Conical Collector Research Articles

Numerical and experimental investigation of the effect of radiant reflector on the conical solar collector for heat transfer enhancement

Solar energy is a widely available and renewable form of energy, offering a promising alternative to fossil fuels. Various methods exist for harnessing solar energy, and one common approach involves the use of solar collectors. However, ongoing research aims to develop new and more efficient collectors. This study focuses on designing a conical solar collector and evaluating its performance based on the ASHRAE standard. The objective is to achieve superior efficiency compared to other collectors in the field. Due to experimental limitations, the optimal geometry of the conical solar collector was determined through numerical modeling. The most effective collector design identified had a small diameter of 58 mm, a large diameter of 336 mm, a height of 146 mm, and featured 12.67 turns. Subsequently, the selected model was subjected to laboratory testing. The results demonstrated that the highest efficiency was attained by incorporating a reflector and maintaining a flow rate of 1.5 l/min, resulting in an efficiency exceeding 81%.

Leaf litter nutrient content reveals benefits to traditional cropping systems in the Amazon

Soil fertility in the Amazon rainforest is very dependent to litter decomposition as a source of organic carbon and nutrients. Thus, land use that promote high litter decomposition might play a positive influence on soil chemical properties. The present study aimed to quantify the nutritional content of litter in anthropized and natural environments in Southern Amazonas. The study was conducted on two properties in the municipality of Canutama, in four areas: native forest, annatto, cupuassu, and guarana. In each area, 10 conical collectors (0.21 m²) were installed at a height of 0.3 m from the ground. The samples collected in each area for each month were dried in a forced circulation oven at 60ºC until reaching constant mass and weighed. Macro- and micronutrient content analyses were performed by sulfuric solubilization (N), nitric perchloric solubilization (Ca, Mg, P, K, Na, S, Cu, Fe, Mn, and Zn) and incineration (B). Variance analysis and comparison of means by Tukey test at the 5% probability level were applied to the data obtained, along with a multivariate analysis. This comparison was carried out by evaluating the overall average of a whole year of litter formation, as well as for formation within each month evaluated. Sulfur (S) was the only macronutrient that did not differ between environments (0.1 and 0.2 g kg-1). Macronutrients and micronutrient contents of litter (N: 16.92; Mg: 1.08; Cu: 16.00; Zn: 31.70; B: 104.40; g kg-1) were significantly highest in the annatto area. Annato also presents higher K (9.92 g kg-1) and P (0.70 g kg-1) contents. The litter of natural forest and guarana are richer in P (0.88 g kg-1) and Ca (g kg-1), respectively. Cupuassu litter showed lower nutritional contents, especially in macronutrients contents (N: 9.04; P: 0.51; K: 0.28; Ca: 0.76; Mg: 0.44; g kg-1). This indicates that traditional Amazonian agroecosystems may positively to improve quality of litter and impact nutrient cycling in soils highly weathered in the region.

Acúmulo e decomposição dos resíduos culturais de cupuaçu, guaraná, urucum e floresta na região sul do Amazonas

The litter deposited on the soil surface at various stages of decomposition is important for primary productivity that impacts the microbial communities and soil carbon storage. The objective of this study was to evaluate the accumulation and decomposition of cultural residues of Theobroma grandiflorum (Willd. ex. Spreng) Schum, Paullinia cupana (Mart.) Ducke, Bixa orellana L., and forest in the Amazon region. The study was carried out in the São Francisco settlement, Canutama in the south of Amazonas, in a randomized block experimental design, and the treatments consisted of four areas with different crops: 1 - P. cupana; 2 - T. grandiflorum; 3 - B. orellana; 4 - Native woodland area (forest), in time subdivided plots: 7, 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, and 330 days after the distribution of the bags in the field, all with four repetitions. To evaluate the contribution and fractions of litter, conical collectors were used in each area, and collections were performed monthly in the period from March 2020 to February 2021. The estimate of the decomposition rate of the litter was done by quantifying the loss of mass, using litter bags, which allow for a direct analysis of the rate of decay over time. The forest and P. cupana environments presented the highest litter production, and greater deposition when compared to environments cultivated with T. grandiflorum and B. orellana. The forest and B. orellana areas showed the highest speed of decomposition, while the opposite situation occurred under T. grandiflorum and P. cupana cultivation.

