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Impeller is a part of centrifugal compressor that has an important role in the pressure generation process. Differences in the shape and size of this component greatly affect the overall ability of the compressor to generate pressure. This research is focused on prediction of centrifugal compressor performance by varying the impeller outlet blade angle. The study was conducted at off design parameter of a single stage centrifugal compressor with an impeller diameter of 236.24 mm and a diffuser outer diameter of 349.83 mm. The number of impeller blades is 18 and the number of diffuser blades is 6 with impeller inlet blade angle (β1) of 42°, and impeller outlet blade angle (β2) of 50°. The maximum efficiency of the designed centrifugal compressor occurs at a mass flow rate of 0.993 kg/s with a value of 83.71%. Result of the numerical simulation shows that the higher value of β2, the higher pressure-ratio that can be produced under all mass flow rate condition. Compressor overall efficiency also increases with the increase of β2 value. However, higher value of β2 results in an increase of instability level of gas flow at impeller outlet and eventually backflow began to occur in the β2 value of 90° that would reduce the volumetric efficiency of the compressor. [ABSTRACT FROM AUTHOR]

Centrifugal compressors are the most commonly used types of compressors in industry. Performance of compressor is one significant parameter to be first determined prior to its design and operation. Centrifugal compressor's is usually expressed in terms of flow, head, speed and efficiency. Determining centrifugal compressor's performance operation is however very costly, due to it requirement for testing after fabricating and manufacturing of the compressor. This research is addressed to predict the centrifugal compressor performance cheaply through a numerical simulation. The study was conducted at a specific off design parameter for designed mass flow rate of 0,98 kg/s of centrifugal compressor. It is a single stage centrifugal compressor with an impeller diameter of 236.24 mm and a diffuser outer diameter of 349.83 mm. The number of impeller blades is 18 and the number of diffuser blades is 6 with a diffuser inlet angle of 15⁰. The numerical simulation was established and validated with experimental study. The simulation was then carried at the range of operating mass flow representing varies operation condition. The results revealed that simulation model has been built to simulate the performance of the centrifugal compressor. The simulation results were validated and accepted at deviation below 5%. In addition, the simulation is enabling to generate performance curve in term of pressure ratio and efficiency with respect mass flow rate. Maximum efficiency of the designed centrifugal compressor occurs at a mass flow rate of 1 kg/s with a value of 80.83%. This numerical method is very promisingly to be further incorporated for industrial application for predicting the centrifugal compressor performance. [ABSTRACT FROM AUTHOR]

Heat Recovery Steam Generator (HRSG) is one of the vital units in various industries in order to improve energy efficiency. Uniform distribution of gas turbine exhaust gas that enters the HRSG becomes one of the important parameters of the HRSG design to minimize corrosion and hot spots that cause the tube to burst. The characterization of the effect offlow diverter was carried out to observe the velocity distribution as a parameter of flow uniformity, the distribution of pressure and temperature of the gas flow that passes through each heat exchanger module as a parameter of HRSG performance. CFD simulation was conducted on the HRSG model which included the inlet duct, the heat exchanger module section which is assumed to be the porous media, and the stack as the flue gas output. Flow diverter configuration consisted of the number of plates 1, 3 and 5 with angles of 30°, 45°, and 60°, respectively. The numerical simulation was establishedand validated with experimental study. The dimensionless numbers, swirl number and Euler number, were considered as the dynamic similarities between the experimental model and the numerical simulation. Flow uniformity from the configuration of 3 plates with angle of 45° was 86.3%, which was 3.522% higher than HRSG without a flow diverter. Other configurations caused flow uniformity decreased. Installation of flow diverter had no significant effect on HRSG performance. [ABSTRACT FROM AUTHOR]

