•In this study, the impact of internal fins in PTC operating with gases is presented.•Air, helium and CO2 are tested in smooth absorber and with fins of 5–10mm and 15mm.•Greater fin length leads to ...higher thermal efficiency and 10mm is the optimum length exergetically.•Helium is the best working fluid exergetically, with CO2 and air to follow.•Up to 290°C, helium performs better energetically, while CO2 in higher temperatures.
In this study, the use of internal fins in parabolic trough collectors operating with gas working fluids is examined. Air, helium and carbon dioxide are the investigated working fluids, while Eurotrough ET-150 is the examined solar collector. The design and the simulation of this solar collector are performed with the commercial software Solidworks Flow Simulation. The internal fins lead to higher thermal efficiency but also to higher pressure losses; something very important for the solar fields of Concentrated Power Plants. Thus, the collector is examined energetically and exergetically in order to take into account the increase in the useful output with the simultaneous greater need of pumping power. Various fin lengths are examined and finally the fin of 10mm was proved to be the most appropriate exergetically. In working fluid comparison, helium is the most efficient working fluid exergetically for all the examined cases. In the thermal efficiency comparison, helium performs better up to 290°C, while carbon dioxide is the best choice in higher temperature levels. Moreover, the optimum mass flow rate for the helium was proved to be 0.03kg/s and for the other working fluids the value of 0.015kg/s seems to lead to the most satisfying results.
This study develops a 3D-CFD model to analyze the thermal performance of perforated fin heat sinks and evaluates four perforated continuous and interrupted fin heat sinks with distinct geometric ...patterns. Using the Finite-Volume Method (FVM) to discretize the governing equations, the SolidWorks 2019 flow simulation software was implemented to solve and validate the latter, demonstrating that the CFD simulation model employed in the current study is reliable. The performance parameters of the heat sink are presented in terms of Reynolds number and heater power. The results indicate that modules B and C achieved higher heat transfer rates, average heat transfer coefficient, and Nusselt number compared to the other modules. Module A had the highest fin efficiency and module D exhibited greater fin effectiveness than the other ones.
Purpose. The main purpose of our work is to substantiate the geometric parameters of a variable moment of inertia pulley, which can reduce the weight of a drive with such a pulley. Methodology. It ...was found that the masses of the pulley and support elements have the greatest influence on the weight of the drive, so we focused on the pulley. Improvement of the pulley design and determination of its rational geometric parameters were carried out in three stages. At the first stage, the size of the rim was reduced in accordance with the diameter of the rope. At the second stage, a multivariate calculation was performed for a pulley with spokes that expand toward the rim. Holes were made in the spokes to reduce the pulley weight. The fundamental difference of the pulley calculated at the third stage is the absence of holes in the spokes, which makes it possible to increase the rigidity of the structure. The control parameter was the angle of expansion of the spokes. The problem of establishing a rational value for this angle was solved using the SolidWorks computer program with the Simulation application, subject to the constraints on the safety factor (at least two) and the structural rigidity parameters (displacement along three coordinate axes and the resulting displacement at the level of the values for the base structure). Findings. It has been established that the weight optimization of a drive with a variable moment of inertia pulley is advisable to be carried out by reducing the masses of the pulley and supporting elements. The best design is that of a variable moment of inertia pulley that contains spokes (without holes) that expand toward the rim; the rational angle of expansion of the spokes is 25°. If a pulley with reasonable geometric parameters is used, the mass of the drive will decrease by 16% in the case of a 33 % reduction in the mass of the pulley itself compared to the mass of the basic design. Originality. A new design is proposed and rational parameters of the variable moment of inertia pulley are substantiated, which make it possible to reduce the mass of the drive with such a pulley. Practical value. The use of the pulley of this design will reduce the load on the electric motor during startup, as well as the load on the supporting structures.
Мета. Основною метою нашої роботи є обґрунтування геометричних параметрів шківа змінного моменту інерції, за яких можна зменшити масу приводу з таким шківом. Методика. З’ясовано, що найбільший вплив на масу приводу мають маси шківа та опорних елементів, тому далі було приділено увагу саме шківу. Поліпшення конструкції шківа й визначення його раціональних геометричних параметрів проведено в три етапи. На першому етапі зменшено розміри ободу відповідно до діаметра каната. На другому етапі проведено багатоваріантний розрахунок шківа зі спицями, які розширюються в напрямку до ободу. У спицях виконано отвори для зменшення маси шківа. Принциповою відмінністю шківа, розрахованого на третьому етапі, є відсутність отворів у спицях, що дозволяє підвищити жорсткість конструкції. За параметр керування було взято кут розширення спиць. Задачу встановлення раціонального значення цього кута розв’язано з використанням комп’ютерної програми SolidWorks із додатком Simulation за умови дотримання обмежень щодо коефіцієнта запасу міцності (не менше двох) та параметрів жорсткості конструкції (переміщення уздовж трьох координатних осей та результуюче переміщення – на рівні таких величин для базової конструкції). Результати. Установлено, що вагову оптимізацію приводу зі шківом змінного моменту інерції доцільно проводити за рахунок зменшення мас шківа та опорних елементів. Кращою є конструкція шківа змінного моменту інерції, яка містить спиці (без отворів), що розширюються в напрямку до ободу; при цьому раціональний кут розширення спиць становить 25°. За умови використання шківа з обґрунтованими геометричними параметрами маса приводу зменшиться на 16 % у разі зменшення маси самого шківа на 33 % порівняно з масою базової конструкції. Наукова новизна. Запропоновано нову конструкцію та обґрунтовано раціональні параметри шківа змінного моменту інерції, за яких можливим є зменшення маси приводу з таким шківом. Практична значимість. Використання шківа зазначеної конструкції дозволить зменшити навантаження на електродвигун під час пуску, а також навантаження на опорні конструкції.
