Heating Rate Measurements Research Articles

Experimental study on gamma heating rate measurement based on differential calorimeter

This study focuses on the analysis of coupled heat transfer in a differential calorimeter, based on in-pile test data. The theoretical calculation method is developed by considering heat conduction, convection, and radiation. Additionally, a three-dimensional numerical simulation is conducted to compare and analyze the results. It has been observed that as the reactor power increases, the gamma heating of stainless steel and aluminum materials also increases in an approximately linear manner. When comparing the calculation methods, it can be deduced that there exists a significant thermal resistance at the cold end of the measuring cell. Based on the aforementioned analysis, the temperature calculated after modifying the numerical calculation model demonstrates a high level of agreement with the experimental data, with a maximum deviation of less than 2.46 °C. As the reactor power increases, the proportions of radiation and convection heat in both the calibration cell and the measuring cell also increase. Specifically, the proportion of heat dissipation in the measurement section of the calibration cell ranges from 0.72% to 1.51%, while in the measurement section of the measuring cell, it ranges from 3.69% to 9.41%. These values are relatively low, which is advantageous in minimizing the calculation deviation of gamma heating in materials.

Calibrated heating rate measurements using electric-field-induced electron extraction in ultracold neutral plasmas

The heating rate of plasma electrons induced by external fields or other processes can be used as an experimental tool to measure fundamental plasma properties such as electrical conductivity or electron–ion collision rates. We have developed a technique that can measure electron heating rates in ultracold neutral plasmas (UNPs) with $\sim 10\,\%$ precision while simultaneously referencing the measurement to a calibrated amount of heating. This technique uses a sequence of applied electric fields in four sections: to control the ratio of electrons to ions in the UNP; to provide a time for the application of fields that cause electron heating and subsequent thermalization of the electrons after the application of those fields; to extract electrons from the UNP using a method sensitive to electron temperature that allows the measurement of electron heating; and to extract the remaining electrons to measure the total electron (and therefore ion) number. The primary signal used to measure the heating rate is the measurement of the number of electrons that escape in the third section of the experiment as a larger number of escaping electrons indicates a larger amount of heating. We illustrate the use of this technique by measuring electron heating caused by high-frequency radiofrequency (RF) fields. In addition to the main technique, several subtechniques to calibrate the electron temperature, electron density, amount of heating and applied RF field amplitude were developed as well.

Enhanced production of human interferon α2b in glycoengineered Pichia pastoris by robust control of methanol feeding and implications of various control strategies

Interferon α2b (IFNα2b), a prominent cytokine molecule, is bestowed with immunomodulatory, antiproliferative, and antiviral properties. Like any other recombinant protein produced in methylotrophic yeast Pichia pastoris, Human interferon α2b (huIFN α2b) production in P. pastoris depends on methanol utilization during the induction phase. This study investigates the impact of varying residual methanol concentrations on huIFNα2b productivity and assesses control strategies towards the tight control of residual methanol concentration in fed-batch experiments carried out in the fermentation calorimeter. Real-time monitoring of P. pastoris metabolism was facilitated by metabolic heat rate measurements and exhaust gas analyser. Optimal methanol concentration screening performed at different concentrations viz., 1.5, 3, 5, and 7 g/L, revealed the highest huIFNα2b productivity at 3 g/L (0.21 mg/g h). Methanol sensor provided input data for three different control strategies (on/off, proportional integral (PI), and model-based adaptive PI) to maintain optimal methanol levels (3 g/L). Model-based adaptive control resulted in the highest huIFNα2b yield, productivity (244.34 mg/L, 0.31 mg/g h), surpassing on/off (188.7 mg/L, 0.16 mg/g h) and PI (202.3 mg/L, 0.28 mg/g h) control strategies. The model-based adaptive PI control framework developed in this study could be employed for other heterologous protein production in P. pastoris.

