kombinasi menjadi gas dan uap maka ada sistem pendingin menjadi kurang optimum karena gas buangnya sudah terpakai sebagai sumber panas HRSG. Dalam penelitian ini temperatur udara masuk gas diturunkan hingga temperatur 15o C. Untuk penurunan temperatur ambient hingga 150C terjadi kenaikan daya output turbin gas sebesar 15,14 MW dan kenaikan efisiensi themal siklus sebesar 3,9 %. Sumber panas yang didapatkan generator chiller berasal dari HRSG dengan laju aliran massa steam sebesar 6,37 kg/s. Hal ini mengakibatkan penurunan daya output turbin uap berkurang sebesar 3,27 MW. Akan tetapi, dengan adanya sistem pendingin pada absorption chiller ini daya output yang dihasilkan oleh turbin gas meningkat sebesar 11,87 MW.

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As we know, Indonesia has many sources of energy that can be used as fuel for power generation, among others, Air Energy, Solar Energy, Wind Energy, Geothermal Energy and Energy Gas. Gas power plants have many advantages of energy because it does not bergntung laiinnya on weather conditions such as wind, light intensity or rate of water flow. The potential of Indonesian natural gas as a fuel source Gas Power Plant (power plant) is very abundant.

According to the study of geological bodies Ministry of Energy and Natural Resources (EMR), the potential of natural gas in Indonesia in 2008 alone reached 170 TSCF, with the composition of Indonesia has a reserve to production (R / P) reached 59 years into the future. Gas power plants have a fairly low efficiency due to the exhaust gas temperature is still high. Efficiency can be improved by utilizing the cooling system to increase its efficiency. However, if the plant has been made with a combined cycle gas and steam into the existing cooling system becomes less optimal because the exhaust gas has been used as a heat source HRSG.

In this study the gas intake air temperature is reduced to a temperature of 15°C. To decrease ambient temperatures of up to 150C an increase in power output of 15.14 MW gas turbine and an increase in efficiency of 3.9% themal cycles. The heat source is obtained chiller generator comes from HRSG with steam mass flow rate of 6.37 kg / s. This resulted in a decrease in the steam turbine output power is reduced by 3.27 MW. However, the presence of the absorption chiller cooling system's power output generated by gas turbines increased by 11.87 MW."

"Media pendingin menggunakan ice slurry merupakan media yang paling efisien untuk menjaga kualitas ikan pasca tangkap nelayan. Penelitian dan pengembangan mengenai ice slurry generator perlu terus dilakukan. Salah satu pengembangan yang dapat dilakukan adalah dengan penambahan komponen evaporator. Penelitian berbasis eksperimen ini bertujuan untuk menganalisis pengaruh variasi debit pompa dan lama pengadukan terhadap karakteristik produksi ice slurry generator dengan pre-cooler evaporator. Karakteristik produksi tersebut antara lain adalah waktu pendinginan pada evaporator pre-cooler, konsentrasi es, fraksi massa, dan kapasitas produksi generator. Variasi debit pompa yang diambil adalah 7,93 Lpm, 9,6 Lpm, 11,27 Lpm, 12,93 Lpm, 14,6 Lpm, dan 16,27 Lpm. Untuk variasi lama pengadukan yang diambil adalah 20 menit, 30 menit, 40 menit, 45 menit, 50 menit, dan 60 menit. Berdasarkan eksperimen yang dilakukan didapati laju penurunan temperatur paling cepat adalah sebesar minus 0,00412ºC/detik dengan rerata laju perpindahan kalor sebesar -784,817 Joule per detik pada nilai debit pompa 11,27 Lpm. Konsentrasi es tertinggi didapat pada waktu pengadukan 60 menit. Semakin lama pengadukan, fraksi massa akan semakin meningkat. Didapati kapasitas produksi generator sebesar 257,14286 Liter per 24 jam.

