Energy Transfer Coefficient Research Articles

Modeling Nonspherical Hailstones

Abstract Hail research and forecasting models necessarily involve explicit or implicit—and uncertain—physical assumptions regarding hailstones’ shape, tumbling behavior, fall speed, and thermal energy transfer. Whereas most models assume spherical hailstones, we relax this assumption by using hailstone shape data from field observations to establish empirical size–shape relationships with reasonable degrees of randomness considering hailstones’ natural shape variability, capturing the observed distribution of triaxial ellipsoidal shapes. We also incorporate explicit, random tumbling of individual hailstones during their growth to simulate their free-falling behavior and the resultant changes in cross-sectional area (which affects growth by hydrometeor collection). These physical attributes are incorporated in calculating hailstones’ fall speeds, using either empirical relationships or analytical relationships based on each hailstone’s Best and Reynolds numbers. Options for drag coefficient modification are added to emulate hailstones’ rough surfaces (lobes), which then modifies their thermal energy and vapor exchange with the environment. We investigate how applying these physical assumptions about nonspherical hail to the Penn State hail growth trajectory model, coupled with Cloud Model 1 supercell simulations, impacts hail production and examine the reasons behind the resulting variability in hail statistics. The choice of hailstone size–mass relation and fall speed scheme have the strongest influence on hail sizes. Using nonspherical, tumbling hailstones reduces the number of large hailstones produced. Applying shape-specific thermal energy transfer coefficients subtly increases sizes; the effects of lobes vary depending on the fall speed scheme used. These physical assumptions, although adding complexity to modeling, can be parameterized efficiently and potentially used in microphysics schemes. Significance Statement In numerical modeling of hailstorms, we usually consider hailstones to be spherical to simplify calculations, but in nature, hailstones generally are not spheres and can be rather lumpy and have spikes. The purpose of this study is to examine how the model result would change when nonspherical hailstone shape is implemented. We examine the relationship between hailstone shape and physical processes during hail growth in effort to explain why these changes occur and offer insights on how nonspherical hailstone shape may be parameterized in bulk microphysics schemes.

Enhanced near-field radiative heat transfer between borophene sheets on different substrates

Abstract Near-field radiative heat transfer (NFRHT) has the potential to exceed the blackbody limit by several orders of magnitude, offering significant opportunities for energy harvesting. In this study, we have examined the NFRHT between two borophene sheets through the calculation of heat transfer coefficient (HTC). Due to the tunneling of evanescent waves, borophene sheet allows for enhanced heat flux and adjustable NFRHT by varying its electron density and electron relaxation time. Additionally, the near field coupling is further examined when the borophene is deposited on dielectric or lossy substrates. The maximum HTC is closely related to the real part of the dielectric substrate. As a case study, the HTC on the lossy substrate of MoO3, ZnSe and SiC are calculated for comparison. Our results indicate that MoO3 is the optimal substrate to get the enhanced energy transfer coefficient. It results in a remarkable value of 1737 times higher than the blackbody limit owing to the enhanced photon tunneling probability. Thus, our study reveals the effect of substrate on the HTC between borophene sheets and provides a theoretical guidance for the design of near-field thermal radiation devices.

Effect of an external axial magnetic field on thermal convection of an electric conducting fluid in a rotating spherical shell

We investigated the interaction between the thermal convection structure in a rotating spherical shell and a uniformly applied magnetic field acting externally toward the axis of rotation. We considered a system that the inner and outer spherical boundaries are heated and cooled both isothermally and the effects of induced magnetic fields are neglected. The convection structure of this system is characterized by the generation of travelling waves around the axis of rotation. We numerically investigated how this is affected under the magnetic field. The characteristics of the disturbance (i.e., growth rate and phase velocity) were estimated from the exponential amplification period using three-dimensional (3D) simulations and compared with those obtained from linear stability analyses (LSA). In particular, the effects of the magnetic field on the kinetic energy and Nusselt number were investigated for a quasi-steady state using 3D simulations. Our numerical results revealed that the applied magnetic field destabilizes the flow field and enhances heat transfer. This is noteworthy, contrary to the common sense that magnetic field stabilizes the flow field and reduces the heat transfer coefficient. However, the magnetic field strengths at which the kinetic energy and heat transfer coefficient took their maximum values differ slightly.