Heating rate measurement and characterization of a prototype surface-electrode trap for optical frequency metrology

We present the characterization of a prototype surface-electrode (SE) trap as a first step towards the realization of a compact, single-ion optical clock based on Yb$^+$. The use of a SE trap will be a key factor to benefit from clean-room fabrication techniques and technological advances made in the field of quantum information processing. We succesfully demonstrated trapping at a 500 $\mu$m electrodes distance and characterized our trap in terms of lifetime and heating rate. This is to our knowledge the highest distance achieved for heating rates measurements in SE traps. This simple 5-wire design realized with simple materials yields a heating rate of $\mathbf{8\times 10^3}$ phonons/s. We provide an analysis of the performances of this prototype trap for optical frequency metrology.

Experimental and numerical results for a new single-cell calorimeter dedicated to nuclear heating rate measurement

Experimental and numerical results for a new single-cell calorimeter dedicated to nuclear heating rate measurement

An in-depth study of nonlinear parametric characterization for thermoelectric generator modules

Thermoelectric (TE) parameters provide indispensable data for the optimal design, accurate modeling, and performance assessment of off-the-shelf TE modules. However, the lack of unified characterization methods for these nonlinear data creates challenges for the design of large-scale TE systems. This paper aims at a thorough exploration of the accuracy, efficiency, and applicability of five typically reported characterization methods in terms of temperature-dependent material-level TE parameters (Seebeck coefficient, thermal conductivity and electrical resistivity). A common test setup was built and specifically improved for the convenient and high-precision measurement of heat rate. The four methods except for the Buist’s modified Harman method can characterize the satisfactory material-level TE parameters only if the thermoelectric generator (TEG)’s irreversible factors are considered including the thermal resistances of substrates and interlaminar contact resistances. The applicability of each method in a large temperature range is discussed by simulation beyond their inherent limits of adopted setups in this paper. Most methods show significant deviations at high temperatures due to their inherent parametric spatial-independence assumptions. From the perspective of their theoretical feasibility and practical accuracy, the quasi steady-state method is more advantageous than others. This research can guide the employment of characterization methods and assist the design and optimization of large-scale TE systems.

Novel optical heating rate measurement in hypersonic flow using phenol formaldehyde luminescence

A phenyl formaldehyde resin sphere model is created and subjected to Mach 7 flow. The model produces temperature-dependent luminescence without chemical modification or doping with a luminescent probe. The luminescent images are captured at a rate of 20 Hz during a total testing time of 5.5 s. The luminescent images are used to non-intrusively calculate spatially and temporally resolved maps of the temperature over the surface of the model. From this, the heating rate at various locations along the sphere model is calculated. This heating rate is compared to an analytical model for hypersonic flow over a hemisphere.

The impact of cloudiness and cloud type on the atmospheric heating rate of black and brown carbon in the Po Valley

