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"The enhancement of heat transfer performance in heat exchanger is achieved by reducing the size of the hydraulic diameter or by using a working fluid that has a better thermal conductivity compared to conventional working fluids. The application of a small hydraulic diameter can be found in the microchannel heat exchanger (MCHE). The design and the testing of the MCHE were done in this research. The MCHE was tested with several working fluids, such as the distilled water, the Al2O3-water nanofluids at 1%, 3% and 5% volume concentration, and the SnO2-water nanofluids at 1% volume concentration. The temperature of inlet and outlet were set at 50o C and 25o C, respectively. The variations of flow rate at the inlet were applied from 100 ml/min up to 300 ml/min. The addition of nanoparticle in the base fluid was proven to improve the heat transfer of the MCHE, the 5% Al2O3-water and 1% SnO2-water nanofluids are able to absorb the heat 9% and 12% higher than the base fluid. The overall heat transfer coefficient of MCHE with 5% Al2O3-water and 1% SnO2-water nanofluids were 13% and 14% higher than the base fluid."

"Experimentation on and implementation of phase-change materials for thermal storage is attracting increasing attention by those seeking a potential resolution to energy issues. This study investigates beeswax as a high thermal-capacity phase-change material with the objective of analyzing the thermal properties and behaviors of beeswax/CuO nano-PCM. The study uses differential scanning calorimetry apparatus to measure the melting temperature and thermal capacity of nano-PCMs. The study found nano-PCM melting temperatures of 63.62°C, 63.59°C, 63.66°C, 63.19°C, and 62.45°C at 0.05, 0.1, 0.15, 0.2, and 0.25 wt%, respectively. FTIR testing found no chemical reaction between CuO and beeswax. The existence of CuO nanoparticles enhanced thermal conductivity of beeswax but reduced its heat capacity. However, the change in latent heat caused no significant effects in the performance of beeswax/CuO. Thus, the results showed that heat transfer of composite beeswax/CuO melts faster than base phase-change material"

"ABSTRAKNaskah ini mendeskripsikan bagaimana: pengaruh massa muatan refrigeran ODP tinggi dan ODP GWP nol terhadap kinerja termal dalam bentuk COP; dan jatuh tekanan pada alat penukar kalor kanal mikro sebagai aplikai pada bidang tata udara secara eksperimental. Kanal yang digunakan memiliki diameter hidrolik 1.46 mm, sebanyak 96 kanal. Didapatkan nilai COP tertinggi sebesar 1.88 dengan pengisian refrigeran R22 300 gr, dan nilai COP tertinggi sebesar 1.92 dengan pengisian refrigeran R290 300 gr. Sementara, jatuh tekanan yang dihasilkan berkisar pada 5 bar dengan R22 dan R290.

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ABSTRACTThis document describes the effect of high ODP and zero ODP GWP refrigerants on thermal performance in term of COP and pressure drop of the microchannel heat exchanger in air conditioning applications, experimentally. It is found that the maximum COP is 1.77 when charged with 250 gr of HCFC refrigerant, and 0.12 when charged with 100 gr of R290. The pressure drop ranges from 5.0 bars to 5.6 bars when charged with 300 gr and 250 gr of R22 respectively."

"ABSTRAKNaskah ini mendeskripsikan bagaimana: pengaruh massa muatan refrigeran ODP tinggi dan ODP GWP nol terhadap kinerja termal dalam bentuk COP; dan jatuh tekanan pada alat penukar kalor kanal mikro sebagai aplikai pada bidang tata udara secara eksperimental. Kanal yang digunakan memiliki diameter hidrolik 1.46 mm, sebanyak 96 kanal. Didapatkan nilai COP tertinggi sebesar 1.88 dengan pengisian refrigeran R22 300 gr, dan nilai COP tertinggi sebesar 1.92 dengan pengisian refrigeran R290 300 gr. Sementara, jatuh tekanan yang dihasilkan berkisar pada 5 bar dengan R22 dan R290.

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ABSTRACTThis document describes the effect of high ODP and zero ODP GWP refrigerants on thermal performance in term of COP and pressure drop of the microchannel heat exchanger in air conditioning applications, experimentally. It is found that the maximum COP is 1.77 when charged with 250 gr of HCFC refrigerant, and 0.12 when charged with 100 gr of R290. The pressure drop ranges from 5.0 bars to 5.6 bars when charged with 300 gr and 250 gr of R22 respectively."