Enhancement of heat transfer from solar thermal collector using nanofluid

Abstract Global energy consumption is increasing due to population growth and with it the adverse impact of fossil fuels on the environment, making it necessary to use renewable energy sources and convert them to electrical energy using different technologies. However, the solar energy potential remains unused, while it has numerous advantages, including as a source of clean electricity and heat. One of the main difficulties in energy-saving and compacted design is how to increase the heat transfer of solar equipment. As an innovative approach to enhancing fluids’ heat transfer performance, some of the most active techniques are to exchange the working fluid with nanofluids. This work attempted to demonstrate heat transfer behavior changes when using nickel oxide (NiO), aluminum oxide (Al2O3), and copper oxide (CuO) as nanofluids at concentration volumes of 0.05, 0.075, and 0.1%. For this goal, a conical solar collector was built using local public steel sheets. Insulating polyurethane foam padding is used inside the cone. The sun’s energy is focused on the absorbing surface using thin reflective aluminum foil. The study also includes a literature review showing how nanofluids can improve heat transfer in solar collectors. The results showed that adding nanoparticles can increase the rate of heat transfer and CuO nanofluids have better augmentation in heat transfer than Al2O3 or NiO-water nanofluids where 1% CuO nanofluids increases the efficiency by up to 7% compared to water.

Experimental Investigation on the Thermal Performance of a Conical Solar Water Heater Using Mixed Asphalt Absorber Plate

Abstract In the present research, an investigational study on thermal performance of a mixed asphalt conical solar water heater (MACSWH) was analyzed under field conditions. The key target of the present research is to evaluate the dynamics of heat and performance of a conical solar collector with an attached mixed asphalt as an absorber plate. In the current experimental test setup, the mixed asphalt as an absorber plate with a diameter of 0.20 m and thickness of 0.05 m was set in the middle of the focal area for accumulating the solar radiation, reflecting from a polished zinc conical reflector. The aperture diameter of the MACSWH was 0.45 m with a concentration ratio of 2.20. The copper pipe had a total length of 2 m, and the inclination angle of the conical was fixed at 15 deg. The experimental results provide evidence that the mixed asphalt set as an absorber plate at the center of the focal area was an effective practical approach to improve the performance of a conical solar collector. This method raises the maximum percentage difference between inlet water temperature and outlet water temperature by approximately 47.27%, while the maximum temperatures of absorber plate, copper pipe, and efficacy are at 82 °C, 62 °C, and 72%, respectively.

Thermo-Economic Performance Evaluation of a Conical Solar Concentrating System Using Coil-Based Absorber

Pollution and the increase in greenhouse gas (GHG) emissions have long been linked to the world’s increasing need for fossil fuels to generate energy. Every day, the energy consumption is increasing; therefore, it is important to improve technologies that use renewable energy sources. With the abundant availability of sustainable energy, solar power is becoming a necessity. However, solar energy has a low energy density and therefore requires a large installation area, which requires heat collection and heat storage technology. Much research is now being done on the conical solar systems to improve efficiency including calculating an optimal cone angle, finding the best flow ratio and the best absorber design, etc. Therefore, in this study, thermal performance of a conical solar collector (CSC) was assessed with a new design of concentric tube absorber (addition of a coil) and compared to the existing circular tube absorber. It was found that 6 L/min flow rate of heating medium (distilled water and CuO nanofluid) gave lower payback period and higher solar fraction of the system in both cases of absorber tube, i.e., without coil and with coil. However, comparatively, thermal efficiency of CSC with coil-based absorber was almost 10–12% higher than conventional system (without coil) regardless of type of heating medium used.

