Heating Power Levels Research Articles

Exploring a preheating strategy for lithium-ion battery pack using graphene-enhanced microencapsulated phase change materials

Lithium-ion batteries (LIBs) are fundamental to the operation of electric vehicles due to their superior energy density and extended cycle life. However, the performance of LIBs deteriorates significantly in subzero temperatures. This study investigates the potential of graphene-enhanced microencapsulated phase change materials (G-MEPCM) as a solution to improve the preheating performance of LIBs in cold environments. Numerical analysis has been conducted to evaluate the thermal performance of the LIB/G-MEPCM system under varying conditions, including different graphene contents, ambient temperatures, heat transfer coefficients, and heating power levels. Results indicate that higher graphene content within MEPCM improves thermal uniformity and reduces internal temperature differences, with 4 wt% graphene content identified as optimal for achieving a balance between rapid heating and temperature uniformity. Besides, increasing the heat transfer coefficient decreases the average temperature and increases the temperature difference of the battery pack. On the contrary, increasing ambient temperature increases the average temperature and decreases the temperature difference of the battery pack. When ambient temperature equals to −25 °C, the temperature difference of battery pack is 21.4 % higher than that when ambient temperature equals to −10 °C. Furthermore, both the average temperature and temperature difference of the battery back increase with the increases of the heating power.

Two-phase closed thermosiphon with grooved the evaporator section applied for low-grade energy recovery: Thermo-hydrodynamic performance and potentials

High thermal conductivity and simple structure of two-phase closed thermosyphons (TPCTs) facilitate it extensively applied in low-grade thermal recovery, such like geothermal and solar energy exploitation. In present work, by incorporating threaded grooves into the evaporator section of the TPCTs, heat transfer performance could be significantly enhanced. Thermal transport mechanism of thermosyphons with various threaded groove structures was comprehensively investigated, and corresponding thermo-hydrodynamic performance was modelled through CFD/VOF simulations. Numerical procedures were validated well after comparison with experimental ones felled within 5.0 %. Under various heating power levels and filling ratios, heat transfer performance of thermosyphons with threaded grooves evidently surpassed that of smooth thermosyphons. Depending on delicate numerical results, critical point at 33 % filling ratio and 90 W heating power were confirmed that total thermal resistance of the grooved thermosyphon decreased almost close to 4.6 %. Furthermore, deviating from that critical point, higher heating power and lower filling ratio instead confined heat transfer performance of the threaded TPCT, which was primarily due to the rate of bubble generation and growth being significantly was slower than its detachment rate from the wall. In addition, heat and mass transfer performance of thermosyphons with threaded grooves of various pitches and apex angles were further analyzed under various conditions. Our results indicated that, when the groove apex angle turned to 90°, overall thermal transportation capability of the TPCT achieved optimal, with a decline in thermal resistance of up to 6.5 % compared to thermosyphons with smaller apex angles. Apex angle primarily affected the number of nucleation sites and the bubble detachment rate. Additionally, as the screw pitch decreased, boiling heat transfer enhancement, leading to more robust boiling heat transfer of TPCTs. Under high heating power, thermosyphons with larger screw pitch exhibited superior heat transfer performance. Overall, this innovative TPCTs with threaded grooves could be well applied in low-grade energy exploitation, particularly like as geothermal and solar energy fields.

Experimental and numerical study on thermal management performance of PCM-based heat sinks with various configurations fabricated by additive manufacturing

Due to the low thermal conductivity of PCM, the enhancement of thermal performance becomes a crucial issue for the application of PCM-based heat sinks in electronic device cooling. To address this, efficient and integrative PCM-based heat sinks using fin and structured porous material (SPM) are designed and fabricated by additive manufacturing (AM). This work aims to investigate thermal performance of PCM-based heat sinks and the role of fin and SPM used as thermal conductivity enhancers (TCEs). The enhanced heat transfer mechanisms in PCM-based heat sinks using different types of TCEs are determined, and parametric analysis is conducted considering various volume fractions of TCEs (10 %, 15 %, and 20 %). Moreover, the effects of heating power levels and convective heat transfer coefficients on thermal behavior of PCM-based heat sink are analyzed. The results indicate that incorporating SPM in heat sink enhances thermal performance more effectively than using fins for an equivalent TCE fraction. Both heating power and convective heat transfer coefficient have a significant on thermal performance. This research demonstrates the potential of the novel heat sink with SPM in cooling electronic devices and provides the experimental and numerical database for the optimal design and future application of PCM-based heat sink.

