Impulse Heating Research Articles

Oxidation of Ferrous Alloys and Coatings Under Isothermal, Impulse Heating, and Diesel Engine Operation: Part II—MCrAlY Coatings for Protection of 4140 Steel

Oxidation of Ferrous Alloys and Coatings Under Isothermal, Impulse Heating, and Diesel Engine Operation: Part II—MCrAlY Coatings for Protection of 4140 Steel

Oxidation of Ferrous Alloys and Coatings Under Isothermal, Impulse Heating, and Diesel Engine Operation: Part I—4140 Steel

Oxidation of Ferrous Alloys and Coatings Under Isothermal, Impulse Heating, and Diesel Engine Operation: Part I—4140 Steel

Use of Duplex PVD Coatings to Increase the Life of Moulds and Cores for die Casting of Aluminium Alloys in the Automotive Industry

The paper presents the results of research aimed at increasing the life of moulds and cores for high-pressure aluminium casting. The castings produced are intended for the automotive industry. Local impulse heating was applied to the surface of the base material of the Uddeholm Dievar moulds. Three heating rates were used. After surface treatment, structural analysis was performed. PVD coating nACRo3 was applied to the surface treated in this way. Coating deposition was performed by Larc technology. The quality of the coating was evaluated on the basis of the Scratch test and the Mercedes test. After laser treatment of the material surface and application of nACRo3 coating, the surface microgeometry was evaluated according to ISO 25 178. The coated surface was then immersed in an Al - Si-based alloy melt at a temperature of 680 ± 20°C and remaining in the melt for 120 and 300 min. Experimental work has confirmed that the resistance of the mould surface has significantly increased.

Тепловой поток в гармонической решетке при одном неканоническом распределении ее начальных состояний

The heat motion in a one-dimensional semi-infinite chain of coupled harmonic oscillators is studied for the Maxwell distribution of initial velocities and zero initial displacements of the chain particles. It is believed that such initial conditions are achieved by an impulse heating of the sample. Exact analytical expressions for the state correlation functions, local temperature, and local heat current of the chain are obtained.

On pulsing heating of the heat transfer medium in thermal delivery systems

The questions connected with the influence of pulsed heating of the coolant on the operating efficiency and the parameters of the heat supply systems are considered. When implementing such a method in the heating systems of private residential buildings (houses) «hot water boiler – heat exchangers – living quarters», where the working body (heat carrier) is water, it is necessary, along with maintaining comfortable conditions inside the premises, to create an efficient operating mode with minimizing fuel consumption, which may possibly be mutually exclusive influencing factors. In addition, the theoretical justification of the efficiency of using pulsed heating of heating medium in heating systems of residential buildings is extremely limited in the technical literature, which served to formulate the purpose of this work. To achieve it, a mathematical model of the thermal performance of the individual heating system of the building with pulsed heating of the coolant has been developed. Based on the analysis of the heat carrier heating dynamics equation, the main parameters of impulse heating of a heat supply system of a building are determined, the rational values for the duration of the heat input and the pause between the pulses, and the duty cycle of the pulses, depending on the heating surface of the heating devices in the buildings and the thermal losses to the environment. The essential influence of these functional parameters on the characteristics of the impulse heat supply and the heat carrier heating intensity has been shown. The ranges of the change in the pulse frequency have been determined, within which the pulse mode of heat supply in heating systems can be more effective. The concept has been introduced, by analogy with the regular mode of heating (cooling), the rate of heating (cooling) of the coolant – the rate of change in its temperature

Thermal state of a heating element under impulse heating

The paper describes the calculation procedure of heating element thermal state based on the experimental study of heating element thermal processes under impulse heating in a subcooled pool. This procedure can be used to analyze the thermal state of the reactor fuel element in case of accidents with unauthorized introduction of excessive reactivity in process of core loading and accidents in pool-type reactors.