"Many studies show that nanofluids, especially with carbon nanotubes, improve heat transfer. Other studies show that a nanofluid is a good candidate for solar systems because of its good absorptivity. We are facing an increasing number of miniaturized and more powerful systems. Especially in microelectronics, small heat sinks with high heat transfer are being developed, called micro-channel heat sinks (MCHS). In this paper, the heat transfer behavior of carbon nanotube–water nanofluid in a microchannel solar collector is studied experimentally. The exchanger is composed of 16 micro-channel hydraulic diameters of 1 mm and a glass or quartz cover with a surface area of 25 cm2. Solar radiation is simulated by a halogen lamp. The experimental set-up includes a solar meter, pressure, and temperature sensors, and it is allowed to control the flow. The nanofluid is a solution of water containing a 0.01%, 0.05%, 0.1%, and 0.5% weight fraction, respectively, of the carbon nanotubes, which are 9.2 nm in diameter and 1.5 µm in length. Viscosity and density are measured experimentally. The evolution of efficiency and the pressure drop are presented according to the Reynolds number and are compared with the results obtained with distilled water."

"Lumpur alum yang dihasilkan dari IPA Citayam digunakan sebagai adsorben untuk menyisihkan senyawa methylene blue dari air limbah. Lumpur alum dikarakterisasi menggunakan metode SEM-EDX dan XRF untuk melihat kondisi morfologi dan komposisi penyusun lumpur alum. Tujuan utama penelitian ini adalah untuk menentukan kondisi optimum dalam penyisihan senyawa methylene blue, yang merupakan senyawa yang sering digunakan sebagai model bahan kimia organik. Desain eksperimen full factorial 2k digunakan dalam optimasi proses adsorpsi. Empat faktor bebas yaitu diantaranya pH, suhu, konsentrasi adsorben, dan konsentrasi methylene blue diteliti menggunakan metode adsorpsi batch. Hasil menunjukkan bahwa semua faktor merupakan faktor yang signifikan dengan faktor konsentrasi adsorben merupakan faktor yang paling signifikan diikuti dengan faktor konsentrasi methylene blue, pH dan terakhir suhu. Dengan menggunakan software Minitab 19, didapatkan bahwa kondisi terbaik untuk menyisihkan methylene blue dengan adsorben lumpur alum yaitu saat pH 8; suhu 60 oC; konsentrasi adsorben 1 g/L; dan konsentrasi methylene blue 0,05 g/L. Rata-rata penyisihan methylene blue dalam kondisi tersebut yaitu sebesar 75,27%. Interaksi antar faktor yang signifikan secara berurutan yaitu konsentrasi methylene blue-konsentrasi adsorben, pH-konsentrasi methylene blue, suhu-konsentrasi methylene blue, suhu-konsentrasi adsorben dan pH-konsentrasi adsorben sedangkan interaksi antara pH-suhu tidak signifikan mempengaruhi penyisihan methylene blue. Selain itu, hasil karakterisasi lumpur alum menunjukkan bahwa karakter lumpur alum juga memainkan peran penting dalam adsorpsi methylene blue ke lumpur alum.

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Alum sludge produced from Citayam WTP is used as an adsorbent to remove methylene blue compounds from wastewater. Alum sludge was characterized using SEM-EDX and XRF method to see the morphological conditions and composition of alum sludge. The main objective of this research is to determine the optimum conditions for the removal of methylene blue compounds, wich are compounds that are often used as a model for organic chemicals. Full factorial 2k is used in the optimization of the adsorption process. Four independent factors, including pH, temperature, adsorbent concentration, and methylene blue concentration were examined using the batch adsorption method. The results showed that all factors were significant factors with adsorbent concentration factor being the most important factor followed by the methylene blue concentration, pH and temperature. Using Minitab 19 software, it was found that the best conditions for removing methylene blue with alum sludge adsorbents were at pH 8; temperature 60 oC; adsorbent concentration 1 g/L; and the concentration of methylene blue 0,05 g/L. Average removal of methylene blue in these conditions is 75,27%. Interactions between factors that are significantly sequential are methylene blue concentration-adsorbent concentration, pH-methylene blue concentration, temperature-methylene blue concentration, temperature-adsorbent concentration and pH-adsorbent concentration while interaction between pH-temperature do not significantly affect the removal of methylene blue. In addition, the results of the characterization of alum sludge indicate that alum sludge character also play an important role in the adsorption of methylene blue to alum sludge.

