FIBERGLASS CIRCULAR TURBULATOR IN COUNTER FLOW DOUBLE PIPE HEAT EXCHANGER: A STUDY OF HEAT TRANSFER RATE AND PRESSURE DROP

This preliminary investigation studied the effect of circular turbulator vortex generator on heat transfer rate and pressure drop in a circular channel countercurrent double pipe heat exchanger with water working fluid. Increasing the number of circular turbulator yielded increasing heat transfer rate and pressure drop. The problem generated when increased pressure drop occurred in relation to more energy consumption of the water pumping system. Therefore, optimization in circular turbulator number is necessary to minimize the pressure drop about distance length between circular turbulator, tube diameter and thickness, type of material and crystal lattice, as well as the geometrical shape of fluid passage (circular or square). This study applied PVC outer tube and copper alloy inner tube, as well as fiberglass circular turbulator. The optimum results showed that seven parts of circular turbulator increasing heat transfer rate by 30% and pressure drop by 80% compared to that passage in the absence of circular turbulator at cool water debit of 7 L/min

CHLORIDE SENSOR FABRICATION BASED ON SPE Ag/AgCl THROUGH CYCLIC VOLTAMMETRIC TECHNIQUE: SCAN RATE EFFECT

The Cyclic Voltammetric (CV) technique is one of the Ag/AgCl fabrication processes. In electrochemical processes using this CV technique, the microstructure of the surface of a substrate or electrode can affect the scan rate. Thus, this study aims to identify the scan rate effect of the Cl-ion sensor fabrication process using the CV technique on the performance of the Cl-ion sensor. First, the CV process was carried out in one cycle to grow the AgCl layer on the Ag surface. Then, this process was carried out at varied scan rates of 20, 40, 60, 80, and 100 mV/s. After completing the Ag/AgCl fabrication process, it was followed by the characterization process, selectivity coefficient test, lifetime test, and validation test to compare the test results of the Cl SPE Ag/AgCl ion sensor with Ag/AgCl commercial. The results showed that the optimum Cl-ion sensor response was obtained at the scan rate of 60 mV/s. Then, based on the validation test, the Cl-ion in the two samples did not show significant differences. Therefore, it indicates that the SPE Ag/AgCl ion sensor has the same performance as the Ag/AgCl commercial

MATERIAL SELECTION OF PROPOSED AIR RECEIVER TANK APPLIED FOR ELECTRICAL GENERATOR

Air receiver tank in electrical generator used as pressured air vessel is mainly consisted of shell cylinder and head part. This work has searched for the more suitable material to be used for the shell and head of the proposed air receiver tank because the older material (SPV 355) has some limitations. This study has been conducted based on several parameters in standard references. The calculations have applied relevant technical formulas such as corrosion factor, thickness design, and Maximum Allowable Working Pressure (MAWP). There are three types of selected materials available that are expected to yield similar previous condition parameters addressing to operational pressure 10 bar and temperature 40oC, i.e., SA-36 (Type I), SA-516 Gr 70 (Type II), and SS-304 (Type III). The economic factor is also taken into consideration. Considering the economic cost and mechanical characteristics, finally the material of Type II is selected to be the most appropriate material to replace SPV 355 material for the proposed air receiver tank. In the upcoming, this study is useful for the knowledge of material design

EFFECT OF SiO2 AND ZnO NANOPARTICLES TO INCREASE REFRIGERATION MACHINE PERFORMANCE

In this investigation, the impact of silicon dioxide (SiO2) and zinc oxide (ZnO) nanoparticles on the performance of a refrigeration machine system was systematically examined. The focus was on evaluating the coefficient of performance (COP) concerning the utilization of a polyolester (POE) lubricant, R600a refrigerant, and distinct nanoparticles (SiO2 and ZnO) within the refrigeration system. The nanoparticles were individually introduced into the R600a refrigerant in masses of 0.5 g, 1.0 g, and 1.5 g. The experimental outcomes demonstrated a noteworthy enhancement in COP with the addition of nanoparticles. Specifically, the introduction of 1.5 g of SiO2 resulted in a substantial increase of 25.88% in COP, marking it as the most influential dosage. Similarly, the addition of 1.0 g of ZnO led to a significant COP increase of 13.6%, representing the optimal quantity for ZnO. Furthermore, the inclusion of 1.5 g of SiO2 brought about a remarkable reduction in energy consumption, with a decrease of 25.58%, while 1.5 g of ZnO resulted in a notable 16.28% decrease in energy consumption. The experimental configuration involved the use of 20 g of refrigerant and 500 ml of POE lubricant. Comparative analysis demonstrated that the refrigeration system incorporating nanoparticles outperformed the conventional R600a refrigeration system devoid of nanoparticles. This study contributes valuable insights into the potential enhancements in refrigeration system efficiency through the strategic incorporation of SiO2 and ZnO nanoparticles, offering a promising avenue for optimizing the performance of refrigeration technology

PENGARUH PENDIDIKAN KESEHATAN TENTANG PROSES PENUAAN TERHADAP TINGKAT KEMAMPUAN KELUARGA DALAM MERAWAT LANSIA DENGAN GANGGUAN ELIMINASI DI KELURAHAN SEWUKAN MAGELANG

Penelitian ini bertujuan untuk mengetahui pengaruh pendidikan kesehatan tentang proses penuaan terhadap tingkat kemampuan keluarga dalam merawat lansia dengan gangguan eliminasi di Kelurahan Sewukan Magelang tahun. Metode penelitian pra-eksperimen dengan jenis one group pretest-postest tanpa kelompok kontrol. Responden penelitian terdiri dari 15 orang diambil dengan tehnik simple random sampling. Pengumpulan data menggunakan lembar observasi dengan uji Paired t-test menggunakan taraf signifikan 0,05. Nilai yang didapatkan yaitu nilai p = 0,012. Pendidikan kesehatan tentang proses penuaan berpengaruh terhadap tingkat kemampuan keluarga dalam merawat lansia dengan gangguan eliminasi di Kelurahan Sewukan Magelang

