Use Of Surface Area Research Articles

Impacts of geometric factors on the hydrothermal characteristics in a shell and cone-shaped coil heat exchanger

Cone coils have a larger surface area and produce more turbulence, which enhances the heat exchange rate, making them a more efficient option for improved heat transfer than simple coils in shell-and-coil heat exchangers. In addition to reducing fouling and the requirement for maintenance, the cone shape may also provide the benefit of a self-cleaning action. Ensuring a more even flow distribution maximizes the heat exchanger's surface area use and reduces poor-flow zones. Applications needing compact solutions without compromising performance significantly benefit from this design's versatility, allowing customization to meet unique operational demands. This work evaluates numerically the impact of employing a cone-shaped coil tube in a shell-and-coil tube heat exchanger, considering various configurations and coil pitches. A commercial CFD code is used to perform the numerical simulations based on the finite volume approach. The present study has two sections. In the first part, three different coil configurations were considered. The best case was considered according to the numerical results obtained from the first section. Then, in the second part, the impact of the cone coil pitch on the hydrothermal characteristics was analyzed. The obtained numerical outcomes revealed that the best performance evaluation criteria factor belongs to the cone-shaped coil with divergent configuration by about 64.1 % and 57.45 % more than the cone-shaped coil with convergent configuration at De = 1,000 and De = 2,500, respectively. Moreover, the cone-shaped coil with a divergent configuration displayed higher JF values by approximately 61.54 % and 58.06 % than a cone-shaped coil with a convergent configuration at De = 1,000 and De = 2,500, respectively. Among different evaluated cone coil pitches, the maximum performance evaluation criteria factor belongs to the case with pitch values of 40 mm. Moreover, the JF value increases by approximately 4.76 % and 5.56 %, respectively, at De = 1,000, when the pitch value grows by around 60 % and 100 %. Furthermore, when the pitch value climbs by 60 % and 100 %, at De = 2,500, the JF value rises by roughly 12.16 % and 19.59 %, respectively.

Hydrothermal analysis of hybrid nanofluid flow inside a shell and double coil heat exchanger; Numerical examination

In a shell-and-coil heat exchanger, employing a double coil instead of a simple coil causes more heat transfer compared to a simple coil because the double coil improves heat exchange through enhanced fluid flow and turbulence, enabling a longer tube length in constrained locations.. In addition to reducing fouling and the requirement for maintenance, the helical shape may also provide the benefit of a self-cleaning action. Ensuring a more even flow distribution also maximizes the heat exchanger's surface area use and reduces low flow zones. Applications needing compact solutions without compromising performance especially benefit from this design's versatility, allowing customization to meet unique operational demands. In numerous industrial applications, helical coils offer substantial benefits in terms of effectiveness, upkeep, and design freedom.In the present work, heat transfer and fluid flow in a shell-and-coil tube heat exchanger equipped with a double helical coil are evaluated numerically. The employed heat transfer fluids are water-based hybrid nanofluids, including TiO2-Mgi/water and AG-HEG/Water. The obtained outcomes are compared with the results of pure water. The range of considered Reynolds numbers is 500 – 2000. This work consists of two sections. In the first part, the impact of the type of hybrid nanofluid on the hydrothermal behaviour of the proposed heat exchanger is analysed. The volume concentration of the nanoparticles here is ϕ1 = ϕ2 = 0.3. In the second section, the best hybrid nanofluid is selected according to the results of the first section; then, the impact of the nanoparticles' volume concentration on the thermal performance of the proposed heat exchanger is evaluated. Three various nanoparticle volume concentrations, including ϕ1 = ϕ2 = 0.1, ϕ1 = ϕ2 = 0.3, and ϕ1 = ϕ2 = 0.5, are considered, and the results are compared with those of the pure water case (ϕ1 = ϕ2 = 0).The obtained results show that amongst the different heat transfer fluids considered, the Water/MgO-TiO2 model shows the most outstanding value of thermal performance in all the studied Reynolds numbers. Also, the obtained numerical results show that the use of the proposed double coil tube leads to an increase in the heat transfer rate.

