Showing papers on "Calorimeter published in 2021"

Heat loss distribution: Impedance and thermal loss analyses in LiFePO4/graphite 18650 electrochemical cell

Abstract: We report here thermal behaviour and various components of heat loss of 18650-type LiFePO4/graphite cell at different testing conditions. In this regard, the total heat generated during charging and discharging processes at various current rates (C) has been quantified in an Accelerating Rate Calorimeter experiment. Irreversible heat generation, which depends on applied current and internal cell resistance, is measured under corresponding charge/discharge conditions using intermittent pulse techniques. On the other hand, reversible heat generation which depends on entropy changes of the electrode materials during the cell reaction is measured from the determination of entropic coefficient at various states of charge/discharge. The contributions of irreversible and reversible heat generation to the total heat generation at both high and low current rates are evaluated. At every state of charge/discharge, the nature of the cell reaction is found to be either exothermic or endothermic which is especially evident at low C rates. In addition, electrochemical impedance spectroscopy measurements are performed on above 18650 cells at various states of charge to determine the components of internal resistance. The findings from the impedance and thermal loss analysis are helpful for understanding the favourable states of charge/discharge for battery operation, and designing better thermal management systems.

A Simplified Mathematical Model for Heating-Induced Thermal Runaway of Lithium-Ion Batteries

Abstract: The present study aims to develop a simplified mathematical model for the evolution of heating-induced thermal runaway (TR) of lithium-ion batteries (LIBs). This model only requires a minimum number of input parameters, and some of these unknown parameters can be obtained from accelerating rate calorimeter (ARC) tests and previous studies, removing the need for detailed measurements of heat flow of cell components by differential scanning calorimetry. The model was firstly verified by ARC tests for a commercial cylindrical 21700 cell for the prediction of the cell surface temperature evolution with time. It was further validated by uniform heating tests of 21700 cells conducted with flexible and nichrome-wire heaters, respectively. The validated model was finally used to investigate the critical ambient temperature that triggers battery TR. The predicted critical ambient temperature is between 127 °C and 128 °C. The model has been formulated as lumped 0D, axisymmetric 2D and full 3D to suit different heating and geometric arrangements and can be easily extended to predict the TR evolution of other LIBs with different geometric configurations and cathode materials. It can also be easily implemented into other computational fluid dynamics (CFD) code.

The very forward CASTOR calorimeter of the CMS experiment

Abstract: The physics motivation, detector design, triggers, calibration, alignment, simulation, and overall performance of the very forward CASTOR calorimeter of the CMS experiment are reviewed. The CASTOR Cherenkov sampling calorimeter is located very close to the LHC beam line, at a radial distance of about 1 cm from the beam pipe, and at 14.4 m from the CMS interaction point, covering the pseudorapidity range of $-$6.6 $\lt\eta\lt$ $-$5.2. It was designed to withstand high ambient radiation and strong magnetic fields. The performance of the detector in measurements of forward energy density, jets, and processes characterized by rapidity gaps, is reviewed using data collected in proton and nuclear collisions at the LHC.

Getting High: High Fidelity Simulation of High Granularity Calorimeters with High Speed

Abstract: Accurate simulation of physical processes is crucial for the success of modern particle physics. However, simulating the development and interaction of particle showers with calorimeter detectors is a time consuming process and drives the computing needs of large experiments at the LHC and future colliders. Recently, generative machine learning models based on deep neural networks have shown promise in speeding up this task by several orders of magnitude. We investigate the use of a new architecture—the Bounded Information Bottleneck Autoencoder—for modelling electromagnetic showers in the central region of the Silicon-Tungsten calorimeter of the proposed International Large Detector. Combined with a novel second post-processing network, this approach achieves an accurate simulation of differential distributions including for the first time the shape of the minimum-ionizing-particle peak compared to a full Geant4 simulation for a high-granularity calorimeter with 27k simulated channels. The results are validated by comparing to established architectures. Our results further strengthen the case of using generative networks for fast simulation and demonstrate that physically relevant differential distributions can be described with high accuracy.

High-resolution calorimetry in pulsed magnetic fields.

Abstract: We have developed a new calorimeter for measuring the thermodynamic properties in pulsed magnetic fields. Instrumental design is described along with the instrument construction details, including the sensitivity of a RuO2 thermometer. Operation of the calorimeter is demonstrated by measuring the heat capacity of three samples: pure germanium, CeCu2Ge2, and κ-(BEDT-TTF)2Cu[N(CN)2]Br, in pulsed fields up to 43.5 T. Obtaining field stability is key in measuring high-resolution heat capacity under pulsed fields. We also examine the performance of the calorimeter by employing two measurement techniques: the quasi-adiabatic and dual-slope techniques. We demonstrate that the calorimeter developed in this study is capable of performing high-resolution calorimetry in pulsed magnetic fields, which opens the door to new opportunities for high-field thermodynamic studies.

