Evaluating the Effect of Cover Materials on Greenhouse Microclimates and Thermal Performance

This study compared and analyzed changes in the microclimate and thermal environment inside single-span greenhouses covered with a single layer of plastic film, polycarbonate (PC), and glass. The results of the experiment show that the PC-covered greenhouse was the most favorable for managing the nighttime heating effect during the cold season. However, the glass-covered greenhouse was found to be the most favorable for managing the cooling effect during the hot season. Although the plastic-covered greenhouse was inexpensive and easy to install, the air temperature inside varied significantly, and it was difficult to control its indoor environment. The thermal load leveling values showed that the PC-covered greenhouse had the lowest variation, confirming its superiority in terms of environmental control and energy savings. In terms of the overall heat transfer, heat was generally transferred from the interior to the exterior of the greenhouses. In the plastic-covered greenhouse, however, heat was transferred in the opposite direction at night due to the influence of radiant cooling. The occurrence of the minimum and maximum heat transfer values had a tendency similar to that of the occurrence of the minimum and maximum air temperatures inside the greenhouses.

EMC3-EIRENE simulations of neon impurity seeding effects on heat flux distribution on CFETR

The numerical modelling of the heat flux distribution with neon impurity seeding on CFETR has been performed by the three-dimensional (3D) edge transport code EMC3-EIRENE. The maximum heat flux on divertor targets is about 18 MW m-2 without impurity seeding under the input power of 200 MW entering into the scrape-off layer. In order to mitigate the heat loads below 10 MW m-2, neon impurity seeded at different poloidal positions has been investigated to understand the properties of impurity concentration and heat load distributions for a single toroidal injection location. The majority of the studied neon injections gives rise to a toroidally asymmetric profile of heat load deposition on the in- or out-board divertor targets. The heat loads cannot be reduced below 10 MW m-2 along the whole torus for a single toroidal injection location. In order to achieve the heat load mitigation (<10 MW m-2) along the entire torus, modelling of sole and simultaneous multi-toroidal neon injections near the in- and out-board strike points has been stimulated, which indicates that the simultaneous multi-toroidal neon injections show a better heat flux mitigation on both in- and out-board divertor targets. The maximum heat flux can be reduced below 7 MWm-2 on divertor targets for the studied scenarios of the simultaneous multi-toroidal neon injections.

A novel therapeutic strategy of multimodal nanoconjugates for state-of-the-art brain tumor phototherapy

Background The outcome of phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT) for glioblastoma multiforme (GBM), is disappointing due to insufficient photoconversion efficiency and low targeting rate. The development of phototherapeutic agents that target GBM and generate high heat and potent ROS is important to overcome the weak anti-tumor effect. Results In this study, nanoconjugates composed of gold nanoparticles (AuNPs) and photosensitizers (PSs) were prepared by disulfide conjugation between Chlorin e6 (Ce6) and glutathione coated-AuNP. The maximum heat dissipation of the nanoconjugate was 64.5 ± 4.5 °C. Moreover, the proximate conjugation of Ce6 on the AuNP surface resulted in plasmonic crossover between Ce6 and AuNP. This improves the intrinsic ROS generating capability of Ce6 by 1.6-fold compared to that of unmodified-Ce6. This process is called generation of metal-enhanced reactive oxygen species (MERos). PEGylated-lactoferrin (Lf-PEG) was incorporated onto the AuNP surface for both oral absorption and GBM targeting of the nanoconjugate (denoted as Ce6-AuNP-Lf). In this study, we explored the mechanism by which Ce6-AuNP-Lf interacts with LfR at the intestinal and blood brain barrier (BBB) and penetrates these barriers with high efficiency. In the orthotopic GBM mice model, the oral bioavailability and GBM targeting amount of Ce6-AuNP-Lf significantly improved to 7.3 ± 1.2% and 11.8 ± 2.1 μg/kg, respectively. The order of laser irradiation, such as applying PDT first and then PTT, was significant for the treatment outcome due to the plasmonic advantages provided by AuNPs to enhance ROS generation capability. As a result, GBM-phototherapy after oral administration of Ce6-AuNP-Lf exhibited an outstanding anti-tumor effect due to GBM targeting and enhanced photoconversion efficiency. Conclusions The designed nanoconjugates greatly improved ROS generation by plasmonic crossover between AuNPs and Ce6, enabling sufficient PDT for GBM as well as PTT. In addition, efficient GBM targeting through oral administration was possible by conjugating Lf to the nanoconjugate. These results suggest that Ce6-AuNP-Lf is a potent GBM phototherapeutic nanoconjugate that can be orally administered. Graphical Abstract

