Mechanical improvement in solar aircraft by using tangent hyperbolic single-phase nanofluid

Solar power is the primary thermal energy source from the sunlight. This research has carried out the study of solar aircraft with solar radiation in enhancing efficiency. The thermal transfer inside the solar aircraft wings using a nanofluid past a parabolic surface trough collector (PTSC) is investigated thoroughly. The source of heat is regarded as solar radiation. For several impacts, such as porous medium, thermal radiation, and varying heat conductivity, the heat transmission performance of the wings is examined. By using the tangent hyperbolic nanofluid (THNF), the entropy analysis has been performed. The modeled momentum and energy equations are managed using the well-established numerical methodology known as the finite difference method. Two distinct kinds of nano solid-particles have been examined, such as Copper (Cu) and Zirconium dioxide (ZrO2), while Engine Oil (EO) being regarded as a based fluid. Different diagram parameters will be reviewed and revealed as figures and tables on speed, shear stress, temperature, and the surface drag coefficient and Nüselt number. It is observed that in terms of heat transfer for amplification of thermal radiation and changeable thermal conductance parameters, the performance of the aircraft wings raises. In contrast to traditional fluid, nanofluid is the best source of heat transmission. Cu-EO's thermal efficiency over ZrO2-EG falls to the minimum level of 12.6% and has reached a peak of 15.3%.

Applied Mathematical Modelling and Heat Transport Investigation in Hybrid Nanofluids under the Impact of Thermal Radiation: Numerical Analysis

Nanofluids are solid-liquid mixtures that have a dispersion of nanometer-sized particles in conventional base fluids. The flow and heat transmission in an unstable mixed convection boundary layer are affected by the thermal conductivity and dynamic viscosity uncertainty of a nanofluid over a stretching vertical surface. There is time-dependent stretching velocity and surface temperature instability in both the flow and temperature fields. It is possible to scale the governing partial differential equations and then solve them using ordinary differential equations. Cu and Al2O3 nanofluids based on water are among the possibilities being investigated. An extensive discussion has been done on relevant parameters such as the unsteadiness parameter and the mixed convection parameter's effect on solid volume fraction of nanoparticles. In addition, alternative nanofluid models based on distinct thermal conductivity and dynamic viscosity formulas are examined for their flow and heat transmission properties. On the basis of the comparison, it is concluded that the results are spot on for steady state flow.

Comparative Study on Effects of Thermal Gradient Direction on Heat Exchange between a Pure Fluid and a Nanofluid: Employing Finite Volume Method

This work aims to determine how the temperature gradient orientation affects the heat exchange between two superposed fluid layers separated by zero wall thickness. The finite volume method (FVM) has been developed to solve the governing equations of both fluid layers. To achieve the coupling between the two layers, the heat flow continuity with the no-slip condition at the interface was adopted. The lower part of the space is filled with a nanofluid while the upper part is filled with a pure fluid layer. We have explored two cases of temperature gradient orientation: parallel gradient to gravity forces of our system and perpendicular gradient to gravity forces. We took a set of parameters, Ri and ϕ, to see their influence on the thermal and hydrodynamic fields as well as the heat exchange rate between the two layers. The main applications of this study related to biological systems such as the cytoplasm and the nucleoplasm are phase-separated solutions, which can be useful as models for membranelles organelles and can serve as a cooling system application using heat exchange. The Richardson number and the volume of nanosolid particles have a big impact on the rate of change of heat transmission. When a thermal gradient is perpendicular to gravity forces, total heat transmission improves with increasing solid volume percentage, but when the thermal gradient is parallel to gravity forces, overall heat transfer decreases significantly.

Energy-Efficient Building Design for a Tropical Climate: A Field Study on the Caribbean Island Curaçao

Based on an extensive literature review on passive building designs for tropical climates, seven energy-efficient building design principles for tropical climate areas were deduced. These are: 1. To orientate a building design in such a direction that it protects from excessive solar radiation; 2. To accommodate for indoor natural ventilation; 3. That it makes maximal use of indirect instead of direct natural light; 4, That it reduces the amount of heat transmission through the roof as much as possible by natural ventilation between roof and ceiling and by lowering the roof surface temperature; 5. By preventing the use of high thermal mass materials; 6. By reducing through the exterior walls as much as possible heat transmission by e.g., preventing direct sunlight on the external walls and applying reflective paints on the external walls and; 7. By creating outdoor and transition spaces such as balconies, terraces atriums and corridors. The insights from the literature review were used as input to conduct a field study to evaluate the practice of applying passive building design principles. To this end, for 626 buildings on the Caribbean island Curaçao, it was investigated to what extent the recommended passive design principles for tropical climates were actually applied. Based on the results of the field study, several recommendations are made to improve the practice of applying passive building principles.

