11 research outputs found
Design and Analysis of a Vertical Axis Ocean Current Turbine Tunnel Using SolidWorks Computational Fluid Dynamics
The development of renewable energy in the marine power generation sector presents a promising approach to producing electrical energy in a sustainable and environmentally friendly manner. Indonesia, with its vast oceanic territory, holds significant potential for harnessing marine energy. However, the relatively slow speed of ocean currents in the region, typically ranging from 0.1 m/s to 1.5 m/s, poses a challenge to the efficiency of marine power generation. To overcome this limitation, this research focuses on the design and analysis of a vertical-axis ocean current turbine tunnel aimed at increasing the speed of ocean currents, thereby enhancing the overall efficiency of energy production. The study combines a thorough literature review with experimental research methods, utilizing SolidWorks Computational Fluid Dynamics (CFD) software to simulate the tunnel's impact on ocean current velocity. The simulations reveal that the tunnel construction significantly boosts current speeds, increasing them from 1.0 m/s to 1.7 m/s, and from 1.5 m/s to 2.6 m/s. This increase in velocity directly translates to higher kinetic energy available for conversion into electrical power by the turbine. Moreover, the study shows that the tunnel construction contributes to a more uniform flow of ocean currents, as evidenced by the Reynolds numbers obtained—100.250 at a current speed of 1.0 m/s and 150.375 at 1.5 m/s. These values, being below 2000, indicate laminar flow conditions within the tunnel, which are beneficial for optimizing turbine performance by reducing turbulence and ensuring a stable energy output. The findings underscore the effectiveness of the tunnel design in improving the efficiency of vertical-axis ocean current turbines, making it a viable solution for enhancing renewable energy production in regions with low ocean current speeds
Performance Evaluation of Ammonia Refrigeration Systems in a Texturizing Plant
This study evaluates the performance of an ammonia refrigeration system used as a cooling medium in a texturizing plant. The analysis was conducted over a 10-day period, focusing on key performance indicators such as compressor work, condenser exhaust heat, refrigeration effect, mass flow rate, Coefficient of Performance (COP), and overall system efficiency. The data revealed that the system performed optimally on Day 5, achieving a peak efficiency of 91%, with compressor work at 304.1 kJ/kg and condenser exhaust heat at 1414.6 kJ/kg. In contrast, the lowest efficiency was recorded on Day 3, at 77%. The refrigeration effect reached its highest value of 491.3 kJ/kg on Day 3, highlighting efficient heat absorption despite lower overall system efficiency. On Day 4, the mass flow rate was 0.001049929 kg/s, with an actual COP of 1.39, while the ideal COP peaked on Day 10 at 1.69, reflecting the system’s theoretical maximum efficiency under optimal conditions. The study emphasizes the critical role of the condenser in the system’s performance. Optimizing the condenser’s operation by controlling temperature, pressure, and flow rates, alongside regular maintenance, significantly impacts system efficiency. The findings suggest that careful monitoring of operational parameters, including compressor work and refrigerant flow, can enhance the overall efficiency and reliability of ammonia refrigeration systems in industrial settings. This research provides practical insights into improving the cooling performance, reducing energy consumption, and ensuring consistent production quality in texturizing plants
Performance Evaluation of a Condenser at a Combined Cycle Power Plant Using the LMTD Method
This study evaluates the performance of the condenser at the Cilegon Combined Cycle Power Plant (CCPP) using the Logarithmic Mean Temperature Difference (LMTD) method to measure the heat transfer rate. Routine maintenance carried out on the condenser in the form of cleaning the condenser water box and condenser tube from garbage and crust on the condenser tube wall. Currently, condenser maintenance follows a routine schedule that is tied to steam turbine maintenance, without taking actual condenser performance into account. This can lead to inefficiencies and unnecessary downtime. The goal of this research is to assess the heat transfer rate of the condenser before and after maintenance to judge its effectiveness. Data on temperature changes were gathered in June 2023, before maintenance, and again in July 2023, after an overhaul. The analysis shows that the heat transfer rate increased from 51,362,294.48 kcal/h to 127,246,219.7 kcal/h, while the LMTD value rose from 0.76°C to 1.86°C. Based on these results, the study suggests a new approach to maintenance that focuses on performance. Specifically, maintenance should be done when the heat transfer rate drops below 110,000,000 kcal/h. This approach will help ensure the condenser works at its best, improve the plant's overall efficiency, and prevent the need for unnecessary maintenance. By aligning maintenance with performance data, the plant can boost output while lowering costs and downtime