Numerical investigations of heat transfer around a hot block subject to a cross-flow and an extended jet hole using ternary hybrid nanofluids

In the last few years, modern heat transfer technologies significantly improved to provide more efficient systems in industries. One of those technologies is cooling electronic components in laminar flow using water nanofluids, which is interesting. This research used a ternary hybrid nanofluid with various nanoparticle forms to conduct a numerical investigation of three-dimensional heat transfer and fluid flow over a heated block exposed to a horizontal flow and an impinging jet. The effects of several variables such as the Reynolds number ratio [Formula: see text], volume fraction of nanoparticles [Formula: see text], length of extended jet hole [Formula: see text], and the influence of the inclination angle of the impinging jet inlet [Formula: see text] on the fluid flow and heat transfer were examined. Using the Ansys-Fluent 14.5 program and under laminar flow conditions, the finite-volume method was applied with the help of the SIMPLE algorithm to solve continuity, momentum, and energy equations. Several characteristics are assessed, including velocity streamline, isotherm contours, Nusselt number contours, the average Nusselt number ([Formula: see text]), the friction factor [Formula: see text], and drop pressure [Formula: see text]. The findings of the current analysis revealed that adding an impinging jet can boost the heat transfer rate up to [Formula: see text] better than a non-impingement jet. Also, a significant enhancement in the heat transfer rate was obtained when growing one of these parameters α, [Formula: see text], and E. Moreover, the ternary hybrid nanofluid with different nanoparticle forms significantly boosts the heat transfer rate compared to the traditional nanofluid. The maximum heat transfer is reached as the velocity of the impinging jet rises. Inclining the angle of the impinging jet inlet with [Formula: see text] toward the channel inlet boosted the rate of heat transfer up to [Formula: see text] compared to the perpendicular impinging jet [Formula: see text]. A strong consensus has been reached with the theoretical and experimental findings found in the literature.

Heat island study over Madras city and neighbourhood

Based on surface temperature, humidity and wind data collected from 77 points over a period of eight days in and around Madras using mobile surveys, the heat island characteristics at Madras have been assessed. The maximum heat island intensity is seen to be about 4°C. The humidity pattern apart from showing maritime influence also indicates a minimum over the heat pocket. The mixing height is found to be more over urban area than over rural area indicating lower pollution potential over the former due to the mixing over a larger depth than in the latter.

Comparative Study of Thermal Performance of Different Nanofluids in a Double Backward-Facing Step Channel: A Numerical Approach

Two-dimensional numerical simulations are conducted to study forced convection flow of different water-based nanofluids (ZnO, Al2O3, and SiO2) with volume fractions ( ϕ ) = 0–5% and fixed nanoparticle size (dp) = 20 nm for Reynolds numbers (Re) = 50–225 over a double backward-facing step with an expansion ratio (ER) = 2 under constant heat flux (q″ = 3000 W/m2) condition using the finite volume method. Results indicate that the local Nusselt number increases with volume fraction and Reynolds number for all working fluids. In comparison to water, the maximum heat transfer augmentation of about 21.22% was achieved by using water-SiO2 nanofluid at Re = 225 with ϕ = 5% and dp = 20 nm. Under similar conditions, the Al2O3 and ZnO nanofluids demonstrated 14.23% and 11.86% augmentation in heat transfer in comparison to water. The skin friction coefficient decreases with the increase in Re for all working fluids. No significant differences are observed in the values of skin friction coefficient among all working fluids at a particular Re. These results indicate that the heat transfer enhancement has been achieved with no increased energy requirements. In addition, the velocity increases with the rise in Re, with SiO2 nanofluid exhibiting the highest velocity as compared to other working fluids.