Influence of laser irradiation on change properties of bulk amorphous Zr-Pd metallic alloys

We study the morphological features of laser irradiation zones formed on the surface of the bulk metallic glasses. We use the nanoindentation method for estimation alloys properties caused by impulse heating during irradiation.

Measurement of thermophysical property of plasma forming tungsten nanofiber layer

Thermophysical property of a nanostructured tungsten layer formed on a tungsten film was investigated. A 1-µm-thick tungsten film deposited on a quartz glass substrate was irradiated with a high density helium plasma at the surface temperature of 1500 K. The plasma irradiation led to the formation of highly porous fiberform-nanostructured tungsten layer with a thickness of 3.5 µm. Impulse heating was applied at the interface of the film/substrate, and transient heat diffusion was observed using a pulsed light heating thermoreflectance apparatus. The thermoreflectance signals clearly differed between the nanostructure existing and mechanically removed regions; the difference can be attributed to thermal effusivity of the nanostructured tungsten layer. The estimated thermal conductivity of the nanostructured tungsten decreases to ∼2% of that of bulk when the density of the nanostructure is assumed to be ∼6% of the bulk value.

Investigation of the high-temperature properties of zirconium nitride by impulse current heating method

The zirconium nitride specimens were obtained as a thin (2.5 μm) layer deposited on the insulating K-8 glass substrates by the magnetron sputtering technique. The impulse current heating permitted reaching the nitride melting region in 5 μs. The current, the voltage, and the radiation at the wavelength of 856 nm were registered. The energy input (the enthalpy), E, the heat capacity, C p , the resistivity, ρ (referred to the initial specimen dimensions), and the temperature, T, were calculated. The results on the resistivity, the specific heat, and the melting temperature (2700 K) of the zirconium nitride under a high content of nitrogen (about 49 at %) and oxygen (about 11 at %) in the specimen were obtained. The limit temperature in the investigation was as high as 3400 K.

C60 three-dimensional polymerization by impulse heating effect

Impulse laser heating combined with a quick sample cooling in a diamond anvil cell provides unique conditions for the 3D polymerization reaction of C60. The reaction proceeds under the 8–10 GPa pressure and 2700 K temperature in the case of heating-cooling cycle time around 0.1 μs. Such a short heating time permits to increase the maximal temperature of the fullerite sample by 1700 K on conditions that C60 are still surviving. As a result, the pressure of the phase transition to 3D polymerized fullerite phase with 519 GPa bulk modulus was essentially decreased. Furthermore, the transition has proceeded at quasi-hydrostatic conditions without activation by applying a plastic deformation.

Studying heat transfer during impulse heating of model fragments of fuel rod claddings

Results from an experimental study of heat transfer carried out on model fragments of fuel rod claddings during impulse supply of power are presented. The time taken for reaching steady state for different parameters of impulse and the values of heat-transfer coefficient are determined. A relation generalizing the experimental data is suggested. Results obtained from a numerical simulation of heat transfer are presented.

Extension of the Response Time Method and the Areal Heat Diffusion Time Method for One-Dimensional Heat Diffusion after Impulse Heating: Generalization Considering Heat Sources inside of Multilayer and General Boundary Conditions

Since the conventional response function method represents the temperature response of the front surface, the interfaces, and the rear surface of the specimen as the convolutions of responses by pulse heating at the front surface and the rear surface, heat sources inside the multilayered material have not been considered nor have the temperature profile inside the multilayered thin films been expressed explicitly. In this work, the applications of the response function method and the areal heat diffusion time method (AHDTM), which is an algorithm to analyze one-dimensional heat diffusion after impulse heating across multilayered materials, are extended considering heat sources inside a multilayer under general boundary conditions. By this extension, the temperature responses of multilayered thin films heated by a pulse light with a finite penetration through the material can be explicitly and systematically expressed, although it can be calculated by the Green's function method only for a uniform single-layered material and those synthesized on a substrate as the first application. The temperature response of a two-layered material imposed isothermal boundary condition is investigated as the second application of this extension.