Paraffin wax is applied to a solar water heater (SWH) as a thermal energy storage material due to its high energy density. Several previous studies have shown that integrating water and paraffin wax in the SWH tank can increase the thermal energy storage capacity. However, the thermal stratification of thermosyphon-type SWHs with horizontal tanks has not been explicitly disclosed. This paper investigates the thermal stratification of water inside the SWH tank containing paraffin wax. Paraffin wax was filled into a cylindrical capsule. The capsules were then put into the SWH tank and arranged parallel to the axis of the tank. The experiment was conducted for the duration of the charging process. The solar radiation intensity, the water, and the paraffin wax temperature were recorded. The resulting data was accustomed to graph the evolution of water and paraffin wax temperature. Based on the graph, thermal stratification was formed visually inside the tank. Stratification analysis was conjointly performed with the Richardson number calculation. The calculation shows that the value of Richardson's number is more than one. These results explain that thermal stratification occurs in the SWH tank. The addition of capsules containing paraffin wax can maintain thermal stratification. [ABSTRACT FROM AUTHOR]

Industrial development has impact to the production of carbon dioxide gas emissions, particularly resulted from combustion exhaust gases in production process. Almost 90% of the gases that cause the greenhouse effect is produced by the increasing of carbon dioxide in the atmosphere. Porous material is one the promising adsorbent material for inorganic elements, such as carbon dioxide gas. The activated carbon used in this study was produced from seaweed solid waste. A high cellulose composition in seaweed solid waste, which reached 43.47%, making the seaweed solid waste has potency to be a precursor of activated carbon. Many research developments to improve the performance of activated carbon as an adsorbent have been carried out. One of the most promising groups of adsorbents for carbon dioxide capture are metal organic frameworks (MOFs) as microporous materials with crystal structures. The purpose of this study is to create a new type of composite using the activated carbon derived from seaweed solid waste and Metal Organic Frameworks (MOFs) to enhance the adsorption capacity of carbon dioxide gas. Activated carbon was carried out using carbonization process in temperature of 4000C for 60 minutes and 6000C for 30 minutes. Then bio-chars were activated using NaOH solution with concentration of 40% and 20%. Copper and Nickel as metals in MOF were selected in this study. The MOFs/AC composite were investigated to find out their porosity and surface area using BET analyzer, and the potency to adsorp carbon dioxide gas using Temperatur Programme Desorption (TPD)-CO2. The compositon of metals were measured using an X-Ray Fluorescence (XRF). The composite material of MOF with activated carbon resulted higher CO2 adsorption capacity than activated carbon produced by chemical activation using NaOH solution. The presence of collaborative or cooperative effects originating from different components can increase the adsorption capacity of CO2 molecules because an active site is formed on the surface between Cu-MOFs and Ni-MOFs with activated carbon. [ABSTRACT FROM AUTHOR]

The seaweed industries produce amount of solid waste that was discharged directly into the environment. Seaweed solid waste has high cellulose and carbon contents, therefore it can be used as a precursor of activated carbon. The method for production of activated carbon consisted of two processes, namely the carbonization process and the chemical activation process using NaOH activator. The nature of the precursors, the effect of temperature and carbonization time, and the effect of the concentration of activator on the chemical characteristics of the activated carbon product were investigated and discussed in this study. The selected carbonization temperature and time were 400°C and 600°C within 30, 60, and 120 minutes. The chemical activation process was carried out using NaOH activator and the ratio of activator mass/carbon mass was 4:1 with variations in the concentration of the activator solution applied were 20%, 40%, and 60%. Proximate analysis was carried out to determine the chemical characteristics of activated carbon, including yield content, moisture content, volatile matter content, ash content, and the calculation of fixed carbon. Variations in NaOH concentration (20%; 40%; 60%) affected the yield parameters, water content, ash content, volatile matter, and fixed carbon content. The highest yield of charcoal produced from the carbonization process at 600°C 60 minutes was 81.01%. The highest air content of 9.85% was obtained at a variation of 600°C 120 minutes with a concentration of 60% NaOH. The highest ash content of 10.25% was obtained at a variation of carbonization 600°C 60 minutes with 40% NaOH concentration. The volatile matter content of 23.11% was obtained at a variation of carbonization 400°C 60 minutes with a concentration of 60% NaOH. The highest carbon content was reached 76.91% at a variation of carbonization 400°C and 30 minutes with 20% NaOH concentration. [ABSTRACT FROM AUTHOR]

