Internal Heater Research Articles

Enhancing the Reliability of NO2 Monitoring Using Low-Cost Sensors by Compensating for Temperature and Humidity Effects

The study investigates methods to enhance the reliability of NO2 monitoring using low-cost electrochemical sensors to measure gaseous pollutants in air by addressing the impacts of temperature and relative humidity. The temperature within a plastic container was controlled using an internal mica heater, an external hot air blower, or cooling packs, while relative humidity was adjusted using glycerine solutions. Findings indicated that the auxiliary electrode signal is susceptible to temperature and moderately affected by relative humidity. In contrast, the working electrode signal is less affected by temperature and relative humidity; however, adjustments are still required to determine gas concentrations accurately. Tests involving on/off cycles showed that the auxiliary electrode signal experiences exponential decay before stabilizing, requiring the exclusion of initial readings during monitoring activities. Additionally, calibration experiments in zero air allowed the determination of the compensation factor nT across different temperatures and humidity levels. These results highlight the importance of compensating for temperature and humidity effects to improve the accuracy and reliability of NO2 measurements using low-cost electrochemical sensors. This refinement makes the calibration applicable across a broader range of environmental conditions. However, the experiments also show a lack of repeatability in the zero air calibration.

Thermally manageable and scalable reactor configurations towards efficient hydrogen release from liquid organic hydrogen carriers

In the global pursuit to minimize carbon emissions, hydrogen has emerged as a prominent alternative energy solution. This research introduces a thermally efficient, scalable, and potentially carbon–neutral system for releasing hydrogen, employing methylcyclohexane as a liquid organic hydrogen carrier (LOHC). Our heat supply mechanism utilizes benzyltoluene as a liquid–gas phase change material (PCM) to facilitate effective heat transfer from the heating units to the reactor. We have developed catalysts with high dispersion and Pt loading of Pt/γ-Al2O3 that maintain performance over extended periods, achieving a hydrogen extraction rate of 2.3 Nm3H2(g)/h (equivalent to 5 kgH2/day) in a bench-scale reactor. The bench-scale setup achieves near-equilibrium conversion at a space velocity of 2 LLOHC/(Lcat-h) and 310 °C. The PCM-enhanced system supports a scalable catalytic bed design and simplifies heat supply and startup through the use of various heating methods. We then compare catalytic dehydrogenation reactor setups using single and hybrid heat sources; the former includes an internal Joule heater, offering simplicity and reduced heat loss but depends heavily on electrical energy, while the latter combines the internal Joule heater with an external fuel combustor, facilitating rapid startup albeit with increased heat loss. Lastly, we suggest future research directions to address existing technological hurdles and to expand the application of this system in scaling up hydrogen release processes.

Mathematical Modeling of the Adsorption-Catalytic Process with Internal Heater in a Multisectional Arrangement

Mathematical Modeling of the Adsorption-Catalytic Process with Internal Heater in a Multisectional Arrangement

MAGNETIC CONVECTION-RADIATION INTERACTION IN WAVY POROUS TRIANGULAR CONTAINERS USING HYBRID NANOFLUIDS: ENTROPY ANALYSIS

The free convection in triangular enclosures can be found in various practical applications such as microelectronic devices, design of building roofs and attics, geophysical applications, solar collector electric machinery, ventilation in rooms, and cooling of electronic devices. Therefore, this study aims to examine the free convection in sinusoidal, wavy porous triangle-shaped containers full of Al<sub>2</sub>O<sub>3</sub>-CuO/water hybrid nanosuspension under the impacts of internal heat generation, inclined Lorentz force, and thermal radiation. The two heating mechanisms are classified into two distinct situations: Case 1 (C1) is a triangle-shaped domain that has a heated portion on the left edge and the lower edge is cold; Case 2 (C2) is a triangle-shaped domain with a cold part on the left edge and a lower heated wavy edge. The dimensionless forms of governing system with the considered conditions are transformed numerically using the finite elements approach via the characteristic-based split (CBS) algorithm. The gained outcomes are portrayed graphically via streamlines, isotherms, entropy features, and the Bejan issue. The heat transfer rate and fluid flow in view of internal heated and wavy walls play a significant role. The influence of the magnetic force highly controls the flow structures inside the cavity; fluid velocity moves in below the heated wavy surface because of the magnetic force performed in the incline orientation. The growth in the undulation number weakens the highest absolute value of the streamlines, or the convective case strength in the cavity. The vertical temperature increases the nanoparticle volume fraction and (St)<sub>avg</sub> into the cavity at α = 30° to 60°.