Genetic and epigenetic effects of lgl tumor suppressor mutations on longevity under temperature stress

Human populations are polymorphic for risk factor mutations predisposing to diseases and cancer. The evolutionary conservative tumor suppressor gene lethal (2) giant larvae (lgl), whose null variants are widespread in natural Drosophila populations, can be used as a model to study this phenomenon. We studied the effect of lgl deletion and insertion mutant alleles on the survival and longevity of their carriers depending on the genotype, cross direction, and exposure to permanent or impulse temperature stress. Under constant temperature stress, the viability and longevity of lgl/+ deletion heterozygotes increased compared to the control flies carrying two normal doses of this gene. This haploid effect was maternally mediated. Exposure of deletion heterozygotes at successive oogenesis stages to moderate impulse temperature stress affected progeny survival in a similar way. The effect of impulse heating at the pre-embryo stage was bidirectional: positive in the case of impulse warming of mature eggs and negative during egg differentiation. However, in both cases, deletion of one allele of the tumor suppressor gene in lgl/+ females increased survival of the next generation and delayed senescence. These data were compared to similar epigenetic transgenerational effects reported earlier for humans.

Particle, heat, and sheath power transmission factor profiles during ELM suppression experiments on DIII-D

Edge localized modes (ELMs) are predicted to be a significant problem for ITER due to impulse heating of the divertor target plates. During low collisionality experiments on DIII-D where ELMs were suppressed using resonant magnetic perturbations (RMP), target plate profiles of particle flux ( J sat), electron temperature ( T e), and floating potential ( V f) have been measured with Langmuir probes (LP) and compared to IRTV heat flux profiles. During ELM suppression, J sat and T e increase and the J sat profile broadens. A three-peak structure, most visible in the V f, agrees with the spacing and q 95 dependence of an n = 3 toroidal pattern predicted by the TRIP3D code. The heat flux calculated from Langmuir probe data (using sheath theory) is observed to get ∼2× larger during ELM suppression than between ELMs before the RMP is turned on. The sheath power transmission factor profile has been determined from IRTV and Langmuir probe data.

Influence of Annealing Environment and Film Thickness on the Phase Formation in the Ti/Si(100) and (Ti +Si)/Si(100) Thin Film Systems

Influence of an annealing environment and film thickness on the phase formation in the Ti(30 nm)/Si(100), [(Ti+Si) 200 nm]/Si(100) thin film systems produced by magnetron sputtering and the Ti(200 nm)/Si(100) thin film system produced by electron-beam sputtering were investigated by X-ray and electron diffraction, Auger electron spectroscopy (AES), secondary ion mass-spectrometry (SIMS) and resistivity measurements. Solid-state reactions in the thin film systems under investigation were caused by diffusion processes during annealing in the different gas environments: under vacuum of 10-4 - 10-7 Pa, flow of nitrogen and hydrogen. It is shown that the decrease of Ti layer thickness from 200 to 30 nm in the Ti/Si(100) film system causes the increase of the transition temperature of the metastable C49 TiSi2 phase to the stable C54 TiSi2 phase up to 1070 K at vacuum annealing. During annealing in the nitrogen flow of the Ti(30 nm)/Si(100) thin film system the C49 TiSi2 is the first crystal phase which is formed at 870 K. For annealings of the [(Ti+Si) 200 nm]/Si(100) thin film system by impulse heating method or for furnace annealings in inert gas atmosphere of N2, Ar, H or higher vacuum (10-5 Pa) the crystallization process has two stages: the first metastable C49 TiSi2 phase is formed at 870 K and then at higher temperatures it is transformed to the stable C54 TiSi2 phase.