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"Menjadi kanker terbanyak ke empat yang dialami oleh wanita, diagnosis yang cepat dan tepat diperlukan dalam tatalaksana kanker serviks. Terdapat beberapa cara dalam diagnosis kanker serviks, seperti colposcopy dan biopsi. Namun masih terkendala dengan waktu yang terlalu lama, biaya yang besar, dan interpretasi hasil pada manusia yang kerap kali berbeda. Seriring dengan perkembangan ilmu pengetahuan dan teknologi, kebutuhan akan teknologi baru meningkat untuk mengatasi kendala tersebut. Differential Scanning Calorimetry (DSC) menjadi suatu pilihan dalam mengkarakteristikan nilai profil termogram yang khas ada pada sel kanker serviks mengingat DSC sangat sensitif terhadap perubahan suhu. Penelitian ini menggunakan sampel yang dikelompokkan menjadi sel normal serviks, sel kanker serviks HeLa tanpa perlakuan, dan sel kanker serviks HeLa dengan pemberian doxorubicin. Tiap kelompok memuat 4 sampel. Sel dikultur dan di ekstraksi sebanyak 5 mL dengan konsentrasi 2,5 x 108 /ml. Kemudian sel beserta medium RPMI 1640 diambil 10 μl dan diletakkan kedalam DSC-60 plus series (shimadzu) sebagai pembaca nilai profil termogram. Hasil pembacaan pada DSC berupa grafik yang dianalisis bagian puncaknya untuk mendapatkan komponen nilai profil termogram, yakni titik lebur dan entalpi lebur. Selanjutnya nilai titik lebur dan entalpi lebur dilakukan pengujian dengan uji ANOVA satu arah. Hasil pembacaan DSC menunjukkan adanya 1 puncak transisi pada kelompok sel kanker serviks HeLa tanpa perlakuan. Khususnya pada kelompok sel kanker serviks HeLa dengan pemberian doxorubicin, grafik menunjukkan 2 puncak transisi. Nilai titik lebur dan entalpi lebur pada kelompok sel kanker serviks HeLa tanpa perlakuan adalah 143,12 ± 10,2 oC dan 1,35 ± 0,34 kJ/g Kedua nilai tersebut berbeda bermakna diantara kelompok sel normal serviks serviks dan sel kanker serviks HeLa dengan pemberian doxorubicin. DSC dapat membedakan nilai profil termogram sel kanker serviks HeLa dengan sel normal serviks dan sel kanker serviks HeLa dengan pemberian doxorubicin sehingga DSC diharapkan menjadi pilihan dalam diagnosis dan pemantauan terapi.

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Being the fourth most cancer experienced by women, a prompt and appropriate diagnosis is needed in the management of cervical cancer. There are several modalities in the diagnosis of cervical cancer cells, such as colposcopy and biopsy. But there is still obstacles such too long time, large costs, interpretation of results in humans that are often different, and procedures that are less comfortable for patients. Along with the development of science and technology, the need for new technologies is increasing to overcome these obstacles. Differential Scanning Calorimetry (DSC) is an option in characterizing typical thermogram profile values in cervical cancer cells because DSC is very sensitive to temperature changes.

This study used samples grouped into normal cervical cells, untreated HeLa cervical cancer cells, and HeLa cervical cancer cells with doxorubicin administration. Each group contains 4 samples. Cells were cultured and extracted as much as 5 mL with a concentration of 2.5 x 108/ ml. Then the cell with RPMI 1640 medium was taken 10 µl and placed into DSC-60 plus series (shimadzu) as a reader for the thermogram profile value.

The reading results on the DSC in the form of a graph that analyzed the transisional peak to get the thermogram profile value component, which is the melting point and enthalpy change. Furthermore, the value of the melting point and enthalpy changes were tested by one-way ANOVA test. DSC readings showed a transition peak in the HeLa cervical cancer cell group without treatment. Especially in the HeLa cervical cancer cell group with doxorubicin administration, the graph shows 2 transition peaks. Melting point values and enthalpy changes in the HeLa cervical cancer cell group without treatment were 143.12 ± 10.2 oC and 1.35 ± 0.34 kJ/g. Both values were significantly different between normal cervical cell groups and HeLa cervical cancer cells with doxorubicin administration. DSC can differentiate the profile value of the thermogram of HeLa cervical cancer cells with normal cervical cells and HeLa cervical cancer cells by administering doxorubicin so that DSC is expected to be an option in therapeutic diagnosis and monitoring."