EXPRESS METHOD FOR CALCULATING THE SPECIFIC HEAT OF EXPLOSIVE TRANSFORMATION OF CHNO CONDENSED EXPLOSIVES

Разработан экспресс-метод расчета теплоты взрыва СаHbNcOdконденсированных взрывчатых веществ с различным кислородным балансом от резко отрицательного до положительного. Предложенный метод использует минимальный набор входных данных, состоящих из элементного состава, плотности энтальпий образований исходного взрывчатого вещества и его продуктов детонации. Расчет теплоты взрыва основывается на корреляционной связи между минимальной и максимальной теплотами взрыва с плотностью высокоэнергетического соединения. В статье подробно приведены реакции разложения взрывчатых веществ для случаев с минимальной и максимальными теплотами взрыва. Проведены расчеты теплоты взрыва по новому способу и методу Пепекина по представленной в статье базы взрывчатых веществ, а также приведены результаты сравнения, которые показали большую точность (в 2,3 раза) предложенного метода. An express method has been developed for calculating the explosion heat of cahbncod condensed explosives with different oxygen balance from sharply negative to positive. The proposed method uses a minimal set of input data consisting of the elemental composition, enthalpy density of the formations of the initial explosive and its detonation products. The calculation of the heat of explosion is based on the correlation between the minimum and maximum heat of explosion with the density of a high-energy compound. The article describes in detail the decomposition reactions of explosives for cases with minimum and maximum explosion heats. Calculations of the heat of explosion according to the new method and the pepekin method are carried out according to the explosives database presented in the article, and comparison results are also presented, which showed a better accuracy (2.3 times) of the proposed method.

ANALYSIS OF THE HEATING CAPACITY OF ELECTRICALLY HEATED WINDOWS

Electric window heating has been used for some time in Europe and the Americas, but in Ukraine it only enters the market as an independent heating device and raises the question of its heating capacity in winter and the benefits of using them. There are several works in this field that determine the efficiency and contribution to the energy needs of an electric-heated window house, but it is necessary to answer more specifically the question of the heating capacity of such windows as a single heating system, for example rooms of certain sizes.In the work present the design, thermophysical processes occurring in such windows and, by computer simulation of the thermal state of the window with the selected typical room, the results of the study of the heating capacity of the windows, depending on the relative glazing area to the total area of the outer enclosure and the ambient temperature conditions not exceeding the maximum heat emission 450 / and temperature 45 °С on the inner glass of the double-glazed window. the presented thermal model of the window with the room is implemented as a computer program with the possibility of a detailed analysis of the heating capacity of the window, depending on the parameters of the room and the outside temperature, as well as optimization of operational parameters to maintain comfortable conditions.

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

This article studied the effects of pin angle on heat generation and temperature distribution during friction stir welding (FSW) of AA1100 aluminum alloy and St-14 low carbon steel. A validated computational fluid dynamics (CFD) model was implemented to simulate the FSW process. Scanning electron microscopy (SEM) was employed in order to investigate internal materials’ flow. Simulation results revealed that the mechanical work on the joint line increased with the pin angle and larger stir zone forms. The simulation results show that in the angled pin tool, more than 26% of the total heat is produced by the pin. Meanwhile, in other cases, the total heat produced by the pin was near 15% of the total generated heat. The thermo-mechanical cycle in the steel zone increased, and consequently, mechanical interlock between base metals increased. The simulation output demonstrated that the frictional heat generation with a tool without a pin angle is higher than an angled pin. The calculation result also shows that the maximum heat was generated on the steel side.

Experimental analysis of dropwise condensation heat transfer on a finned tube: Impact of pitch size

Condensation is one of the essential processes in diverse industries due to its widespread use in various industrial applications such as power generation, water desalination, and air conditioning. Much research has been conducted to achieve better efficiencies and better heat transfer performances in condensers in the past decades. Condensation is divided into dropwise and filmwise based on the surface free energy, surface roughnesses, and condensate characteristics. This study investigated the influence of the 1-Octadecanethiol coating on vertically grooved copper tube’s condensation heat transfer characteristics. The hydrophobic surfaces have been created using self-assembled monolayers (SAMs) on the pure copper tubes (99.9% Cu). Moreover, four different pitch sizes of 1.5, 2, 2.5, and 3.5 mm have been implemented on the surface. Finally, the heat flux and the heat transfer coefficient as functions of logarithmic mean temperature difference are reported in the result section. For validation, the results obtained from the experiment were compared with available data in the literature, and an acceptable agreement was achieved. According to the results, it was found that the 1.5-mm pitch size has the highest heat flux, and the 3.5-mm pitch size has the lowest heat flux. Additionally, it can be inferred that the maximum heat flux of 696.71 kW/m2 was attributed to the 1.5-mm pitch size for logarithmic mean temperature differences of 64.3 K, which is approximately 1.24 times higher compared to the plain tube.