Bowo Yuli Prasetyo

Water is one of the essential natural resources for the sustaining life of all beings on this planet. In general, groundwater is used to meet daily needs, although the availability of this water source becomes a major concern, particularly in some areas with limited access to it. Air condensation is a solution for providing water in such areas. This study aims to explore the potential of utilizing the thermoelectric technology as an alternative solution for water provision. An experiment is conducted using a system consisting of single liquid-cooled thermoelectric cooling devices/modules (TECs). Three types/variants of TECs with different cooling capacities are tested at three different operating voltages. During the tests, changes in physical quantities are recorded for analysis, along with amount of water produced. The results demonstrate notable performance differences between all TEC variants. The highest cooling capacity is achieved by the TEC-1 variant, albeit with higher current usage. The TEC-3 variant delivers the lowest performance of all. TEC-2 obtains the highest water yield, producing 46.9 g of water at 12 V, while TEC-1 and TEC-3 produce 34.4 and 13.2 g, respectively. The highest condensation rate, i.e., 3.72%, is achieved by TEC-2, at 9 V, while the lowest energy consumption, i.e., 3.74 kWh/L, is shown by TEC-2, at 12 V.

Penelitian berupa simulasi CFD yang dilakukan di “LG VRF System Training Center Classroom 2” pada jurusan teknik refrigerasi dan tata udara Politeknik Negeri Bandung. Simulasi CFD dilakukan dengan menggunakan software bernama Ansys Fluent. Proses simulasi CFD dibagi menjadi tiga bagian besar yaitu pre-processing, solver, dan post processing. Proses validasi merupakan proses memastikan keakuratan hasil simulasi dengan cara membandingkan data pengukuran dengan hasil simulasi. Nilai error validasi temperatur memiliki nilai terkecil sebesar 1,128% dan error terbesar sebesar 2,710%. Hasil simulasi vector pada ruang kelas, nilai udara yang keluar dari diffuser menghasilkan udara berkecepatan 2 m/s lalu menurun hinga 0 m/s. pada supply dan return FCU dengan menggunakan menghasilkan udara berkecepatan 1,95 m/s. Hasil simulasi contour berupa visualisasi distribusi temperatur udara pada diffuser mengeluarkan udara bertemperatur 24,7 °C. FCU mengeluarkan udara bertemperatur sebesar 24,7°C yang ditahan oleh tembok bagian timur yang bersuhu sekitar 26,5°C.

Sistem refrigerasi tabung vortex merupakan pendingin sekaligus pemanas. media pendingin tabung vortex adalah udara bertekanan. Tabung vortex tidak menggunakan refrigeran sehingga sangat ramah lingkungan, namun belum ada yang melakukan penelitian terhadap kapasitas pendinginan dan temperatur udara dingin keluaran tabung vortex mengenai pengaruh katup sumbat. Tujuan penelitian ini supaya dapat mengetahui kapasitas pendinginan dan temperatur udara dingin terhadap katup sumbat dan tekanan input. Variasi sudut katup sumbat pada penelitian ini menggunakan sudut 30˚, 60˚dan 90˚. Masing-masing sudut diuji menggunakan tekanan 1 bargauge, 2 bargauge, 3 bargauge dan 4 bargauge. Hasil dari pengujian kapasitas pendinginan dan temperatur udara dingin keluaran tabung vortex didapat bahwa variasi sudut 30˚ mampu mencapai temperatur dingin lebih rendah dan kapasitas pendinginan lebih besar dibandingkan variasi sudut yang lain.

Air Conditioning merupakan sebuah kebutuhan untuk mendapatkan kenyamanan saat melakukan berbagai aktivitas manusia di dalam ruangan dan water heater menjadi salah satu sistem yang menjadi kebutuhan manusia. Penggunaan sistem dari air conditioning dapat dimodifikasi untuk menambahkan sistem water heater dengan menggunakan heat exchanger jenis double pipe dan air ditampung oleh water tank untuk kapasitasnya disamakan dengan besaran kondensor yang ada pada sistem. Pada penelitian ini bertujuan untuk memanfaatkan panas yang terbuang sebagai media memanaskan air dengan menambahkan sistem heat exchanger. Heat exchanger tipe double pipe memerlukan pipa tambahan untuk memanaskan air dengan menggunakan pipa pvc sebagai pipa luar dan pipa refrigeran menggunakan pipa tembaga. Hasil dari penelitian ini didapatkan panjang pipa heat exchanger yaitu 14 meter untuk pipa air dan pipa refrigeran. Air yang berhasil dipanaskan dengan mengalir pada pipa dari temperatur awal sebesar 29°C hingga 37,5°C dalam kurun waktu 120 menit.

Thermoelectric devices have been widely used in various applications, including cooling and power generation. The potential application of thermoelectric cooling systems has been studied. However, these systems still face challenges in achieving optimal performance compared with other cooling systems. Several factors, including the hot-side cooling method, influence the performance of thermoelectric systems. This study aimed to investigate the effects of different hot-side cooling methods on the thermoelectric performance and thermal behavior of thermoelectric cooling systems. The testing methods involved the combination of the thermoelectric module with five hot-side heat exchangers, including a square heatsink, a round heatsink, a two-pipe heat pipe, four-pipe heat pipe, and a liquid cooler, with variations in the operating voltage. The experimental results reveal that the different heat exchangers considerably affected the system performance. The liquid cooler consistently achieved the lowest hot- and cold-side temperatures among all heat exchangers. In the case of the ratio of the cooling capacity and temperature difference across the module, the liquid cooler attained the highest values at 12 and 9 V. In addition, the square heatsink exhibited the highest ratio at 6 V. Meanwhile, the coefficient of performance (COP) values were relatively similar in the various heat exchangers, with the liquid cooler generally showing higher COP values.