Heat transfer characteristics and low-temperature performance of a lithium-ion battery with an inner cooling/heating structure

To improve heat dissipation and low-temperature performance, the paper presents a novel lithium-ion battery with an inner cooling/heating structure. A copper pipe with an internal heater strip is inserted into the battery to enhance its heat dissipation capability and heat it from the inside at low temperatures. To verify the novel battery's performance, a sample battery is prepared and its heat transfer characteristics at 25 °C and discharge performance at −20 °C are experimentally researched. The results show that the battery's heat transfer characteristics and low-temperature performance can be significantly improved by the inner cooling/heating structure. For the heat dissipation characteristics, compared with the original battery, at 25 °C, the peak external temperatures of the sample battery are reduced by 0.6 °C and 1.4 °C under 1 C charge rate and 1.5 C discharge rate conditions, respectively. For the low-temperature performance, the battery discharge performance can be comprehensively improved by the strategy of preheating and simultaneous heating. Under −20 °C and 1 C discharge rate conditions, compared with the battery without heating, using 3.70 W preheating and simultaneous heating power, the discharge capacity and initial discharge voltage of the battery are increased by 46.0 % and 0.66 V, respectively.

Well-fed African striped mice are prepped for cold spells

Being too cold or getting overheated is a strain for creatures that maintain a stable body temperature; some just go with the flow, allowing their body temperature to fluctuate to conserve energy. In contrast, creatures that maintain a constant body temperature must continually fuel their furnaces to remain warm during cold spells, and small rodents are particularly vulnerable as their tiny frames haemorrhage heat. So how do they manage to remain warm during colder times of year? Shaun Welman and Nomakwezi Mzilikazi from Nelson Mandela University, South Africa, teamed up with Martin Jastroch from Stockholm University, Sweden, to find out how tiny African striped mice (Rhabdomys pumilio) keep warm through the seasons.Heading out to collect the mini rodents near Gqeberha (formerly Port Elizabeth), South Africa, during winter, summer, autumn and spring, Welman and Mzilikazi measured the rodents’ metabolic rates as they rested overnight by recording how much oxygen the animals consumed. The pair then kickstarted the animals’ internal heaters by injecting them with noradrenaline, and remeasured their oxygen consumption to find out how much energy they were putting into generating warmth. A day later, the researchers chilled the mice by replacing the air in their surroundings with heliox (79% helium and 21% oxygen), which carries heat away from the animals’ bodies to cool them rapidly, while recording their oxygen consumption to find out how much energy they were using to try to remain warm when conditions were really cold. So how did the animals from different seasons fare? Surprisingly, all of the animals maintained a stable body mass of ∼48 g, even though African striped mice from another region of South Africa – where the climate is predictable, but food is unreliable – gained mass to survive winter. In addition, the Gqeberha animals’ metabolic rates doubled when resting in winter. The mice also turned up their brown fat heaters – which produce warmth without shivering – in autumn, consuming more oxygen than they had in the summer. And, when Welman and Mzilikazi chilled the mice with heliox, the summer mice had the lowest metabolic rate when they became hypothermic, while the winter, spring and autumn mice had metabolic rates that were about 50% higher. In short, the winter Gqeberha mice were consuming more energy than they did in summer.So, which of the mice's tissues were using the most energy to maintain their body temperature? Welman and Jastroch checked the animals’ brown fat, but found that even though the winter mice carried more of the tissue, the key proteins responsible for brown fat heat production fell by 25%. Brown fat could not be responsible for the winter metabolic rise. Instead, the mice were building up other organs, including the liver and intestines, to increase their metabolic rate to keep warm during the cold season.But why have the Gqeberha African striped mice opted for a profligate lifestyle during winter when other rodents conserve energy? Welman suspects that the temperate region's bountiful food supply allows the mice to maintain their high-octane way of life across the seasons. But why they do so is more baffling.Mzilikazi thinks it has something to do with the unpredictable cold snaps that strike Gqeberha. ‘We argue that sporadic cold spells at the study site pressurised African striped mice to maintain a high level of heat production throughout the year’, she says. So, the mice keep their brown fat on standby, in case of sudden cold periods between autumn and spring. But keeping their heaters prepared for spontaneous action could place them at risk if their plentiful food supply dries up thanks to climate change.

