Thermal Module Research Articles

Memory computing based on thermal memory elements

The article analyses the possibility of using elements of thermal memory to create a system that allows to perform calculations in memory. Such a computing system is built on devices that are used simultaneously for storing input data, performing a logical operation, and storing the output result. The authors conclude that it is possible to emulate this behaviour by using thermal memory elements with dielectric (SiO2) by a layer of thermal insulation. Special attention is paid to the logic gates of computing systems and their realisation on the basis of thermal memory elements. Simulation modelling of the work of such elements is carried out on the ANSYS Workbanch platform using the Transient Thermal module for non-stationary thermal calculations. On the basis of the modelling, the possibility of creating two basic logic gates “AND” and “OR” is established. The results can be used to create more integrated structures, such as artificial neural networks.

Analysis of heating of printed circuit board conductors on a metal base for spacecraft devices at pulsed current

The article presents the results of the analysis of heating of printed circuit conductors of printed circuit boards mounted on a metal base, on-board device of spacecraft when pulsed current flows through them. Thermal transient and impulse characteristics of a system consisting of a printed conductor and a printed circuit board are considered. The analysis of the dependence of the temperature rise rate of printed conductors and the duration of transient processes on the linear dimensions of the system elements is given. It is noted in the article that the time of transient processes most strongly depends on the thickness of the layer of insulating materials. All the results were obtained in the process of modeling transients in the ANSYS 2019 R1 Transient Thermal module. Practical recommendations on the consideration of thermal transients in printed conductors in the design of printed circuit boards are given.

DeepThermal Outdoor: A first-person thermal imaging dataset

Recently, thermal imaging modules equipped for infantry soldiers have been a trend to improve the combat ability of soldiers. Soldiers have to perform many different tasks at the same time, so it is necessary to equip them with the tools of automatic target detection, especially human objects detection, in practice. Hence, there is a need to intelligently optimize the effectiveness of thermal imaging equipment. New artificial intelligence and deep learning(DL) approaches are applicable methods that show superior accuracy compared to previous methods. However, state-of-the-art DL methods depend on the generality and diversity of the training data set. To address this issue, our paper presents the DeepThermal Outdoor thermal imaging data set, which is collected from equipment mounted on the body of infantry at various terrain locations. The labeled dataset focuses on human objects with different locomotion postures, and it contains 10,190 images and 22,464 labeled human-objects. Finally, the experiment is conducted with several DL methods using the proposed dataset, and the results show its contribution to the improvement of the performance of DL methods to detect humans on thermal images as well as to evaluate the practical applicability of a DL.

Calculation of upper support shafts cooling system parameters by means of the finite element method

Problem. The paper proposes a method for solving the problem of the temperature regimes of the upper support shafts using the finite element method. Thus, using the experimentally obtained values of the cooling air flow of the shafts, the possibility of using the State Thermal module of the Ansys software for a multi-iteration study of the temperature distribution and determining the ranges of thermal expansion was considered. It is an important task during engineering tasks solution. Goal. The goal of the paper is to develop a methodology to solve thermal exchange tasks using FEA methods based on the experiment research of the thermal processes. Methodology. Solution of the tasks involved application of the theoretical approach in order to build up multi-purpose solid models with the range of initial data to provide a simulation research. Results. The proposed method allows to determine the efficiency of the cooling system in a wide range of changes in air flow parameters and the compliance of the established thermal clearances of the bearing assemblies. Originality. Engineering tasks of the denoted area are rarely solved with FEA, especially thermal package. Thus, implementation of the software with experimental research kit allows in timely manner check the thermal state of the shafts and indicate possible cooling air leaks at the very first stage to avoid time consuming technical service. Practical value. The use of the denoted methodology allows to adjust cooling system in terms of sufficient shaft thermal state of bearing clearances and keep updated cooling parameters to maneuver the main ventilation system.

Разработка тепловой изоляции с упорядоченной структурой, основанной на ТПМП Неовиуса