Abstract. We experimentally quantified the impact of cloud fraction and cloud type on the heating rate (HR) of black and brown carbon (HRBC and HRBrC). In particular, we examined in more detail the cloud effect on the HR detected in a previous study (Ferrero et al., 2018). High-time-resolution measurements of the aerosol absorption coefficient at multiple wavelengths were coupled with spectral measurements of the direct, diffuse and surface reflected irradiance and with lidar–ceilometer data during a field campaign in Milan, Po Valley (Italy). The experimental set-up allowed for a direct determination of the total HR (and its speciation: HRBC and HRBrC) in all-sky conditions (from clear-sky conditions to cloudy). The highest total HR values were found in the middle of winter (1.43 ± 0.05 K d−1), and the lowest were in spring (0.54 ± 0.02 K d−1). Overall, the HRBrC accounted for 13.7 ± 0.2 % of the total HR, with the BrC being characterized by an absorption Ångström exponent (AAE) of 3.49 ± 0.01. To investigate the role of clouds, sky conditions were classified in terms of cloudiness (fraction of the sky covered by clouds: oktas) and cloud type (stratus, St; cumulus, Cu; stratocumulus, Sc; altostratus, As; altocumulus, Ac; cirrus, Ci; and cirrocumulus–cirrostratus, Cc–Cs). During the campaign, clear-sky conditions were present 23 % of the time, with the remaining time (77 %) being characterized by cloudy conditions. The average cloudiness was 3.58 ± 0.04 oktas (highest in February at 4.56 ± 0.07 oktas and lowest in November at 2.91 ± 0.06 oktas). St clouds were mostly responsible for overcast conditions (7–8 oktas, frequency of 87 % and 96 %); Sc clouds dominated the intermediate cloudiness conditions (5–6 oktas, frequency of 47 % and 66 %); and the transition from Cc–Cs to Sc determined moderate cloudiness (3–4 oktas); finally, low cloudiness (1–2 oktas) was mostly dominated by Ci and Cu (frequency of 59 % and 40 %, respectively). HR measurements showed a constant decrease with increasing cloudiness of the atmosphere, enabling us to quantify for the first time the bias (in %) of the aerosol HR introduced by the simplified assumption of clear-sky conditions in radiative-transfer model calculations. Our results showed that the HR of light-absorbing aerosol was ∼ 20 %–30 % lower in low cloudiness (1–2 oktas) and up to 80 % lower in completely overcast conditions (i.e. 7–8 oktas) compared to clear-sky ones. This means that, in the simplified assumption of clear-sky conditions, the HR of light-absorbing aerosol can be largely overestimated (by 50 % in low cloudiness, 1–2 oktas, and up to 500 % in completely overcast conditions, 7–8 oktas). The impact of different cloud types on the HR was also investigated. Cirrus clouds were found to have a modest impact, decreasing the HRBC and HRBrC by −5 % at most. Cumulus clouds decreased the HRBC and HRBrC by −31 ± 12 % and −26 ± 7 %, respectively; cirrocumulus–cirrostratus clouds decreased the HRBC and HRBrC by −60 ± 8 % and −54 ± 4 %, which was comparable to the impact of altocumulus (−60 ± 6 % and −46 ± 4 %). A higher impact on the HRBC and HRBrC suppression was found for stratocumulus (−63 ± 6 % and −58 ± 4 %, respectively) and altostratus (−78 ± 5 % and −73 ± 4 %, respectively). The highest impact was associated with stratus, suppressing the HRBC and HRBrC by −85 ± 5 % and −83 ± 3 %, respectively. The presence of clouds caused a decrease of both the HRBC and HRBrC (normalized to the absorption coefficient of the respective species) of −11.8 ± 1.2 % and −12.6 ± 1.4 % per okta. This study highlights the need to take into account the role of both cloudiness and different cloud types when estimating the HR caused by both BC and BrC and in turn decrease the uncertainties associated with the quantification of their impact on the climate.

Electric energy dissipation and electric tortuosity in electron conductive cement-based materials

The emergence of multifunctional cement-based materials in the construction industry has the potential to shift the paradigm from strength-only performance to new functionalities enabled by electron conducting capabilities in one of the most material- and energy-intensive industry sectors worldwide. To enable such developments, we present results of a hybrid experimental-theoretical investigation of the electrical conductivity and resistive (Joule) heating of highly heterogeneous nanocarbon (nCB)--cement-based composites (pastes and mortars). By analogy with diffusivity, we find that electrical conductivity is determined by the electric tortuosity of a ``volumetric wiring'' permeating a highly heterogeneous matrix from percolation to saturation. From a combination of electrical conductivity and Joule heat rate measurements, we show that the electric energy dissipation at the origin of the Joule heating originates from spatial electric-field fluctuations, reminiscent of the fluctuation-dissipation theorem. We report that these fluctuations---in first order---are well captured by functional relations of the electric tortuosity of the composite material, and synthesize these observations into a first-order dissipation-tortuosity model. We suggest that harvesting the benefits of electron conducting cement-based materials, such as resistive heating, electromagnetic shielding, and energy storage, will ultimately focus on settling the competition between conductor concentration and electric tortuosity. Given the global environmental footprint of concrete, the results open venues for the sustainable development of concrete for existing and emerging green technology applications.

