Numerical simulation and combustion analysis of coal and biomass co-combustion

China began entering the 14th Five-Year Plan period in 2021. With the proposed carbon-neutral long-term goal, the strategic position of clean energy is becoming increasingly prominent. using biomass power generation is one of the main application ways. In order to study the mixed combustion process of coal and biomass, this paper takes 300MW lignite boiler as the research object and uses Fluent software to explore the influence of biomass types and the location of biomass nozzle on the mixed combustion, and obtains the corresponding temperature field, flue gas component field and the distribution of pollutant NO. The results showed that when the biomass particles were sprayed into a fixed position with a certain proportion, the NO emission of wheat, corn and cotton straw was reduced, and the effect of wheat straw was the most obvious. When a certain proportion of wheat straw and coal are co-fired, the higher the biomass nozzle position, the higher the peak temperature in the main combustion zone, and the better the emission reduction effect of NO.

ANALISIS UNJUK KERJA KOLEKTOR SURYA PELAT DATAR DENGAN PENAMBAHAN SIRIP BERLUBANG BERDIAMETER BEDA SEBAGAI NOSEL YANG DISUSUN SECARA STAGGERED

The solar collector is a device that collects solar radiation and converts it into useful heatenergy. Several types of solar collectors include the parallel flow flat plate solar collector and theperpendicular flow absorber plate solar collector. Previous design of flat plate solar collectorperpendicular flow absorber plate usually uses plates with the same hole diameter. To improve theperformance of this solar collector, modifications have been made by adding perforated fins withdifferent diameters which are arranged staggeredly as an air flow channel or nozzle. The intendedmodification of nozzle diameter is to make the nozzle diameter size different from the large diameter nearthe inlet to the small diameter near the oulet and compared to the reverse nozzle position. Making thediameter of the nozzle near the inlet is larger than the diameter of the hole near the outlet aims to makethe mass flow of air passing through the hole near the inlet larger, so that the flow of air massesexperiences more heat transfer while the diameter of the hole near the outlet is made small is to reducethe mass flow of air which is wasted faster through the outlet channel. With the variation of the holediameter from large to small, it is expected that the heat transfer that occurs in the solar collector will bemore optimal, but it should also be seen in the reverse position. The research was carried outexperimentally. The results of his research show that the useful energy and efficiency of solar collectorswith large to small diameter slotted fins are higher than those with small to large diameter slotted fins.

OPTIMASI JUMLAH, POSISI, DAN DIAMETER NOZEL TURBIN PELTON MELALUI ANALISIS QFD DAN UJI EKSPERIMENTAL

Penduduk Indonesia belum sepenuhnya mendapat layanan penerangan listrik, terutama yang berada di daerah terpencil dan berada di lereng-lereng bukit, sementara di lokasi tersebut terdapat potensi energi yang cukup untuk mengerakkan turbin air sebagai penggerak generator listrik. Turbin pelton adalah salah satu jenis turbin impuls yang performancenya dipengaruhi oleh debit air, nosel, dan jumlah sudu, atas dasar tersebut penulis menyajikan artikel yang menerapkan metode quality function deployment (QFD) dan pengujian eksperimental terhadap prototipe turbin pelton di laboratorium Universitas Buana Perjuangan Karawang. Langkah-langkah dalam penelitian ini meliputi studi literatur dan lapangan, perancangan, pembuatan alat uji, pengujian, analisis data, dan kesimpulan. Variasi pengujian berdasarkan pada diameter, posisi dan jumlah nosel terhadap sudu turbin yang berjumlah 12 buah dan berdiameter150 mm, sedangkan untuk pembangkit listriknya menggunakan generator mini berdaya 350 watt. Hasil pengujian yang diperoleh adalah daya input (Pin) terbesar dengan nilai 73,6 watt terdapat pada dn 9 mm dengan posisi nozel atas dan bawah dan jumlah nozel 2 buah. Daya turbin (Pt) ) terbesar dengan nilai 70,1 watt terdapat pada dn= 6 mm, posisi nosel di atas dan jumlah nozel 1 buah, efisiensi turbin (ηt) terbesar dengan nilai 95,4 % terjadi pada dn = 9 mm dengan jumlah nosel 1 buah dengan posisi nosel di atas, daya generator (Pgen) terbesar 11,7 watt terjadi pada dn = 9 mm dengan jumlah nosel 1 buah dengan posisi nosel di atas, effisiensi generator (ηgen) terbesar dengan nilai 17,9 % terjadi pada dn = 9 mm dengan jumlah nosel 1 buah dengan posisi nosel di atas dan efisiensi sistem terbesar (ηsis) 17,1% terjadi pada dn = 9 mm dengan jumlah nosel 1 buah d posisi nosel di atas. Kata kunci: Turbin pelton, quality function deployment (QFD), pengujian eksperimental The Indonesian population has not fully received electric lighting services, especially in remote areas and on hillsides, while there is sufficient energy potential to drive water turbines to drive electricity generators. Pelton turbine is one type of impulse turbine whose performance is influenced by water discharge, nozzle, and some blades, on this basis the author presents an article that applies the QFD method and experimental testing of the Pelton turbine prototype in thelaboratory of Buana Perjuangan University, Karawang. The steps in this research include literature and field studies, design, manufacture of test equipment, testing, data analysis, and conclusions. The variation of the test is based on the diameter, position, and some nozzles for the turbine blades, which are 12 pieces and 150 mm in diameter, while for the power plant it uses a 350-watt mini generator. The test results obtained are the largest input power (Pin) with a value of 73.6 watt is found at dn 9 mm with the position of the top and bottom nozzles and the number of nozzles is 2 pieces. The largest turbine power (Pt) with a value of 70.1 watts is found at dn = 6 mm, the position of the nozzle is above and the number of nozzles is 1, the largest turbine efficiency (ηt) with a value of 95.4% occurs at dn = 9 mm with a total 1 nozzle with the nozzle position is above, the largest generator power (Pgen ) of 11.7 watt occurred at dn = 9 mm with some 1 nozzle with the nozzle position is above, the largest generator efficiency (ηgen ) with a value of 17.9% occurred in dn = 9 mm with the number of nozzles 1 piece with the nozzle position on the top and the largest system efficiency (ηsis) 17.1% % occurred at dn = 9 mm with the number of nozzles 1 piece with the nozzle position on the top. Keyword: Pelton turbine, quality function deployment (QFD) experimental testing