Currently, materials with a random pore arrangement are mainly used as thermal insulation. Such materials, as a rule, have low strength. To solve a number of structural tasks, a heat-insulating material with a high specific strength is required.To date, for these purposes sandwich panels with layers of honeycomb cells filled with air are applied. In this regard, the current goal is to develop more efficient materials with an ordered structure, which will have greater thermal resistance and strength. For numerical simulation of thermal conductivity in a porous material with an ordered structure, the Steady-State Thermal module of the ANSYS software package has been used. Polymers that are often used in 3D printing, such as PETG plastic and Phrozen photopolymer, are chosen as materials for a porous medium with the Neovius TFMT structure. As a result of the study of thermal conductivity in an elementary cell of the Neovius surface in the ANSYS software package, the values of the effective thermal conductivity coefficient are obtained for various characteristic of geometric parameters (cell wall thickness, length of the edge of the cube in which the cell of the Neovius surface is inscribed). Based on the results obtained, it has been found that the dependence of the coefficient of effective thermal conductivity on the cell wall thickness (as well as on the relative cell thickness) is linear. It has been also determined that the geometry under study has a quasi-isotropic thermal conductivity, since it has cubic symmetry. Based on these results, the corresponding graphical and analytical dependencies are designed. The developed heat-insulating material with an ordered structure based on Neovius TPMT is proposed to be used as thermal insulation. The obtained graphical and analytical dependences make it possible to determine the coefficient of effective thermal conductivity of a material with a structure based on the Neovius TFMT with known characteristic geometric parameters (cell wall thickness, cube edge length). The results obtained can be used to design thermal insulation for several tasks when, in addition to thermal insulation properties, structural strength is also important. The porous structure can be produced using modern 3D printing methods, such as selective laser sintering (SLS), laser stereolithography (SLA), etc.

Effect of mechanical vibration on phase change material based thermal management module of a lithium-ion battery at high ambient temperature

Phase change material (PCM) based thermal management is regarded as a promising method for cooling power systems of lithium-ion battery electric vehicles. The battery thermal management modules of electric vehicles usually work under vibration conditions and it has been widely recognized that mechanical vibration can enhance heat transfer. However, the knowledge on effects of mechanical vibration on PCM-based lithium-ion battery thermal management systems is still sparse. To bridge the knowledge gap, the effect of mechanical vibration on a PCM-based lithium-ion battery thermal management module with a high environment temperature is investigated comprehensively for the first time. A variety of parameters, such as PCM thickness, vibration amplitude and vibration frequency, are discussed in detail. Some new findings are reported: (1) mechanical vibration has a significant influence on the PCM-based lithium-ion battery thermal management module, especially for a PCM layer with a moderate thickness; (2) when the vibration amplitude increases over a certain high value, the influence of mechanical vibration becomes nearly insensitive to the variation of vibration amplitude; (3) the thermal performance does not depend on vibration frequency monotonically. The research can provide guidance for the design of thermal management modules of electric vehicles.

Energy and exergy evaluation of a baffled-nanofluid-based photovoltaic thermal system (PVT)

In this paper, a differently baffled-nanofluid-based photovoltaic thermal module is proposed and numerically evaluated from both an energy and an exergy perspective. To obtain the optimum module, several systems including; the PV module (PVM), the simple channel collector PVT module (SPVTM), and the baffled channel collector PVT module (BPVTM), were investigated using three working fluids, including pure water, CuO/water nanofluid, and CNT/water nanofluid. Following a comparison of these seven various case studies, the overall performance of the suggested system from both energy and exergy in order to choose the ideal system was assessed about several variables, such as flow rate, radiation intensity, volume fraction, and wind speed. The results show that baffle-based PVT systems outperform simple-based modules in terms of efficiency. Also, the performance of the baffled model is well amplified by using nanofluids. When compared to the SPVTM/water, the BPVTM/CuO and BPVTM/CNT increase thermal power by 9.46 and 14.0%, respectively, increase electrical power by 1.41 and 2.12% and also reduce solar cell temperature by 9.22 and 13.82%. Power generation from the BPVTM/CNT is the highest among the other cases investigated. The overall exergy efficiency of the baffled PVT module with CuO/water and CNT/water increases by 0.44% and 2.38%, respectively, in comparison to that with water. The findings suggest that while low flow rates are generally better for the system's exergy performance, high flow rates are more advantageous from an energy perspective. The performance of the PVTM with CuO/water nanofluid is marginally better than the unit with water. However, the CNT/water nanofluid systems significantly outperform the water and CuO/water systems.

Influence of fault current on electromagnetic-thermal characteristics of HTS coated conductors