Development and properties of new powder materials

Problem. The study analyzed powder materials to obtain wear-resistant coatings. Field tests for wear resistance were conducted using the method of friction between two surfaces. The tests were carried out on the universal test bench SMC-2 at a rotation speed of 200 rpm. A pressure of 100 kgf was applied to the test sample. Goal. The wear resistance test cycle comprised 200,000 revolutions, with lubrication provided through the drop method. Special powders were used in the experiment, including PG-SR3, PN55T45, and PR-Ni70Cr17S4R4 + 20% PT-Al5N with a PT-Al5N under layer. Methodology. The selection of wear-resistant coatings was based on the analysis of the following properties: adhesion strength of the coating to the base material, wear resistance of the coatings, hardness, and porosity. Results. Metallographic analysis of the structure of plasma coatings obtained from powders PG-SR3, PN55T45, and PR-Ni70Cr17S4R4 + 20% PT-All5N with three different plasma heater power levels (10 kW, 15 kW, and 20 kW) indicated that the densest and most reliable coating among those studied is the coating made from PR-Ni70Cr17S4R4 + 20% PT-Al5N powder. Practical value. Therefore, there is no need to increase the heater power beyond 15 kW when spraying this type of powder. The research concluded that when obtaining wear-resistant coatings, the optimal choice is PR-Ni70Cr17S4R4 + 20% PT-All5N powder with a PT-Al5N under layer.

An Experimental Study of the Transfer of Heat in Nanofluid of a Tiny-Channel using Several Innovative Arrangement Designs

This work presents an experimental investigation of the heat transfer (HT) and pressure drop characteristics associated with three different configuration models of minichannel heat sinks. This study utilizes a coolant consisting of TiO2 nanoparticles dispersed in water at a weight concentration of 10%. The performance of this nanofluid coolant is then evaluated and compared to that of distilled water under several heating powers ranging from 100 to 300 W. The findings suggest that the thermal performance of TiO2 nanofluid is significantly influenced by heating power (HP), and its HT efficiency can be enhanced more efficiently at lower levels of HP. However, it has been observed that when the HP decreases, the pressure drop increases. This effect is more pronounced in TiO2 nanofluid than in pure water, which can be attributed to the difference in viscosity with temperature. The Nusselt number remains constant regardless of the increase or reduction in HP. Consequently, when pure water is utilized, the experimental Nusselt number aligns with the Peng and Peterson empirical correlation for all HPs, with an accuracy of 15%. The TiO2 nanofluid was used to test the lowest wall temperature, 40 °C. This measurement was obtained at a Reynolds number of 1100, equivalent to a heat power (HP) of 100 W. Furthermore, it is noted that when the fluid passes through the mini channel, there is an increase in the axial temperature from the input to the outlet of the heat sink (HS). The maximum enhancement observed for a power input of 100 W is 19.59% when utilizing configuration A. This is attributed to the combination of a weak buoyancy force and an increase in the surface area of HT. The HP highly influences the system's thermal performance, and its effective HT characteristics are more pronounced at lower HP levels.