Performance analysis of coaxial thermocouples for heat flux measurement of an aerodynamic model on shock tube facility

The K, E and J-types of coaxial thermo-sensors have been used to measure surface heat flux at the nose, spatial position-1 and spatial position-2 over an aerodynamic model subjected to a homemade shock tube flow facility. The high pressure shock has been applied to the aerodynamic model for 60 ms subsequently their variation in transient temperatures have been recorded for four experimental shots. The surface heat flux has been predicted from the transient temperatures by using one-dimensional heat transfer theory in a semi-infinite solid body. The average errors have been found between four experiments for transient temperature and surface heat flux are less than ±0.2% and ±4% respectively. A two-dimensional numerical model has been developed by using commercial software Ansys to solve the high enthalpy flow facility as exists in shock tube arrangement to validate the experimental results. The accuracy found in transient temperatures and surface heat fluxes are ±0.51% and ±0.633%. These coaxial thermo-sensors will help the design and development of aerodynamic vehicles in terms of measurement of heating rate on different inclined surfaces, missile nose, hypersonic aircraft technology, gun barrel test, advanced production technology, engine measurements etc.

Confirmation of Nuclear Heating Rate for Installation of Cold Neutron Source at HANARO

In order to determine the capacity of the cold neutron source refrigerator of HANARO, the nuclear heating rate at CN vertical hole is measured by using the heat-flow calorimetric method and confirmed by the calculation. The heating rate measurement device of HANARO was composed of a calorimeter sensor, an air containing aluminum sleeve for fitting the sensor to the CN hole, aluminum weight and a lead wire assembly. The calorimeter sensor consists of a cylindrical Al sample and container, two thermocouples and the electric heater for the calibration of the calorimeter. The sample is separated by an air gap from the Al container surrounded by an air containing Al sleeve. After installation of the calorimeter at a measurement position of HANARO, the heat transfer inside the calorimeter was simulated by the electric heating for the sample. The nuclear heating rates at the CN hole were determined at three reactor powers of 1, 4 and 8 MW by using the calibration curve and the temperature measurements at each reactor power. The measured nuclear heating rate per unit mass of Al sample at 8 MW reactor power is 0.143 W/g and it is equivalent to the 0.494 W/g at 30 MW. The nuclear heating rate was calculated by using the MCNP code. The calculation model for the whole facility including the reactor core and the reflector tank were established. In the calculation procedure, the heat generations by various radiations were evaluated with considering the prompt, delayed and activation effects. The measured heating rate was reasonably well supported by the calculation using the cold neutron facility design code. It will be very useful for the moderator cell of cold neutron source of HANARO.

Thermodynamics and kinetics of the Fenton reaction in foods

A major cause of food oxidation is free-radical generation via the Fenton reaction. Calorimetric measurement of heat rate during the reaction between food antioxidants and H2O2 with added Fe(II), the catalyst in the Fenton reaction, is used to ascertain the reactions occurring and evaluate stoichiometric, thermodynamic and kinetic parameters for the reactions at 25 °C. The reaction of ascorbic acid with H2O2 at varying pH and concentrations of ascorbic acid, Fe(II), and H2O2 was used as a model system. Measurements were also made on antioxidants, fruit juices, fruit purees, tea, and coffee. Enthalpies of formation of ascorbate monoanion (-1124 ± 3 kJ/mol) and dehydroascorbate anion (-1069 ± 2 kJ/mol) are estimated from literature data and Thornton’s Rule to give ΔrH = −325 kJ/mol for H2O2(aq) + C6H7O6−(aq) = C6H5O6−(aq) + 2H2O(l). The experimental results show an initial very rapid reaction of ascorbate monoanion to dehydroascorbate anion followed by an undefined series of reactions with variable stoichiometry (4 ± 2 H2O2/ascorbate) that are overall described by first order kinetics. An empirical linear relation between the maximum heat rate observed and ascorbate concentration was found, but no definitive relation was found between total heat and amount of ascorbate. However, the model directly and rapidly provides stoichiometric, thermodynamic and kinetic properties of the radical scavenging activity of food antioxidants and commercial food products. The total heat measured under specified conditions is related to the radical scavenging capacity of the sample; higher values correspond to higher capacity for radical scavenging and vice versa.