"Heat exchanger merupakan bagian vital dalam sebuah perangkat elektronik yang dapat menjaga suhu optimum dari alat tersebut. Penelitian tentang microchannel heat exchanger telah sangat berkembang untuk aplikasi kearah pendingin elektronik pada satu dekade terakhir ini. Microchannel heat exchanger memiliki beberapa keunggulan yakni memiliki dimensi yang lebih kecil dan memiliki koefisien perpindahan kalor yang lebih baik daripada alat penukar kalor lainnya. Dalam pengujian ini, peneliti akan mencoba membuktikan performa dari koefisien perpindahan kalor dari microchannel heat exchanger tersebut beserta efek negatifnya. Peneliti akan mencoba menguji pengaruh pressure drop pada saluran microchannel heat exchanger. Kemudian dalam pengujian ini juga digunakan fluida kerja air,nano fluida Al2O3 1%, dan nano fluida SnO2 1% dengan fluida dasar air. Dari hasil pengujian ini didapatkan bahwa perpindahan kalor akan lebih baik jika menggunakan nano fluida sebagai fluida kerja pendingin.

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Heat exchanger is a vital part in an electronic devices that can maintain the optimum operation temperature of that devices. Research on microchannel heat exchanger application has been highly developed on electronics cooling towards the last decade. Microchannel heat exchanger has several advantages which have smaller dimensions and heat transfer coefficient better than the other heat exchanger. The experiment also want to measure the pressure drop in microchannel. It used water, nanofluids Al2O3 1%,and nanofluids SnO2 1% as working fluids in cold side microchannel heat exchanger. Result from this research indicate that heat transfer would be better if we use nanofluids as cooling working fluids."

"Kinerja perpindahan kalor pada alat penukar kalor dapat ditingkatkan dengan mengurangi ukuran diameter hidrolik atau dengan menggunakan fluida kerja yang memiliki konduktivitas termal lebih baik dibandingkan dengan fluida kerja konvensional. Salah satu contoh penggunaan diameter hidrolik yang kecil adalah microchannel heat exchanger (MCHE). Pada penelitian ini, perancangan alat dan pengujian kinerja perpindahan kalor pada MCHE berkonfigurasi counter-flow dengan menggunakan fluida kerja air dan nano fluida Al2O3-air dengan konsentrasi 1%, 3%, dan 5% sebagai fluida pendingin telah dilakukan. Dalam pengujian, temperatur masuk fluida pada sisi panas dan sisi dingin MCHE diatur tetap pada temperatur 50°C dan 25°C, sedangkan debit aliran pada saluran masuk divariasikan dari 100 ml/menit hingga 300 ml/menit. Hasil pengujian menunjukkan bahwa peningkatan konsentrasi partikel nano pada fluida dasar dapat meningkatkan kinerja perpindahan kalor fluida dasar tersebut. Pada konsentrasi partikel nano tertinggi yang digunakan dalam pengujian, nano fluida Al2O3-air konsentrasi 5% dapat menyerap panas sebesar 9% lebih baik dibandingkan air biasa dan dapat meningkatkan koefisien perpindahan kalor keseluruhan MCHE sebesar 13% lebih besar dibandingkan dengan air.

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The heat transfer performance in heat exchanger can be enhanced by decreasing its hydraulic diameter or using working fluid that has better thermal conductivity than the conventional one. One of the examples of small hydraulic diameter application is microchannel heat exchanger (MCHE). Designing the MCHE and doing experimental investigation of the heat transfer performance on counter-flow MCHE by using water and Al2O3-water nanofluid with nanoparticle concentration 1%, 3%, and 5% as coolant fluid has been done in this experiment. Inlet fluid temperatures in hot and cold side are set at 50°C and 25°C, meanwhile the inlet flow rate is set from 100 to 300 ml/minute.

The experimental results show that the increase of nanoparticle concentration in the base fluid can enhance its heat transfer performance. In highest concentration of nanoparticle used in this experiment, Al2O3-water 5% nanofluid can absorb heat 9% better than conventional water do and can enhance the overall heat transfer coefficient of MCHE 13% higher than water."