The effect of collector parameters on nanofiber yarns produced by electro yarn spinning machine with conical collector

In this work, electrospun yarns were produced by a nanofiber yarn spinning machine with a conical collector. In the first part, two different polymers (PAN and PVDF-HFP) were used in nanofiber yarn spinning with two different types of conical collector which are made of stainless steel and aluminium. In the second part, four different types of aluminium collector having different wall thickness and surface properties were used. For all yarns produced, the effect of different parameters has been analyzed in terms of fibre fineness distribution, yarn fineness and yarn linear density, yarn strength and breaking elongation. The results show that yarns produced by using aluminium collector are finer and have higher strength compare to the ones produced by stainless steel collector while PVDF-HFP nanofiber yarns are finer and have higher tensile strength compare to PAN. The results also show that yarns get coarser while fibres get finer as the collector wall thickness is increased in general.

Litter input in cerrado, cerradão and forest environments in Amazon, Brazil

Production and decomposition of litter is one of the most important entry sources of nutrients into the soil layers, especially in Amazonian environments, where the soils with low natural fertility are. The study aimed to quantify the litter-forming material intake in cerrado, cerradao and forest environments in the Amazon. Ten conical collectors were set up in each study environment. Collections were monthly held for one year. After each collection, the fractions of leaves, branches, reproductive material and barks were all screened. The total litter production was of 4.24; 11.48 and 12.58 Mg ha-1 year-1 in the cerrado, cerradao and forest areas, respectively. The monthly deposition in the cerrado ranged from 0.13 Mg ha-1 to 0.75 Mg ha-1, while in the cerradao the values were 0.52 and 2.18 Mg ha-1 and in the forest, they were between 0.70 Mg ha-1 and 1.97 Mg ha-1. The analysis and interpretation of the results allowed concluding that the litter deposition, for both the forest and cerradao areas, is higher than the one for the cerrado area, having a greater deposition in a period of water scarcity observed for all areas of this study, with the leaves fraction having contributed with the highest percentage.

Analysis of polyacrylonitrile nanofiber yarn formation in electrospinning by using a conical collector and two oppositely charged nozzles

Nanofiber production by electrospinning has become a common production method as it is an easy and flexible system producing nanofibrous webs. However, direct spinning of nanofibers into a yarn would lead to conversion of nanofibers into woven or knitted fabrics easily, therefore improving end-use possibilities of these fibers substantially. In this work a successful nanofiber yarn spinning system using polyacrylonitrile polymer is established and yarn formation by polymers ejected from two nozzles with opposite charges was analysed and potential of this system for bicomponent yarn production was shown. Fiber formation from each nozzle was also examined by high speed camera while distribution of the electric field strength and loads in the electrostatic state was analysed by electric field simulation . Finally, polyacrylonitrile nanofiber yarns produced at different collector and winding speeds were analysed in terms of fiber and yarn properties. Furthermore, the first fabric sample with nanofiber yarns woven manually was presented.

Elaboration of design and calculation of energy and power parameters of a facility for lime unloading from a shaft furnace

Operation of shaft furnaces for lime burning in the required technological mode to a great extent is effected by reliability and technical abilities of their finished product unloading systems. A system proposed for unloading a shaft furnace for lime burning, enabling to deliver in a stable mode crashed material providing it has large sintered pieces. The system includes a stationary round table, located symmetrically relating the vertical axis of the furnace body under the conical collector exit opening. The table has four semi-round scraper knives connected by hinges with four pushing rods, acting by drive hydraulic cylinders. Alternately one pair of cylinders is working for pushing, the other – for pulling the rods. It results in the scraper knives making turn motions relatively the table, rolling along its edge and pushing off it bulk material by their back round part. To design a pilot sample of the proposed unloading system for shaft burning furnace, a methodology was elaborated to calculate its power parameters. The methodology takes into account the technological loads, arising at the realization of the process of measured delivery of the burnt lime from the furnace. The proposed methodology enables to determine the required values of pressure and consumption of oil station working liquid. The oil station provide operation of the cinematically interconnected four hydraulic cylinders, which make the two pair of scraper knives moving along a set trajectory on the table surface of the furnace to deliver from it the bulk material. The rightness of the technical solutions applied to the design of the elaborated shaft furnace unloading system as well as the correctness of the proposed theoretical dependences used for calculation of its energy and power parameters, were confirmed by the experiments. The experiments were carried out at an operating physical model, manufactured in the scale 1:10 to the natural facility.