Wind turbine dynamic shading: The effects on combined solar and wind farms

The Dutch climate agreement anticipates the large-scale implementation of solar and wind energy systems on land and water. Combining solar and wind farms has the benefit of multiple surface area use, and it also has the advantage of energy generation from both solar and wind energy systems, which is rather complementary in time; thus, a better balance can be found between electricity generation and demand and the load on the electricity grid. In combined solar and wind farms (CSWFs), the turbines will cast shadows on the solar panels. This concerns the static shadow from the construction tower of the turbine as well as the dynamic shadow caused by the rotating blades. This paper reports on the results of millisecond data monitoring of the PV farm of a CSWF in the Netherlands on land. Static and dynamic shadow effects are discussed, as well as their dependency on farm design. It is observed that the dynamic shade of the wind turbine blade causes serious disturbances of the DC inputs of the inverter, resulting in deviation of the maximum power point tracking monitored. The shadow of the wind turbine results in a total energy loss of about 6% for the given period, park configuration, PV modules, inverter type, and setting.

OPTIMIZATION MODEL FOR RESERVOIR WATER BODY SURFACE AREA USE IN THE FLOATING PHOTOVOLTAIC POWER PLANT

This research intends to optimize the use of reservoir inundation surface area as the Floating Photovoltaic Power Plant (PLTS). The research location is in the Waduk Jatigede, Cijeungjing Village-Jatigede District-Sumedang Regency, West Java Province, Indonesia. The Jatigede is a multi-function reservoir. This reservoir is used for raw water, irrigation, flood control, recreation, sport, and Floating Photovoltaic Power Plant (PLTS). Based on the data of solar radiation intensity, wind velocity, and surface temperature, this research intends to analyze the effect of EBT on the optimization model for using reservoir water surface.The methodology includes the optimization of reservoir water body surface area use for the Floating Photovoltaic Power Plant (PLTS) using Simplex Linear Programming. The optimization is implemented under the three scenarios as follows: 1) Design of floating PLTS island area with attending the bathymetry measurement; 2) Design of floating PLTS island area without attending the bathymetry measurement by the dimension is 160 m x 320 m; 3) Design of floating PLTS island area without attending the bathymetry measurement by the dimension is 320 m x 320 m. The results show that 1) The utilization of reservoir inundation surface area based on the optimization result is 16,703,000 m2 or 1,670.3 ha (42.25%) from the total of reservoir inundation surface area that is 3,953 ha with the electrical production of PLTS is 3,078 MWp or in average is 5,617 GWp per-year; and 2) the evaluation of Waduk Jatigede performance indicates that the operation pattern based on the simulation by using the Simplex Method can fulfil the demand. The last result of simulation has the reliability of 79.17%, the volatility is 80.00%, and the vulnerability is 28.74%. It means that the reservoir has the ability in amount of 79.17% for fulfilling the demand. Meanwhile the reservoir ability for returning back to the satisfied condition from the failure condition to fulfil the demand is 82.92%, and in the case of the failure, 28.74% of demand cannot be fulfilled with the average deficit is 7.67 million m3 per 15 days every failure event.

Interpregnancy Interval After Termination of Pregnancy and the Risks of Adverse Outcomes in Subsequent Birth

Interpregnancy Interval After Termination of Pregnancy and the Risks of Adverse Outcomes in Subsequent Birth

Facile synthesis of graphite-reduced graphite oxide core-sheath fiber via direct exfoliation of carbon fiber for supercapacitor application.

A graphite-reduced graphite oxide (rGO) core-sheath structured fiber was synthesized through chemical exfoliation of graphitic carbon fiber. The graphitic carbon fiber was oxidized to form a graphite-graphite oxide core-sheath fiber and followed by thermal exfoliation to form a graphite-rGO core-sheath fiber. The core-sheath fiber with a three-dimensionally (3D) structured rGO sheath possesses a high surface area and pore size around 5.5 nm. A two-electrode supercapacitor constructed with this core-sheath fiber-based paper exhibited a high specific capacitance (140 F g(-1) at a current density of 1 A g(-1)), high power density of 45 kW/kg, and good cycling stability (10% capacity loss after 3000 cycles). The surface area normalized capacitance reached as high as 59.4 μF cm(-2), indicating the effective use of surface area. The low equivalent series resistance value of 0.45 ohm in the Nyquist plot indicates an extremely small resistance between the graphite core and rGO sheet sheath. The hierarchical three-dimensional structure enables one to maximize the advantages of both graphite and rGO sheets. The 3D-structured rGO sheets sheath with regular pore structure is favorable for ion diffusion due to its interconnected porous system, while the graphite core provides an electron transport pathway with high conductivity.