In this paper, the electromagnetic-thermal coupling numerical model is used to study the loss and temperature distribution of two typical high temperature superconducting (HTS) coated conductors (CCs) under short-circuit fault, as well as the dynamic evolution law with time. The electromagnetic module adopts the widely used H-formulation, and the thermal module adopts the general form of heat conduction equation. The coupling between the two module is realized by using the loss calculated by the electromagnetic module as the heat source of the thermal module and combining the Jc0(B, T) relationship. A modified E-J relation suitable for any current density range is used to describe the resistivity of superconductors. Due to the difference of magnetic and thermal properties of the two kinds of structural tape substrate materials and geometric dimensions of copper stabilized layer, the losses of the two kinds of structural tape under different fault currents show obvious differences. At low fault transport current, the magnetic substrate of type B tape (NiW substrate) will obviously make the magnetic flux density perpendicular to the superconducting layer greater than that of type A tape (Hastelloy substrate), thus making the loss of type B tape greater. Under the condition of high fault transport current, the fault current will be shunted between different layers of the tape. Type B tape has a thicker copper stabilizer, which makes the current density of type B tape copper layer lower than that of type A tape, and the temperature rise and loss of type B tape are lower. Specifically, when Ip/Ic0 is less than about 0.65, the total loss of type A tape is less than that of type B tape. When Ip/Ic0 is greater than about 0.65, the total loss of type A tape is greater than that of type B tape.

Modeling of energy and exergy efficiencies in high vacuum flat plate photovoltaic–thermal (PV–T) collectors

This work deals with the performance evaluation of novel flat photovoltaic–thermal (PV–T) modules under vacuum. Through a 1D (dimensional) steady-state-energy-balance numerical model developed in MATLAB, two different layouts are studied: the first consisting of a photovoltaic (PV) cell installed just below the glass encapsulating the flat panel, and the second where the PV cell is placed on the selective solar absorber (SSA). In both cases the thermal and electrical efficiencies have been evaluated at different SSA operating temperatures, in the range of 323 K to 423 K. The analysis has been conducted at different energy bandgap (Ebg) of the PV cell and assuming a variable transmittance or emittance of the PV cell, depending on the design. The two systems efficiency comparison has been carried out at the same operating temperature. Overall, this work highlights the importance of high vacuum insulation, which guarantees the reduction of convective thermal losses, and shows that the maximum energy is produced for PV cells with Ebg≈1.5-1.7 eV, depending on layout and operating temperature, by including the thermal output in the PV–T​ optimization. The energy and exergy efficiencies obtainable using the proposed PV–T​ systems are considerably improved compared to the results previously reported in the literature.

Research and Application of Temperature Load of Switchgear

Abnormal changes in the temperature and load current of the high-current switchgear will directly affect the reliable operation of the equipment. In order to effectively monitor the temperature of the switchgear and ensure the reasonable arrangement of temperature measurement sensors, this paper realizes the optimal arrangement of sensors and the temperature prediction of the switchgear through simulation and test of the switchgear. Firstly, Ansoft electro thermal simulation module is used for joint simulation, the change of temperature field and the heating of current carrying bus are analyzed, the test data of temperature change under different environmental conditions are obtained, and the relationship between the temperature sensor and the distance between the hot spot is mastered. Then the temperature load curves under different currents are obtained through the test, and the accuracy of the research results is verified by the combination of theoretical simulation and field test. The test results can not only provide guidance for the temperature sensor installation scheme of substation field operation and maintenance personnel, but also improve the stability of equipment operation.

Hybrid Opto‐Thermocycler for RT‐qPCR Detects SARS‐CoV‐2

AbstractAlthough real‐time quantitative reverse transcription polymerase chain reaction (RT‐qPCR) is the gold standard for detecting the virus severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) and other pathogens, the coronavirus disease 2019 (COVID‐19) pandemic has highlighted the scarcity of instruments, devices, and reagents for polymerase chain reaction (PCR) testing in constrained settings. At least for under‐resourced countries, it has become critical to deploy instruments that can be rapidly constructed and satisfy this demand. Instead of separating the optical system from the thermal module (typical of qPCR thermocyclers), we report a portable Hybrid Opto‐Thermocycler—dubbed HybOT Cycler—that takes advantage of the high‐temperature tolerances (>100 °C) of electronic and optical components to combine thermal control, illumination, and fluorescence detection into a highly integrated hybrid module. This simple configuration allowed us to reduce the overall number of components, thus simplifying its assembly and reducing the instrument size. The HybOT Cycler is wirelessly controlled from an application installed in a tablet. PCR assays are carried out in a bubble‐free microfluidic device that can be easily replicated from an acrylic mold. Using the HybOT Cycler, down to 100 copies/µL of genetic material of the virus SARS‐CoV‐2 with 95% sensitivity and 100% specificity is detected. The HybOT Cycler can assist in diagnosing SARS‐CoV‐2 and other pathogens in resource‐poor settings.