Experimental tests and signal unfolding of a scintillator calorimeter for laser-plasma characterization

Abstract: With the development of high-intensity and high-repetition rate laser systems, it has become crucial to be able to detect and characterize in real time the high-energy byproducts (mainly electrons and photons) of laser-generated plasma. A novel multi-purpose scintillator-based electromagnetic calorimeter focused on high-energy particle and photon measurements and capable of working on a shot-by-shot basis at high-repetition rate is being developed at the ELI Beamlines center. Preliminary tests of this device under photon and electron irradiation from conventional and laser-driven sources are summarized and the results are here presented. A corresponding signal unfolding technique which was ad-hoc developed to reconstruct energies of one or two thermal populations in short time is described in detail.

A Micromachined Picocalorimeter Sensor for Liquid Samples with Application to Chemical Reactions and Biochemistry.

Abstract: Calorimetry has long been used to probe the physical state of a system by measuring the heat exchanged with the environment as a result of chemical reactions or phase transitions. Application of calorimetry to microscale biological samples, however, is hampered by insufficient sensitivity and the difficulty of handling liquid samples at this scale. Here, a micromachined calorimeter sensor that is capable of resolving picowatt levels of power is described. The sensor consists of low-noise thermopiles on a thin silicon nitride membrane that allow direct differential temperature measurements between a sample and four coplanar references, which significantly reduces thermal drift. The partial pressure of water in the ambient around the sample is maintained at saturation level using a small hydrogel-lined enclosure. The materials used in the sensor and its geometry are optimized to minimize the noise equivalent power generated by the sensor in response to the temperature field that develops around a typical sample. The experimental response of the sensor is characterized as a function of thermopile dimensions and sample volume, and its capability is demonstrated by measuring the heat dissipated during an enzymatically catalyzed biochemical reaction in a microliter-sized liquid droplet. The sensor offers particular promise for quantitative measurements on biological systems.

Construction and commissioning of CMS CE prototype silicon modules

Abstract: As part of its HL-LHC upgrade program, the CMS Collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with $\sim$30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1~$cm^2$, and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration.

Ultrasensitive Calorimetric Measurements of the Electronic Heat Capacity of Graphene.

Abstract: Heat capacity is an invaluable quantity in condensed matter physics and yet has been completely inaccessible in two-dimensional (2D) van der Waals (vdW) materials, owing to their ultrafast thermal relaxation times and the lack of suitable nanoscale thermometers. Here, we demonstrate a novel thermal relaxation calorimetry scheme that allows the first measurements of the electronic heat capacity of graphene. It is enabled by combining a radio frequency Johnson noise thermometer, which can measure the electronic temperature with a sensitivity of ∼20 mK/Hz1/2, and a photomixed optical heater that modulates Te with a frequency of up to Ω = 0.2 THz. This allows record sensitive measurements of the electronic heat capacity Ce < 10 -19 J/K and the fastest measurement of electronic thermal relaxation time τe < 10 -12 s yet achieved by a calorimeter. These features advance heat capacity metrology into the realm of nanoscale and low-dimensional systems and provide an avenue for the investigation of their thermodynamic quantities.

Artificial Neural Networks on FPGAs for Real-Time Energy Reconstruction of the ATLAS LAr Calorimeters

Abstract: The ATLAS experiment at the Large Hadron Collider (LHC) is operated at CERN and measures proton–proton collisions at multi-TeV energies with a repetition frequency of 40 MHz. Within the phase-II upgrade of the LHC, the readout electronics of the liquid-argon (LAr) calorimeters of ATLAS are being prepared for high luminosity operation expecting a pileup of up to 200 simultaneous proton–proton interactions. Moreover, the calorimeter signals of up to 25 subsequent collisions are overlapping, which increases the difficulty of energy reconstruction by the calorimeter detector. Real-time processing of digitized pulses sampled at 40 MHz is performed using field-programmable gate arrays (FPGAs). To cope with the signal pileup, new machine learning approaches are explored: convolutional and recurrent neural networks outperform the optimal signal filter currently used, both in assignment of the reconstructed energy to the correct proton bunch crossing and in energy resolution. The improvements concern in particular energies derived from overlapping pulses. Since the implementation of the neural networks targets an FPGA, the number of parameters and the mathematical operations need to be well controlled. The trained neural network structures are converted into FPGA firmware using automated implementations in hardware description language and high-level synthesis tools. Very good agreement between neural network implementations in FPGA and software based calculations is observed. The prototype implementations on an Intel Stratix-10 FPGA reach maximum operation frequencies of 344–640 MHz. Applying time-division multiplexing allows the processing of 390–576 calorimeter channels by one FPGA for the most resource-efficient networks. Moreover, the latency achieved is about 200 ns. These performance parameters show that a neural-network based energy reconstruction can be considered for the processing of the ATLAS LAr calorimeter signals during the high-luminosity phase of the LHC.