Establishment of rights on agricultural lands

According to the provisions of Article 56 (1) of the Regulation on the Application of the Law on the Conservation of Agricultural Land /www.lex.bg/, the construction of sites - public property of the state or municipalities - is possible to use agricultural land. This use extends within a certain period of time and takes place outside the site (track) of the site. Temporary use of agricultural land is related to the need for similar land plots in the construction of mostly underground and aerial linear objects and, if necessary, by conducting geological and other surveys. According to the text of Article 64, paragraph 1 of the Law on Energy /www.lex.bg/, the servitudes arise in the extension of existing and under construction of new air and underground power lines, over ground and underground hydrotechnical facilities for the production of electricity, heat transmission lines, gas pipelines, oil pipelines and oil pipelines in favor of the persons who will build and operate the energy site. The emergence of servitudes is closely related to spatial planning as they are an element of the spatial structure. According to the text of Article 64 (4) (1) of the Law on Energy, servitudes arise when there is a detailed development plan which determines the location of the respective properties. As stated in Article 66 of the Energy Act, the type and location of the energy sites and of the areas of service land included within the limits of the servitudes under this Act shall be determined in general and detailed development plans.

Mixed Convection Stagnation Point Flow of a Hybrid Nanofluid Past a Permeable Flat Plate with Radiation Effect

This article focuses on the stagnation point flow of hybrid nanofluid towards a flat plate. The cases when the buoyancy forces and the flow are in the opposite direction and the same direction are discussed. The effect of radiation and suction is also taken into account. The similarity transformations are used to convert the partial differential equations into nonlinear ordinary differential equations. These equations are computed numerically via the bvp4c function in MATLAB software. A comparison with the previously published articles is carried out, where an outstanding agreement is observed. The dual solutions exist in the case of opposing flow (λ<0) and the suction parameter S>0.6688. Meanwhile, only unique solutions exist in the case of assisting flow (λ>0). The existence of dual solutions leads to stability analysis. From the analysis, the first solution is confirmed as a stable solution. Furthermore, the heat transmission rate increases, while the skin friction coefficient decreases as the radiation rate increases. An increase in the radiation rate from 0 (no radiation) to 1.0 increases the heat transmission rate by 5.01% for water, 4.96% for nanofluid, and 4.80% for hybrid nanofluid. Finally, it is worth mentioning that the present study yields new and original results. This study has also not been done by other researchers, indicating its novelty.

Simulation Analysis of Daylight Characteristics and Cooling Load Based on Performance Test of Covering Materials Used in Smart Farms