Effect of Water Flow Pattern on the Treatment of Discharged Sewage by Biological Accelerator-Bio-Film Process

The paper studied the effect of water flow pattern on the treatment of disorderly discharged sewage in tidal rivers by bio-film process. The results indicated that biomass was greater under the fluctuation turn flow than under the folding flow around. Under the fluctuation turn flow, the concentration of COD was 168mg/L and the removal rate of COD was 37.1%. Under the folding flow around, the concentration of COD was 187mg/L and the removal rate of COD was 29.4%. The results indicated that the removal rate of COD was higher 7.7% under the fluctuation turn flow than under the folding flow around. The reason was that under the fluctuation turn flow, soft packing fiber was derided by water, and the effective use of surface area was great and microbial growth space was large.

Effects of in vivo exercise on ankle cartilage deformation and recovery in healthy volunteers: an experimental study

To monitor ankle cartilage 3D volume changes after in vivo exercise and during recovery. Based on 3D MRI, 3D volumes of talar and tibial cartilage were calculated before and after 30 bilateral knee bends in 12 healthy volunteers. 3D volumes were calculated at five time points (one pre- and four post-scans) determining deformation and recovery for both cartilage plates of interest. Post-scans ran immediately after the exercise and were repeated according to a 15 min interval. 3D volumes were subjected to repeated measures GLM. Additionally, relative surface area use during deformation was compared between plates using a Wilcoxon Signed Ranks test and its correlation with deformation was investigated using Spearman's rho. Mean 3D volume change percentages for talar cartilage after the exercise were: -10.41%, -8.18%, -5.61% and -3.90%. For tibial cartilage mean changes were: -5.97%, -5.75%, +0.89% and +1.51%. For talar cartilage changes were significant, except following 30 min post-exercise. For tibial cartilage no changes were significant. At all time points, no significant differences in relative volume changes between both cartilage plates existed. Although no significant differences in relative surface area use between plates were revealed, a moderate to strong correlation with deformation existed. Ankle cartilage endures substantial deformation after in vivo loading that was restored within 30 min for the talus. Overall cartilage contact area involvement might be associated with cartilage quality maintenance in the upper ankle. Talar cartilage is suggested to play a critical role in intra-articular shock attenuation when compared to tibial cartilage.

Effect of Pore-size of Mesoporous SBA-15 on Adsorption of Bovine Serum Albumin and Lysozyme Protein

In this paper, the effects of pore-size of SBA-15 on the adsorption kinetics and equilibrium of large protein molecules Bovine serum albumin (BSA) and lysozyme (LYS) have been investigated. The mesoporous molecular sieve SBA-15 with six different pore sizes were synthesized with P123 triblock copolymer as the template agent, and 1,3,5-trimethylbenzene (TMB) and isopropyl alcohol as the pore-expanding agent. The samples were characterized by N 2 adsorption/desorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). It is found that BSA and LYS were adsorbed rapidly on SBA-15 materials with large pores. The BSA adsorption capacity of sieve with the pore diameter of 21.4 nm reached 500 mg·g −1 within 25 minutes. However, if the pore diameter was smaller than 14 nm, the BSA adsorption capacity of the sieve was only about 220 mg·g −1. The adsorption equilibrium data fits in the Langmuir model, where the coefficient of effective use of specific area of mesoporous molecular sieve was found to be 0.03, 0.18, 0.37 and 0.48, corresponding to the pore diameter of 10.1 nm, 13.2 nm, 15.4 nm and 21.4 nm, respectively. The equilibrium loading amount of LYS on SBA-15 materials with pore size of 15.4 nm could be up to 1000 mg·g −1. The coefficient of effective use of surface area of mesoporous molecular sieve with diameter of 3.9 nm, 7.4 nm, 10.1 nm, 13.2 nm and 15.4 nm was 0.10, 0.47, 0.56, 0.71 and 0.79, respectively. It is also noted that greater pore size of mesoporous molecular sieve would lead to a higher coefficient of effective use of surface area.