Continuous milli-scale reaction calorimeter for direct scale-up of flow chemistry

Abstract: Reaction calorimetry of flow processes is important for scale-up and safety in flow chemistry. Due to the increasing number of flow processes, corresponding flow calorimeters are required as an alternative or addition to high-precision batch calorimeters. In this work, a milli-scale isoperibol continuous flow calorimeter was used to measure the heat of reaction based on an elaborated heat transfer model. This allows for reaction calorimetry without calibration. The model was tested with a selective, fast and exothermic neutralization reaction of acetic acid and sodium hydroxide at different flow rates, concentrations and viscosities. Deviations of the mean heats of reaction from the literature values were only about 2%. The calorimetric data can further be used for direct scale-up with tube bundle mixer heat exchangers having similar heat transfer characteristics. In addition, a reaction screening at different flow rates allows to find the maximum temperature and maximum heat generation. This data is useful in safety analyses of continuous processes. For these reasons, continuous reaction calorimetry provides a practical scale-up tool for flow processes.

Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

Abstract: Fast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted. A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.

The CaloCube calorimeter for high-energy cosmic-ray measurements in space: performance of a large-scale prototype

Abstract: The direct observation of high-energy cosmic rays, up to the PeV energy region, will increasingly rely on highly performing calorimeters, and the physics performance will be primarily determined by their geometrical acceptance and energy resolution. Thus, it is extremely important to optimize their geometrical design, granularity and absorption depth, with respect to the totalmass of the apparatus, which is amongst the most important constraints for a space mission. CaloCube is an homogeneous calorimeter whose basic geometry is cubic and isotropic, obtained by filling the cubic volume with small cubic scintillating crystals. In this way it is possible to detect particles arriving from every direction in space, thus maximizing the acceptance. This design summarizes a three-year R&D activity, aiming to both optimize and study the full-scale performance of the calorimeter, in the perspective of a cosmic-ray space mission, and investigate a viable technical design by means of the construction of several sizable prototypes. A large scale prototype, made of a mesh of 5x5x18 CsI(Tl) crystals, has been constructed and tested on high-energy particle beams at CERN SPS accelerator. In this paper we describe the CaloCube design and present the results relative to the response of the large scale prototype to electrons.

Continuous Monitoring of the Early-Age Properties of Activated GGBFS with Alkaline Solutions of Different Concentrations

Abstract: This study monitors the early-age reaction kinetics and measures the heat of reaction of alkali-activated ground granulated blast-furnace slag (GGBFS) using an isothermal calorimeter, and t...

Analysis of Two Calculation Methods of Heat Flux Based on Slug Calorimeter

Abstract: The temperature of plasma jet is difficult to be measured directly because of its high temperature. The heat flux is often used to measure the thermodynamic properties of plasma jet and high temperature flow field. In this paper, two methods of heat flux calculation using slug calorimeter in plasma jet flow field are analyzed. One calculation method is based on one dimensional thermodynamic equation, ignoring the heat loss in the measurement process, called the noloss calculation equation; the other calculation method is to subtract the heat loss from the noloss method. This paper uses numerical simulation and experimental methods to verify the accuracy of the two heat flux calculation equations. The heat flux value is calculated according to the measured data, and the temperature curve is calculated in reverse from the calculated heat flux value. Finally, the calculated temperature curve is compared with the measured temperature curve. The temperature curve with loss heat flux is more consistent with the measured temperature curve. The loss calculation equation can obtain a more accurate heat flux value than the noloss calculation equation, and the error between the two is within 10%. The loss equation is calculated accurately, but it is difficult to give real-time results. There is an error in the noloss equation, but the calculation is simple and gives real-time results.

