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In recent years, several applications of micromixers have been reported to have a number of advantages, including the use of small amounts of plasma, short reaction times, and good reaction efficiency. The samples analyzed in this study were blood plasma and distilled water. The process is carried out by passive mixing which is based on a microchannel structure to enhance the diffusion of molecules for efficient mixing. The arrow shape was chosen as the micromixer design because it has a better blending performance than the T and Y shapes. The types of obstacles also used to improve the mixing process. The simulation was carried out on COMSOL Multiphysics software version 5.6. The results showed better mixing results for the micromixer design with triangle right facing obstacles with the highest Reynolds number was 9.4326. Then followed by ellips obstacles with a value of 9.4322, then without obstacles that is 9.4309, after that the triangle left facing with a value of 9.4006, and finally the lowest Reynolds number is a design with a diamond obstacles of 9.2514. [ABSTRACT FROM AUTHOR]

Nanofluids generate considerable interest in increasing the heat transfer performance of a system, specifically as a coolant. A study of Aluminum Oxide (Al2O3) nanoparticles in water and ethylene glycol (60:40) mixture is conducted by using computational fluid dynamics (CFD) to investigate its potential by assuming a single-phase and constant thermophysical properties model. This study aims to analyze its heat transfer enhancement by using a theoretical properties model in several volume concentrations: 0.3%, 0.6%, 1.0%, and 1.5%. A straight tube geometry by neglecting its wall thermal conductivity is used under laminar conditions and constant heat flux and 293 K inlet temperature, compared with various Reynolds numbers. The model is validated using Shah Correlation, resulting 8% maximum deviation. The Einstein theoretical model fails to predict the viscosity properties resulted in more than a 10% deviation from the current experimental findings. Notwithstanding the theoretical prediction, the simulation observed that a 1.5% volume concentration increased higher heat transfer enhancement around 3%. [ABSTRACT FROM AUTHOR]

Tidal turbine is a horizontal axis turbine utilizing tidal energy to generate electricity while several existing studies related to the tidal turbine have been carried out, especially on the tidal turbine design to increase the turbine performance. The tidal turbine design is improved in various methods, namely augmenting a diffuser, modifying the diffuser angle, and appending a brim at the end of the diffuser as used in wind turbines with the aim of keeping vortex away from the tidal turbine outlet to minimize pressure drop. This study aims to compare the use of the brim by observing the level of effectiveness and the efficiency of the output power. The comparison is made by modeling the tidal turbine at four diffuser angles and the use of brim. The four diffuser angles were varied started from 10.43° to 35.97° with tidal current velocity around 0.7 m/s. The model is then analyzed by applying the computational fluid dynamics approach utilizing ANSYS application. It is then expected to obtain higher level of effectiveness and power efficiency of the tidal turbine by introducing the brim combined with diffuser augmentation. [ABSTRACT FROM AUTHOR]

Indonesia has the opportunity to become a country with a very high level of risk of water shortages. This means that water reserves are no longer sufficient to meet demand. The desalination method is needed to solve the problem of the water crisis in Indonesia. In this study, a new alternative desalination method with droplet atomization was developed that utilizes the phenomenon of air entrainment. This study analyzes the effect of nozzle diameter on the spray angle to characterize the mist in the desalination process from the design results. The research was conducted by observing the spray angle using a video camera image processing program. It was found that the nozzle diameter affected increasing the nozzle spray angle with increasing pressure. The 0.5 diameter nozzle has a wider spray angle than the others, with the highest angle of 62,250 at a pressure of 9 bar. [ABSTRACT FROM AUTHOR]

In in-vivo bone tissue engineering, therapeutic efficacies are often unsatisfactory because the stem cells lose significant viability post-transplantation. The damaged cell may also present an unfavorable environment for cell growth. This means that cell transplantation would require the cells to be kept in a particular environment with substances that can support their survival, induce bioactivity, and enhance retention at the administered sites. This need drives the development of stem cells encapsulation in a biomaterial-based microcapsule. Our previous study has been conducted to encapsulate mesenchymal stem cells (MSC) in a feasible laboratory setting. It showed the survival of the MSC in the alginate system. However, higher throughput and uniform size of the encapsulated cells are needed. Therefore, this study introduces a Lab-on-a-chip setup to produce encapsulated stem cells as required quality. Here, an initial study on droplet generation was carried out using Computational Fluid Dynamics software. The study will use the volume of fluid methods with multiphase calculation taking oil as primary phase and water as a secondary phase. The CFD simulation shows that droplet size can be controlled at the range of 100-400 µm by varying the flow rate parameters. A comparative study also showed to confirm our result. This paper can be used for further studies in controllable droplet generation for stem cell encapsulation. [ABSTRACT FROM AUTHOR]