Dynamics of acoustically levitated ice impacts on smooth and textured surfaces: Effects of surface roughness, elasticity, and structure

Atmospheric ice collisions on exposed outdoor infrastructure are a rarely explored surface design challenge. A primary obstacle to realistic ice particles in the laboratory setting is freezing a droplet without a solid surface present and then allowing it to impact a substrate without physical intervention. Using acoustically levitated ice formation with subsequent release onto a controlled area, a third class of ice-countering system called “ice-impacting” is introduced. Stainless steel 316 (SS), epoxy resin-coated (ER), and laser-textured (LT) surfaces with known surface roughness, hardness, and structural characteristics were subjected to 40 ice droplet impacts each. The impact effect on surface properties and the effect of these properties on solid-solid interfacial impact dynamics, in turn, were examined using an analysis framework based on fundamental conservation laws. Elasticity was the most significant factor in droplet behaviour as the ER surface exhibited rebounding for 78 % of impacts, nearly double the rates of the stainless steel surfaces. However, surface roughness also played a role, particularly for droplets with rotational motion, as immobilization occurred for 66 % of impacts on the rougher LT surface. Moreover, the nanostructures on that textured surface resulted in droplet redirection perpendicular to the surface directionality. In contrast, the other surfaces experienced no consistent change in rebound angle. Elasticity also affected momentum retention: the ER surface had a translational restitution coefficient of 0.32 compared to 0.17 for the SS/LT surfaces. Surface roughness was a predominant aspect of energy retention, as the LT surface had a translational-to-rotational energy transfer coefficient of 0.07 (0.23 for the smoother surfaces), resulting in an overall energy retention coefficient of 0.09 compared to 0.28 for the SS and ER surfaces on average. The results show that the interplay between elasticity, roughness, and structure at a dynamic solid-solid interface must be considered to optimize their effectiveness when designing ice-countering surfaces.

A hybrid radiative energy transfer and image source method for high-frequency vibrational coupled plates

A hybrid approach composed of the radiative energy transfer method (RETM) and image source method (ISM) is proposed in this study for estimating the vibrational energy of coupled plates loaded by high-frequency point excitation. The vibrational energy at a receiver is represented by energy density and intensity, which are superposed by incoherent rays emitted by the load point in the analyzed domain and reflected/transmitted by the domain boundaries. The energy rays reflected/transmitted at the boundaries are described by two modes: diffuse reflection/transmission, which is a basic assumption in RETM, and the other obeys Snell’s law of reflection/refraction, which is deduced by Fermat’s principle and often applied in ISM. The local energy response distribution in the loading subsystem is described by ISM. The energies in other subsystems are described by RETM. The energy transfer relationship between subsystems is expressed by the energy transfer coefficient. At the boundary of coupled plates, a Fredholm equation of the second type is established through the balance among the outgoing energy of the diffuse reflection fictitious sources and the incident energy of actual sources, other diffuse reflection sources, and specular reflection image sources, which can be used to determine the intensity of the diffuse reflection fictitious sources. The average energy transfer coefficient in the transmission direction half-space is used to express the energy transfer relationship associated with diffuse reflection sources, while the energy transfer relationship associated with specular reflection sources is expressed directly by the energy transfer coefficient. Numerical tests show that the energy distributions and energy flow fields of typical coupled plates are well predicted by the proposed hybrid RETM-ISM approach. Compared with RETM, hybrid RETM-ISM is more consistent with the FEM solution.

Structure and Spectral Properties of Er3+-Doped Bismuth Telluride Near-Infrared Laser Glasses.

TeO2-Bi2O3-B2O3-ZnO laser glasses doped with Er3+ were synthesized through an optimized melt-quenching method. The absorption spectra at 808 nm LD pumping were studied. Various spectral tests and data analyses indicate that the maximum fluorescence emission intensity can be obtained when the Er3+ doping concentration reaches 2%. In this case, the emission cross-section can reach up to 9.12 × 10-21 cm2 and the gain coefficient at 1.55 μm is 6.17 cm-1. Simultaneously, the sample has a lower phonon energy in the high-frequency band at 1077 cm-1, which reduces the probability of non-radiative relaxation. The calculated energy transfer coefficient CD-A is 13.8 × 10-40 cm6/s, reflecting the high cross-relaxation probability of Er3+ in the sample, which promotes the luminescence of 1.55 μm and favors the emission in the near-infrared region. The comprehensive results demonstrate that the prepared Er3+-doped bismuth telluride laser glass can be used as a promising and high-quality gain material for near-infrared lasers.