Thermal behavior and failure mechanism of large format lithium-ion battery

Abstract: Thermal runaway (TR) behavior of 38 Ah lithium-ion batteries with various states of charge (SOC) is experimentally investigated in this work using extended volume plus accelerating rate calorimeter (EV+ ARC). Some of the critical kinetic parameters, such as onset exothermic temperature (Tonset), temperature of TR (TTR), and maximum temperature (Tmax), can be obtained to characterize the risks of TR event. The impact of SOC on thermal stability of the battery is researched. It is found that the higher the SOC state, the lower the battery safety. Thermal features of both the cathode and anode, as well as the materials, are also investigated. The morphology and the structure change of the materials are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Finally, a general theory is proposed and detailed reactions are summarized in this work. The thermal runaway follows a mechanism of chain reactions, during which the decomposition reactions of the battery component materials occur one after another.

Thermal Property Measurements of a Large Prismatic Lithium-ion Battery for Electric Vehicles

Abstract: Because of the high cost of measuring the specific heat capacity and the difficulty in measuring the thermal conductivity of prismatic lithium-ion batteries, two devices with a sandwiched core of the sample-electric heating film-sample were designed and developed to measure the thermal properties of the batteries based on Fourier’s thermal equation Similar to electrical circuit modeling, two equivalent thermal circuits were constructed to model the heat loss of the self-made devices, one thermal-resistance steady circuit for the purpose of measuring the thermal conductivity, the other thermal-resistance-capacitance dynamic circuit for the purpose of measuring the specific heat capacity Using the analytic method and recursive least squares, the lumped model parameters of these two thermal circuits were extracted to estimate the heat loss and correct the measured values of the self-made devices Compared to the standard values of the reference samples of the glass and steel plates, the measured values were corrected to improve the measurement accuracies beyond 95% through steady thermal-circuit modeling Compared to the measured value of the specific heat capacity of the battery sample at 50% state of charge using the calorimeter, the measured value using the self-made device was corrected in order to elevate the measurement accuracy by about 90% through dynamic thermal-circuit modeling As verified through the experiments, it was reliable, convenient, and low cost for the proposed methodology to measure the thermal properties of prismatic lithium-ion batteries

Thermal analysis and hazards evaluation for HTP-65W through calorimetric technologies and simulation

Abstract: Di-tert-butyl peroxy-hexahydro terephthalate (HTP-65W), a newly developed organic peroxide, has been used in manufacturing acrylonitrile–butadiene–styrene copolymer and as an initiator in the polymerization. However, few studies focus on the thermal hazards of HTP-65W. The purpose of this study was to investigate the thermal decomposition phenomenon of HTP-65W under different conditions via calorimetric technologies and simulation. According to simultaneous thermogravimetric analyzer curves, two mass loss stages were detected at about 79 °C and around 64–72% mass loss happened in the first stage. Furthermore, the real view system was used to observe the apparent physical phenomenon like color and state change in HTP-65W during the reaction. Utilizing accelerating rate calorimeter and adiabatic kinetic method, the exothermic phenomena occurred at around 75 °C. The apparent activation energy (Ea) and rate constant of reaction under adiabatic conditions were 172.0 kJ mol−1 and 4.0 × 1025 mol L−1 s−1. Through differential scanning calorimetry and kinetics simulation, an exothermic peak appeared between 87 and 168 °C caused by the thermal decomposition of HTP-65W, and the Ea calculated using Flynn–Wall–Ozawa and Friedman methods were 143.4 and 128.4 kJ mol−1, respectively. To prevent thermal loss prevention accidents, time to maximum rate under adiabatic condition was obtained as 24 h under 63.9 °C and self-accelerating decomposition temperature was 61 °C for 50 kg package size of HTP-65W. Results of this study can support to prevent the potential thermal hazards of HTP-65W happened during storage, transportation, and manufacturing process.

Thermal kinetics analysis of polymerization reaction of styrene-ethylbenzene system

Abstract: To explore the reaction thermodynamics of a styrene-ethylbenzene mixed system, a differential scanning calorimetry (DSC) analysis was performed on the mixed system with styrene: ethylbenzene mass ratios of 1:0, 4:1, 3:2, and 2:3 at heating rates of 2.5, 5, 7.5, and 10 K/min. The activation energy of the mixed reaction system was calculated using the model-free Kissinger kinetic method, to determine a mixed system of relative stability mixing proportion. The thermodynamic parameters of the styrene-ethylbenzene mixture system at the optimal ratio were obtained using an adiabatic accelerating calorimeter. Further, dynamic thermal parameters such as the activation energy of the hybrid system, pre-exponential factor and order of reaction, TMR, TMRad, and TD24 were calculated.