Titanium Dioxide: Inhalation Toxicology and Epidemiology

Titanium dioxide (TiO(2)) is manufactured worldwide in large quantities for use in a wide range of applications and is normally considered to be toxicologically inert. Findings of tumours in the lungs of rats exposed chronically to high concentrations of TiO(2), but not in similarly exposed mice or hamsters, suggest that the tumorigenic response may be a rat-specific phenomenon but nonetheless raises concerns for potential human health effects. With the limited toxicological understanding of species differences in response to inhaled TiO(2) and a similarly limited amount of epidemiological information with respect to TiO(2) exposure in the workplace, a consortium of TiO(2) manufacturers in Europe (under the European Chemistry Industry Council; CEFIC) and in North America (under the American Chemistry Council; ACC) initiated a programme of research to investigate inter-species differences as a result of exposure to TiO(2) and to conduct detailed epidemiological surveys of the major manufacturing sites. The toxicology studies exposed rats, mice and hamsters to pigment-grade TiO(2) (PG-TiO(2), 0, 10, 50 and 250 mg m(-3)) or ultrafine TiO(2) (UF-TiO(2), 0, 0.5, 2 and 10 mg m(-3)) for 90 days and the lung burdens and tissue responses were evaluated at the end of the exposure period and for up to 1 year after exposure. Results demonstrated clear species differences. Rats and mice had similar lung burdens and clearance rates while hamsters showed high clearance rates. At high lung particle burdens, rats showed a marked progression of histopathological lesions throughout the post-exposure period while mice and hamsters showed minimal initial lesions with recovery apparent during the post-exposure period. Lung neutrophil responses, a sensitive marker of inflammatory changes, reflected the development or recovery of the histopathological lesions. The use of surface area rather than gravimetric lung burden provided closer correlates of the burden to the biological effect across both TiO(2) types. The epidemiological investigations evaluated the mortality statistics at 11 European and 4 US TiO(2) manufacturing plants. They concluded that there was no suggestion of any carcinogenic effect associated with workplace exposure to TiO(2).

Cautious Arguments in Favor of Body Surface Area–Based Dosing

Cautious Arguments in Favor of Body Surface Area–Based Dosing

The influence of soil age on calculated mineral weathering rates

Mineral weathering rates for two chronosequences of soils have been calculated using an empirical method based on mineralogy, the depletion of elements relative to a conservative element and the computer model PROFILE. Weathering rates calculated by the empirical and depletion methods showed a decrease in rates with soil age whilst those calculated using the PROFILE model showed an increase with soil age. The counter intuitive PROFILE prediction is due to the use of surface area—normalised reaction rate coefficients which assume that: 1) mineral reactivity is constant with time and, 2) total mineral surface area is equivalent to reactive surface area. In Europe, mineral weathering rates in soils are an important input in determining levels of acid deposition above which ecosystem damage will occur (critical loads). As soils in Great Britain and much of NW Europe can range in age from <10 3 to >10 5 a, it is suggested that, until computer models can take account of soil age and the concomitant changes in mineral reactivity and surface area, modelled weathering rates will be subject to large uncertainties

Use of surface area and porosity to characterise the chemical upgrading of ilmenite

Mechanical milling, chemical attrition and various leaching processes modify the surface and physical properties of ores, and ultimately influence their behaviour during processing. Measurements of surface area and porosity can assist in understanding the behaviour of, and optimizing the upgrading of, finely divided problematic ores. During the upgrading of titanium-bearing mineral sands, iron-rich coatings on the mineral particles often impair the concentration of individual components. Owing to their porosity, these coatings have a significant surface area compared with the other sand constituents. The effect of leaching of ilmenite samples is described in terms of surface area, pore volume and pore size distribution. These physical measurements show that the oxide coatings are eroded into mesoporous regions in the diameter range 50 to 700 Å, and become weakened. This structural weakening enables the coatings to be easily removed by attritioning.

The logistic equation for modelling bacterial oxidation kinetics

Bacterial oxidation is being used increasingly for the pretreatment of refractory gold-bearing sulphide concentrates. South African organizations have been involved in the implementation of this technology at both pilot and production scale. These plants and their performance are discussed. The successful development and implementation of these processes on an industrial scale requires a sound basis of kinetic modelling for the characterization of the oxidation kinetics and the design of bioreactors. It was the objective of this work to test the suitability of the logistic equation in modelling the bacterial oxidation of a number of refractory gold-bearing sulphides; to compare the kinetics constants obtained from batch and continuous data and to investigate the use of surface area as a basis for correlating rate constants. Several sets of experimental data, together with data from the literature have been analyzed. Both pyrite and arsenopyrite data were found to be in good agreement with the predictions of the logistic equation for both batch and continuous systems. In all cases it was found that the rate constant for continuous bacterial oxidation was higher than that for batch. The use of surface area concentration will be shown to be a most useful basis for correlating kinetic constants, accounting for variations in both solids concentration and particle size.