Combined influences of radiation and inclined magnetic field on natural convection in a cavity with complex geometry

In the current study, the influence of inclined magnetic field and optical thickness on the natural convection heat transfer of participating magnetic fluid flow in a complex geometry are investigated, for the first time. The physical model is a 2D square enclosure with an internal elliptical heater. The radiative transfer equation is used instead of the Roseland approximation to calculate the divergence of the radiative heat flux. The multiple-time-relaxation lattice Boltzmann method is adopted to calculate the velocity and temperature fields. The complex boundary conditions are treated using the immersed boundary technique and the radiative transfer equation by the finite volume method. The findings are accessible in terms of streamlines, isotherms, Nusselt number, percentage reduction of the heat transfer, and correlation of Nusselt number for a wide range of optical thicknesses (0 ≤ τ ≤ 100), Hartmann numbers (0 ≤ Ha ≤ 500), and magnetic field inclinations (0° ≤ γ ≤ 90°) in fixed values of Rayleigh number (Ra = 106) and Planck number (Pl = 0.1). The results showed that at Ha = 500, in an optically thin medium (τ ≤ 1), the maximum reduction of the heat transfer because of the magnetic effect is less than 15%, while this is 61% and 66% for τ = 100 and the non-radiative state, respectively.

Numerical investigation on non-Newtonian melting heat transfer of phase change material composited with nanoparticles and metal foam in an inner heated cubic cavity

In this paper, the non-Newtonian melting heat transfer of a latent heat thermal energy storage (LHTES) system composited with phase change material (PCM), nanoparticles and metal foam is numerically investigated inside an internal heated cubic cavity. The enthalpy-porosity method and power-law fluid model are adopted to model melting process for nano-enhanced PCM, and the Darcy-Forchheimer law and local thermal non-equilibrium model are assumed for metal foam. The effects of Rayleigh number (Ra), nanoparticle fraction (Φ), metal foam porosity (ε) and heater size on evolvement of solid-liquid interface, temperature of liquid PCM (θnf) and metal foam (θs), and full melting are addressed. The results reveal that with the increase of Ra, the convective heat transfer of PCM dominates the melting characteristic of the composite LHTES unit and accelerates the melting rate. With the increase in Φ, the non-Newtonian rheological behavior of liquid PCM is more pronounced with erratic convection flow due to increase of consistency parameter. Moreover, the convective heat transfer enhancement of θnf with addition of nanoparticles compensates for the conductive heat transfer enhancement of θs with increased ε. The internal heater size also plays an important role in the melting performance of composited PCM.