Different Patterns Of Nutrient Cycling In Contiguous Phytophysiognomies Of Atlantic Forest, Brazil

ABSTRACT The present study aimed to evaluate fine aboveground litterfall, deposition of nitrogen and phosphorus from total litterfall and leaf litter decomposition in areas of tall forest (Mata Alta) and low forest on sandy soils (Mussununga) in southeastern Brazil. Fine litterfall was collected monthly for two years (from June/2007 to May/2009) in 10 conical collectors (0.25 m2) in each phytophysiognomy (1 ha plots). The material was subsequently separated into leaves, branches, flowers and fruits, and unidentified material. Leaf decomposition rates were evaluated using 15 litterbags, three of which were collected every 30 days. Higher litterfall occurred in both phytophysiognomies during the rainy season, with leaves predominating. The lowest litterfall, nutrient input, and leaf litter decomposition values appeared to be nutrient conservation strategies, contributing to the ecological functioning of the Mussununga where soil fertility was lower than in the Mata Alta.

Ball pen probe in strongly magnetised RF plasmas

A study of ball pen probes (BPPs) in a rf strongly magnetised plasma is reported for the first time. These probes have been successfully used in fusion plasmas, with magnetic fields up to 2.5 T, to measure the plasma potential. In this paper experimental results of various ball pen designs (2 and 4 mm diameter with flat and conical collectors) are presented up to 0.5 T in a low pressure capacitively coupled rf plasma. A theory of the BPP is developed, showing that the increase of the collector potential and plateau region, with collector retraction, requires the electron current to decrease faster than the ion current. Experimentally, it is found that to develop effective electron screening the electron Larmor radius should be smaller than the tunnel internal diameter. Smaller tunnels improve screening due to the tunnel entrance wall sheaths. Inside the tunnel a plateau region forms at 81 mT reducing to a broad peak at higher field strengths. Ion shielding and surface losses (for small tunnel diameters) reduce the collector peak width and maximum potential with increasing magnetic field. Conical collectors were found to increase the length of the plateau region and broaden the peak. Particle in cell simulations were in good agreement with the experimental results. The electron shielding and plateau regions were reproduced but not the broad peak at higher field strengths. Good agreement between both 2 mm BPPs and an emissive probe was found only at 81 mT to within 3 V or 1.3 electron temperatures (Te). For all BPPs at higher field strengths (≥ 250 mT) the maximum collector potential underestimated the emissive probe by more than 2.7 Te (7 V). At these field strengths all BPPs agree with each other to within 1.5 Te (4.1 V). Possible reasons for these disagreements are discussed.

Farklı stok yoğunluklarının deniz hıyarı Holothuria tubulosa (Gmelin, 1788) yumurtalarının açılma ve yaşama oranlarına etkileri

In this study, it was aimed to determine the opening and survival rates of Holothuria tubulosa eggs at four different stocking densities (1,5,15,30 eggs / ml ) and to determine the effect of stocking density on egg size and larval size in different stages. Fertilized Holothuria tubulosa eggs were stocked in cylindrical conical collectors with a capacity of 30 l. Eggs were counted under light microscope at fertilization, early gastrulation, late gastrulation and hatching stages. It was found that there is an inverse relationship between stock intensity and opening rate (r = -0.848; p<0.001). The lowest hatching and survival rate was determined in 30 eggs / ml group (p <0.05). However, different stocking densities did not affect the diameter of the egg in different embryological stages (p> 0.05) and the length of early auricularia larva at 65 h (p> 0.05). As a result, the optimal stocking density for the highest hatching and survival rates of the fertilized eggs of Holothuria tubulosa was determined as 1-5 eggs / ml .

Litterfall: A Bio-indicator for Edge Effect in a Semi-deciduous Seasonal Forest

ABSTRACT This study aimed to evaluate the use of litterfall as an indicator of fragmentation in a Semi-deciduous Seasonal Forest in Alem Paraiba, MG, Brazil. Litterfall was collected monthly for one year in conical collectors (0.25 m2 of surface), located at seven distances from the forest edge: 10, 30, 60, 100, 160, 250 and 350 m. The litterfall was dried in an oven and separated (leaves, branches, reproductive structures, miscellaneous). Litterfall was greater near the forest edge, probably due to a predominance of species with high leaf deposition (pioneers and deciduous). Litterfall had peaks at the beginning of the rainy season for the average obtained from the seven distances from the forest edge. The edge effect did not clearly influence the contribution of the fractions or the seasonality of total litterfall.