Comparison of photon interaction coefficients for tumor compositions and healthy tissues simulated by Monte Carlo

This study compares interaction coefficients of photons (namely, mass attenuation, energy absorption and energy transfer coefficients) for some tumor tissues with simlar healthy tissues. Monte Carlo calculations were performed for adenoidcystic carcinoma, melanoma, rectal adenocarcinoma, sarcoma and squamous cell lung carcinoma. The simulation model involved a monoenergetic point source producing a pencil beam. Depending on the parameter under study, average flux, energy flux, or dose deposition from photons that travels in an absorber were scored in the range of 10 keV–20 MeV energy using MCNP6.1. The same model was used to compute the interaction coefficients of health tissues (namely, gastrointestinal tract-small intestine wall, lungs-parenchyma, salivary glands, skin, soft tissue (female+male)) for comparison purposes. The results showed that, depending on the contents of the tumor samples, photon interaction coefficients of a tumor may differ from those of a similar healthy tissue. This behavior was distinct, especially for energies up to 100 keV, and was attributed to the presence of relatively higher atomic number elements in the absorber.

Novel Ordinary Differential Equation for State-of-Charge Simulation of Rechargeable Lithium-Ion Battery

Lithium-ion battery energy storage systems are rapidly gaining widespread adoption in power systems across the globe. This trend is primarily driven by their recognition as a key enabler for reducing carbon emissions, advancing digitalization, and making electricity grids more accessible to a broader population. In the present study, we investigated the dynamic behavior of lithium-ion batteries during the charging and discharging processes, with a focus on the impact of terminal voltages and rate parameters on the state of charge (SOC). Through modeling and simulations, the results show that higher terminal charging voltages lead to a faster SOC increase, making them advantageous for applications requiring rapid charging. However, large values of voltage-sensitive coefficients and energy transfer coefficients were found to have drawbacks, including increased battery degradation, overheating, and wasted energy. Moreover, practical considerations highlighted the trade-off between fast charging and time efficiency, with charging times ranging from 8 to 16 min for different rates and SOC levels. On the discharging side, we found that varying the terminal discharging voltage allowed for controlled discharging rates and adjustments to SOC levels. Lower sensitivity coefficients resulted in more stable voltage during discharging, which is beneficial for applications requiring a steady power supply. However, high discharging rates and sensitivity coefficients led to over-discharging, reducing battery life and causing damage. These new findings could provide valuable insights for optimizing the performance of lithium-ion batteries in various applications.

Broadband ∼2 μm luminescence properties and energy transfer in Tm3+/Ho3+ co-doped TeO2–Al2O3–BaF2 glass

Tm3+/Ho3+ co-doped tellurite aluminate glasses were prepared using the melt-quenching technique. Under 808 nm laser diode (LD) excitation, these glasses exhibit intense 2 μm band luminescence, with a full width at half-maximum (FWHM) of 144 nm. The energy transfer mechanism between Tm3+ and Ho3+ was explored to investigate the luminescence behavior further. Furthermore, the forward energy transfer coefficient (Tm3+→Ho3+) is greater than the backward energy transfer coefficient (Ho3+→Tm3+), indicating that Tm3+ can effectively sensitize Ho3+. As mentioned above, Tm3+/Ho3+ co-doped tellurite aluminate glass is a competitive material in the laser field.

Waveform conversion characteristic analysis of elastic waves in a hull grillage structure

Waveform conversion is closely related to energy transmission and redistribution in a coupled structure. In this research, a modified spectral element method (SEM) is used to analyze the characteristics of waveform conversion of finite-size coupled hull grillage based on the Timoshenko elastic foundation beam theory. Based on a theoretical derivation, the energy transfer coefficient of the coupling point and the energy density of the energy efferent and afferent structure are calculated by adding a non-reflecting boundary in an SEM program to research the parameter effects on waveform conversion. This research provides useful guidance for structural design for vibration reduction at a high frequency.

A wave model of high frequency vibrational energy transfer in a wedge-shaped combined plate structure

