Design and Simulation of Electronic Load Controller with DC Dummy Load on Run Off River Type Micro Hydro Power Plant

Micro-hydro power plants are widely installed for electricity in rural areas with power quality is often an issue. In micro-hydro power plants with the Runoff River type, an electronic dummy load controller (ELC) is frequently used to control the frequency system. A dummy load can be either an Alternating Current (AC) or a Direct Current (DC). The principle of dummy load control is to make the output power always constant at the nominal power of the generator. The generator output power is steady when the consumer is changed, coupled with the dummy load. This research article is focused on a simulation of ELC settings with a DC Dummy Load so that the frequency and voltage on the generator side become relatively constant. This article also shows the effect of DC dummy load on generator power quality. The design of ELC Dummy Load DC is a 4-bit combination load with 16 different current values. The simulation running results illustrate the ability of the Dummy Load to maintain a voltage value of about 380 Volts and a frequency of 50 Hz. Therefore, it can be said that the generator output power quality due to the use of ELC Dummy Load DC control is not sufficient in the quality of the produced power. Total Demand Distortion (TDDi) and Total Harmonics Distortion (THDv) are up to 20

Design of Pavement Structure Based on An Empirical Mechanistic Design Approach for Roads with AC-WC Asphalt Mixture Using Buton Granular Asphalt (BGA) and Modifiers

Indonesia relies heavily on imported asphalt, consuming around 5 million tons per year, despite having substantial domestic buton granular asphalt (natural asphalt) deposits of up to 662 million tons. This research aims to analyze the potential of using buton granular asphalt B 50/30 (ASB) and a liquid asphalt modifier (SC70) as additional materials in AC-WC asphalt mixtures (AC-WC+ASB+SC70), evaluate the empirical-mechanistic design correlation, and determine flexible pavement design based on MDP 2017 method from Ministry of Public Work and Housing, Indonesia. The study employed laboratory testing using Marshall and UMATTA methods. The results showed that with the estimated bitumen content (Pb) 6%, the optimum asphalt modifier content (OMC) was 2.3%, and the UMATTA test indicated the Smix value of AC-WC+ASB+SC70 was 1202 MPa at 20°C, exceeding the typical AC-WC value of 1100 MPa. The flexible pavement design comprised a 4 cm AC-WC layer, 6 cm AC-BC layer, 18 cm AC-Base layer, and 30 cm of LPA. The findings suggest that the use of ASB and SC70 can effectively extend pavement service life. The higher the asphalt mixture's modulus value (Smix), the better the flexible pavement performance. This approach offers a sustainable solution to Indonesia's reliance on imported asphalt, leveraging its abundant domestic BGA resources

Health Risk Analysis Due To PM10 and PM2.5 Exposure in Ambient Air in Bandung Regency

This study aims to identify and analyze non-carcinogenic health risks posed by Particulate Matter (PM10 and PM2.5) exposure in Bandung Regency. The region is experiencing increased emissions of air pollutants due to rapid economic and population growth, especially in industrial and traffic-intensive areas. The study was conducted using the Environmental Health Risk Analysis (EHRA) technique to estimate the public health risks due to PM10 and PM2.5 exposure. Data were obtained through interviews, questionnaires, and direct measurements for PM10 and PM2.5 concentrations. The results showed that the average concentrations of PM10 and PM2.5 in the industrial area of Soreang-Kopo highway were higher (61 μg/m³ for PM10 and 46 μg/m³ for PM2.5) compared to the non-industrial area of Soreang-Ciwidey highway (30 μg/m³ for PM10 and 20 μg/m³ for PM2.5), but still below the quality standards set by regulation, PP RI No. 22 of 2021 which are 55 μg/m³ for PM2.5 and 75 μg/m³ for PM10. The highest level of health risk or RQ for PM10 and PM2.5 is 0.50 so it is declared safe (RQ<1), but even so there are 4 respondents who show RQ values>1, so further risk management is needed such as reducing pollutant concentrations, exposure time, and exposure frequency

CFD-Based Comparative Analysis of Conical Dimple and Conical Protrusion in a Reverse Flow Solar Air Heater