Centrifuge modeling of temperature effects on the pullout capacity of torpedo piles in soft clay

This study presents the results from centrifuge modeling experiments performed to understand the effects of temperature changes on the vertical pullout capacity of scale-model torpedo piles embedded in soft clay layers. The model torpedo pile is a pointed stainless-steel cylinder with fins at the top, installed by self-weight to the base of a clay layer using a stepper motor. An internal electrical resistance heater was used to control the pile temperature. The torpedo pile was first heated until the temperature and pore water pressure of the surrounding clay layer stabilized (drained conditions), after which the torpedo pile was cooled. Pullout tests performed on torpedo piles indicate that allowing drainage of excess pore water pressures induced by heating to different temperatures followed by cooling leads to an increase in axial pullout capacity with maximum temperature but does not affect the pullout stiffness. Push-pull T-bar penetration tests performed before and after pile heating indicate that an increase in undrained shear strength of the clay occurs near the torpedo pile, and post-test gravimetric water content measurements indicate a greater decrease in void ratio occurred in the soil layers heated to higher temperatures. The pullout capacity of the torpedo pile was found to follow a linear trend with maximum pile temperature change, but with a smaller slope than that observed for end-bearing energy piles tested in previous studies in the same clay.

Ultra-compact nonvolatile plasmonic phase change modulators and switches with dual electrical–optical functionality

Programmable photonic integrated circuits (PICs) are the foundation of on-chip optical technologies, with the optical modulators being one of the main building blocks of such programmable PICs. However, most of the available modulators suffer from high power consumption, low response time, and large footprint. Additionally, they show a large resistance modulation; thus, they require high switching voltage. In consequence, they operate much above CMOS-compatible voltages of 1.2 V and with high insertion losses. Furthermore, the state and information they carry are lost once the power is turned off—so, they are volatile. Thus, realizing modulators and phase shifters that overcome all those problems still remains a challenge. To overcome some of those limitations, the nonvolatile phase change materials implemented in the plasmonic structures are proposed that can offer many advantages as result of high electric field interaction with nonvolatile materials. Consequently, novel plasmonic nonvolatile switches proposed here can operate by phase modulation, absorption modulation, or both and under zero-static power. For the first time, the nonvolatile phase modulator is proposed that requires only 230 nm long active waveguide to attain full π phase delay with an insertion loss below even 0.12 dB. Simultaneously, under the requirements, it can operate as an amplitude modulator with an extinction ratio exceeding 2.2 dB/μm while the insertion losses are kept below 0.185 dB/μm. Furthermore, the heating mechanism can be based on the external heaters, internal heaters, electrical (memory) switching, or optical switching mechanism, which provide a lot of flexibility in terms of a design and requirements.

Solid oxide electrolysis cell with internal heater

Solid oxide electrolysis cell with internal heater

Fast cooling and internal heating in hyperon stars

Abstract Neutron star models with maximum mass close to 2 M⊙ reach high central densities, which may activate nucleonic and hyperon direct Urca neutrino emission. To alleviate the tension between fast theoretical cooling rates and thermal luminosity observations of moderately magnetized, isolated thermally-emitting stars (with Lγ ≳ 1031 erg s−1 at t ≳ 105.3 yr), some internal heating source is required. The power supplied by the internal heater is estimated for both a phenomenological source in the inner crust and Joule heating due to magnetic field decay, assuming different superfluidity models and compositions of the outer stellar envelope. It is found that a thermal power of W(t) ≈ 1034 erg s−1 allows neutron star models to match observations of moderately magnetized, isolated stars with ages t ≳ 105.3 yr. The requisite W(t) can be supplied by Joule heating due to crust-confined initial magnetic configurations with (i) mixed poloidal-toroidal fields, with surface strength Bdip = 1013 G at the pole of the dipolar poloidal component and ∼90 per cent of the magnetic energy stored in the toroidal component; and (ii) poloidal-only configurations with Bdip = 1014 G.