RANCANG BANGUN THERMOBATH UNTUK KALIBRASI SUHU DENGAN TERMOKOPEL TIPE-K MENGGUNAKAN REFRIGERAN HFC-134
Thermobath adalah alat laboratorium yang berisikan air ataupun cairan lainnya sebagai beban pendingin yang dapat mempertahankan temperatur tersebut agar tetap konstan dalam waktu tertentu. Dalam perancangan thermobath penulis menggunakan kompresor 1/6 PK, pipa tembaga ¼ inch, katup ekspansi berupa ball valve, refrigeran HFC-134, dan fluida berupa air dengan volume 2 Liter. Perancangan didasarkan akibat mesin pemanas atau pendingin pada perindustrian dan perusahaan masih banyak memakai refrigeran yang memiliki potensi kerusakan lapisan ozon, penggunaan gas refrigeran semakin banyak untuk menjalankan suatu kerja pada sistem kompresi uap. Alat kalibrasi thermobath menghasilkan panas yang sesuai dengan yang terbaca pada alat ukur dengan bantuan termokopel yang sudah terkalibrasi. Penggunaan termokopel tipe-K ini dirancang menggunakan modul Arduino Max 6675 sebagai safety control agar thermobath tidak melebihi temperatur yang sudah diatur. Uji coba thermobath dilakukan hingga temperatur fluida mencapai 12°C dan 5°C, dengan nilai rata-rata pressure gauge sebelum dan sudah katup ekspansi berturut-turut 2,8 MPa dan 0,4 MPa serta 3,1 MPa dan 0,35 MPa. Laju pendinginan pada temperatur 12°C membutuhkan waktu 35 menit sementara laju pendinginan temperatur 5°C didapatkan dalam waktu 60 menit, laju pendinginan temperatur 5°C lebih lama sekitar 5 menit dan memiliki selisih paling besar 14,32% untuk mencapai suhu 12°C. Nilai COPaktual tertinggi ada pada pengujian temperatur 12°C dengan nilai 1,9 dan penyerapan kalor evaporator sebesar 78,403 kJ, dibandingkan uji temperatur 5°C dengan nilai 1,5 dan kalor serap evaporator 68,570 kJ
The Effect of Heat Flux on the Frequency of Bubble Appearance in a Boiling Pool
This research was conducted to determine the effect of heat flux on the frequency of bubbles appearing in boiling ponds. All fluid movement in pool boiling is caused by natural convection currents. The boiling pool consists of four areas of the pool boiling regime. The division of the four areas is based on the value of the heat flux and the difference between the surface temperature of the heater and the fluid. Using a two-phase heat transfer unit (H654 P.A. Hilton machine), The results showed that the power used greatly influences the boiling process, and besides that, the volume of water used also affects the duration of the boiling process. Based on tests using various power levels of 75 W, 110 W, 168 W, 237.5 W, and 290 W. The occurrence of bubbles will be faster and more numerous when using a lower volume of water and greater power. The heat transfer will be greater if a bubble appears, where latent heat plays a very important role. With mathematical analysis, an increase of 1 bubble per minute occurs for every increase in heat flux of 1.3 W/m2
Heat Transfer Coefficient Characteristic Study of Natural Refrigerant with Substitute for R-134a
The wide-spread use of halocarbon refrigerants are making negative impact on Earth. Natural Refrigerant, such as hydrocarbon, is one alternative of several option to use. Mixing hydrocarbon are develop to improve the heat transfer characteristic. For example is, Musicool-134 (MC-134) is a mixture with two major substance of propane and iso-butane. The experimental apparatus is using a microchannel with a diameter of 0.5 mm and length of 0.5 m. The evaporative process was conducted in the experiment. The result of the experiment is that if the high coefficient value then the heat flux value is also high
Study Characteristic Thermal Electric Generator (TEG) Type SP1848 27145 SA