Parabolic trough collector is one of the most usual solar collectors for applications up to 400 °C. The thermal enhancement of this collector concentrates a lot of interest and various techniques are ...tested in order for the thermal efficiency to be maximized with a reasonable penalty in the pressure drop. The use of nanofluids as working fluids, as well as the use of flow turbulators, mainly inserts and internal fins or tube dimples are the main techniques which are examined. The objective of this work is to give a complete literature review of the existing studies on this domain and to present a numerical comparative analysis between the most usual thermal enhancement techniques. More specifically, the use of oil-based nanofluids with 6% CuO is compared with the use of internal rectangular fins in the absorber, while the combination of these techniques is also examined. The analysis is conducted with a validated CFD model in SolidWorks Flow Simulation for various fluid temperature levels. According to the final results, the use of nanofluids leads to 0.76% thermal efficiency enhancement, the use of internal fins to 1.10% and the combination of these techniques to 1.54%. Moreover, emphasis is given in the pressure drop of the examined cases and in the evaluation criteria which are used in every case.
Parabolic trough collectors are the most mature technology for utilizing the solar energy in high temperature applications. The objective of this study is the thermal efficiency enhancement of the ...commercial parabolic collector IST-PTC by increasing the convective heat transfer coefficient between the working fluid and the absorber. There are two main factors which influence on this parameter, the working fluid type and the absorber geometry. For this reason three working fluids are investigated, thermal oil, thermal oil with nanoparticles and pressurized water. Moreover, a dimpled absorber tube with sine geometry is tested because this shape increases the heat transfer surface and increases the turbulence in the flow. The final results show that these two techniques improve the heat transfer coefficient and the thermal efficiency of the collector. More specifically, the use of nanofluids increases the collector efficiency by 4.25% while the geometry improvement increases the efficiency by 4.55%. Furthermore, collector parameters such as the heat loss coefficient, the exergetic efficiency, the pressure losses and the absorber temperature are presented for all the examined cases. The model is designed with Solidworks and is simulated by its flow simulation studio.
•The commercial parabolic collector IST-PTC is simulated with Solidworks.•The developed model is validated by data taken from literature.•The use of nanoparticles inside the thermal oil is investigated.•The use of absorber with an internal wavy surface is examined.•The final results show that the two ways increase the efficiency about 4.5%.
Purpose. To develop methodological recommendations for studying the characteristics of screen welded assemblies of ГВЧ-31 С type using specialized tools of the SolidWorks Education Edition software ...package. Methodology. The methodology for analyzing welds when designing a vibrator fixation system is based on the use of current software tools, in particular SolidWorks Simulation in combination with SolidWorks Motion, as well as the HOT SPOT STRESS technology. To analyze the accuracy of determining the dynamic loads arising during the screen operation, the results of modeling using the SolidWorks Motion program are compared with those obtained by traditional methods using the Lagrange equation of the second kind. The computation discrepancy is within 10 %. Findings. It has been determined that it is rational to analyze welds using the SolidWorks Education Edition software shell, taking into account the least profitable option, namely, when their edges are not finished. Furthermore, during solid-state modeling, the formation of a cavity in the weld is simulated in the form of a gap between the welded elements. The stress-strain state analysis of welded constructions using the Finite Element Method has revealed that when the computational mesh cell size is reduced, the stress value increases significantly, which indicates the result singularity and the need for further application of the HOT SPOT STRESS method. In the course of research, it has been determined that the highest stresses in welds occur on the central rib. The duration of use of welded joints is more than 2·106 cycles. Originality. For the first time, the methodology has been substantiated for determining the service life of welded elements of screen constructions using the latest computer analysis tools. The method makes it possible to calculate the dynamic forces arising in constructions performing oscillatory movements, as well as to analyze the stress-strain state of welds using the HOT SPOT STRESS technology and assess their service life. Practical value. It has become possible to implement the method for calculating the stress-strain state of welds in the design of a vibrator fixation system and assessing their service life, which is important for analyzing and determining the parameters of various vibrating machines. The results derived from the investigation were incorporated by the local entity, Ukrprommineral, to modernize the screens.