Transient heat flux measurement analysis from coaxial thermocouples at convective based step heat load

The measurement of surface heating rate is an imperative parameter in the force convection ground-based facility for short duration investigation due to the heat transfer rate is changing rapidly. The coaxial thermocouples are suitable to measure the transient heat flux in fast varying heat transfer application because of having fast response time in the range microseconds or less. In this addition, the K-type, E-type, and J-type of coaxial thermocouples are contrived as well as the thermal coefficient resistance (TCR) and sensitivity (S) has been calculated from oil-bath based technique. These handmade coaxial thermocouples are exposed in a forced convection flow facility having three different input step heat loads as well as their transient heat fluxes are estimated using one-dimensional heat conduction modeling for the semi-infinite body. The numerical simulation has also been carried out with the analogous experimental parameters using ANSYS-FLUENT v.15.0 and compared with the outcome of the experimental approach and it is found that the average value of the transient temperatures having 0.3% error and surface heat flux recovered from this temperature is 10%. This study reveals the measuring ability of these handmade coaxial thermocouples at low temperature and low velocity on short duration transient measurements.

Dynamic calibration of temperature sensors from light rays for transient measurement

Measurement of transient heat fluxes in the applications involving very short duration of a heating environment which has been promised for the candidate by measurement of surface heating rates with thin film gauges (TFG). They are basically resistance temperature detectors having to measure in a very short duration of time. In the present study, a platinum based TFG has been fabricated and dynamically calibrated (radiation based) in the laboratory with a view to assessing the performance of platinum thin film gauges (PTFG) in the dynamic environment. These examinations are focusing to explore the probability of using TFG for small duration transient measurements with pure radiation mode of heat transfer. Radiation based heat flux is applied on the gauge by using the halogen bulb in a square box and its response is obtained through measured transient temperature. Subsequently, the surface heat fluxes are estimated by using radiation-based heat transfer. The purpose of this work is to statically calibrate each handmade heat transfer gauges by using quartz as substrate material deposited on platinum paste. This experiment has been carried out by oil bath based experimental technique. The similar experimental environment is also studied to observe the transient temperature response by using numerical simulation. The experiments are carried out by exposing the platinum TFG to various known step heat load of known input wattage, for the duration of 10 seconds. Then, the voltage signals are recorded due to change in temperature of air-flow past the TFG. The numerical simulation (ANSYS-Fluent v. 14.5) is performed in the similar experimental environmental conditions, for the same heating loads. Experimentally recorded temperature signals from the gauges are compared with simulated temperature histories obtained through finite element analysis. Cubic spline methods of the 1-D heat conduction equation are used to predict surface heat flux and compared with input heat loads. The presently developed calibration set-up is seen to very useful for radiation-based measurements of TFG.

Study of the Response of a New Compact Calorimetric Cell for Nuclear Heating Rate Measurements

This paper presents experimental and theoretical studies of a new compact calorimetric cell under laboratory conditions. Producing a reduced-size calorimetric cell, intended to be used to quantify the nuclear heating rate inside material testing reactors by differential calorimetry, is a major challenge and offers new complementary measurement prospects. The new compact design, called CALOrimeter with radial thermal transfers for nuclear REactors, is obtained with a special geometry favoring heat transfers in the radial direction in order to decrease the height of the sensor. Results obtained during a crucial preliminary step corresponding to out-of-pile calibration without nuclear rays are presented and compared with those of three different configurations. The influence of different parameters, such as a specific area of the cell structure, fluid temperature and velocity, and the nature of the material of the cell structure, is shown and analyzed with a 1-D thermal model coupling conductive and radiative thermal exchanges. Comparisons of different configurations and conditions lead to a discussion of the advantages of this new compact design.