Numerical simulation of pulsatile flow through a coronary nozzle model based on FDA’s benchmark geometry

Abstract Computational fluid dynamics (CFD) is a powerful tool to extent knowledge of biomechanical processes in cardiovascular implants. To provide a standardized method the U.S. Food and Drug Administration (FDA) initialized a CFD round robin study. One of the developed benchmark standard models is a generic nozzle geometry, consisting of a cylindrical throat with a conical collector and sudden expansion on either side. Several fluid mechanical data obtained from international institutes by means of CFD and particle image velocimetry (PIV) measurements under different flow regimes (Re = 500, 2000, 3500, 5000 and 6500) are freely available. This database includes only steady state simulations. In this study we performed pulsatile CFD simulations to consider the physiological environment of the coronary vessels. Furthermore, the nozzle geometry was scaled down to coronary dimension (D inlet = 12 mm to 3 mm) while retaining the average Reynolds number Re = 500 constant. The pulsatile character is described by a Womersley number of Wo = 2.065. Our CFD code was previously validated by using FDA’s data for steady state inflow conditions. It could be shown that time averaged wall shear stress and shear stress values agree well with steady state results. We conclude that steady state simulations are valid for hemodynamic analyses if only time averaged values are needed. This could save computational costs of future hemodynamic investigations. In addition, this study expands FDA’s benchmark case by pulsatile inlet condition for further code validation. This could be necessary for the development of new numerical methods as well as for validation of CFD codes used in the approval process of medical devices.

Experimental validation of mathematical models of identical aluminum and stainless steel engineered conical solar collectors

This paper studies the mathematical modeling of a conical solar collector (CSC) based on different reflector materials and view angles. The optical performance testing using both stainless steel reflector (SSR) and aluminum mirror reflector (AMR) was performed under similar conditions at reflector view angles of 35°, 40°, and 45°, respectively. Main operational parameters related to the thermal/optical efficiencies of the SSR and AMR systems were determined and compared with each other. In addition, the interdependent transient temperature responses of both system components were predicted using Matlab® ordinary differential equation (ODE) solvers. For the purpose of model validation, simulation results from both systems were compared with experimental data. Results showed that the highest efficiencies and maximum water temperatures were achieved at reflector view angle of 45°, but these values were significantly higher in AMR system than SSR system for all of the aforementioned cases.

An investigation of the Performance of a Conical Solar Water Heater in the Kingdom of Bahrain

Domestic water heater corresponds to 25% of the house energy consumption and can play an important role to reduce energy house expenses. Solar energy offers a preferred renewable energy resource because of its economic and environmental advantages. It is considered the best alternative to reduce domestic water heater energy consumption cost. Converting solar energy into heat can be considered among the simplest used systems. Solar thermal conversion is more efficient than solar electrical direct conversion method. Solar water heater systems are particularly easy to use and to repair. The integrated conical solar collector water heater (ICSCWH) is so far the easiest among water heating systems. The ICSCWH converts directly and efficiently the solar flux into heat. In order to expand the utilization of ICSCWH systems, many design modifications have been examined and analyzed. This study provides an experimental investigation and mathematical simulation of an ICSCWH system equipped with a glass cover resulting in the increase of the maximum absorption. Integrating the cone-shaped heat collector with an aluminum spiral pipe flow system may enhance the efficiency of the proposed system. In order to maximize the solar radiation of the system, the solar water heater has been designed in a conical shape, which removes the need to change its orientation toward the sun to receive the maximum sun radiation during the day. In this system, the heating of water has been obtained using the spiral pipe flow without the use of the solar cells and mirrors in order to reduce the total cost. The storage water tank of this system is coupled with a conical solar collector. Based on the above design, the solar water heater has been fabricated and tested. In addition, an analytical modeling approach aiming to predict the flow rate within the conical integrated collector storage solar water heater (ICSSWH) and its efficiency, was developed. Modeling through a numerical simulation approach based on energy equations was performed. Considering the entire water amount and the total area of the cone, the amount of water (facing the sun per unit absorbing area in the two symmetrical parts of the system) is found to increase, which is expected to reach a maximum water temperature at a high performance. Our experimental findings show that the daily performance is around 32% and the highest water temperature of about 45°C is obtained in the system at 4 pm, according to seasons and weather conditions. An efficient and simple mathematical simulation approach for the new conical solar water heater is described then validates using experimental data.