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Cooling medium using ice slurry is the most efficient medium to maintain fish quality after fishing. Research and development on ice slurry generators need to continue. One of the developments that can be done is by adding an evaporator component. This experimental-based research aims to analyze the effect of variations in pump discharge and stirring time on the production characteristics of an ice slurry generator with a pre-cooler evaporator. The production characteristics include cooling time in the pre-cooler evaporator, ice concentration, mass fraction, and generator production capacity. The pump discharge variations taken were 7.93 Lpm, 9.6 Lpm, 11.27 Lpm, 12.93 Lpm, 14.6 Lpm, and 16.27 Lpm. For variations of stirring time taken are 20 minutes, 30 minutes, 40 minutes, 45 minutes, 50 minutes, and 60 minutes. Based on the experiments conducted, it was found that the fastest temperature drop rate was minus 0.00412ºC/second with an average heat transfer rate of -784,817 Joules per second at a pump discharge value of 11.27 Lpm. The highest ice concentration was obtained at a stirring time of 60 minutes. The longer the stirring, the mass fraction will increase. The generator production capacity was found to be 257,14286 Liters per 24 hours."

"Sektor bangunan di Indonesia membutuhkan sistem pendingin udara untuk menciptakan zona kenyamanan termal. Secara umum, energi listrik berasal dari pembakaran bahan bakar fosil, adalah bentuk energi tidak terbarukan dan memiliki masalah lingkungan. Di Indonesia, energi matahari dapat dimanfaatkan sepanjang tahun. Pemanfaatan energi matahari untuk sistem pendingin oleh panas memiliki keuntungan yang signifikan; yaitu sumber energi bersih, tersedia tanpa biaya langsung dan dapat diakses secara proporsional ketika beban pendinginan meningkat. Energi matahari untuk sistem absorption chiller di Indonesia adalah salah satu teknologi yang menjanjikan yang dapat memecahkan masalah energi dan lingkungan. Bekerja bersama Kawasaki Thermal Engineering dan Waseda University, Universitas Indonesia telah merancang dan membangun Solar Thermal Cooling System (STCS) pertama di Indonesia. Sistem ini menggunakan mesin chiller penyerapan efek-tunggal-ganda; terletak di gedung Manufactur Research Center (MRC), Fakultas Teknik Universitas Indonesia. Dari tipikal data uji lapangan, STCS dapat mengurangi konsumsi energi primer antara 11 dan 48% dibandingkan dengan kompresi uap dengan COP 3,1. Selain itu, disain dan penelitian ini juga memprediksi kinerja sistem ini di enam kota besar di Indonesia berdasarkan data uji lapangan: Jakarta, Surabaya, Medan, Yogyakarta, Makassar, dan Bali. Rata-rata dalam satu bulan untuk enam kota adalah 25,8 MWh pengurangan konsumsi gas setara dengan pengurangan 13,8 ton emisi CO2.

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Building sector in Indonesia requires air conditioning systems to create comfort zones. Generally powered by fossil fuel combustion, electricity poses environmental issues as a non-renewable form of energy. In Indonesia, solar energy remains accessible throughout the year. Utilizing solar energy for heat-driven cooling systems offers significant advantages: a clean energy source, available at no direct cost, and proportionally accessible with increased cooling demand. Solar energy for absorption chiller systems in Indonesia presents a promising technology to address energy and environmental concerns. In collaboration with Kawasaki Thermal Engineering and Waseda University, the University of Indonesia has designed and constructed Indonesia's first Solar Thermal Cooling System (STCS). This system uses a double-effect absorption chiller, located at the Manufactur Research Center (MRC) building, Faculty of Engineering, Universitas Indonesia. Field test data indicates that the STCS can reduce primary energy consumption between 11 and 48% compared to vapor compression systems with a COP of 3.1. This design and research predict the system's performance in six major cities in Indonesia—Jakarta, Surabaya, Medan, Yogyakarta, Makassar, and Bali. On average, for these six cities in a month, there's a reduction of 25.8 MWh in gas consumption, equivalent to a decrease of 13.8 tons of CO2 emissions."