The Minister of Energy and Mineral Resources states that 2% of Indonesia's total population of around 5.2 million Indonesians do not have access to electricity. Most of these people live in remote areas – areas located far away from the district center with low-income civilians. Indonesia has a large potential for renewable energy sources, one of which is water energy. The potential of water energy in Indonesia is 46 GW which is divided into 3 classes - large, medium, and small capacity. For remote areas, small capacity is widely used and suitable as it requires small space to be installed and is classified into mini, micro, and pico. The process of converting water energy into electrical energy is done using water turbines. One example of water turbines is a vortex turbine. Vortex Turbine is a new type of pico-hydro turbine utilizing basin to form a natural vortex phenomenon. Water Vortex Energy can be harnessed to produce Electrical Energy by turning the Water Vortex Turbine. This study focuses on the effect of orifice diameter and blade depth installation on the performance of the Water Vortex Turbine. The orifice diameter and blade depth installation were varied based on Mulligan's Ratio which spans from 0.14-0.18 for orifice-basin ratio and 0.1-0.3 for blade depth installation-basin height ratio. Computational Study was conducted using ANSYS CFD Fluent to analyze fluid flow as it passes through the basin and strikes the blades. The Straight-typed blade was utilized. It was found that the maximum efficiency of 56% is obtained when the Orifice-Basin ratio is 0.14 with optimum turbine angular velocity at 300. [ABSTRACT FROM AUTHOR]

Consideration of energy consumption and its impact on the environment has been driving the heating, ventilating, and air conditioning (HYAC) industry to develop and test more energy-efficient units. The Air Handling Unit (AHU) is one of the important components of the HYAC system that has undergone a lot of improvements in terms of energy efficiency through increased coil surface area, thus its unit size. Yariation of AHU models requires energy performance testing and rating standard which is currently guided by ASHRAE Standard 37. The standard provides a limited guideline on the distance between the floor and the inlet duct length of the vertical AHU units which, although giving flexibility during testing, can lead to the variation of testing results of the same unit. This study uses a computational approach and experiment result to examine the effect of floor distance on the air velocity profile and fan power of a vertical ducting arrangement for an AHU unit. The unit geometry specification is obtained from the experimental campaign at Oklahoma State University, USA as part of ASHRAE research project. The results indicate that for all cases the air velocity 1 m downstream the opening is well distributed. The experiment also shows that different floor distances do not have a big influence on fan power. [ABSTRACT FROM AUTHOR]

Pneumatic actuation type valves have been used successfully applied in many lab-on-chip applications because of their low cost, simple fabrication techniques, and easy to operate. Overall, micro valves module consisted of thermoplastic polyurethane (TPU) film that sandwiched with elastomer silicone layers. TPU films itself is already available in the market and toxic-free whenever contacted with sensitive organic material. The film acted as a diaphragm that pneumatically actuated the valve to be open in a control chamber. In this work, we designed and simulated the valve module to allow fluid flow by applying vacuum pressure on the film at the control chamber. Our study showed that by using a vacuum pressure at -1,467 Pa, the TPU film shall be deflected at a maximum distance of 1.6 mm. This gap resulted in a flow rate of liquid at a rate of 1-5 mL/hr. We also demonstrated that the fabrication of the complete module was relatively easy since using basic mold transfer technique. The performance of the valve was confirmed by measuring the flow rate and liquid before and enter the valve actuation point. It showed that the margin was less than 3% by comparing flow that entered and left the valve chamber. [ABSTRACT FROM AUTHOR]

Engineering an active micropump module to integrate in a portable Polymerase Chain Reaction (PCR) is the ultimate goal of this study. This paper investigates the design of pneumatic pumping module to be embedded in a microfluidic system such as PCR kit. A simulation was introduced to verify the design of the pneumatic micropump module to serve the pumping action in the system. Ultimately, the testing showed that the realized micropump module confirmed the functionality of the pump without any leakage and backflow. [ABSTRACT FROM AUTHOR]

Increased of heat flux generated by electronic equipment in particular components of a computer (CPU) should always be accompanied with a good cooling in order to achieve optimal operating capability with a high level of reliability. The use of loop heat pipes in thermal management of electronic cooling becomes one of alternative solution. Before LHPs are implemented as an alternative cooling method for electronic device, a quantity of reliability factors should be considered and evaluated such as wick structure and material, type of working fluid, long term life tests, and other tests. The purposes of this experimental study are to examine and analyze the application of sintered copper powder as a wick on a loop heat pipe, type of cooling system on LHP and the orientation of LHP. The performace of nanofluid as working fluid in loop heat pipe were also investigated in this experiment. The performance of the loop heat pipe was also affected by the type of condenser; the water cooled loop heat pipe has the highest temperature reducing value compared to the heat sink fan. The orientation of loop heat pipe also affected the performance of loop heat pipe. This proved that gravity and capillary pressure affecting the performance of loop heat pipes. Temperature differences between the evaporator and condenser sections with nanofluids were less that pure water, i.e. thermal resistance of the LHP when charged with nanofluids was less. It makes nanofluid attractive as working fluid in loop heat pipe technology. [ABSTRACT FROM AUTHOR]