No abstract

Indonesia is a tropical country with relatively warm temperatures, so it is necessary to use air conditioning in daily activities. The use of the air conditioner causes the large use of electricity. This prompted the government to intervene by issuing the Minister of Energy and Mineral Resources Regulation No. 57 of 2017 regarding the provisions for labeling energy from air conditioning units that are marketed in general. To test the air conditioner unit requires a room called a psychrometric chamber which is an isolation room where the temperature and humidity can be controlled. Before use, the psychrometric chamber is needed to be tested first by analyzing the air loop using CFD, ensure the installation design is completed, and compare between the ideal condition (CFD) and actual condition (on the field). In this case, the object used is Universitas Indonesia's indoor side of the psychrometric chamber, air conditioner 18,000 Btu/h split type, and other supporting components. The method used is air enthalpy based on SNI ISO 5151 regulation by measuring, modeling, installing, simulating, and compare temperature and air velocity data between CFD as ideal condition and actual psychrometric chamber. The result shows that the temperature difference at the AHU inlet is 4.7 ℃, the AC inlet is 2.9 ℃, the air velocity difference at the AHU inlet is 2.8 m/s, AC inlet is 2.6 m/s, and indoor air loop systems side installation is completed.

Higher energy demands in favorable energy prices increasing people's affordability of the cooling devices, causing most building and residential areas to wear air conditioning systems. Higher energy saving, efficiency, and eco-friendly equipment have become a challenge for manufacturers and researchers. Also, Indonesia's government rules the energy efficiency by SKEM (Minimum Standard of Energy Performance) by air conditioning equipment's labeling. In this study, the use of perforated ceiling was selected due to the excellent air distribution performance of the panels. This study analyzes the air circulation distribution (air loop) in a psychometric chamber using computational fluid dynamics (CFD), especially placing the air conditioner test unit. The numerical studies are performed with porous media models. A CFD model was used to analyze the air distribution in the psychrometric chamber. The simulation results show that the higher value of C1 resulted in a higher value of velocity. Furthermore, the pressure drop in the test chamber did not show any significant influence. In all cases, the influence of C1 value did not significantly affect the air movement in the test chamber.

One of the solutions to overcome the lack of electricity problem in rural area is Crossflow pico-scale hydropower. In improving cross-flow turbine performance, understanding fluid phenomena is needed. Particle image velocimetry (PIV) measurement is one of the methods used to visualize the fluid flow phenomena inside the turbine. Expensive price of seeding particle leads to find the solution for this PIV method. The objective of this study is to use a cheap seeding particle from cheaper materials, mainly resin and rhodamine B. Besides that, in this study, PIV measurement is compared to 2D computational fluid dynamics (CFD) with multiphase volume of fluid model. From the results, several phenomenon can be observed at both of the methods (PIV and CFD) such as separation in the blade tip. Therefore, this study showed that an inexpensive material resin and rhodamine B as a seeding particle has a potential and ability to represent flow inside pico-hydro cross-flow turbine.

Air quality plays a significant role during the coronavirus pandemic. Air acts as a spreading media as well as a control measure for infection in polluted spaces. Insufficient ventilation around the building may lead to a rise of pollutants carrying the virus. One way to improve ventilation is by increasing the air change rate. This study investigates the air change rate effectiveness in reducing droplets spreading in a classroom. Cases with various layouts of inlet and outlet vents are considered, and the spread of droplets is studied. The airflow analysis shows the impact of the different ventilation layout configurations. The results show that the CFD model simulation indicates an optimum ventilation configuration to decrease the droplet spread. The discrete phase model results also determine the trajectory of droplets spread along the classroom. CFD results show that in the selected configuration, a significant number of droplets are expelled to the outside and reduce their concentration inside the classroom.