Parallelepiped Form Research Articles

Energetically optimal dimensions of parallelepiped-shaped industrial structures

Technical structures with a parallelepiped form are frequently used in various areas of industry. For example, as fluid containers, ice and minerals piles, underground and surface storages and cooling chambers. A task of determining the optimum dimensions of the structure to minimize the energy expenses to support a normative temperature in the structure arises. The minimum surface area of the structure at a given volume is accepted as a criterion of optimality. A problem of unconstrained optimization for a structure with a parallelepiped form was formulated and solved. Equations to determine the optimum dimensions of width, height and length of the structure were obtained. It was determined that a cube is the most optimal form.

Heat Transfer Coefficient from the Sheet-Piped Light-Absorbing Panels of the Flat-Plate Solar Water-Heating Collectors to the Heat Transfer Fluid in Their Heat-Removing Channels

It has been proposed to introduce a new parameter into the practice of the heat calculation and testing of the flat-plate solar water-heating collectors (FSWHCs)—the coefficient of heat transfer from the light-absorbing panel (LAP) to the heat transfer fluid in its internal heat-exchange channels (HECs) reduced to the unit area of the frontal surface of their cases. The mechanism of the formation of this parameter is studied, the design expression is derived, and a practical example of the calculation to define its value is performed. The structures of the flowing LAPs of a sheet-piped thin parallelepiped form are selected as the objects of the investigation. The reliability of the results of the investigations is proved by comparing the values of the specific (relative to the area unit of the frontal surface of the case) heating efficiency of the collector obtained based on the various formulas.

Determination of the Convective Heat-Exchange Coefficient in Inner Channels of Light-Absorbing Heat-Exchange Panels of Flat-Plate Solar Water-Heating Collectors Based on the Results of Their Short-Term Thermal Testing in Full-Scale Conditions

The results of investigations to determine the convective heat-exchange coefficient in the inner heat-exchange channels (HECs) of the light-absorbing heat-exchange panels (LAHPs) of flat-plate solar water-heating collectors (FPSWHCs) are given based on the results of their short-term heat testing in fullscale quasi-stationary conditions. The research method is based on determining the value of the required parameter from the heat-balance equation formed for the inner surfaces of the LAHP HEC walls. The structures of the flow LAHPs with a sheet-piped and thin parallelepiped form are selected as the test objects. The thermal tests of the FPSWHC are carried out during the near-midday hours of the light day to ensure the quasi-stationary mode condition. The reliability of the proposed method and results of the investigations is proved by comparing the values of the thermal-efficiency coefficients of the FPSWHC LAHPs obtained using two independent approaches.

Modelagem generativa integrada à eficiência energética: estudo da otimização da forma de edificações institucionais

Decisions making in architectural design early stages have a significant impact on energy efficiency and internal performance of buildings. A design process that utilizes energy efficiency parameters in early stages can accelerate the creation process and adding value to the design, as well as contributing to user well-being and environment improving. The purpose is verify the potential integration generative modeling to energy efficiency, through the form optimization integrated to Inmetro PBE Edifica prescriptive method of envelope energetic performance. Therefore, an equation of RTQ-C Consumption Indicator for bioclimatic zone 3 applied to study of institutional buildings. Initial parallelepiped form was programming in Rhino / Grasshopper software. The variables was defined according to RTQ-C prescriptive method equation, such as building length, width and height, openings height, glasses solar factor and vertical shading angle. The genetic algorithm used to generate the best form to meet energy efficiency parameters. Other volumetric possibilities were studied, being these: horizontal multiplication, vertical multiplication with rotation and vertical multiplication of unique form. The forms obtained the efficiency level A from RTQ-C traditional method application, which proves a viability of proposed method. In this way, it is possible to perceive the potentialities of generative modeling integrated to energy efficiency, which can revolutionize the architect design.Keywords: generative modeling, RTQ-C, energy efficiency.

Wood chips flow in a rotary kiln: Experiments and modeling

Rotary kilns are well suited for processing woody biomass by torrefaction to produce bioenergy. One of the key issues for process design lies in the flow pattern modeling. The Saeman model is classically used to predict the mean residence time (MRT) and the bed depth profile of powder materials in rotary kilns. Its ability to describe wood chips flow arises. In the present study, residence time distribution (RTD) experiments are conducted with raw and torrefied wood chips. Effects of operating parameters – kiln slope, rotational speed and inlet flow-rate – on the average residence time, the variance and the mean solid hold-up are discussed. A plug flow with small extent of dispersion is emphasized, even if some segregation phenomena are highlighted. Torrefaction did not evidence any significant influence on the flow pattern. With a discrepancy of 20% between the measured and computed mean residence time, the predictive capacity of the classical Seaman model proved to be insufficient. The model is adapted to predict accurately the load profile and the mean residence time of particles with parallelepiped form. The discrepancy between experimental and calculated results is so reduced from 20% to 5% for the MRT and from 25% to 5% for the mean solid hold-up.

Experimental study of the inclined solar film evaporator

The present study investigated the experimentation of an inclined solar film evaporator in the meteorological conditions of the town of Bizerte, in Tunisia. The experimental device used in this study has a parallelepiped form. It is primarily constituted by an inclined metal plane plate. A water film falls on the external face of this plate through a porous tissue. A glass cover, placed on a wooden frame put on the plate, is exposed to the solar radiation acting as a solar panel. An ascending air flow enters in the evaporator where it is in direct contact with the falling water film. This experimental device is designed and supplemented by a protocol of measurements to conduct this study. The thermocouples installed along the metal plate were connected to an automatic acquisition making it possible to read and store the measured temperatures values. The evaporated flow is measured by an electronic balance and a stopwatch. The humidity and the air velocities are measured using a digital multifunction device. The series of measurement are carried out in natural and forced convections. The profile of the liquid film temperature and the variation of the evaporated flow are measured for the two convection modes. To quantify the effectiveness of the solar evaporator, the thermal and mass yields are calculated. The results show that the evaporated flow is more significant in forced convection and that the thermal and mass yields of the solar evaporator are higher than 80%.