Computational Modelling of Cardiac Trabecula Mechanics

Cardiac trabeculae are thin strips of muscle within the ventricles that can be readily excised and used to investigate contractile mechanics of cardiac muscle. Recently, the Auckland Bioengineering Institute has developed a novel cardiac myometer that simultaneously measures force, length and shape of actively contracting isolated cardiac trabeculae. Here we have developed a muscle-specific computational model based on optical coherence tomography geometric surface data that replicates passive mechanics of trabecula. We hypothesised that the muscle's surface geometry data, in addition to force-length data, would improve the fit between the model simulated mechanics and the experimental data. The trabecula model was optimised using two different objective functions (muscle length or shape) driven by a pressure boundary condition. For both objective functions, there was a region of optimal parameters the optimiser tended towards but, due to the coupling between parameters, the ability to find the true optimal parameters was hindered. Due to the limitations of the data, we found that the addition of surface data did not improve parameter estimation and that using only the force-length data provided sufficient information to produce an optimal fit. References A. Anderson. The Cardiac Myometer: Measuring Matters of the Heart. PhD thesis, University of Auckland, 2016. K. F. Augenstein, Brett R. Cowan, Ian J. LeGrice, Poul M. F. Nielsen, and Alistair A. Young. Method and apparatus for soft tissue material parameter estimation using tissue tagged Magnetic Resonance Imaging. Journal of Biomechanical Engineering, 127(1):148–157, February 2005. C. Bradley, Andy Bowery, Randall Britten, Vincent Budelmann, Oscar Camara, Richard Christie, Andrew Cookson, Alejandro F. Frangi, Thiranja Babarenda Gamage, Thomas Heidlauf, Sebastian Krittian, David Ladd, Caton Little, Kumar Mithraratne, Martyn Nash, David Nickerson, Poul Nielsen, Oyvind Nordbo, Stig Omholt, Ali Pashaei, David Paterson, Vijayaraghavan Rajagopal, Adam Reeve, Oliver Rohrle, Soroush Safaei, Rafael Sebastian, Martin Steghofer, Tim Wu, Ting Yu, Heye Zhang, and Peter Hunter. OpenCMISS: A multi-physics and multi-scale computational infrastructure for the VPH/Physiome project. Progress in Biophysics and Molecular Biology, 107(1):32–47, October 2011. doi:http://dx.doi.org/10.1016/j.pbiomolbio.2011.06.015 M. L. Cheuk, A. J. Anderson, J. C. Han, N. Lippok, F. Vanholsbeeck, B. P. Ruddy, D. S. Loiselle, P. M. F. Nielsen, and A. J. Taberner. Four-Dimensional Imaging of Cardiac Trabeculae Contracting In Vitro Using Gated OCT. IEEE Transactions on Biomedical Engineering, 64(1):218–224, January 2017. doi:http://dx.doi.org/10.1109/TBME.2016.2553154 M. L. Cheuk, N. Lippok, A. W. Dixon, B. P. Ruddy, F. Vanholsbeeck, P. M. F. Nielsen, and A. J. Taberner. Optical coherence tomography imaging of cardiac trabeculae. In 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, pages 182–185, August 2014. doi:http://dx.doi.org/10.1109/EMBC.2014.6943559 J. M Guccione, Andrew D McCulloch, and LK Waldman. Passive material properties of intact ventricular myocardium determined from a cylindrical model. J Biomech Eng, 113(1):42–55, 1991. J. C. Han, Andrew J. Taberner, Robert S. Kirton, Poul M. Nielsen, Nicholas P. Smith, and Denis S. Loiselle. A unique micromechanocalorimeter for simultaneous measurement of heat rate and force production of cardiac trabeculae carneae. Journal of Applied Physiology, 107(3):946–951, September 2009. doi:http://dx.doi.org/10.1152/japplphysiol.00549.2009 M. P. Nash and P. J. Hunter. Regional mechanics of the beating heart. In Cardiac Perfusion and Pumping Engineering, volume Volume 1 of Clinically-Oriented Biomedical Engineering, pages 83–127. WORLD SCIENTIFIC, July 2007. doi:http://dx.doi.org/10.1142/9789812775597_0004 J. H. Omens, D. A. MacKenna, and A. D. McCulloch. Measurement of strain and analysis of stress in resting rat left ventricular myocardium. Journal of Biomechanics, 26(6):665–676, June 1993. doi:http://dx.doi.org/10.1016/0021-9290(93)90030-I V. Y. Wang, H. I. Lam, Daniel B. Ennis, Brett R. Cowan, Alistair A. Young, and Martyn P. Nash. Modelling passive diastolic mechanics with quantitative MRI of cardiac structure and function. Medical Image Analysis, 13(5):773–784, October 2009. doi:http://dx.doi.org/10.1016/j.media.2009.07.006

Heating Rate of Light Absorbing Aerosols: Time-Resolved Measurements, the Role of Clouds, and Source Identification.