Cow manure can be used as biogas and produces digested cow manure by-products. Digested cow manure still has a calorific value, low water content, and low sulfur content, so it can be used as environmentally friendly energy. Due to the low energy density of ingested cow manure, pelletization is required. The advantage of pelletizing digested cows is that they do not use a binder, only the water content is adjusted. The dough is formed using a die and roller type pelletizer. The purpose of this study was to determine the effect of production capacity, and test bio-pellets as fuel in biomass stoves and boilers. Digested cow manure bio-pellet can be used as fuel for biomass stoves with an average consumption of 0.3 kg/liter of water. However, bio-pellet from digested cow manure cannot be used directly in the boiler industry, it still needs to be mixed with other fuels to increase the calorific value. [ABSTRACT FROM AUTHOR]

DME can be synthesized from natural gas, coal, biomass, and/or coal seam, and is a sulfur-free, near-zero aromatics synthetic fuel which is considered as an excellent substitute for conventional diesel and liquefied petroleum gas (LPG). Currently, various production technologies are developed and many commercial projects are actively being progressed. This paper presents recent development and future prospect of Dimethyl Ether (DME) as an alternative energy, simple review for biomass energy, comparison of biomass and coal conversion to DME. The use of lignite coal as the basic material for the manufacture of DME is less profitable because it produces H2S gas which is harmful to the environment, thus requiring a purification unit to remove the gas. The addition of these units increases production costs. Meanwhile, biomass has higher availability and contains lower sulfur than coal. Biomass that has the potential as a substitute for lignite is tofu waste because of the highest availability and the highest syngas yield. [ABSTRACT FROM AUTHOR]

Energy sourced from fossil to be the only main source of energy to full-fill all aspects of needs. But, fossil fuels as energy sources are non-renewable sources so could run out at a certain time. The decreasing of fossil sources production, especially crude oil, encourage the government of Indonesia to generate, develop, and improve the potency of New-and Renewable Energy (NRE) sources. Solar panel is the most reliable NRE sources to reach the projection of NRE utilization increased by 31.2% in 2050. Li-ion batteries are electrical energy storage devices that are most preferred to be used in solar panels. Li-ion battery with cylindrical model made of LiNi0.85Co0.15Al0.05O2 (NCA) and LiNixMnyCo1-x-yO2 (NMC) cathode material shows good electrochemical performance (energy density, specific capacity, cycle, and stability) and toughness. The cathode material synthesis method is important because it determines battery performance. The combination of co-precipitation and solid-state methods is the best choice to produce cathode materials that provide the best performance for Li-ion batteries for solar panels. [ABSTRACT FROM AUTHOR]

Creative thinking skills are very important in the 2lst era. The 2lst-century skills require a person to have 4C skills (Critical Thinking, Communication, Creative Thinking, and Collaboration) where creative thinking skills are in the 4C. We can integrate creative thinking skills into the teaching and learning process by implementing a specific model, namely research-based learning (RBL). This will be done by elaborating STEM problems, namely Science, Technology, Engineering, and Mathematics. In this study, we will focus on food preservation. By combining the model and the approach, in this study we will develop research-based learning materials with a STEM approach to improve the student's creative thinking skills in using chitosan as a breakthrough for the preservative of processed meat. This study used the Research and Development (R&D) method of the 4D model consisting. The learning material products are lesson plans, students worksheets, and assessment instruments. Data collection instruments for testing validity, practicality, and effectiveness are questionnaires, observation sheets, and feasibility validation sheets (content, format, and language). The results show that the learning materials satisfy content validity, format validity, and language validity. The result of practicality and effectivity tests shows a significant contribution with the results of the statistical inferential paired sample t-test, a 2-tailed significance value of 0.00 is obtained, which is smaller than ≤ 0.05. [ABSTRACT FROM AUTHOR]