Wedge shaped combined plate structure (WCPS) is broadly applied in large-sized transport equipment such as aerospace and shipping. However, with the increase of equipment operating running, it is easy to cause high-frequency vibration of structure components. Therefore, studying the energy transfer and vibration response of high-frequency vibration in WCPS is significant for the structural design of aerospace and shipping. The promising method is energy finite element analysis (EFEA). However, the energy transfer coefficient at joint of WCPS is needed in EFEA. The current studies about the energy transfer coefficients are focus on the joint between two uniform thickness plate. But it is some different that getting the energy transfer coefficient for WCPS, because the near-field solve representation for wedge-shaped plate is complicated due to the non-uniform thickness of wedge-shaped plate member in WCPS. In this research, geometric acoustic approximation and an equilibrium equation on both ends of joints were used to derive the equation of the energy transfer coefficient for the WCPS. Then by setting coupling nodes, construction of a coupling matrix to characterize discontinuity of energy density at the coupling position of the WCPS and energy density governing equation of wedge-shaped plates were integrated. In doing so, the EFEA modeling of the WCPS was developed and the energy density distribution on each node of the WCPS could be obtained. Same-sized uniformly coupled structures is analyzed, the vibration energy distribution characteristics of two types of coupling structures were compared. The results show that the energy density value of the wedge plate member attenuate more slowly than that of the uniform plate member due to the acoustic black hole aggregation effect in the wedge plate part, and there is an abrupt change in the energy density value at the joint of WCPS. As a result, the factors influencing high-frequency vibration energy transfer were investigated.

Radiation attenuation characterization of some biological samples by using the Klein–Nishina formula

Radiation has beneficial applications in medicine and nuclear sciences, but it can also be harmful due to its ionizing properties. So, radiation usage has a significant role in different research fields. In the present study, the Klein–Nishina (K–N) approach was used to evaluate the electronic and energy-transfer cross sections of Water, bone, adipose, soft, long, breast, brain and skin tissues. Compton mass attenuation coefficients (CMAC) and Compton mass energy transfer coefficients (CMACtr) were determined in the energy range 0.284–15 MeV. Different methods, based on the effective charge, were used to determine the parameters of the materials for the energy range. The cross sections were firstly calculated for elements that made up the materials. The investigated parameters of the materials were then determined using the relevant cross sections in the energy range. The results were compared with each other and some possible results from the literature. Klein–Nishina electronic cross sections, Compton mass attenuation coefficients and Compton mass energy transfer coefficients of the studied materials were decreased with increasing γ-ray energy like the elements. A good agreement was observed for CMACs and CMACtrs based on Zeff1/A and Zeff3/A (Diff. ≤ 16.4%) for Bone Compact. In addition, a comparison with the literature was done for CaCO3 in CMAC for some photon energies. The maximum difference (%) between used methods and literature was observed as ≤ 19.0%. The reported data should be useful using the gamma rays in Compton scattering energy region.

Numerical study of structural optimization for improving gas-liquid flow and microalgae carbon fixation rate in air-lift photobioreactors

In this paper, the gas-liquid flow pattern and CO2 dissolution transport process of microalgae solution in an air-lift photobioreactor (PBR) are investigated by numerical simulations. In order to promote the gas-liquid mass transfer efficiency to enhance the carbon fixation, we propose different optimization schemes for the structure. Firstly, a two-phase flow model and a mass transfer model are employed to investigate the fluid flow characteristics. The flow state is evaluated by velocity in light direction, turbulent kinetic energy (TKE), gas hold-up and CO2 mass transfer coefficient. The results show that the gas flow rate of 0.2 V/V/min is the optimum value for the inlet. Secondly, CO2 mass transfer and carbon fixation rates are analyzed for different inlet CO2 volume fractions. With the increase of CO2 volume fraction, the carbon fixation rate first increases and then decreases, the highest fixation rate reaching 2.21 × 10−4 mol m−3 s−1 at 6 %. Finally, based on numerical simulations, three optimized structures with different spacing of baffles are proposed and evaluated the performance in comparison with the original. The results show that the gas distribution and CO2 mass transfer are significantly improved, with the one-sided baffle structure is the best. In summary, this study provides a new and useful reference to evaluate the gas-liquid mixing and improve the microalgae carbon fixation rate.

Analysis of drying characteristic, effective moisture diffusivity and energy, exergy and environment performance indicators during thin layer drying of tea in a convective-hot air dryer