This study examined the thermohydraulic performance of reverse flow solar air heaters (RFSAH) incorporating conical surface roughness geometries. A 3D computational fluid dynamics (CFD) model, developed using SolidWorks 2022, was employed to simulate heat transfer enhancement. The simulation utilized the average August solar radiation data for Bauchi, Nigeria (567 W/m²). Two conical roughness configurations were investigated, dimples and protrusions. The effects of the Reynolds number, pitch ratio, and height ratio on the heat transfer and fluid flow were analysed. The results revealed that conical protrusions exhibited a higher peak thermohydraulic performance factor (TPF) of 3.899. The optimal conditions for conical protrusions were determined to be Re = 5988.84, P/e = 5.7, and e/D = 0.2127, achieving a TPF of 5.0672, a 1.3-fold increase compared with unoptimized protrusions. These findings showed the potential of using surface geometries to enhance the efficiency of solar thermal systems while maintaining a favourable balance between the performance and pressure drop

Air Quality Evaluation Based on PM10 and PM2.5 Concentrations at the Entrance Gate of Kota Baru Parahyangan, West Bandung Regency

Initially, Kota Baru Parahyangan was expected to have healthy air quality, because it is located far from the center of Bandung and the surrounding environment is still in the form of rice fields and small forests. However, because the entrance to Kota Baru Parahyangan is a confluence of vehicles from the west, east and the Padalarang toll gate, it causes severe vehicle congestion. The consequence of this density is an increase in PM10 and PM2.5 concentrations in the area. Therefore, the purpose of this study is to determine the air quality in the entrance gate area of Kota Baru Parahyangan. Particulate matter measurements of PM10 and PM2.5 were conducted for one week (7 days), from Monday to Sunday. There were three testing points carried out at the entrance gate area, namely at two points at the density location and one point towards the residential and business center. When evaluated using PP No. 22 of 2021, the measurement results show that the PM10 concentration for 7 days of measurement is still below the quality standard, but for PM2.5 there are 3 days where the concentration is above the quality standard. Meanwhile, when evaluated based on Permen LHK No. 14 of 2020, the average air pollutant standard index (ISPU) status for PM10 is “Medium” for points 1 and 2, and “Good” for point 3, but for PM2.5 the average status is “Medium” for all points. These results prove that the density of vehicles will have an impact on reducing air quality at points 1 and 2, while point 3, where the density of vehicles is relatively small compared to points 1 and 2, still has “Good” air quality for PM10. The relatively high concentrations of PM10 and PM2.5 at points 1 and 2 need to be addressed by the developers of Kota Baru Parahyangan and the West Bandung Regency government

The Effect of Aging on AC-BC Asphalt Mixture with Molasses as a Substitute for Asphalt

Asphalt aging is one of the causes of quality deterioration in flexible pavement. Previous studies have shown that molasses can be used as a substitute for asphalt. This study uses molasses at 15% of the asphalt weight. Aging tests were conducted on AC-BC asphalt mixtures, which are intermediate layers often used in areas with high deformations. Asphalt aging occurs in both short and long terms. Short-term aging occurs during mixing, tested using Short-Term Oven Aging (STOA), while long-term aging occurs during service life, tested using Long-Term Oven Aging (LTOA). STOA testing involves heating the loose mixture in a laboratory oven for 4 hours at 135°C, while LTOA involves heating solid specimens in a laboratory oven for 2 days and 5 days at 85°C. The test results indicate that aging affects the characteristics of asphalt mixtures, as evidenced by an increase in Void in Mixture (VIM) and Void in Mineral Aggregate (VMA) values, while stability, flow, Void Filled with Bitumen (VFB), and density values tend to decrease. The test results also show that HMA AC-BC +15% Molasses is better at maintaining stability values, as evidenced by the higher stability value of HMA AC-BC + 15% Molasses compared to HMA AC-BC Control

Impact of Cathode Variations on the Mechanical Properties of Hard Anodizing in Sulfuric Acid 15% and Phosphoric Acid 1%