Water use as a heat storage material in solar water heaters (SWH) has disadvantages, including its low energy density, which requires a large volume of thermal energy storage. Phase-change material (PCM) is a latent type of heat storage material that has the advantage of being a high energy density. Therefore, PCM is quite interesting to be applied to SWH systems. In the operation of SWH, it is necessary to know the characteristics of hot water usage. This paper aimed to determine the characteristics of a continuous and gradual discharging method on SWH that applies PCM. This study used a thermosyphon type of SWH. The tank was placed horizontally on the top side of the collector with a volume of 60 liters. Twenty-four cylindrical capsules containing paraffin wax were inserted into the tank. Thermocouples were installed on the waterside and the PCM side. Continuous and gradual methods were carried out in the discharging experiment. Experiments using a continuous discharging method given information that water temperature decrease continuously in the tank. Experiments with a gradual discharging method showed PCM's contribution, which can transfer thermal energy to the water. The gradual discharging method explained that the SWH system produced hot water that can be used for bathing as many as five people every day with water temperatures of 45 °C at an average solar radiation intensity of 514.89 W/m2. The use of PCM makes a positive contribution to the thermal energy storage in the tank. [ABSTRACT FROM AUTHOR]

Centrifugal pump is indispensable equipment for various industrial applications which mainly used to move fluid by supplying head at specified flow rate. Pump performance is influenced by occurrence of losses which consist of volumetric, hydraulic and mechanical losses which further quantified by corresponding efficiency. In its application, real operating pump performance is quite difficult to predict without referring to manufacture data report which measure pump performance directly during operation of the pump This research is aimed to investigate numerically the pump performance variation with respect to the number of blades. A specified pump has operating condition of head 12.08 m, flowrate of 0.0015 m3/s, rating rotation of 2800 rpm with 7 blades is investigated. The performance analysis is performed through numerical simulation using ANSYS. Performance comparison is carried in varied blade number of 5,7 and 9. The performance of centrifugal pump is determined in terms of head (H) and flow rate (Q), as well as pump hydrodynamic efficiency (h). It is found that the higher head occured in the case of 9 blades up to a certain limit. On the other hand, hydrodynamic efficiency in the case of 7 blade is higher than the other two cases for simulated flow rate range. From the head and flow rate relationship, it is noted that the pattern produced by plotting head and efficiency against flow rate indicate that there is an optimum number of impeller blade for centrifugal pump. [ABSTRACT FROM AUTHOR]

Recently, biomass gasification technology for supplying heat has attracted several energy-intensive industries, such as ceramics and hot mixed asphalt production, as the fossil fuel pricing escalates, and environmental issues dominate the news. It offers higher energy efficiency, raw material flexibility, a wider range of capacities, and lower greenhouse gas emissions. Palm kernel shell is a potential biomass source in Indonesia as feedstock of the gasification process because of its high calorific value, abundance, and being considered as carbon-neutral and sustainable. The gasification process performance should be measured based on carbon conversion efficiency (CCE) and cold gas efficiency (CGE) to guarantee the operation's reliability. This study aims to develop the performance evaluation method of an industrial updraft woody and woody-like biomass gasification system using air as a gasifying agent for supplying heat through a thermodynamic approach. The model developed was created using licensed Aspen Plus v.11 software. The constructed model was validated with several laboratory experiments of previous researchers using various types of biomass considering carbon monoxide and hydrogen contents in the producer gas. The thermodynamic model showed a good agreement with the experimental data assessed based on root mean square error (RMSE) value for H2 and CO being 3.02 and 2.10, respectively. The developed model was implemented to evaluate performance of an asphalt mixing plant with palm kernel shell updraft gasifier as a heating source of aggregate. It was observed that at the operation condition of equivalent ratio (ER) of 0.082, the CCE and CGE were 46% and 38%, respectively. The model dictates that this installation unit should be operated at an ER value of 0.28, which is equivalent to a feedstock flowrate of 990 kg/h and an air gasifying agent flowrate of 1250 Nm3/h to achieve near to 95.20% of CCE and 76.34% of CGE. At the same time, about 50% savings on feedstock was also identified. [ABSTRACT FROM AUTHOR]