The objective of this study is mainly to analyze the drying kinetic parameters, effective diffusivity, and thermodynamic performance indicators (energy, exergy, heat, and mass transfer coefficients) of tea under different drying conditions of different drying temperatures (DT) and thin layer thicknesses (TT). Experimental drying was conducted at drying temperatures of 70°C, 80°C, and 90°C with thin layer thicknesses of 10 mm, 15 mm, and 20 mm. The results show that a higher drying temperature and a lower thin layer thickness can increase evaporation moisture content and shorten drying time. By evaluating and comparing the fitting of five drying models adopted by the coefficient of determination (R2) and chi-square (χ2), it can be found that the logarithmic model is the best to describe drying behavior. The effective moisture diffusivity shows a positively correlated trend with the increase in DT and TT, with the value of activation energy ranging from 14.030 to 22.344 kJ mol−1 K−1. The specific moisture evaporation rate (SMER), energy efficiency, exergy efficiency, and sustainability index (SI) descend as the TT increases at all DT; the specific energy consumption (SEC) and improvement potential (IP) rate perform in an opposite manner, but the TT remains unchange. The conclusion drawn from the thermodynamic parameters is opposite to the aforementioned. As the TT increases, the heat and mass transfer coefficients show a significant decrease trend. In addition, the heat and mass transfer coefficients are given as functions of DT and TT, and further knowledge shows that the mass transfer coefficient is positively correlated with DT but the heat transfer coefficient is negatively correlated. In conclusion, this article provides new insights into the effects of drying characteristics, energy consumption characteristics and heat and mass transfer characteristics in the process of tea drying under different drying conditions, and provides certain theoretical reference bases for promoting the optimization of industrialized tea drying production machinery design and drying process optimization.

Drying kinetics and mass transfer parameters of mung beans dried using a convective dryer

Convective drying of mung bean seeds was conducted to investigate drying kinetics and mass transfer parameters at temperatures of 40, 50, 60, 70, and 80°C and a fixed air velocity of 1.2 m s-1. Drying characteristics were determined by drying rate, moisture ratio, diffusion coefficient, activation energy, Biot number, and mass transfer coefficient. Drying models such as Newton, Page, Henderson and Pabis, Logarithmic, Midilli, Two-term, and Diffusion approximation were applied and fitted to the moisture ratio of the experimental data. The drying rate was significantly affected by the drying temperature. The Midilli model was considered the most suitable for experimental drying curves. The effective moisture diffusivity ranged from 3.19×10-9 to 10.76×10-9 m2 s-1, with an activation energy of 59.78 kJ mol-1. Similar to the mass transfer coefficient, the Biot number increased with increasing drying temperature. The simultaneous transfer of heat and mass was controlled by diffusion and surface.

Numerical investigation on the effect of bionic fish swimming on the vortex-induced vibration of a tandemly arranged circular cylinder

The effect of bionic fish swimming on the vortex-induced vibration (VIV) of a circular cylinder arranged in tandem at a low Reynolds number of 150 is numerically investigated in this work. The bionic fish placed upstream of the cylinder with gap ratios of 1, 3, and 5 and that located downstream of the cylinder with gap ratios of 3 and 5 are examined in the simulations that were carried out in the reduced velocity range of Ur = 2–15. It is found that both the gap ratio and the reduced velocity have a significant influence on the VIV response and wake flow structure. When the bionic fish is placed upstream, the maximum response amplitude of the downstream cylinder is much greater than that of an isolated one. Two flow regimes are identified in terms of the shear layer reattachment, i.e., the continuous reattachment and the alternate reattachment. Comparing the vortex shedding frequencies of the cylinder and the swimming fish, it is found that the frequency of the cylinder is always locked in the fish swimming frequency, and multiple frequencies occur at Ur = 5. When the bionic fish is arranged downstream, four flow regimes are observed, including the extended-body, continuous reattachment, alternate attachment, and co-shedding regimes. Furthermore, the time-mean energy transfer coefficient of the cylinder is considerably higher at Ur = 5 than that when the fish is placed upstream of the cylinder.

Photo- and X-ray Induced Cytotoxicity of CeF3-YF3-TbF3 Nanoparticle-Polyvinylpyrrolidone-"Radachlorin" Composites for Combined Photodynamic Therapy.

The Ce0.5Y0.35Tb0.15F3 nanoparticles with a CeF3 hexagonal structure were synthesized using the co-precipitation technique. The average nanoparticle diameter was 14 ± 1 nm. The luminescence decay curves of the Ce0.5Y0.35Tb0.15F3 nanoparticles (λem = 541 nm, 5D4-7F5 transition of Tb3+) conjugated with Radachlorin using polyvinylpyrrolidone coating as well as without Radachlorin were detected. Efficient nonradiative energy transfer from Tb3+ to the Radachlorin was demonstrated. The maximum energy transfer coefficients for the nanoparticles conjugated with Radachlorin via polyvinylpyrrolidone and without the coating were 82% and 55%, respectively. The average distance between the nanoparticle surface and Radachlorin was R0 = 4.5 nm. The best results for X-ray-induced cytotoxicity were observed for the NP-PVP-Rch sample at the lowest Rch concentration. In particular, after X-ray irradiation, the survival of A549 human lung carcinoma cells decreased by ~12%.

