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This work is devoted to the study of the influence of height and the number of heaters on the nature of the flow and isotherms in a three-dimensional cube filled with Al2O3/H2O nanofluid with a volume fraction of 1% at Pr = 7.06586. Numerical simulation was performed on the base of the numerical finite volume method and the coupled scheme. It simulated the natural convection with nanofluid. Verification of the mathematical model was performed by comparing the results with the results of other authors. Having obtained satisfactory results, numerical results of U and V velocities, temperature contours and calculations of average Nusselt numbers for six cases of the main problems were obtained. [ABSTRACT FROM AUTHOR]

The occurrence of late spring frosts due to climate change causes great damage to plantation production worldwide. The main objective of the paper is to provide a comprehensive overview of the problem and to outline effective protective measures against late spring frosts. The nature of frost depends on regional, altitudinal, and geographic differences, but they all share a common problem: they remove heat, resulting in the freezing of new plant growth and flowers. Tissue freezing is affected by critical temperatures and the frost type, intensity, and duration. Protection against late spring frosts can be broadly divided into three categories: active, passive, and chemical measures. In the field of agricultural engineering, various techniques have been thoroughly researched, and their effectiveness has been confirmed by research. These include various sprinkler systems, different heating devices, and large-diameter fans. Conclusive findings are being made on the performance of these systems in sub-zero temperatures and their cost-effectiveness. Climate change increases the importance of protecting permanent crops from late spring frosts and requires advances in agricultural technology to meet changing production demands and challenges. [ABSTRACT FROM AUTHOR]

Multi‐walled carbon nanotubes (MWCNTs) were synthesized by a microwave method. MWCNTs had filamentous shapes (10 μm) and were intertwined in bundles (40–60 nm diameter). The rapid oxidation of MWCNTs with a loss of 90% of weight was observed from 530 to 630°C. 2% Residue was present at 630°C, which gradually decreased to 1.2% at 1000°C. In a silicone elastomer, increased thermal conductivity at a concentration of 8% MWCNTs was observed. The highest thermal conductivity of the nano‐modified elastomer was 0.48 W/m°C with 8.0 wt% MWCNTs. The highest electrical conductivity was 2.4 × 10−5 S cm−1 at 8.0 wt% MWCNTs. Both the thermal and electrical conductivities showed percolation behavior with the percolation thresholds at 6 and 5 wt%, respectively. The MWCNTs synthesized by microwave method gave a good power economy in comparison to MWCNTs obtained by chemical vapor deposition (CVD) on NiMg catalyst. Microwave‐synthesized MWCNTs showed high stability at a potential of 250 V in an electrical resistance heater application due to the presence of Fe on the surface of MWCNTs. The developed heater can effectively operate at 220 V, which enables the use of the tubes in household appliances, such as heat fans, irons, and washing machines. Highlights: Synthesis of MWCNTs by microwave plasma treatment of ferrocene and graphite.Characterization of MWCNTs by different techniques.Concentration dependence of electro‐ and thermal conductivity of MWCNTs in elastomers.Electro‐physical parameters studies of elastomers modified with MWCNTs.Heat generation studies in elastomeric matrix with MWCNTs. [ABSTRACT FROM AUTHOR]

The occurrence of late spring frosts due to climate change causes great damage to plantation production worldwide. The main objective of the paper is to provide a comprehensive overview of the problem and to outline effective protective measures against late spring frosts. The nature of frost depends on regional, altitudinal, and geographic differences, but they all share a common problem: they remove heat, resulting in the freezing of new plant growth and flowers. Tissue freezing is affected by critical temperatures and the frost type, intensity, and duration. Protection against late spring frosts can be broadly divided into three categories: active, passive, and chemical measures. In the field of agricultural engineering, various techniques have been thoroughly researched, and their effectiveness has been confirmed by research. These include various sprinkler systems, different heating devices, and large-diameter fans. Conclusive findings are being made on the performance of these systems in sub-zero temperatures and their cost-effectiveness. Climate change increases the importance of protecting permanent crops from late spring frosts and requires advances in agricultural technology to meet changing production demands and challenges.

Wax printing is one of the most widely used techniques to print hydrophobic barriers on hydrophilic microfluidic paper‐based analytical devices (µPADs) based on its simplicity, speed, and low cost, allowing large‐scale production. Nonetheless, its function is just passive, without any action on fluids. Thus, this work proposes multifunctional hydrophobic composites based on conductive graphene nanoplatelets (GNPs) integrated into the wax matrix to allow a dual role of barrier and heater, the latter being required in a large variety of temperature‐sensitive reactions and microfluidic applications. The effect of GNP weight content on the physicochemical properties of the wax, printed wax, and generated heating are evaluated. Wax prints with mechanical stability and adequate impregnation through the paper are obtained after post‐thermal curing. With respect to the functional response, controlled temperatures ranging from room temperature to ≈107 °C can be achieved after just 10 s. Two proofs of concept are presented involving thermochromic inks, specific printed systems designs, and low‐power batteries. The benefits of µPADs allied to the increased functionality and performance of the developed waxes, hold great promise to meet the requirements for a next generation of versatile, effective, and accurate µPADs for an increasing number of applications. [ABSTRACT FROM AUTHOR]