The Effect of Power Rate Microwave Heating on Limestone Carbonated Hydroxyapatite Scaffold Using Gas Foaming Method

Microwave heating was used with a gas foaming method for fabricating limestone carbonated hydroxyapatite scaffold (SCHA). Carbonated hydroxyapatite (CHA) was produced from limestone as a calcium source using the co-precipitation method. For further treatment, 0.6 gr CHA powder was mixed in 1 ml H2O2 solution as a blowing agent. The slurry-foam-like CHA was heated in a microwave with different levels of heating power from 180 W to 720 W. The SCHA samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and Scanning electron microscope (SEM). The crystallinity and crystallite size were affected due to different rates of heating power in the microwave-assisted method. The increasing temperature decreased the crystallite size from 37.49 to 33.97(nm). However, other crystallinity trends were observed at 180 W because the lower power heating needed a longer time to be formed SCHA. The different power rates have an insignificant contribution to the morphology of the scaffolds.

Organic and Inorganic Hybrid Composite Phase Change Material for Inhibiting the Thermal Runaway of Lithium-Ion Batteries

To deal with the flammability of PA (paraffin), this paper proposes a CPCM (composite phase change material) with a high heat-absorbing capacity for mitigating the thermal runaway of lithium-ion batteries. Two heating power levels were used to trigger thermal runaway in order to investigate the influence of heating power on thermal runaway characteristics and the mitigation effect of the PCM (phase change material). Thermal runaway processes and temperature changes were recorded. The results showed that heating results in a violent reaction of the battery, generating a high temperature and a bright flame, and the burning of PA increases the duration of a steady flame, indicating an increased threat. SA (sodium acetate trihydrate) effectively inhibited PA combustion, and the combustion time was reduced by 40.5%. PA/SA effectively retarded the rise in temperature of the battery, and the temperature rise rate was reduced by 87.3%. Increased heating power caused faster thermal runaway, and the thermal runaway mitigation effect of the CPCM was dramatically reduced. This study may provide a reference for the safe design and improvement of thermal management systems.

Determining the access to H–mode in the ITER pre–fusion and fusion power operation phases at low plasma current with full–radius TGLF–SAT2 simulations of L–mode plasmas

The pre–fusion power operation 1 phase of ITER is planned to be characterized by electron cyclotron resonance heating only. Under the assumption that the access to H–mode is determined by a critical ion heat flux at the plasma edge, full–radius ASTRA simulations with the TGLF–SAT2 transport model are performed in order to compute the ion heat flux produced by the thermal exchange between electrons and ions in different operational conditions. Both hydrogen and deuterium plasmas at 5 MA are considered, respectively at 1.8 T and 2.65 T, corresponding to one third and half of the nominal maximum magnetic field. Different levels of electron cyclotron heating power are considered in sets of simulations with increasing values of the electron line averaged density. The predictions are compared with the currently available scaling of the critical ion heat flux. In hydrogen, 20 MW of electron heating power are predicted to allow H–mode access in a vanishingly small density window, whereas 30 MW and 40 MW would allow more substantial H–mode operational windows. Despite the fact that in deuterium plasmas the thermal exchange between electrons and ions is smaller by the hydrogen to deuterium mass ratio compared to hydrogen plasmas, the lower H–mode power threshold in deuterium leads to the prediction that an even broader and more robust domain to access H–mode is obtained at half field at 40 MW in deuterium as compared to operation in hydrogen at one third of the maximum magnetic field, even at the same power.

An active approach to heat transfer enhancement in indirect heaters of city gate stations: An experimental modeling

A major problem with gas pressure reduction stations is the very low thermal efficiency of indirect water bath heaters (IWBHs) used to prevent gas hydration. In this study, an innovative active method based on the ultrasonication technology is investigated to improve heat transfer in IWBHs. Considering the sophisticated thermos-physical phenomena involved in this problem and its complex governing equations, a laboratory-modeled ultrasonic heater is used to conduct the experiments. The results have been successfully validated using an empirical relationship. In order to evaluate the effect of ultrasonic vibrations, all the tests were done in two modes, namely without vibration and with vibrating at different ultrasonic power levels. The results show that the positive thermal impact of ultrasonic vibration on increasing the heat transfer rate is more evident at lower fluid flow rates and lower heater power levels. In the current experiments, the maximum value of ultrasonic heat transfer enhancement was evaluated as 166 % at a fluid flow rate of 0.5 LPM and a heater power of 200 W. Findings of this novel research can lead to the efficiency enhancement of existing gas pressure reduction stations and significant energy savings.