Effects of gradient porous metal foam on the melting performance and energy storage of composite phase change materials subjected to an internal heater: A numerical study and PIV experimental validation

This work aims to explore the effects of gradient porous metal foam on the 3D melting heat transfer as well as the heat storage performance of a latent heat thermal energy storage (LHTES) unit inside an internal heated cubic cavity. A modified structure of metal foam with gradient porosity of three stratification layers is proposed to optimize the melting characteristic of the composite phase change materials. The enthalpy-porosity method is adopted to model melting process, and the Darcy-Forchheimer law and local thermal non-equilibrium model are assumed for metal foam. The numerical code of proposed model is in good consistency with the experimental results of particle image velocimetry (PIV) visualization. The effects of porosity gradient with equal and non-equal stratification heights, as well as pore per inch (PPI) on the melting performance, heat transfer and heat storage are investigated. The results indicate that the competitive relation between the conduction and convection induced by the gradient porosity influences the heat transfer and energy storage. The energy storage of negative gradient is greater than that of positive gradient, but the average rate of energy storage of the former is lower than that of the latter. In the middle melting stage, the total average Nusselt number increases with larger porosity gradient for positive cases and decreases for negative cases. With the increase of the stratification height of middle layer, the heat transfer efficiency of positive cases weakens, while it is enhanced for negative cases. Moreover, the increase of PPI can reinforce the conduction effect and improve the average rate of energy storage of the LHTES unit for both positive and negative cases.

Effect of internal heat generation or absorption on conjugate thermal-free convection of a suspension of hybrid nanofluid in a partitioned circular annulus

This study aims to explain the impact of the presence of a solid conductive partition on the thermal-free convective motion mechanism and heat transmission process within a concentric circular annulus filled with a water-based hybrid nanoliquid containing Copper (Cu) and Alumina (Al2O3) nanoparticles. The thermal natural convective flow is formed within the annulus due to the temperature difference which is externally imposed between the internal heated cylinder and the external cooled one and internally generated by the interior heat generation/absorption (IHG/A) phenomenon. The technique of finite volume is applied to discretize and approximately solve the non-dimensional conservation equations. The influence of selected factors such as the nanoparticles concentration, Rayleigh number, fluid/solid heat conductivity ratio, and the IHG/A parameter on the thermo-hydrodynamic behavior and heat exchange rate is interpreted. The findings show that, in the presence of a conductive solid partition, the combined effects of the IHG/A phenomenon and the combined nanoparticles considerably modify the flow and heat exchange behaviors within the annulus. We also employed a new correlation to predict the mean heat exchange rate in the defined input parameter range.

Three-dimensional numerical investigation on melting performance of phase change material composited with copper foam in local thermal non-equilibrium containing an internal heater

This work aims to numerically study the 3D melting heat transfer of latent heat thermal energy storage (LHTES) systems with phase change material (PCM) embedded in copper foam inside an internal heated cubic cavity. The enthalpy-porosity method to model the phase change process is employed and the Darcy-Forchheimer law and local thermal non-equilibrium (LTNE) model are assumed for the metal foam. The numerical code of proposed model shows good agreement for copper foam composited PCM melting with carefully designed experiments. Special attentions are given to detect the effects of Rayleigh number (Ra), porosity (ε), Darcy number (Da) and heater size on evolvement of solid-liquid interface, temperature stratification and full melting. The results show that increasing Ra enhances convective heat transfer in the upper part of the porous cavity; though the completely melting time remains almost unchanged. For a fixed porosity, decrease of Da reduces the melting rate in the medium melting stage, and the temperature distribution of low Da is dominated by the heat conduction in porous media at the later stage, but Da shows a negligible effect on the complete melting time. For a fixed Da, increase of porosity decelerates the complete melting time. Apart from that, the heater size also plays an important role in the melting performance of composited PCM.

A Study of the Gettering Characteristics of Getter Pumps for Different Gases

The gettering characteristics of Ti–Zr–Al getter pumps with internal and external heaters have been measured for Н2 and CO. The results are compared to the measured similar characteristics of an NEX‑Torr D 100-05 combined pump from SAES Getters and a titanium sublimation film at temperatures of 300 and 77 K.