A thermal performance-enhancing strategy of photovoltaic thermal systems by applying surface area partially covered by solar cells

In this work, a single unit called photovoltaic thermal with solar thermal collector enhancer has been developed, whose absorber plate is partially covered by photovoltaic cells. This design increases the photothermal energy conversion ratio and absorbed energy by the system, resulting in a higher thermal power, thermal exergy, and outflow temperature compared to a conventional photovoltaic thermal module. This research examines the impacts of different glazing arrangements on the system performance using a three-dimensional transient model to determine the most efficient design from energy and exergy viewpoints. Moreover, the effects of various parameters on system performance, such as tilt angle, azimuth angle, mass flow rate, and dust accumulation on the system surface, are discussed. Finally, a comparative study between the proposed system, the standalone solar thermal collector, and the standalone photovoltaic thermal system is carried out in terms of energy, exergy, and economics. Results indicate that the proposed system has 31.24 % greater overall power and 35.07 % shorter payback time than a conventional standalone unglazed photovoltaic thermal system when only its solar collector enhancer part is covered by glass.

Study on thermal storage performance of heat storage tank with phase change material balls

In order to promote the application of heat storage device using phase change material (PCM), a water tank filled with sodium acetate trihydrate ball was designed, and its performance was studied. The effects of inlet temperature, flow rate on the charging and discharging time, hot water supply, thermal storage efficiency of PCM tank were analyzed through experiments and simulations. A new concept “heat loss rate of the heat exchange blind area” was put forward, by which the impact of PCM ball position on the heat exchange blind area was analyzed. The results show that with the increase of inlet temperature and flow rate, the charging and discharging time decrease. The hot water supply and the thermal storage efficiency reaches their maximum value (28.3L/h, 78 %) at the flow rate of 25L/h and the inlet temperature of 80 °C. When the height of the bracket in PCM tank is 60 mm, the heat loss rate of heat exchange blind area decreases by 47 %. The best height of PCM balls is 90 mm, which increases the average temperature of heat exchange blind area by 1.8 %. The study has guided significance for the practical application of water tank with phase change thermal storage module.

Steady-state thermal hydraulic modelling and turbine trip transient simulation of the NuScale integral pressurised water reactor using the ASTEC code

A steady state model of the NuScale reactor has been built using the thermal hydraulic module CESAR of the severe accident code ASTEC. Construction of the model was achieved through iterations based on convergence towards data provided by NuScale pertaining to important operating properties—core temperatures, coolant mass flow rate and secondary steam temperature—at 100% power (160 MW) and also at lower power levels. Good agreement with reference values was achieved to within 3% deviation. With a similar methodology, the previous model was adjusted to give a second steady state model meant to provide conservative initial conditions from which a turbine trip transient simulation would be performed. Sound agreement with literature was achieved, with maximum deviations of less than 1.8% for monitored parameters. Lastly, a turbine trip transient was simulated and compared to reference data from analyses performed with NRELAP5 and RELAP5/SCDAPSIM. The most important system behaviors and event timings are well captured and reproduced, with discrepancies arising from inevitable estimates made due to lack of information.

Overall deformation of steel-concrete-steel immersed structures during construction stage considering temperature effect

Temperature effect is one of the most significant factors to be considered in large-scale structures. For steel–concrete-steel composite immersed structures, the overall deformation is a closely watched indicator in the construction process. The main aim of this study is to investigate the overall deformation of steel–concrete-steel composite immersed structures during the construction stage, and thus a new numerical method comprehensively considering the temperature effect and material properties of early-age concrete is proposed. In the proposed method, a new finite element program for composite immersed structures, including thermal and structural modules, is developed in ANSYS. Firstly, the time-varying temperature distribution of the structure during the construction stage is accurately simulated by a transient thermal analysis, allowing for concrete hydration, solar radiation, air temperature, and changes of thermal properties comprehensively. Secondly, based on the ANSYS User-Programmable Features (UPFs), the stress–strain constitutive law of the concrete is redefined by modifying the material subroutine to consider the hardening and shrinkage of early-age concrete, then the overall structural deformation during the construction stage is estimated in the case that accurate temperature distribution and material properties are fully considered. Finally, a full-scale model of the composite immersed tunnel in Shenzhong Link is taken as an application case. The accuracy of simulation results is verified with the data of on-site monitoring. The results show that the temperature field of the composite immersed structure is obviously non-uniform and time-varying, and the overall contraction in lateral and longitudinal directions happens after the construction due to the variation of temperature and behaviors of early-age concrete.