The classroom is one of the important facilities in teaching and learning activities. Just like any other room, ensuring thermal comfort becomes a vital aspect for its occupants. This study aims to evaluate environmental conditions and the thermal comfort experienced by classroom occupants through numerical methods. The evaluation involves the integration of the Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) equations into Computational Fluid Dynamics (CFD) simulations using a user-defined function. Furthermore, extensive field measurements and questionnaire surveys are also employed to support the simulation process. The results indicate that the air temperature tends to be high, reaching 30.91°C. Meanwhile, the air velocity within the room, particularly in the occupied areas, is significantly low, with an average value of 0.04 m/s. According to the ASHRAE Standard 55, the classroom is perceived as uncomfortable, as evidenced by a PMV value of 1.38 and a PPD of 44.94%. Therefore, efforts are required to enhance the thermal comfort in the space.

Heat Pump merupakan suatu mesin yang dapat difungsikan baik untuk pendinginan maupun pemanasan dengan memanfaatkan panas dari kondenser. Kondenser biasanya didinginkan menggunakan fan, tetapi disini didingankan melalui air dan panas airnya dimanfaatkan. Pada tugas akhir ini, Heat Pump difungsikan sebagai pemanas air, sistem ini akan memanfaatkan kompresor sebagai pemeran utama dan mengefisienkan energi panas yang dihasilkan lewat kondenser, pipa kondenser berada di dalam air yang ingin dipanaskan. Pemanasan air sebanyak 20 liter dapat dipanaskan sampai 40 °C dengan waktu 14 menit, sedangkan dari hasil perancangan didapat 16 menit. Secara keseluruhan hasil data yang diambil maka dapat disimpulkan sistem heat pump ini berhasil.

Thermoelectrics can convert electrical energy to thermal energy. The generated thermal energy can be used in various cooling systems (TEC) applications. Improvement of TEC performance influenced by hot-side heat dissipation method, working fluid, and multi-thermoelectric. This study aims to investigate the relation between multi-thermoelectric configuration and the cooling behaviors. The experiment was conducted on the devices equipped with two modules of TEC arranged in series and parallel with variations of input voltage, working fluid mass flow, and temperature. The result reveals variations in cooling behaviors between the two configurations. Parallel configuration TEC gives the highest cooling capacity with a value of 66.62 W, 100% bigger than the series configuration. Meanwhile, the series configuration provides a delta temperature of 11.03 K, 2% higher than the parallel one. The parallel modules cooling performance is the biggest among the two arrangement, with a value of 2.57, which is 147% higher than series one.

The kitchen is a vital area that provides energy sources through food processing for residences. However, the cooking process can also produce pollutants that are harmful to the body. This study aims to investigate the concentration and distribution of contaminants (CO and CO2) generated from the kitchen to all rooms in the house. In addition, Air temperature and velocity are investigated to observe their relationship with the distribution of pollutants. The investigation procedure utilizes a numerical simulation of a dwelling with two different ventilation cases. The simulation results show no significant difference in air velocity between the two cases. While the addition of natural ventilation in the kitchen area can reduce CO and CO2 concentrations throughout the room by 25.8% and 24.9%, respectively. On the other hand, the indoor air temperature can also be reduced by 4.9% with the same treatment. In conclusion, the addition of a window in the kitchen area has a significant impact on reducing temperature and pollutant concentrations all over the room.

Controlling contamination via proper airflow distribution in an operating room becomes vital to ensure the reliable surgery process. The heating, ventilation, and air conditioning (HVAC) systems significantly influence the operating room environment, including temperature, relative humidity, pressurization, particle counts, filtration, and ventilation rate. A full-scale operating room has been investigated extensively through field measurements and numerical analyses. Computational fluid dynamics (CFD) simulation was conducted and verified with the field measurement data. The simulation was analyzed with three different operating room schemes, including at-rest conditions (case 1), normal operational conditions with personnel (case 2), and actual conditions with personnel inside and some medical equipment blocking the return air (case 3). The concentration decay method was used to evaluate this study. The results revealed that the contamination concentration in case 1 could be diluted quickly with the average value of 404 ppm, whereas the concentration in case 2 slightly increased while performing a surgery with the average value of 420 ppm. The return air grilles in case 3, blocked by obstacles from some medical equipment, resulted in the average concentration value of 474 ppm. Other than that, the contaminant dilution could be obstructed dramatically, which revealed that proper and smooth airflow distribution is essential for contamination control. The ventilation efficiency of case 2 and case 3 dropped around 6% and 17.91% compared to case 1 in the unoccupied and ideal condition. Ventilation efficiency also decreased along with decreasing the air change rate per hour (ACH), while with increasing ACH, the ventilation efficiency in case 3 actually increased, approaching case 2 in the ideal condition.