•A novel flow insert with star shape in parabolic trough collector is studied.•The insert geometry is optimized by examining 16 different insert shapes.•The analysis is performed using thermal, ...exergy and overall efficiency criteria.•The collector performance is enhanced for all the examined flow inserts.•The maximum thermal efficiency enhancement is found up to 1%.
The use of flow inserts is a common passive technique for enhancing the thermal performance of parabolic trough solar collectors. The objective of this work is to investigate a novel insert with a star shape. The shape of this insert is optimized by examining different combinations of its geometric characteristics. Totally 16 different cases are studied with the fin length to be varied from 15 mm to 30 mm and the fin thickness from 2 mm to 5 mm. The evaluation criteria of the examined cases are the thermal efficiency, the exergy efficiency and the overall efficiency of the solar collector. The exergy efficiency and the overall efficiency are suitable criteria for evaluation the Nusselt number increase with the simultaneous friction factor increase. The collector is examined for inlet temperatures between 400 K and 650 K with a volumetric flow rate equal to 150 L/min. According to the final results, the thermal efficiency, the exergy efficiency and the overall efficiency are increased for all the examined flow inserts. The thermal efficiency enhancement is higher with the inlet temperature increase and it can reach up to 1%. Moreover, it is found that greater dimensions of the insert lead to higher performance enhancements. The pressure drop is found to increases many times with the use of inserts but the pumping work value is extremely low in all the cases. The analysis is conducted with SolidWorks Simulation Studio with a validated model.
•Twelve different internally finned absorbers are examined in the LS-2 PTC.•The thermal enhancement and the pressure drop are the main calculated parameters.•Four evaluation criteria are used for ...determining the optimum fin geometry.•The fin with 10mm length and 2mm thickness is found to be the optimum case.•The optimum fin presents 0.82% thermal efficiency enhancement compared to smooth case.
Among the solar concentrating technologies, parabolic trough collector (PTC) is the most mature and cost-effective technology for medium and high-temperature levels (150–400°C). This paper investigates the utilization of internally finned absorbers in LS-2 PTC module for various operating conditions. Twelve different longitudinal fins are tested and compared with the smooth case. The analysis is performed with SolidWorks Flow Simulation, using a validated model by literature results. Generally, it is proved that both greater length and thickness lead to higher thermal enhancement and to higher pressure losses. Various methods are presented for evaluating together the thermal efficiency or Nusselt number enhancement versus the increase in pressure drop or in the friction factor. Taking into consideration four different criteria, the absorber with 10mm fin length and 2mm fin thickness is found to be the overall optimum case. For this case, the thermal efficiency is enhanced about 0.82%, the Nusselt number increase 65.8%, while the friction factor and the pressure losses are about the double compared to the smooth case.
A data buoy for measuring coastal wave-action has been designed and constructed. The buoy is essentially a 0.6 m diameter sphere that is made of fiber-glass with aluminum, steel and polymer parts. ...While the overall geometry of the buoy is superficially similar to that of existing commercial spherical buoys (e.g. Wave-Rider by Datawell), the present design is based on a simple robust structure and mass-market electronics. A significant dual-use feature of this design is that the structure is usable as a float in a wave-energy generation device. This is possible due to the essentially isolated central structure and an electronics enclosure that is sealed both from the external environment and from the bulk shell of the buoy. This also allows the electronics to be mounted in an easily- modified, rack configuration that can be removed from the buoy shell. In a wave-energy generation set-up the electronics rack would be removed and the central cylinder will become part of a linear-motion type generator, with at least +/- 25 cm of internal movement available to it that is waterproof (for near surface or shallow immersions). Alternatively, for large wave motions, the buoy can couple to an energy-generating device using flanges that mate with its bolt circle pattern. However, at the moment, the buoy enclosure is dedicated to wave-action measurement, i.e., a data buoy with an onboard inertial measurement unit (IMU) and a radio-link to send real-time data to a receiving unit that can be on a boat or at the seashore. Basic GPS data are also transmitted. This is of interest if the buoy is being deployed in a drifting (un-moored) mode. This paper will only discuss the mechanical design and fabrication of the structure.
The purpose of this study was to determine the optimal operating speeds for a modified linkage cum hopper type planting unit that was used in low-speed automated vegetable transplanters. The ...transplanter utilizes a biodegradable seedling plug-tray feeding mechanism. The movement of the planter unit was simulated at different operating conditions using kinematic simulation software, and the resulting trajectories were compared based on factors such as plant spacing, soil intrusion area, soil intrusion perimeter, and horizontal displacement of the hopper in soil and found optimal result at 200, 250 and 300 mm/s and 40, 50 and 60 rpm combinations. The optimal operating speeds were then tested in a soil bin facility and found to perform well when transplanting pepper seedlings, with measured plant spacing that was close to the theoretical spacing. The planting depth in each case was not significantly different and the planting angle in different speed combinations was found to be significantly different, but within permissible limits. The mulch film damage was low for the selected optimised speed combinations. This study resulted in the determination of the optimal speeds for the transplanter, which can be used as a basis for optimising the other mechanisms within the transplanter.