The weakness of an outdoor solar water heater (SWH) experiments is the difficulty in determining its thermal behavior. The fluctuation of solar radiation intensity causes the supply of energy received by SWH also fluctuate. The result is that the thermal behavior of the SWH cannot be known for specific parameters. This paper aims to investigate the thermal behavior of an active type SWH containing paraffin wax using the constant heat flux method. A phase change material (PCM) inserted into the capsule. The capsules were arranged in a tank to form a heat exchanger (HE). The thermocouples were mounted both on the waterside and the PCM side. The solar simulator installed on the top of the collector, and the SHW system placed indoors. The heat flux and water flow were set at 1000 W/m2 and 2 LPM, respectively. The temperatures of water and PCM for 143 minutes charging recorded. The data obtained were used to analyze the thermal behavior of water and PCM. The results showed that the average heating rate of water and PCM was 0.227 °C/min and 0.205 °C/min, respectively. The value of this adjacent average heating rate shows that HE has functioned well in removing heat energy from water. The accumulated thermal energy produced was 13.08 MJ. Indoor experiments can reveal the thermal behavior of the SWH-PCM systems. [ABSTRACT FROM AUTHOR]

Simulations for co-axial types are carried out in two types, namely the kind where the inner tube inserted into the resonator area and the second type of inner tube inserted through the thermoacoustic core. In the first type of co-axial simulation the acoustic power produced was much smaller compared to the kind of standing wave, while the second type of co-axial simulation obtained higher acoustic power compared to the type of standing wave. Performance simulation on the co-axial thermoacoustic engine (CoATE) with 25 mm inner tube diameter showed that the acoustic energy generated at 30.65 watts, 30.23 watts, 29.62 watts, 28.83 watts, and 27.85 watts for 580 mm, 530 mm and 480 mm, 430 mm, and 380 mm inner pipe, respectively. [ABSTRACT FROM AUTHOR]

In order to investigate the performance and cost analysis of electrocoagulation process, various electrolytes are picked out to remove Fe, color, and turbidity in peat water through batch and continuous reactors. Peat water has brownish red color, acidity, high turbidity, and a large concentration of Fe which exceed the water standard quality. Electrocoagulation is an electrochemical method for water treatment that along the anode where active coagulant as aluminum ions is released into the solution. Several kinds of electrolytes are applied, such as 0.01M NaCl p.a., 0.01M NaCl technical grade, 0.01M NH4Cl p.a., and 0.01M K2SO4 p.a. with process time up to 120 minutes. The results show that the electrocoagulation in a batch process using NH4Cl for 120 minutes obtains the highest of removal percentage of Fe, color, and turbidity, which are 90.92%, 84.93%, and 99.94%, respectively. However, according to scoring evaluation, commercial NaCl using through continuous reactor generates the outputs have fulfilled the water standard quality as well as batch condition with low-cost production about Rp 23.21/Liter, about 64.18% cheaper than without electrolytes addition, and 82.93% more inexpensive than generally chemical treatment. [ABSTRACT FROM AUTHOR]

Outcome based education (OBE) helps to evaluate how well learning process achieves the outcome program and how far students achieved the intended learning outcomes. Problem based learning (PBL) approach is potential to assess the achievement of OBE. The aim of the present work is to describe how teaching and student assessment methods for implementing problem based learning (PBL) in Mass Transfer Operation course were adapted to the online learning during covid-19 pandemic. Based on the result of online class of Mass Transfer Operation course, the problem based learning method may be implemented well and interested to be developed. The students are motivated to experience the new collaborative learning way. The digital education will remain in place even when offline class is allowed. [ABSTRACT FROM AUTHOR]