Theoretical and experimental investigation into incident radiation on solar conical collector

The geometry of a collector is one of the important factors that can increase the incident radiation on the collector surface. In the present study, the incident radiation for a stationary collector with cone geometry, i.e. a conical collector, is theoretically and experimentally investigated. This type of collector is always stable and does not need a fixture to install. Moreover, it has a symmetric geometry, with all its sides facing the sun. The main advantage of this collector is its ability to receive beam, diffuse, and ground-reflected radiation throughout the day. The variation of the incident radiation is theoretically estimated by using an isotropic sky model based on the available data. The theoretical data are validated by an experimental test of a conical collector of a specific size. The results show that the conical solar collector is more operative in receiving total solar radiations than a horizontal plate such as a flat-plate collector and can be a suitable option for solar water heating. A calculation of the incident radiation shows that the incident radiation is maximized when the cone angle of the conical collector is equal to the latitude of the site test.

Numerical and experimental heat transfer analyses of a novel concentric tube absorber under non-uniform solar flux condition

The thermal performance of a novel concentric tube absorber for a conical solar collector (CSC) under forced convection was investigated by numerical and experimental analyses. In this system, the CSC assembly is mounted on dual axis tracking platform that can accurately track the sun position to get maximum concentrated solar radiation over the entire circumference of the absorber. Due to conical-shape reflector, the non-uniformity of the solar flux distribution along the absorber length is high; therefore, the non-uniform concentrated solar flux was applied to the absorber surface as boundary condition in Fluent software. To evaluate the heat transfer characteristics and performance of the system, heat loss and gain factors were derived from the novel concentric tube absorber while varying the flow rate. The concentric tube absorber of the CSC system was developed and analyzed with different operational parameters. The double-tube design provides the uniformly distributed flow and temperature symmetricity along the absorber length. The predicted results of the CSC system were in good agreement with the measured results.

Collection-efficient, axisymmetric vacuum sublimation module for the purification of solid materials.

A vacuum sublimation module of axisymmetric geometry was developed and employed to purify solid-phase materials. The module provides certain practical advantages and it comprises: a metering valve, glass collector, glass lower body, main seal, threaded bushing, and glass internal cartridge (the latter to contain starting material). A complementary process was developed to de-solvate, sublime, weigh, and collect solid chemical materials exemplified by oxalic acid, ferrocene, pentachlorobenzene, chrysene, and urea. The oxalic acid sublimate was analyzed by titration, melting range, Fourier Transform Infrared (FT-IR) Spectroscopy, cyclic voltammetry, and its (aqueous phase) electrolytically generated gas. The analytical data were consistent with a high-purity, anhydrous oxalic acid sublimate. Cyclic voltammograms of 0.11 mol. % oxalic acid in water displayed a 2.1 V window on glassy carbon electrode beyond which electrolytic decomposition occurs. During module testing, fifteen relatively pure materials were sublimed with (energy efficient) passive cooling and the solid-phase recovery averaged 95 mass %. Key module design features include: compact vertical geometry, low-angle conical collector, uniformly compressed main seal, modest power consumption, transparency, glovebox compatibility, cooling options, and preferential conductive heat transfer. To help evaluate the structural (module) heat transfer, vertical temperature profiles along the dynamically evacuated lower body were measured versus electric heater power: for example, an input of 18.6 W generated a temperature 443-K at the bottom. Experimental results and engineering calculations indicate that during sublimation, solid conduction is the primary mode of heat transfer to the starting material.