Au-Based MOFs as Anodic Electrocatalysts for Direct Borohydride Fuel Cells

Researchers are exploring direct liquid fuel cells (DLFCs) as alternatives to proton-exchange membrane fuel cells because of their higher energy density and ease of storing and transporting the fuel. Direct borohydride fuel cells (DBFCs) are of particular interest as they offer a sustainable energy source with their high-power density output and the use of a highly alkaline NaBH4 medium [1]. Ensuring efficient and cost-effective catalysts for DBFCs is crucial for their commercial viability. Metal-organic frameworks (MOFs) have demonstrated significant potential as anodic electrocatalysts for BOR in DBFCs [2]. However, research should explore various modifications to MOFs, such as the incorporation of alternative metal ions or functional groups, to improve their catalytic efficiency and reduce cost. This study evaluated the performance of newly developed MOF-based electrocatalysts for DBFCs. Specifically, six MOF-based materials were synthesized and analyzed for their ability to facilitate borohydride oxidation (BOR) using cyclic voltammetry and chronoamperometry in alkaline media. MIL-101_Au@NH2 and MOF-808_Au@NH2 were found to be highly effective for BOR. The kinetic parameters for BOR with MOF-based electrocatalysts, including activation energy, reaction order, exchanged electrons, and anodic charge transfer coefficient, were determined. The activation energy for BOR was found to be 13.6 kJ mol−1 and 15.3 kJ mol−1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. The number of transferred electrons, n, was found to be 7.0 and 3.1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. This study demonstrates that MOF-based electrocatalysts can enhance DBFCs' performance, while offering insight into the potential usage of MOFs in other fuel cell technologies.[1] B. Šljukić, D.M.F. Santos, "Direct borohydride fuel cells", in: "Direct Liquid Fuel Cells: Fundamentals, Advances, and Future", 1st ed., R.G. Akay, A.B. Yurtcan (eds.), Academic Press, USA, 203-232 (2021)[2] G. Backovic, B. Šljukić, G.S. Kanberoglu, M. Yurderi, A. Bulut, M. Zahmakiran, D.M.F. Santos, Ruthenium (0) nanoparticles stabilized by the metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction, International Journal of Hydrogen Energy, 45, 27056-27066 (2020).

High Compactness Heat Exchanger Manufactured Using Stereolithography Technology and Photosensitive Resin

Heat exchangers have traditionally been produced on mass using metal alloys and complex manufacturing processes. This work proposes an alternative production via for the additive manufacturing of a cost-effective air-to-air heat exchanger, based on the use of the stereolithography technology. The element has been produced on a FormLabs Form3 printer using standard photosensitive resin. The dimensions of the heat exchanger were 100 × 100 × 100 mm3 and the wall thickness was 0.5 mm. The manufacturing cost of the element was 53.11 €. The heat exchanger was experimentally tested in an air handling laboratory under different climatic conditions. The thermal power of the equipment was 200 W, which is equivalent to a power-volume ratio equal to 200 kW/m3. The experimental energy efficiency was equal to 0.54 (for a number of heat transfer units equal to 1.4) and an overall energy transfer coefficient (U) equal to 1823 W/m2K. In addition, the results showed that the thermal conductivity of the material was less influential the smaller the thickness of the heat exchanger channels. The obtained results show that stereolithography is an economical alternative to obtain customized and high compactness heat exchangers, on demand and just in time.

Nuclear Inelastic Scattering Effect in Spectra of Neutrinos at Regime of Weak Coupling with Matter

We consider an effect of inelastic scattering in nucleon gas on the energy spectra of neutrinos during an evolution weakly coupled with hot and dense magnetized matter of dynamoactive supernovae. At a finite temperature neutrinos exhibit exo-and endoenergetic scattering on magnetized nucleons due to the Gamow–Teller neutral current interaction component. On the basis of an analysis of energy transfer properties and cross-sections due to significant additional energy exchange mechanisms arising in a magnetized nucleon gas we obtain a kinetic equation for the neutrino dynamics. It is shown that the energy transfer value magnitude and coefficient change the sign from positive to negative when the incoming neutrino energy exceeds four times the temperature of the stellar material, and almost independs on the magnetic induction. For realistic stellar parameters such effects lead to an increase in the hardness of the neutrino energy spectra, especially for the heavy lepton component. It is shown that such strengthening of neutrino hard energies is favorable for supernova neutrino observations by Large Volume Neutrino Telescopes.