On the response of the exospheric temperature to the auroral heating impulse during geomagnetic disturbances

On the basis of an assumed impulse-type energy input at auroral oval due to the particle precipitation, the response of the exospheric temperature T ∞ has been investigated in terms of changes in input energy, geomagnetic indices and latitude under simplified assumptions It is shown that the resulting T ∞ is proportional to the peak heating rate and inversely proportional to the gradient of the atmospheric density. Even during low solar activity and quiet geomagnetic conditions, the precipitated electron energy density in the thermosphere is found in the range of about 1–1.5×10 −6 erg/cm 3 s, reaching to about 3×10 −6 erg/cm 3 s at 2000 K and is easily supported by the solar wind–magnetospheric interaction. The auroral energy inputs lasting less than 2 h or so hardly generate geomagnetic storms. The inhomogeneous energy equation has been solved in horizontal two dimensions in presence of horizontal heat conduction, to study the T ∞ at other latitudes and its time delay with respect to the peak impulse heating time. This time delay is independent of the storm intensity, i.e., proxy geomagnetic indices and is about 6–7 h at low and mid latitudes and about 3 h or less at high latitudes in agreement with recent coupled magnetospheric–ionospheric–thermospheric models and with the available observed values. The diffusion coefficient of horizontal heat conduction deduced is about 7×10 4 m 2/s. The role of the horizontal heat conduction in the energy budget needs further investigation.

Evolution of dislocation structure in the heat affected zone of a nickel-based single crystal

Using polychromatic microbeam synchrotron diffraction together with electron and optical microscopy, we studied dislocation structure changes of Ni—based single crystal superalloy during impulse heating up to the melting temperature. It is shown that the distribution of the thermal gradient is not monotonic. The maximum value of the thermal gradient is observed in the heat affected zone near the fusion line. Depending on the temperature, the formation of dislocation is accompanied by the partial or complete dissolution of γ′ particles in the matrix. Dislocations form and multiply due to thermal gradients, and their arrangement correlates with temperature gradient field and with the dissolution and reprecipitation of γ′ particles.

A numerical study of the generation and propagation of thermoacoustic waves in water

The generation and propagation of thermoacoustic waves in water are investigated by solving the fully compressible form of the Navier–Stokes equations. A square enclosure filled with water is considered as the computational domain. Thermally induced pressure waves are generated by rapidly heating the left wall. The thermodynamic properties of water are calculated via an accurate equation of state. The effect of the rapidity of the heating process on the production of thermoacoustic waves is studied, using both impulse (sudden) and gradual changes in the left wall temperature. The thermoacoustic waves are significantly stronger for impulse heating and are found to eventually damp out with time due to viscous losses. Gradual change of the left wall temperature reduced the strength of the pressure wave peaks.

Detection of buried objects using infrared imaging of impulse laser heated soils

In this work we examine the time-dependent aspects of thermal imaging of buried metallic and non-metallic objects, when impulse heating of the soil surface is performed. A 1500 W carbon dioxide laser is used to provide the thermal impulse. Time-dependent thermal images are obtained using an infrared focal plane array camera and a gated data acquisition/analysis system. Experimental studies are conducted as a function of object material, size, and burial depth, and incident laser fluence. Quantitative evaluation of the surface temperature differentials as a function of time are presented.

Compressible response of thin liquid film/porous substrate first walls in IFE reactors

Abstract The compressible response of a thin film of liquid subjected to a rapid surface pressure pulse and isochoric nuclear heating is investigated in an attempt to determine the spallation behavior. The use of such films to protect the cavity wall of inertial confinement fusion reactors is currently envisioned. The magnitude and temporal dependence of the surface pressure impulse and nuclear heating are estimated based on data from the Prometheus-L, Osirus and Hiball design studies, all of which use the thin film wall protection concept. Compressible hydrodynamic calculations are performed with the CFDLIB code package from LANL. In both the Prometheus and Osirus cases, no spallation is predicted based on the results of these calculations. However, calculated tensile stresses are less than an order of magnitude below theoretical limits, and uncertainties in data and material behavior may push the film response closer to spallation.