Relation between CO 2-reactivity of coal char and BET surface area

Gasification rates of different carbonaceous materials were measured at temperatures from 1073 K to 1273 K and carbon dioxide partial pressure of 50 kPa. The surface areas of the chars were also measured at various levels of conversion. The conversion rates per unit BET surface area remained mostly constant over the range of higher conversion ( X > 0.4) and rates thus evaluated were expressed by a common straight line in an Arrhenius plot. Thus under the experimental conditions used differences in the gasification rates of various carbonaceous materials were interpreted by use of surface area only.

Partition coefficients and surface areas of some alkylbenzenes.

The experimentally measured log P values (logarithms of partition coefficients) of a number of alkylbenzenes are shown to be quantitatively related to the hydrocarbon surface area HSA of the molecule by pi = 0.0275 X HSA - 0.863 (correlation coefficient =0.996, standard deviation = 0.071). The use of surface area as a correlating parameter eliminates the need for correction factors to account for branching, cyclization, ring fusion, and "backfolding". Futhermore, surface area calculations provide a conceptual basis for understanding how conformation can effect partitioning.

A General Correlation Between Treadwear and Carbon Black Properties

A set of treadwear data representing over eight million tire section-miles of road testing was fitted by a carefully constructed simple model involving only two carbon black properties as independent variables, plus test severity as a parameter. It is shown that the carbon black char acteristics measured by two practical laboratory tests — surfactant (cetyltrimethylammonium bromide) adsorption for accessible specific sur face area and dibutylphthalate absorption on precompressed black for "structure" — can account for virtually all of the observed wear resistance variation among carbon blacks which is not obscured by random exper imental error. This degree of success in correlating roadwear data using only a simple two-parameter description of morphology hinges on use of surface area and structure test methods relatively free of extraneous influences known to affect results obtained by the standard ASTM iodine number and DBP procedures. The weight of data on which the model is based renders predictions by means of the correlation more reliable than results of individual tire tests of conventional design. Potentially attractive economies in quality testing of carbon black are implied by the possibility of "instant" roadwear screening of carbon blacks from diverse sources.

The Effect of Aluminum on the Surface Properties of Kaolinite

AbstractAluminum ions as well as hydroxide precipitates promote improved extraction of iron from kaolinites during leaching. Selective aggregation of ultrafine particles in kaolinites, seemingly induced by precipitation of aluminum hydroxide, gives brightness improvement in excess of that which can be ascribed to iron extraction. Aggregation of anatase, a primary discolorant confined mostly to the fine end of the kaolinite particle size distribution, is the suggested mechanism for complementary brightness improvement.Precipitation of aluminum hydroxide in kaolinite systems substantially changes flocculation characteristics, surface area (methylene blue), and rheology. Edge-edge and edge-face flocculation are promoted where sulfate retention is high, becoming progressively more face-face with sulfate removal. The character of the flocculation can be interpreted by the combined use of surface area and low shear viscosity data.The extent to which kaolinites can be dispersed after processing increases with increase in sulfate retention. Stability of suspensions deflocculated with polyphosphates shows an inverse relationship, decreasing with increase in sulfate retention.

Glare from daylighting in buildings

Glare can be caused by a direct view of the bright sky from the interior of a building. This glare can be an impediment to vision and even a direct hazard, as on a stairway, or it can cause serious or mild discomfort. Even minor effects may accumulate, as with a low but incessant noise, to lead to fatigue during the working day. Both the disabling and annoying effects of glare have been studied in a number of laboratories, and this article summarises some of the most recent conclusions. Glare is a direct function of both the size of the window and the brightness of the sky seen through it, and an inverse function of the brightness of the room interior. Glare can therefore be reduced by cutting down the size and brightness of the visible patch of sky and by increasing the interior brightness by the judicious use of surface areas of high reflectance. These parameters are related in such a way that an overall Glare Index for a room can be computed and values of this Glare Index can be set and codified to ensure that tolerance limits will not be exceeded.

Calculation of Surface Area of the Body

Several recent commentaries have been concerned primarily with the use of surface area of the body as a means of computing parenteral fluid dosages. Since there is, fortunately, a reasonably wide latitude of bodily homeostatic mechanisms, it becomes largely a matter of personal preference whether one utilizes surface area to estimate initial dosages or some other scheme to apply a corrective factor to weight-age relationships. There exists another more profound facet to this issue, namely the relationship, if any, of surface area of the body to such physiologic variables as cardiac output, oxygen consumption, renal functioin, etc. It seems logical to separate three areas for discussion.