Pretreatment process on lignocellulosic biomass of oil palm empty fruit bunch (OPEFB) is an important stage in the process of converting lignocellulosic biomass route into bioethanol because its determines the success of the overall process. The purpose of this research was to conduct characterization OPEFB's fiber resulted from alkali fiber explosion (ALFEX) and low tempereture alkali (LTA) processes, such as composition of lignocellulosic components, functional group of bonding structure, surface morphology structure, crystallinity, and swelling test. The experiment variations were conducted on sodium hidroxide concentrations of 0, 4, 8, 12, and 15% weight. Based on the results of this research, it was concluded that the ALFEX pretreatment more effective to remove the lignin of OPEFB than the LTA process. The highest decreasing of lignin content in the process ALFEX and LTA were 30,37% and 5,30% that occurred in the sodium hydroxide concentration of 12% and 15%, respectively. The FTIR analysis of OPEFB from ALFEX pretreatment results showed changing in the absorption band of infrared radiation at wave number 1370 cm-1, 940 cm-1, and 730 cm-1. The ALFEX and LTA pretreatments could reduce cellulose crystallinity of OPEFB from 58% to 29%. The ALFEX pretreatment was better to open the complex structure of OPEFB lignocellulose than the LTA process. It was shown in the results of SEM photograph that the OPEFB fibers of ALFEX pretreated became smooth, soft and appeared to swell like a sponge and break down from its bundled structure. The swelling test results indicated that the highest's water absorption value of EFB fibers's ALFEX pretreated occurred in 12% sodium hydroxide concentration which absorbed water until 11 times from the initial fibers weight. While the highest's water absorption value of EFB fiber's LTA pretreated occurred in 15% sodium hydroxide concentration which absorbed water only 3 times from the weight of initial fibers.3 [ABSTRACT FROM AUTHOR]

Analysis of greenhouse gas (GHG) emissions has been studied in modern and traditional tempeh industries in Indonesia. Rumah Tempe Indonesia (RTI), a modern tempeh industry, has unique process production compared to other traditional industries such as in Kedaung, South Tangerang, Indonesia, and has used modern equipment for processing tempeh. These characteristics affect the total of GHG emissions resulted in tempeh produced by RTI. The purpose of this study is to compare the total of GHG emissions resulted from tempeh production in RTI and traditional industry in Kedaung. Life Cycle Assessment (LCA) is a tool used to estimate environmental impacts of a product or process. In our study we use an LCA method CML-IA baseline V3.01/World 2000 implemented in PC-tool SimaPro 8.0.1 (Pre 2016). The analysis result of GHG emissions impact represents that tempeh produced by traditional industry in Kedaung has lower GHG emissions than RTI does. We obtain that the total GHG emissions produced by tempeh in Kedaung and RTI are about 0.296 and 0.676 kg CO2 eq/kg tempeh, respectively. This result may indicate that the traditional industry, which uses electrical energy for the boiling and splitting processes, produces lower GHG emissions than modern industry, which needs more electrical energy consumption for whole of process production. The largest CO2 emissions in tempeh produced by Kedaung is generated from the tempeh processing, which reaches 98.17% of the total GHG emissions and the remaining substances are generated from electricity. We found that at RTI the tempeh processing also contributes 69.19 % for the total GHG emissions, while the rest come from untreated wastewater. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on thermal behaviors of phase change material (PCM) during melting process in annulus cylinder. The inner cylinder was functioned as PCM storage, the outer cylinder was designed as shell, and both were made of acrylic. The PCM Storage was heated on its surface by circulating hot water as heat transfer fluid (HTF) in the shell. The variations of HTF temperature are 60, 65, 70°C and its mass flow rate is maintained at 4 liter per minutes. Thermal analysis of the melting process over time is given to provide more specific information of temperature contour change during the process. Solid--liquid melting process is shown by sequential photographs taken by the digital camera during the process in axial and radial direction. The results indicate that at the beginning of melting process, the heat transfer is dominated by conduction between inner wall of PCM storage and solid PCM. When the PCM has melt, convection holds important role in the heat transfer due to density gradient of the liquid PCM. Increasing of 5°C temperature is able to reduce about 34% of the total melting time. [ABSTRACT FROM AUTHOR]