Light absorbing aerosols (LAA) absorb sunlight and heat the atmosphere. This work presents a novel methodology to experimentally quantify the heating rate (HR) induced by LAA into an atmospheric layer. Multiwavelength aerosol absorption measurements were coupled with spectral measurements of the direct, diffuse and surface reflected radiation to obtain highly time-resolved measurements of HR apportioned in the context of LAA species (black carbon, BC; brown carbon, BrC; dust), sources (fossil fuel, FF; biomass burning, BB), and as a function of cloudiness. One year of continuous and time-resolved measurements (5 min) of HR were performed in the Po Valley. We experimentally determined (1) the seasonal behavior of HR (winter 1.83 ± 0.02 K day-1; summer 1.04 ± 0.01 K day-1); (2) the daily cycle of HR (asymmetric, with higher values in the morning than in the afternoon); (3) the HR in different sky conditions (from 1.75 ± 0.03 K day-1 in clear sky to 0.43 ± 0.01 K day-1 in complete overcast); (4) the apportionment to different sources: HRFF (0.74 ± 0.01 K day-1) and HRBB (0.46 ± 0.01 K day-1); and (4) the HR of BrC (HRBrC: 0.15 ± 0.01 K day-1, 12.5 ± 0.6% of the total) and that of BC (HRBC: 1.05 ± 0.02 K day-1; 87.5 ± 0.6% of the total).

Study of the Flow Temperature and Ring Design Influence on the Response of a New Reduced-Size Calorimetric Cell for Nuclear Heating Quantification

This paper concerns experimental studies of different designs of a new compact calorimetric cell under laboratory conditions. This kind of cell is used for the measurement of the nuclear heating rate inside Material Testing Reactors thanks to differential calorimetry. The results, obtained by applying an operating protocol corresponding to a preliminary out-of-pile calibration step, are presented for three designs. The influence of the horizontal-fin design is shown on the calibration curve and the sensor sensitivity. The influence of the external fluid flow temperature is given for the quarter design. The different responses of the calorimetric cell are explained by taken into account a 1D analytical thermal model coupling thermal conductive and radiative transfers.

Measurement of Heating Rates in a Microscopic Surface-Electrode Ion Trap**Supported by the National Natural Science Foundation of China under Grant Nos Y5Z2111001, 91421111 and 11674360.

We report measurement of heating rates of ions confined in our home-made microscopic surface-electrode trap by a Doppler recooling method. The ions are trapped with approximately above the surface, and are subjected to heating due to various noises in the trap. There are 3–5 ions involved to measure the heating rates precisely and efficiently. We show the heating rates in variance with the number and the position of the ions as well as the radio-frequency power, which are helpful for understanding the trap imperfection.

Heat transfer rate within non-spherical thick grains

The prediction of the internal heat conduction into non-spherical thick grains constitutes a significant issue for physical modeling of a large variety of application involving convective exchanges between fluid and grains. In that context, the present paper deals with heat rate measurements of various sizes of particles, the thermal sensors being located at the interface fluid/grain and into the granular materials. Their shape is designed as cuboid in order to control the surface exchanges. In enclosed coneshaped apparatus, a sharp temperature gradient is ensured from a hot source releasing the air stream temperature equal to about 400°C. Two orientations of grain related to the air stream are considered: diagonally and straight arrangements. The thermal diffusivity of the grains and the Biot numbers are estimated from an analytical solution established for slab. The thermal kinetics evolution is correlated to the sample granular mass and its orientation dependency is demonstrated. Consequently, a generalized scaling law is proposed which is funded from the effective area of the heat transfer at the grain-scale, the dimensionless time being defined from the calculated diffusional coefficients.