One Acute Exposure to E-Cigarette Smoke Using Various Heating Elements and Power Levels Induces Pulmonary Inflammation.

Electronic cigarettes (eC) may not be entirely benign. There is a lack of data on the effect of a single acute exposure of eC vapor using various heating sources and power settings upon lung injury. The purpose of this study was to determine if an acute exposure with eC vapor heated with different heating elements and power levels induced inflammatory changes in the lungs and heart. Rats were exposed to pure air or received a single, 4-h exposure to eC vapor. The devices used either a stainless steel (SS) or nichrome (NC) heating element randomized to a low or high atomization power (45 versus 70 W). Rats were euthanized within 48 h of exposure. The eC groups showed accumulation of inflammatory cells in bronchial lumen, near the pleura, and within the alveolar spaces. The numbers of inflammatory cells per field in the lung parenchyma were significantly greater in the rats exposed to eC groups vs. the air group. There were significantly higher inflammatory gene expression changes in the lungs of animals assigned to 70 W power. We observed that eC vapor generated using burnt coils were toxic and could cause acute respiratory distress and myocarditis. In conclusion, one 4-h exposure to eC vapor, in the absence of vitamin E oil or nicotine, significantly increased lung inflammation. Effects were seen after exposures to vapor generated using SS and NC heating elements at either high or low power. Vapor from devices with burnt coils can negatively affect the heart and lung.

Enhanced thermal performances of PCM heat sinks enabled by layer-by-layer-assembled carbon nanotube–polyethylenimine functional interfaces

Rationally designed hybrids of heat sinks (HSs) and phase change materials (PCMs) can mutually complement their fundamental limitations. However, integrating PCMs into HSs inevitably incurs additional thermal resistances and degradation during solid–liquid phase transitions owing to unstable contact interfaces. Herein, we report layer-by-layer (LbL)-assembled multiwalled carbon nanotube (MWCNT)–polyethyleneimine (PEI) functional interfaces between the PCM and HS surfaces to enhance thermal management capabilities. The LbL process used in this study involves direct fabrication of electrostatically adhered nanocoatings of multiple materials via a solution process, which resulted in facile formation of MWCNT-PEI percolation networks on an aluminum HS. The PCM-HS was completed by filling the HS channels with a PCM (n-eicosane). The functional interface increased the active surface areas for thermal transport and optimized the porous structures for the stabilization of the PCM–HS boundary under repetitive solid–liquid phase changes. Comparison of the fabricated specimens (bare and PCM-filled HSs without LbL interfaces) elucidated the enhanced thermal performances in transient-static operating conditions. This was confirmed by experimentally measuring the real-time temperature responses at various levels of heating power and the time delays to reach the set point temperatures, indicating a more than 10% improvement in effectiveness using the LbL interface. Furthermore, the LbL interfaces efficiently alleviated thermal shock or overload under intermittent thermal loads. The developed LbL interface offers a tunable–scalable method to fabricate PCM-filled HSs with advanced thermal properties that cannot be achieved using a conventional HS.

Emission and Gas/Particle Partitioning Characteristics of Nicotine in Aerosols for Electronic Cigarettes.

Nicotine is a dependence-producing component in electronic cigarettes. The nicotine release characteristics of electronic cigarettes are closely connected with human exposure and respiratory health. In this paper, a theoretical model was established to study the effects of the compositions of e-liquids and the heating powers of device on the emission and gas/particle partitioning characteristics of nicotine in aerosols at equilibrium. The simulation results of nicotine emissions were compared with the experimental data. The errors between them were within a reasonable range. At a larger heating power level, a higher nicotine yield and a larger vaporization amount of e-liquids could be observed. Under the same heating power condition, a higher vegetable glycerin content in e-liquids could result in a lower nicotine emission. When the heating powers supplied by the device increased, a larger mass fraction of particle-phase nicotine in aerosols at equilibrium would appear. As more propylene glycol was added into e-liquids, a lower mass fraction of gas-phase nicotine would exist in aerosols at equilibrium. The results may provide more information for the industry to set technical standards for electronic cigarettes and for the government department to make regulatory policies.