This analysis articulately presents the impact of heat transfer along with associated characteristics inside an equilateral triangular enclosure. Aiming to focus on the significance of heat transfer, four heaters (w1,w2,w3,w4) and three cold walls (C1,C2,C3) are brought into notice in equilateral enclosure. The bottom wall of the enclosure moves with uniform velocity (U0̄) in its own axis while the inclined and corner cold walls of the enclosure are fixed. The position of heaters is considered in four quadrants of cylindrical wall while the segments are placed at the corners of enclosure. Mathematical expressions are developed for heaters and cold walls. The computational model is considered in two-dimensional triangular domain. Water liquid is treated as a working fluid (Pr=6.9). Buoyancy effect is incorporated into Navier–Stokes equations using Boussinesq estimation. The governing equations are explored numerically by using Finite Volume Method based ANSYS-Fluent implicit solver software. Comparison has been made for the current results with published work in limiting case. Excellent matched has been seen. The findings show that the heat transfer rate is noted maximum in third quadrant of cylindrical wall (w4) when compared with other walls against Reynolds number. The temperature is noted maximum at the top corner near the segment C3 when Reynolds number increases. The results have it possible applications in thermal insulation of buildings, heating and cooling processes in machineries, furnaces and controlling of fire in buildings etc.

In this study, we synthesized and characterized a 3D network of silver nanowires (AgNWs), employing the polyol approach in ethylene glycol (EG) as the reductant and polyvinylpyrrolidone (PVP) as the structure-directing agent for the growth of AgNWs to design inexpensive, timely responsive AgNWs-based heaters with different substrates. Data obtained from a field emission scanning electron microscope (FESEM) revealed that the average diameter of the synthesized AgNWs was 22 nm, and the average length was 28 µm. UV-visible absorption spectroscopy showed that AgNWs developed in a very pure phase. We investigated the impact of substrate type on the heating dissipation performance by depositing AgNW thin film over three chosen substrates made from readily available materials. The findings indicated that the AgNW-based heater with the wood substrate had the lowest response time of 21 s, the highest thermal resistance of 352.59 °C·cm2/W, and a steady temperature of 135 °C at a low bias voltage of 5 V compared to cement (95 s, 297.77 °C·cm2/W, and 120 °C) and glass (120 s, 270.25 °C·cm2/W, and 110 °C). [ABSTRACT FROM AUTHOR]

On September 26, 2016 Algerian Space Agency launched AlSat-1B, the second in a series of medium resolution earth observation satellites mission. AlSat-1B electro-thermal propulsion system follows the classic design principle that has been used on previous SSTL-100 missions. With a total dry weight of 5.17 kg, the system is filled with 2.35 L self-pressurized butane. The thruster assembly is designed to use 15 W (at 28 V) redundant heater elements, it is designed to have an average mission thrust of 50 mN. With a warm up time of 10 min, the temperature of the butane will be increased by over 250 °C. This is the equivalent of about 35% gain in specific impulse over ambient temperature butane. The spacecraft dry weigh at launch site was 107 kg, the propulsion system is designed to provide at least 19 m/s Delta-v to meet the spacecraft's mission requirement. To investigate the system readiness for flight, a series of performance tests have been completed at the Surrey Satellite Technology Ltd laboratories (United Kingdom), Satellite Development Centre (Algeria) and Satish Dhawan Space Centre rocket launch site (India), the results of these tests as well as initial flight test results are presented in this paper.

The main objective of natural gas pressure reduction station or city gate stations (CGSs) is to adjust gas pressure within a standard range for home usage. CGSs usually utilize heaters for pressure tuning, which generally consume a considerable amount of energy. In this paper, the effect of six influential parameters, namely, the length of gas-coil, the diameter of gas-coil, the radius of heater shell, length of heater shell, fire tube diameter, and length, on the amount of fuel consumption and thermal efficiency is investigated using Sobol statistical sensitivity analysis. The results show that gas-coil length and diameter are not effective in fuel consumption and thermal efficiency. In contrast, increasing the heater shell radius, heater shell length, and fire tube radius has the same effect as they cause a linear increase in fuel consumption. According to results taken from Sobol analysis, they similarly have an influence of 19%-23% on fuel consumption and 21%-22% on thermal efficiency. Finally, it was revealed that the effect of fire tube length on fuel consumption and thermal efficiency of the heater was 37% and 35%, respectively. [ABSTRACT FROM AUTHOR]