Multisite calibration of a semi-distributed hydrologic and thermal model in a large Canadian watershed

ABSTRACT This study compares single-site and multisite calibration methods with upscaled parameters for thermal modelling. Multisite calibration and parameter upscaling are novel for calibrating a hydrological–thermal model. To this end, model calibration and simulations are carried out using a semi-distributed hydrological–thermal model (CEQUEAU). First, a hydrological calibration is carried out. The same calibrated hydrological model outputs are used for all thermal calibrations. The covariance matrix adaptation evolution strategy (CMA-ES) single-objective optimization algorithm is applied to calibrate the thermal module using observed water temperatures at seven monitoring sites within the Nechako Watershed in British Columbia, Canada. Single-site calibration provided the best performance for individual sites, but these sets of parameters performed poorly when applied to the other sites. The multisite calibration and the upscaled methods perform adequately for all sites with overall Root Mean Square Error (RMSE)<2°C as an acceptable threshold. However, the multisite method resulted in the best performance metrics and shortest computing time.

The effect of heat generation via interface recombination in CZTSSe kesterite thin film solar cells: A simulation study

Heat generation via Interface recombination in CZTSSe/CdS kesterite thin film solar cells has been investigated using a simulation model by coupling the thermal, electrical, and optical modules. Three interface defects (CuSn, CuZn, SnZn) located at different energy levels were considered. The defect closer to the midgap (CuSn at 0.55 eV) generate the highest heat power and increasing the defect density from 1014 cm−3 to 1018 cm−3 raised the interface heat generation from 60 W/cm2 to 80 W/cm2. This is nearly half of heat generation rate for CuZn defect located near the valence band. Hsurf raised from 60 W/cm2 to 74 W/cm2 by increasing the surface recombination velocity (S). This detailed simulation analysis recognizes the significant role of interface recombination and its contribution to heat generation and thermal stability in solar cells and demonstrates the importance of interface quality and interface engineering strategies in such devices.

Closed EWOD-based low-cost portable thermal detection system for point-of-care applications

Electrowetting-on-Dielectric (EWOD) is a powerful technology for biological and chemical diagnostics. It offers advantages of low sample volume, high sensitivity, high throughput and the possibility of automation. Of special interest is a miniaturization of a thermal detection system by utilizing the EWOD technique since it can minimize effort while reducing cost and the system size. The present study describes the development of a closed EWOD device for droplet actuation that is integrated with thermal cycling and optical diagnostics. Important steps, including sample and reagent transportation, merging and mixing, and color detection, are performed on the integrated platform. The thermal module uses heating as well as Peltier elements and K-type thermocouples with a PID controller to perform precise thermal cycling needed in clinical and medical diagnostics. Experimentally recorded temperature distribution that is realized in the closed EWOD configuration is numerically validated using the COMSOL simulator. The efficacy of the integrated system is experimentally demonstrated by performing Fehling’s test for glucose detection in a glycerin solution. Furthermore, the device is used to demonstrate the transportation of a liquid drop of blood mimicking liquid at a relatively high temperature of 90 °C. The system thus developed is reliable, providing real-time proof-of-concept and the feasibility of building a low-cost point-of-care EWOD device. • A portable closed EWOD based medical diagnostic system with thermal cycling is demonstrated. • Thermal management using heating and cooling element is integrated with the closed EWOD device. • Temperature distribution within the device is measured experimentally and validated against simulation. • Droplet motion is successfully realized over the temperature range studied, providing real-time proof-of-concept. • The system developed is tested by performing Fehling’s test for glucose detection.

Design and analysis of an innovative photovoltaic-thermal collector with embedded tank

This paper deals with a new design of a photovoltaic-thermal (PVT) collector which incorporates a storage tank at the back of the thermal module to store heat as well as an electrical resistance to increase thermal production when necessary. This work investigates modeling and CFD study with the aim to provide a dynamic model which reflects a realistic behavior of the system. Simulations are performed to validate the model and to highlight the usefulness of the proposed design. Moreover, the modeling proves to be useful in analyzing the influence of internal geometrical parameters, such as thickness of insulation and absorber, type of fluid and also of materials used for absorber and serpentine tube.

Development of a low-cost multi-channel nucleic acid detection PCR instrument and clinical detection application of COVID-19

Since the COVID-19 outbreak at the end of December 2019, a variety of novel Coronavirus nucleic acid detection methods have been proposed at home and abroad. Because of the disadvantages of most existing PCR instruments on the market such as long reaction time and high cost, this study developed a more timesaving and cheaper two-channel real-time quantitative PCR instrument. In this instrument, a PCR system combining a thermal cycle system and real-time fluorescence quantitative technology was designed. The software system and data processing, optical system, thermal cycle module, and hardware module of the PCR instrument were studied. The low-cost, portable real-time quantitative PCR system has been validated with consistent results compared to Bio-rad CFX Connect. At the same time, the same samples were used for the contract experiment with the hospital instrument, and the amplification result was better than the existing instrument in the hospital.