Resistively heated, high pressure, membrane and screw driven diamond anvil cell

ABSTRACT High temperature is of paramount importance in high pressure science. One of the leading tools in this respect is the resistively heated diamond anvil cell (DAC), where the heat is provided by small heaters, positioned close to the diamond/gasket/sample region (internally heated DAC, IHDAC) or by wrapping the DAC body into bigger heaters (externally heated DAC, EHDAC). Although IHDACs can reach sample temperatures higher than 1000 K, they are difficult to handle and the heater/diamond/gasket/sample region may be affected by strong thermal gradients potentially hindering accurate temperature measurements. Here we present a novel EHDAC, which overcomes these issues by uniquely joining: (i) high mechanical precision for multi-Mbar, (ii) high temperature alloys for operating to 1000 K, (iii) membrane or screw driven, easily switchable between each other, (iv) operation into a vacuum chamber, (v) uniform temperature, (vi) facile handling, and (vii) possibility to add internal heaters for achieving even higher temperatures.

A resistively-heated dynamic diamond anvil cell (RHdDAC) for fast compression x-ray diffraction experiments at high temperatures.

A resistively-heated dynamic diamond anvil cell (RHdDAC) setup is presented. The setup enables the dynamic compression of samples at high temperatures by employing a piezoelectric actuator for pressure control and internal heaters for high temperature. The RHdDAC facilitates the precise control of compression rates and was tested in compression experiments at temperatures up to 1400 K and pressures of ∼130 GPa. The mechanical stability of metallic glass gaskets composed of a FeSiB alloy was examined under simultaneous high-pressure/high-temperature conditions. High-temperature dynamic compression experiments on H2O ice and (Mg, Fe)O ferropericlase were performed in combination with time-resolved x-ray diffraction measurements to characterize crystal structures and compression behaviors. The employment of high brilliance synchrotron radiation combined with two fast GaAs LAMBDA detectors available at the Extreme Conditions Beamline (P02.2) at PETRA III (DESY) facilitates the collection of data with excellent pressure resolution. The pressure-temperature conditions achievable with the RHdDAC combined with its ability to cover a wide range of compression rates and perform tailored compression paths offers perspectives for a variety of future experiments under extreme conditions.

Experimental results of advanced technological modifications for a CO2 capture process using amine scrubbing

This paper provides a discussion of the experimental results obtained at the amine-based carbon capture pilot plant having the capacity of 200 m3n/h of flue gas, using 30 wt% ethanolamine solution as a solvent. The objective was to prove the superiority of application of advanced amine flow systems as well as of the novel stripper internal heater fulfilling pilot Technology Readiness Level. Standard process flow sheet, multi absorber feed and split-flow process modifications with and without stripper interheating were examined. A vast number of process parameters were recorded during the trials. The data were critically analysed, compared and presented in the paper. Demonstrated process flow modifications resulted in a reduction of the reboiler heat duty by about 5%, while using internal stripper interheatingby 9÷11 %, comparing to standard amine-based carbon capture plant.

Resonances and nonlinear vibrations of circular cylindrical shells, effects of thermal gradients

In this paper, the results of an experimental campaign focused on the vibrations of shells are presented. More specifically, the goal is to investigate the effect of thermal gradients across the shell thickness on the nonlinear dynamics. The shell is made of polymeric material and an aluminum mass is clamped on one end of the shell; the other shell end is clamped to an electrodynamic shaker, which provides a base harmonic excitation. Tests are performed in a controlled environment where a thermal gradient on the shell thickness is generated by means of a climatic chamber and an internal cartridge heater. Different temperature gradients and base excitation levels have been considered. The nonlinear dynamic scenario is analyzed through amplitude–frequency diagrams, bifurcation diagrams, waterfall diagrams, time histories, Fourier spectra, phase portraits, and Poincaré maps. Results show a strong effect of the temperature on the dynamic response of the shell: subharmonic, quasi-periodic, and chaotic vibrations take place as well as large amplitude vibrations, high sound levels are detected.