Abstract 10299: One Acute Exposure to E-Cigarette Smoke Using Various Heating Elements and Power Levels Induces Pulmonary Inflammation

Background: A new form of lung injury was described in electronic cigarette users beginning July 2019 with patients presenting with respiratory distress. The condition is known as E-cigarette (eC) or vaping product use associated lung injury or EVALI and was thought to be related to Vit E oils used to dilute cannabis. Whether a single acute exposure of eC smoke can induce lung injury has not been reported. The purpose of this study was to determine if such an acute exposure with eC smoke heated with different heating elements and power levels induced inflammatory changes in the lungs and heart. Methods: Rats were exposed to pure air or received a single, 4-hour exposure to eC vapor (50% propylene glycol, 50% vegetable glycerin; tobacco flavoring, n=16 in each group). The devices used either a stainless steel (SS) or nichrome (NC) heating element randomized to a low or high atomization power (45 versus 70 Watts). Rats were euthanized within 48 hours of exposure and hematoxylin and eosin stained lung and cardiac histology sections were assessed. Inflammatory cells were counted from 12 random areas per section at 10 х magnification. Results: The lung alveoli appeared normal in the air group (Figure, panel A); the eC groups using the SS or NC heating element with high or low power showed accumulation of inflammatory cells (mainly macrophages) in bronchial lumen (B), near the pleura (C), and within the alveolar spaces (D). The numbers of inflammatory cells per field in the lung parenchyma were significantly greater in the rats exposed to eC using SS or NC heating element compared to the air control group (P < 0.05, One way ANOVA, Tukey multiple comparison test; panel E). Cardiac tissue appeared normal with no evidence of inflammation. Conclusion: One 4-hour exposure to eC vapor, in the absence of vitamin E oil or nicotine, significantly increased the number of inflammatory cells in the lung. Effects were seen after exposures to vapor generated using SS and NC heating elements at either high or low power.

Thermal efficiency analysis of the phase change material (PCM) microcapsules

The aim of the present study is to evaluate the thermal behavior of cylindrical modules in a thermal energy storage unit as a combined sensible and latent heat. A thermal energy storage unit is designed, fabricated, and connected to a cold and hot water supply at constant temperatures to monitor the performance of the storage unit. The thermal energy storage unit contains the cylindrical microcapsules containing paraffin waxes as a phase change material which is located inside an insulating cylinder storage tank. Water is used as a heat transfer fluid to transfer heat from a hot water reservoir to the thermal energy storage unit during the phase change material charging process and also during the discharging process water receives heat from the thermal energy storage unit. Charge tests are carried out at the constant temperature. Moreover, the effect of different inlet flow on storage unit performance is investigated. Data were analyzed using Design Expert software and regression analysis which indicated that the increase of charge inlet temperature and charge inlet flow leads to the increase of heat power, thermal performance of thermal energy storage unit, and output variables. In comparison to the heat storage system without phase change material, microcapsules phase change material can improve the heat power of the heat storage system. Also, based on the optimization process, the maximum thermal performance of 96.4% and the maximum heat power level of 1.7 kW can be achieved in the optimized condition of the charging inlet temperature of 75 °C, charging inlet flow of 1.8−4 m3/s, and discharging inlet temperature of 35 °C.