In this study, seven of the most commonly applied covering materials in smart farms are selected as the representative samples for analysis, namely, glass, soft film (polyethylene, PE), soft film (polyolefin, PO), rigid plastic film (ethylene tetra fluoro ethylene, ETFE), rigid plastic sheet (poly methyl methacrylate, PMMA), rigid plastic sheet (polycarbonate, PC double layer), and woven film. For each covering material, visible light transmittance and reflectivity, solar radiation transmittance and reflectivity, thickness, solar heat gain coefficient, and the coefficient of heat transmission are measured according to the test methods in the Korean Industrial Standards (KS) to derive input data for the respective materials. In addition, using the optical and thermal input data as derived above, simulations are performed on the cooling load and daylight characteristics of smart farms to derive basic reference data for the selection of adequate covering materials for the design. Based on the analysis result of the daylight characteristics for each covering material, for a shading rate of 60%, the average values of indoor illuminance were 19,879 lux, 20,012 lux, 19,393 lux, 19,555 lux, 16,560 lux, 16,228 lux, and 11,173 lux for glass, PE film, PO film, ETFE, woven film, PMMA, and PC double layer, respectively, between 6 am and 8 pm, which correspond to the hours when daylight enters indoor spaces. Considering the target light intensity for strawberry growth at 10,000–40,000 lux, the above results confirm that all the sample covering materials had an indoor illuminance level above the lower limit range of the target light intensity. For the cooling load evaluation, the PC double layer had the lowest value of 482.8 W/m2, and PO film had the highest value of 633.8 W/m2. The difference between the cooling loads of the PC double layer and the PO film is 151 W/㎡, which amounts to 23.8%, thus indicating that the selected covering material significantly impacts the cooling load. The cooling load exhibited a pattern similar to that of the coefficient of heat transmission and solar heat gain coefficient, which are key influencing factors for most of the sample materials. However, for PMMA, the cooling load was low because it had a higher coefficient of heat transmission than other materials, but its solar heat gain coefficient was relatively low. Another possible reason for the difference is that the solar heat gain coefficient impacts the cooling load. When the cooling set temperature was controlled from Case 1-1 to Case 1-2, the cooling load decreased by 10.7% on average. In addition, when the cooling set temperature changed from Case 1-1 to Case 1-3, the cooling load decreased by 26.1% on average. For cooling set temperature control, maintaining the temperature around the lower temperature range of the optimal growth temperature of the plants increases the yield, but it also incurs increased cooling load and cost. In terms of cost only, while maintaining the cooling temperature for 24 h at 30 °C, which is the upper limit of the optimal growth temperature, would be advantageous, it will lead to a deterioration of the quality and reductions in yield. Therefore, as follow-up studies for further investigation of the findings of this research, there is the need for an evaluation of the yield and quality with respect to the range of cooling set temperatures. When the internal shading rate was increased to 40% (Case 2-2) with reference to Case 2-1, which was a greenhouse without the application of internal shading, the cooling load decreased by 27.4% on average. Furthermore, when the internal shading rate increased to 50% (Case 2-3) with reference to Case 2-1, the cooling load decreased by 29.3% on average. When the internal shading rate increased to 60% (Case 2-4), the cooling load decreased by 31.5% on average.

Simultaneous solutions for convective heat transfer in dusty-nano- and dusty-hybrid nanoliquids

The present study investigates the heat transfer and flow behaviour of magnetohydrodynamic dusty-nano- and dusty-hybrid nanoliquids caused by the stretched surface. We considered the copper oxide (CuO) and magnesium oxide (MgO) nanoparticle suspension in water (H2O) as the base liquid. Similarity transformations are used to transform the partial differential equations to ordinary differential equations and solved by the Runge-Kutta Fehlberg 45 method with a shooting procedure. Outcomes of the velocity and thermal gradients for diverse physical impacts are depicted via plots and the skin friction factor and heat transfer rate are illustrated via tabulated values. Results reveal that dusty-hybrid nanoliquids and their conductive properties play an important role throughout the study. A growth in the mass concentration of dust particles augments the temperature and the Nusselt number, but the reverse reaction to the friction factor and velocity profile has been seen. The Eckert number has a propensity to magnify the temperature of the fluid phase and dust phase. The interaction of dust and nanoparticles extends to the greater heat transmission in the dust phase associated with the fluid phase. Hybridization showed a positive response in the heat transmission of the nanoliquid. The dusty hybrid-nano liquid shows higher heat dispersion compared to the dusty nanoliquid.

Timber Based Integrated Techniques to Improve Energy Efficiency and Seismic Behaviour of Existing Masonry Buildings

The retrofit solutions studied herein aim to improve the seismic and energetic behaviours of existing masonry buildings to guarantee safety and the preservation of the building heritage. The retrofit consists of timber-based products (panels and strong-backs) fixed to the masonry walls using mechanical point-to-point connections; the durability and the hygrothermal performance of the solutions are guaranteed by insulation layers and membranes. The thermophysical properties of the retrofitted walls were evaluated by means of analytical and numerical analyses, considering the heat transmission in both steady and unsteady state conditions and the thermal bridge in correspondence with the corner of the wall. The in-plane seismic behaviour of the retrofitted walls was numerically investigated through nonlinear analyses. The influence of various parameters (such as masonry and insulation properties) on the performance of the retrofit solutions was analysed via parametric simulations.