Aluminum 1100 could be used as domestic appliances material, especially on kitchen equipment. The purpose of this research was to improve the properties of aluminum 1100. In order to improve the physical and mechanical properties, a hard anodizing process was conducted. In the hard anodizing process, 1100 aluminum workpieces are sanded, decreased in alkaline solution and neutralized in acidic solution. The hard anodizing process is carried out by placing the workpiece on the positive pole and the electrode on the negative pole (cathode) of the direct current source. The hard anodizing process of 1100 aluminum alloy was carried out in a mixture of 15% sulfuric acid and 1% phosphoric acid solution, current density of 3A/dm2, anodizing time of 30 minutes, temperature of 5 °C, and cathode variation (Al and Pb). The results showed the formation of an oxide layer on the metal surface consisting of two types of layers, called the barrier layer and the porous layer. The barrier layer has no pores because it has conductive microstructure properties and reaches the maximum thickness. The porous layer formed can increase the overall thickness of the oxide layer, while the barrier layer remains a constant thickness and increases the hardness level of the aluminum. This study resulted in a process efficiency of 83.04% with the best oxide layer thickness of 11.43 μm and the highest hardness of 144.25 HVNoxide layer thickness of 11.43 μm and the highest hardness of 144.25 HVN

The Effect of Maltodextrin Concentration and Drying Temperature on the Instant Coffee Production with Spray Drying Method

The operating temperature and the addition of fillers such as maltodextrin had a valuable effect on the quality of instant coffee production. Based on this, the purpose of this research is to determine the effect of maltodextrin concentration and operating temperature on the quality of instant coffee powder produced by the spray drying method. The variation of operating temperature was conducted in the range of 120 to 170⁰C without the addition of maltodextrin, and the variation of maltodextrin concentration was conducted in the range of 5% to 35% (w/v) with the optimum operating temperature at the lowest water content. The observed quality parameters of the coffee were yield, moisture, ash, caffeine content, and organoleptic tests. The optimum operating temperature was 140⁰C with a moisture content of 5.17% (w/w). The best instant coffee quality was achieved with a 15% concentration of maltodextrin, with a yield of 50.49%, a moisture content of 3.94% (w/w), an ash content of 6.66% (w/w), and a caffeine content of 5.16% (w/w). Based on the organoleptic test, the coffee sample with 15% maltodextrin had a brownish color, a moderately strong aroma, was moderately bitter, and was liked by the panelists

Energy and Exergy Analysis of Chest Freezer Using R134a and R290 as Working Fluids Based on Experimental Data

Although R134a has a very high global warming (GWP) effect, it is still used as a refrigerant in chest freezers. As an alternative to R134a is R290 which has a very low GWP value, which is only 3. Therefore, it is expected that there will be no more chest freezers using R134a and replaced with R290, soon. Thermodynamic studies need to be conducted to see the advantages and disadvantages of the two refrigerants based on experimental data. In this study, a chest freezer which was originally manufactured for R134a with a charging mass of 150 g was used as a test object. Experimental data of the chest freezer using R290 was taken after testing with R134a was completed. Experimentally, the cabin temperatures of the chest freezer using R134a and R290 are -20.5oC and -35.7oC, respectively, and the input power are 264 W and 176 W, respectively. Total irreversibility on the four main components of the chest freezer using R134a is greater than using R290, namely 184.4 W and 107.0 W, respectively. This means that the use of R290 as a working fluid in the chest freezer is more efficient. There are at least three advantages of replacing R134a with R290, namely reducing greenhouse gas emissions because R290's GWP is much smaller than R134a, lower cabin temperature, and decreasing the input power of the chest freezer

The Effect of Pineapple Crude Enzymes and Fermentation Time on The Decaffeination Process of Robusta Coffee

The decaffeination of robusta coffee can be done through fermentation with a crude enzyme containing bromelain enzyme from pineapple. The study aims to determine the activity of the bromelain enzyme by the Kunitz method, the effect of fermentation time and crude enzyme concentration on the decaffeination process, and the characteristics of coffee before and after fermentation using FTIR. The fermentation time was varied from 6 to 36 hours and the crude enzyme concentration was varied from 10 to 80%. The activity of the bromelain enzyme was 36 U/ml. Fermentation time affects the decaffeination process, wherein the longer the fermentation time from 6 hours to 36 hours obtained caffeine content from 2.39% to 0.07%. Besides that, the crude enzyme concentration affects the decaffeination process, which obtained the lowest caffeine content or percent decaffeination at the crude extract concentration of 80% (v/v). FTIR results showed that the decaffeination process affected the reduction of caffeine in coffee samples. It can be shown from the increase in the %T value of the C-N functional group from 40.731 to 54.85