Experimental observations of local plasma parameters in the COMPASS divertor in NBI-assisted L-mode plasmas

This paper presents an experimental characterization of the local plasma parameters in the COMPASS open divertor in deuterium, L-mode plasmas by means of Langmuir probes during neutral beam injection (NBI) heating. The effect of NBI heating of the core plasma on the local divertor plasma parameters is investigated under different plasma configurations and different directions of the magnetic field and plasma current for different line-averaged electron densities. At low line-averaged densities below 6 × 1019 m-3, a low NBI heating power level does not lead to any significant changes in the plasma parameters in the divertor region. It is also found that for a reversed magnetic field the influence of NBI in the divertor is stronger at higher line-averaged electron density and plasma current. In the divertor, the impact of the NBI heating is more pronounced at high delivered powers (above P NBI = 320 kW) and line-averaged densities (above 7 × 1019 m-3). The electron temperature and the floating potential at the outer target increases respectively with 10–50% and 100%, while the plasma potential in the inner divertor increases twofold. At a higher line-averaged density, the NBI heating affects the edge plasma, namely, the electron temperature in the midplane scrape-off layer and the heating moves toward the divertor. Thus, a twice as high electron temperature is observed in the divertor and a bi-Maxwellian electron energy distribution function arises.

Confined DART-MS for Rapid Chemical Analysis of Electronic Cigarette Aerosols and Spiked Drugs.

A confined direct analysis in a real time mass spectrometry (DART-MS) system and method were developed for coupling directly with commercial electronic cigarettes for rapid analysis without sample preparation. The system consisted of a confining heated glass T-junction, DART ionization source, and Vapur interface to assist aerodynamic transport. Suction generated by positioning the electronic cigarette at the junction inlet allowed for direct chemical analysis of aerosolized electronic liquids from both automatic devices powered by drag and manual button-operated devices, which is unachievable with traditional DART-MS. Parametric analyses for the system investigated Vapur suction flow rate, junction heating, puff duration, and coil power levels. Using this method, rapid chemical analyses of electronic cigarette aerosols from electronic liquids, spiked illicit drugs, and polymeric or plasticizer contaminants were performed in <30 s. The confined DART-MS method provides a streamlined tool for rapid screening of illicit and hazardous chemical profiles emitting from electronic cigarettes.

Feasibility study of a gas cartridge loop for the versatile test reactor

A feasibility study of a Gas Cartridge Loop (GCL) for the Versatile Test Reactor (VTR) was carried out to determine the performance requirements of major components and evaluate the performance during normal operation and transient conditions. The major components consist of a circulator/motor, a heater, a test article, a flow guide and a pressure vessel. The pressure vessel incorporates a pressurized, flowing helium loop with capability to test heat-producing test articles up to a 200 mm length of Energy Multiplier Module (EM2) fuel rod at a linear heat rate of 55 kW/m. The heat is rejected to VTR primary coolant sodium flowing along the outside of the GCL pressure vessel. For the baseline design, the helium temperatures at the test article inlet and outlet are 650 °C and 850 °C, respectively, when the mass flow is ~0.01 kg/s. The circulator inlet temperature is 362 °C and the motor power is 11.9 W. An electric heater power is 15.8 kW which is required to maintain the inlet temperature of the test article. Under the normal operating condition, the estimated fuel and cladding temperatures are 1233–1610 °C and 917–1219 °C, respectively.The controllability of the GCL was evaluated for the operational transients during a single fuel cycle by maneuvering either the motor or heater power to keep the test article outlet temperature at 850 °C. For an estimated perturbation of the test article power by ±3.5%, the required motor or heater power variations are ± 4.1% or ± 2.4%, respectively. The safety feature of the GCL was evaluated for the postulated accidents initiated by the VTR and GCL itself under the assumption that the helium flow is pseudo-steady. For the reactivity-initiated accident (RIA) like transient overpower (TOP) of the VTR, the simulation predicted that the margin to fuel melting is 24% and 5% for the protected and unprotected TOP, respectively. For GCL-initiating accidents, the simulation predicted the fuel reaches its melting point when the system loses mass flow by 52% with the nominal heater power or when the system pressure drops by 56% with the nominal motor and heater power level. For both the loss-of-flow and loss-of-pressure cases, the system shall terminate the heater and fission reaction at pre-determined set points. For the loss-of-power case, the GCL requires coastdown capability of the motor for at least several seconds to avoid the test article failure due to fuel melting.

Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

Radial profiles of density fluctuations and the radial electric field, E r, have been measured using Doppler reflectometry during the post-pellet enhanced confinement phase achieved, under different heating power levels and magnetic configurations, during the 2018 W7-X experimental campaign. A pronounced E r-well is measured with local values as high as −40 kV m−1 in the radial range ρ ∼ 0.7–0.8 during the post-pellet enhanced confinement phase. The maximum E r intensity scales with both the plasma density and electron cyclotron heating power level, following a similar trend to the plasma energy content. A good agreement is found when the experimental E r profiles are compared to simulations carried out using the neoclassical codes, the drift kinetic equation solver (DKES) and kinetic orbit-averaging solver for stellarators (KNOSOS). The density fluctuation level decreases from the plasma edge toward the plasma core and the drop is more pronounced in the post-pellet enhanced confinement phase than in reference gas-fuelled plasmas. Besides, in the post-pellet phase, the density fluctuation level is lower in the high iota magnetic configuration than in the standard one. To determine whether this difference is related to the differences in the plasma profiles or to the stability properties of the two configurations, gyrokinetic simulations have been carried out using the codes stella and EUTERPE. The simulation results point to the plasma profile evolution after the pellet injection and the stabilization effect of the radial electric field profile as the dominant players in the stabilization of the plasma turbulence.

A Combined Experimental and Numerical Characterization of the Flowfield and Heat Transfer around a Multiperforated Plate with Compound Angle Injection

The aerodynamic and thermal behaviour of multiperforated zones in combustors is essential to the development of future combustion chambers. Detailed databases are therefore crucial for the validation of RANS/LES solvers, but also regarding the derivation of heat transfer correlations used in 0D/1D in-house codes developed by engine manufacturers. In the framework of FP7 EU SOPRANO Program, the test-rig used in a previous study is modified to be compatible with anisothermal conditions. The plate studied is a 12:1 model with a 90∘ compound angle injection. A heating system is used to generate a moderate temperature gradient of about 20 K between the secondary hot flow and the main cold flow. The aerodynamic field is acquired by a PIV 2D-3C (Stereo Particle Image Velocimetry) system. The surface heat transfer coefficient is derived based on surface temperature distribution acquisitions. Several heating power levels are tested, which allows evaluating the convective heat transfer coefficient and reference temperature through a linear regression. Measurements are conducted on both sides of the plate, which also gives access to those quantities on the injection/suction sides. From a numerical point of view, the configuration is studied using the unstructured ONERA in-house CEDRE solver with an advanced Reynolds Stress Model. A systematic comparison is presented between the experimental and numerical database. Due to the high blowing ratio, the film protection is low in the first rows, with a convective heat transfer coefficient enhancement around three, and freestream cold air brought close to the wall by vortices created at injection. After four rows, the film is building up, leading gradually to a better insulation of the wall. The comparison with the numerical simulation exhibits a qualitative agreement on the main flow structures. However, the mixing between the jets, the film and the freestream is underestimated by the calculation.

Influences of heating and plasma density on impurity production and transport during the ramp-down phase of JET ILW discharge

The aim of this paper is to study the influences of plasma heating and plasma density on impurity production and transport during the plasma-termination phase. We have analyzed the ramp-down (RD) phase of a set of representative high-current JET ITER-like wall discharges: #92 437 (disrupted) and #92 442 (soft landing), characterized by a high plasma current of I p = 3.5MA. Analysis is performed for different time slots within the RD phase, corresponding to different levels of electron line density and auxiliary heating power. Since the deuterium gas fluxes are different, the influence of the separatrix density is also analyzed. The main conclusion from the simulations is the observation that for the same average-electron density, a decrease of the separatrix density leads to an increase of the plasma temperature at the divertor plate, leading to increased W production and consequently to a larger W concentration and radiation in the core. When the central electron temperature approaches the 2 keV level, corresponding to the maximum W and Ni cooling rate, the radiation in the plasma’s center is enhanced. Ni radiation is more important in the RD phase.