"A greater heat load due to the miniaturization of electronic products causes the need for a new cooling system that works more efficiently and has a high thermal capacity. A synthetic jet is potentially useful for the cooling of electronic components. This paper reports the results of our experimental studies and the influence of orifice shape for Impinging Synthetic Jet cooling perfomance. The effect of shape of the orifice of an impinging synthetic jet assembly on the apparatus cooling of a heated surface is experimentally investigated. It will be seen that the characteristics of convective heat transfer will occur by moving the piezoelectric membrane. The prototype of the synthetic jet actuator is coupled with two piezoelectric membranes that operate by 5 volt electrical current and create a sinusoidal wave. The orifice shapes considered are square and circular. The results show the significant influence of orifice shape and sinusoidal wave frequencies on the heat transfer rate that were obtained. The temperature drop with a square orifice is found to be larger than that with circular shapes. A square orifice has a larger covered area if compared to the circular orifice at the same radius, thus resulting in a larger entrainment rate that leads to an increase of heat transfer performance."

"Baja S45C termasuk baja karbon sedang dengan persentase karbon 0,3% - 0,45%. Pada proses perlakuan panas, terdapat proses quenching dimana baja dicelupkan ke dalam suatu media quench secara cepat untuk menghasilkan sifat mekanis yang diinginkan. Pada penelitian ini digunakan micro thermal fluids sebagai media quench dimana micro thermal fluids adalah campuran antara nanopartikel yang terlarut dalam suatu fluida dimana nanopartikel tersebut berukuran dari 1-100 nm. Nanopartikel yang digunakan pada penelitian ini berbasis dari Printed circuit Board (PCB) dengan menggunakan fluida dasar air dan ditambahkan dengan surfaktan Sodium Dodecylbenzene Sulfonate (SDBS). Proses crushing, leaching, pirolisis, dan milling dalam upaya mengolah PCB menjadi nanopartikel. Setelah dilakukan PSA partikel yang melalui proses milling selama 20 jam sehingga 572.6 d.nm sehingga partikel tidak mencapai ukuran nano dan media pendinginnya disebut micro thermal fluid. Nilai kekerasan menunjukkan tren meningkat seiring dengan penambahan partikel, namun cenderung menurun saat dilakukan penambahan surfaktan. Nilai kekerasan tertinggi yang didapat pada sampel yaitu 55 HRC yang merupakan hasil quench dengan variabel 0,3% partikel 0% SDBS pada media pendingin. Kekerasan terendah yang dihasilkan adalah 44 HRC dengan variabel 0,5% partikel 7% SDBS. Mikrostruktur yang dihasilkan dari setiap penambahan partikel dan surfaktan adalah martensite,bainite, & pearlite.

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S45C steel is classified as a medium carbon steel with a carbon percentage ranging from 0.3% to 0.45%.. Quenching is step where the steel is rapidly immersed in a quenching media to achieve desired mechanical properties. Nanofluids were used as quench media where nanofluids are a mixture of nanoparticles dissolved in a fluid where the nanoparticles are sized from 1-100 nm. The nanoparticles used in this study were based on a printed circuit board (PCB) using a water-based fluid and added with surfactant Sodium Dodecylbenzene Sulfonate (SDBS. After 20 hours of milling, the particle size was measured using Particle Size Analyzer (PSA) and found to be 572.6 d.nm, indicating that the particles didn’t reach the nano size range. Therefore, the cooling media was referred to as micro thermal fluid. The hardness value showed an increasing trend with the addition of nanoparticles, but tended to decrease with the addition of surfactant. The highest hardness value obtained was 55 HRC with the variable of 0.3% particles and 0% SDBS in the cooling media. The lowest hardness achieved was 44 HRC with the variable of 0.5% nanoparticles and 7% SDBS. The microstructure resulting from each nanoparticle and surfactant addition was martensite,bainite, & pearlite."