Growth of La<sub>1-<sub>x</sub><i></i></sub>Ba<i><sub>x</sub></i>CoO<sub>3</sub> Single Crystals and their Structural and Magnetic Properties

La1-xBaxCoO3single crystals were grown from KOH melt at 873 K under H2O/O2mixed gas flow. The grown crystals had a parallelepiped form with the edges of about 60 μm. Streaks indicating twin boundaries were observed on the surface planes of the crystals. The crystals showed magnetic anisotropy and anomalousMHhysteresis loops. The magnetocrystalline anisotropy and coupling of ferroelasticity and ferromagnetism were discussed based on the magnetic properties.

A transient polymorph transition of 4-cyano-4′-octyloxybiphenyl (8OCB) revealed by ultrafast differential scanning calorimetry (UFDSC)

In this work, ultrafast differential scanning calorimetry (UFDSC) with heating and cooling rates up to 20 000 K s−1 is used to study the transient polymorph transition of the liquid crystal 8OCB. The square plate form (SP), which was reported to grow only from the solution in binary solvent mixtures at low temperature, is found to be the only form growing from a deeply quenched smectic glass during very rapid heating. If the heating rate is slower than 8000 K s−1, reorganization to the parallelepiped form will start, and if the heating rate is slower than 1000 K s−1, the square plate form will reorganize to the parallelepiped form completely, and only melting of the parallelepiped form is observed. The capacity of the UFDSC to capture the unstable polymorphs of low molar mass organic molecules and to follow their rapid transition is demonstrated in this work.

Growth of La1−xSrxCoO3+δ Single Crystals from KOH Melt and Their Magnetocrystalline Anisotropy

Single crystals of a metallic ferromagnet La1–xSrxCoO3+δ (x = ∼0.44) were grown from KOH melt at 773 K under H2O/O2 mixed gas flow. The grown crystals had a parallelepiped form, and their surfaces were (100) planes of the pseudocubic unit cell. The edges of the largest crystal were about 0.1 mm. The XRD and magnetic susceptibility measurements indicated that the grown crystals are highly homogeneous with respect to La/Sr contents. The magnetization versus magnetic field curve was dependent on the applied field direction to the crystallographic axis, evidencing the presence of magnetocrystalline anisotropy in La1–xSrxCoO3+δ.

Drying of Tunisian sardine ( Sardinella aurita) experimental study and three-dimensional transfer modeling of drying kinetics

Experimental drying curves of sardine muscles ( Sardinella aurita) in parallelepiped form were performed under different drying air conditions (three air temperatures: 35, 40 and 50 °C ± 1 °C, two air velocities: 1 and 2.5 m s −1, and at atmosphere humidity). A diffusive three-dimensional model was established to describe drying of sardine sample in parallelepiped form. The calculated drying curves was compared to the experimental ones in order to determine apparent moisture diffusivity. An empirical equation describing the apparent moisture diffusivity within the sardine muscles was suggested versus temperature and local moisture content of the product. A good agreement was found between experimental and calculated drying kinetics.

Grain size control in nanocrystalline In 2O 3 semiconductor gas sensors

In 2O 3 thin films prepared by sol–gel method make it possible to detect low levels (several hundreds ppb) of nitrogen dioxide in air. The possibility of grain size control in indium oxide-sensing layers has been established by using of two preparation methods—electron beam evaporation (EB) and sol–gel technique (SG). SG-prepared samples show smaller particles sizes (down to 5 nm), higher state of agglomeration, higher sensor resistance in air and higher response to NO 2 in comparison to EB samples. Sol–gel technique leads to the preparation of polycrystalline indium oxide with particle sizes of about 5–6 nm after calcination at 400°C and 20 nm after calcination at 700°C. The initial state of particle agglomeration in initial indium hydroxide sol (IHS), stabilized with nitric acid, influences the structure and surface morphology of the resulting indium oxide. While the In 2O 3 layer prepared by using low agglomerated IHS is smooth and porous, In 2O 3 layers prepared from highly agglomerated IHS consist of two regions—thin layer and crystallite agglomerates in cubic and rectangular parallelepiped form. The last shows the best results in terms of NO 2 sensitivity. Sensor resistance and NO 2 sensitivity increase with the decrease of the grain sizes in In 2O 3.

X-ray Diffraction for Acid Soaps

A little previous work has been published on X-ray diffraction of acid potassium soaps. Piper reported a paper which gives only the long 'spacings for a series of acid potassium soaps and recently, Dumbleton reported the lattice constant of acid potassium myristate. In this paper, X-ray investigation on acid potassium caprate, laurate, palmitate, stearate are reported. Acid potassium caprate and laurate were grown from ethanol solution in elongated parallelepiped form (Fig.-1·1), and acid potassium palmitate and stearate were in plates (Fig.-1·3). Acid potassium myristate is crystallized from hot alcohol in the elongated parallelepiped form (Fig. -1·2), but by slow precipitation it gives plate form (Fig.-1-3). The X-ray diffraction patterns showed remarkable difference between the elongated parallelepiped forms and the plates (Fig.-3·1). The cell dimensions for parallelepiped form were determined (Table-1). It was concluded that there were two phases in acid soaps, one was elongated parallelepiped form (pseud-orthorhombic), and another was plate form (triclinic). It seemed that the stable phase for laurate and caprate was the former, while that for myristate, palmitate and stearate was the latter.