The TEG component, which operates on the Seebeck principle like a thermocouple, is widely used in the market, with TEG SP1848 27145 SA being one of the most common types. However, experiments must be conducted to determine its Seebeck coefficient, voltage, and power output when used with different heat and cold sources. This research aims to observe how the Seebeck coefficient, voltage, and power output of TEG SP1848 27145 SA change with variations in system temperature. To experiment, TEG SP1848 27145 SA is tested with a heater, and water flow rates are varied for cooling. Furthermore, the correlation between output voltage and ΔT has been determined through statistical analysis. The experiment results showed that the voltage output ranged from 0.54–1.03 V at a heater temperature of 86°C and an ΔT system value of 70.5-75°C. The Seebeck value was between 1,551.7-2,998.5 µV, and the power output was 43.5-67.7 mW. Additionally, the statistical analysis found a significant correlation between the temperature variable and output voltage variable, with an adjusted r square value of 89.2% for zero water flow rate and increasing to 95.8% for maximum water flow rate
Effect of Liquid Reynolds Number on Pressure Drop of Evaporative R-290 in 500µm Circular Tube
Due to certain advantages, natural refrigerants have
recently become more popular. Environmental issues motivate this study, focused
on the characteristics of propane (R-290) as a replacement for conventional
refrigerants. The aim of the present research is to characterize the pressure
drop of evaporative R-290 in a microchannel
of 500µm diameter and 0.5 m
length. The variables of the experimental conditions are mass flux between 155 and
1071 kg/m2s and vapor quality between
0 and unity. The results show a laminar flow for liquid R-290 and a turbulence flow
for vapor. Some existing correlations of two-phase flow viscosity were used to predict the pressure drop. For
homogeneous model, Dukler et al.’s (1964) prediction viscosity correlation best
predicted the present experimental pressure drop
Automatic Temperature Measurement And Monitoring System For Milling Process Of AA6041 Aluminum Aloy Using MLX90614 Infrared Thermometer Sensor With Arduino
Manufacturing process of metal part requires real-time temperature monitoring capability to ensure high surface integrity is upheld throughout the machining process. A smart temperature measurement and monitoring system for manufacturing process of metal parts is necessary to meet quality and productivity requirements. A smart temperature measurement can be applied in machining processes of conventional, non-conventional and computer numerical control (CNC) machines. Currently, an infrared fusion based thermometer Fluke Ti400 was employed for temperature measurement in a machining process. However, measured temperature in the form of data list with adjustable time range setting is not automatically linked to the computer for continuous monitoring and data analysis purposes. For this reason, a smart temperature measurement system was developed for a CNC milling operation on aluminum alloy (AA6041) using a MLX90614 infrared thermometer sensor operated by Arduino. The system enables data linkages with the computer because MLX90614 is compatible and linked to Microsoft Exel via the Arduino. This paper presents a workstudy on the performance of this Arduino based temperature measurement system for dry milling process application. Here, the Arduino based temperature measurement system captured the workpiece temperature during machining of Aluminum Alloy (AA6041) and data were compared with the Fluke Ti400 infrared thermometer. Measurement results from both devices showed similar accuracy level with a deviation of ± 2 oC. Hence, a smart temperature measurement system was succeesfully developed expanding the scopes of current system setup
Optimization of the Friction Factor and Frictional Pressure Drop of R22 and R290
Today, the air-conditioning and
refrigeration industry is still searching for environmentally friendly
refrigerants that could replace hazardous, ozone-depleting coolants –
refrigerants that behave similarly, if not better, than the present ones. The
present study examines optimization of the frictional pressure drop of R22 and
R290 using genetic algorithm. Outcomes are compared against the measured
pressure drop obtained from a horizontal 7.6 mm channel with a length of 1.07
meters. Three equations have been used for calculating the Darcy friction
factor and two-phase flow pressure drop for both laminar and turbulent flow
regimes in smooth and rough tubes. The effects of the different correlations
for the friction factor and pressure drop utilized are demonstrated. The
results illustrate that the differences between values of the Darcy friction
factor are very small for the two refrigerants examined, with the frictional
pressure of R-290 higher than R-22. Use of a smaller channel induced a much
higher frictional pressure drop, as well