Assessment of Irrigant Flow and Apical Pressure in Simulated Canals of Single Rooted Teeth with Different Root Canal Tapers and Apical Preparation Sizes-an Ex-Vivo Study

Background:Irrigation dynamics vary in optimally shaped canals. Various factors combine to create a stress-induced environment leading to a dynamic irrigant flow.Aim:Evaluate the irrigant flow and apical pressure using 30 gauge open-ended needle in virtually created root canal model of single-rooted teeth.Materials and Methods:Sixty extracted single-rooted premolars were selected and prepared using a single rotary instrument HY-FLEX CM and grouped as : Group I: 30 size 0.6% taper (n=15), Group II: 30 size 0.4% taper (n=15), Group III: 25 size 0.6% taper (n=15), Group IV: 25 size 0.4% taper (n=15). Post instrumentation imaging was carried out using CBCT, and CAD models were obtained. Subgrouping was done based on the nozzle position, and computational fluid dynamic analysis was carried out for the respective parameters assessed.Results:Statistical significance was elicited in all the groups at different nozzle positions analysed. (p<0.05) A post-Hoc test revealed a significance in the mean flow rate and flow velocity in Group I at low nozzle position (p<0.05) as compared to others.Conclusions:30 size 0.6% tapered preparations proved efficient irrigant flow and least apical pressures at allnozzle positions.

Study of the vortex chamber and its application for the development of novel measurement and control devices

Based on studies of the flow structure in a short cylindrical vortex chamber, the dependence of the flow rate coefficient on its geometric parameters is proposed. It is shown that the liquid flow form in the chamber’s axial vortex the pressure on which surface is corresponds to the pressure of the outflow cavity. These results are used to measure pressure in high-temperature cavities, using a sleeve with a diameter equal to or slightly larger than the diameter of the axial vortex. The sleeve is installed in the vortex chamber, and connects the pressure on its surface to the pressure sensor. The possibility of using a vortex chamber as a damper of pressure fluctuations has been substantiated. The design of the vortex damper and its tests results are presented; these show the possibility of increasing the stabilization time of the outlet pressure more than three-fold. Variants of regulating devices with a vortex chamber, functioning without changing the flow cross-sections, are proposed and the results of their tests are presented. This is achieved either by introducing an obstacle into the chamber cavity or by displacing the axis of the outlet nozzle position.

An Experimental and Finite Element Approach for a Better Understanding of Ti-6Al-4V Behavior When Machining under Cryogenic Environment

Due to increasing demand in manufacturing industries, process optimization has become a major area of focus for researchers. This research optimizes the cryogenic machining of aerospace titanium alloy Ti-6Al-4V for industrial applications by studying the effect of varying the nozzle position using two parameters: the nozzle’s separation distance from the tool–chip interface and its inclination angle with respect to the tool rake face. A finite element model (FEM) and computational fluid dynamics (CFD) model are used to simulate the cryogenic impingement of cryogenic carbon dioxide on the tool–workpiece geometry. Experiments are conducted to evaluate cutting forces, tool wear, and surface roughness of the workpiece, and the results are related to the CFD and FEM analyses. The nozzle location is shown to have a significant impact on the cutting temperatures and forces, reducing them by up to 45% and 46%, respectively, while the dominant parameter affecting the results is shown to be the separation distance. Cryogenic machining is shown to decrease adhesion-diffusion wear as well as macroscopic brittle chipping of the cutting insert compared to dry turning, while the workpiece surface roughness is found to decrease by 44% in the case of cryogenic machining.