APPLICATION OF INQUIRY BASED LEARNING MODEL USING STEM APPROACH TO REDUCE STUDENTS' INTRINSIC COGNITIVE LOAD

This study is an experimental research using a quasi-experimental design with the type of non-equivalent control group pretest-posttest. This research aims to reduce Intrinsic Cognitive Load (ICL) through Inquiry Based Learning (IBL) model based STEM approach. This research was conducted at SMA Negeri 1 Seputih Banyak with the research subjects of class X IPA 1 students and X IPA 4. An data Intrinsic Cognitive Load obtained from essay the pretest-posttest (Task Complexity worksheet). Cognitive load test data analysis was performed using the data normality test, N-gain test and hypothesis test using the Paired Sample T-Test. The experimental class implements the Inquiry Based Learning model based audio and visual using STEM approach while the control class is nonaudio and visual. The results showed by the average value of N-Gain Intrinsic Cognitive Load (ICL) in the experimental class was 0.63 with the moderate category and the control class was 0.18 with the low category. Based on data analysis, can be concluded that there is a positive influence in the form of a decrease in the cognitive load Intrinsic Cognitive Load (ICL) in the experimental class using the Inquiry Based Learning model plus an audio and visual based  STEM approach

COMPARATIVE STUDY USING LOW COST ACETIC AND SULFURIC ACIDS ON ROASTING AND PEROXIDE FOR LEACHING PROCESS TO EXTRACT PB FROM GALENA

This article aims to present the application of acetic acid and sulfuric acid for lead (Pb) extraction from galena concentrate applying roasting (600oC and 60 min.) and peroxide oxidant (0.5 M) for 60 min. leaching process. Nowadays, lead has been broadly applied for batteries, besides for PVC tubes, chemicals, paint color, and alloys for joint.  The peroxide increases the percentage of Pb extraction. This study shows the effect of acid concentrations (1.0 M, 1.5 M, and 2.0 M), temperatures (30, 50, and 70oC), and stirring speed (200, 400, and 600 rpm) on Pb extraction from galena. A particle size of galena ≤ 200 mesh after roasting has been used for leaching process. AAS has been used to determine Pb concentration in solution after leaching process. This study shows that acetic acid is a better leaching agent rather than sulfuric acid due to lead sulfate precipitation. Optimization result shows leaching with acetic acid achieved 35.64 ppm Pb extraction using 2.0 M acetic acid, 50oC, and stirring speed of 200 rpm. The beneficiation of low cost acids as leaching agent is a potential technique for Pb leaching that will be developed for industrial purpose due to its economic reason, simplicity, and fast process. 

The Influence Of Alcohol Compound On Biodiesel Production Through Esterification Reaction: A Mini Review

Biodiesel is a renewable alternative energy that has been developed replacing conventional fuel material. Biodiesel can be produced from estereification reaction. Alcohol compound is a substantial reactant for producing biodiesel. The alcohol will donate )-acyl group to yield biodiesel. Several best alcohol compounds that yield the highest conversion is methanol with FFA conversion achieved 96 – 99,1 %. Methanol yield the highest conversion because it has low steric hindrance so the thermodynamically of esterification reaction getting fast and the FFA conversion becoming high. In the meantime, buthanol gives the lowest, i.e.  87 – 94%. Buthanol has high steric hindrance resulting low FFA conversion. Biodiesel with low FFA conversion is difficult to be used as fuel material, This type of biodiesel may damage injection channel for fuel material and with high acid number may cause engine corrosion. 

PENGARUH MODEL PROBLEM BASED LEARNING (PBL) TERHADAP KEMAMPUAN BERPIKIR KREATIF

The purpose of this research was to know the influence of problem based learning model on creative thinking skill at SMP N 2 Jati Agung. The design of this reserach was quasi experimental with samples students VIIC and VIID that were chosen by Purposive Sampling. The research data were quantitative data which were obtained from pre test, post test and N-gain which analyzed using t-test and qualitative data which were obtained from observation students activity and questionnaire of students responses. The research result showed that experiment class average (53,33) was higher than control class (48,30) and percentage average students activity on experiment class (81,66%) was higher than control class (64,22%) and almost all students give positive responses on using PBL. Therefore, it can be concluded that PBL model influenced creative thinking skill in environmental management subject matter.Tujuan penelitian untuk mengetahui pengaruh model PBL terhadap kemampuan berpikir kreatif di SMP N 2 Jati Agung. Penelitian bersifat quasi eksperimental dengan sampel penelitian siswa kelas VIIC dan VIID yang dipilih secara purposive sampling. Data penelitian berupa data kuantitatif yang diperoleh dari rata-rata nilai pretes postes dan N-gain yang dianalisis menggunakan uji-t dan data kualitatif diperoleh dari observasi aktivitas belajar dan angket tanggapan siswa yang dianalisis secara deskriptif. Hasil penelitian menunjukkan rata-rata peningkatan pada kelas eksperimen (53,33) lebih tinggi dibandingkan kelas kontrol (48,30) dan rata-rata persentase aktivitas belajar siswa kelas eksperimen (81,66%) lebih tinggi dibandingkan kelas kontrol (64,22%) serta mendapat tanggapan positif dari siswa. Dengan demikian dapat disimpulkan bahwa PBL berpengaruh terhadap kemampuan berpikir kreatif dalam materi pengelolaan lingkunganKata kunci: aktivitas belajar, kemampuan berpikir kreatif, model PB