Thermal Modeling Research Papers - Academia.edu (original) (raw)

A pseudo dynamic thermal model has been developed for simulating the heating/cooling energy requirement of conventional greenhouses based on lumped estimation of heat flow parameters in greenhouses. Most of the parameters of greenhouse energy flux have been considered in the model including the sensible heat usage in plant transpiration, and also heat gain from environmental control systems. The developed model can simulate the hourly heating/cooling requirement of greenhouses based on input information about desired indoor environment, dimension and thermal properties of constructional materials, characteristics of selected crop, and local weather data. This model would be beneficial for researchers, engineers and growers to estimate the energy requirement of greenhouses, thereby model would be a useful tool for their decision making about the energy efficient design, and feasibility analysis of greenhouses for a particular locations.

- by
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- HVAC modelling, Thermal Modeling, Controlled Environment Agriculture

In modern systems, electrical power distribution and actuation replace mechanical, hydraulic or pneumatic systems. An estimated 30% of world’s electrical energy was processed by power electronic systems in 2005, with a predicted increase to 80% by 2030. An understanding of future capabilities of power electronics & bottlenecks limiting increases in performance of such systems is required. Designing a filter/converter is a complex engineering task that balances many interacting and often conflicting pressures. A computational tool that accounts for them while seeking optimal (power-dense) designs is of high value for designers.

Contemporary cities experience poor urban environment conditions. High densities have resulted in the genesis of the Heat Island effect that under the undeniable climate change will only get intensified. Reducing the ambient temperatures and improving the microclimate inside the urban fabric appears to be urgent. This paper examines the parameters affecting the urban microclimate. Through the analysis of a typical urban block and the process of fieldwork in the city centre of Thessaloniki, urban geometrical characteristics and environmental conditions are identified. Possible design guidelines aiming to rehabilitate the urban block are also evaluated.

"As the operating temperature and efficiency of the gas turbine engine continue to increase, so does the need for accurate and reliable prediction of the thermal behaviour of the engine discs and casings. The designer has to know the transient temperature distribution of the engine components in order to determine the magnitude and distribution of stress and displacements as well as the requirements of sealing, cooling and purging air. Due to the complex geometries involved, numerical methods are usually employed to obtain these temperature distributions.
This paper reports on the thermal modelling of an experimental multiple cavity rig simulating the internal configuration of the high pressure compressor spool of a modern turbofan gas turbine. An advanced finite element code was used to predict the thermal behaviour of the rig over a transient cycle. Empirical heat transfer correlations were used as boundary conditions. The temperatures predicted from the model compared well with those measured in the experiments, but there are still some problems that must be resolved in order to increase the reliability of the model predictions. "

- by Alexios Alexiou
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- GAS TURBINE, Thermal Modeling, Rotating Cavity, Secondary Air System

Cooling systems take a significant portion of the total mass and/or volume of power electronic systems. In order to design a converter with high power density, it is necessary to minimize the converter's cooling system volume for a given maximum tolerable thermal resistance. This paper theoretically investigates whether the cooling system volume can be significantly reduced by employing new advanced composite materials like isotropic aluminum/diamond composites or anisotropic highly orientated pyrolytic graphite. Another strategy to improve the power density of the cooling system is to increase the rotating speed and/or the diameter of the fan, which is limited by increasing power consumption of the fan. Fan scaling laws are employed in order to describe volume and thermal resistance of an optimized cooling system (fan plus heat sink), resulting in a single compact equation dependent on just two design parameters. Based on this equation, a deep insight into different design strategies and their general potentials is possible. The theory of the design process is verified experimentally for cooling a 10 kW converter. Further experimental results showing the result of the operation of the optimized heat sink are also presented.

- by Andrija Stupar
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- Power Electronics, Thermal Modeling, Cooling systems, Heat Sinks

Climate change and rising energy costs necessitate a shift in how buildings that efficiently provide comfort are envisioned. With initiatives now aiming at bringing energy simulation into the mainstream of environmental design, the applicability of state-ofthe- art simulations in formally non-constrained creative production needs to be re-evaluated. To this end, a teaching experiment that includes multidomain simulations as drivers into the early architectural design process has been conducted; Master of Architecture students create a community centre with low energy use and high daylight utilization, presented in case studies. Performance increases are achieved by making appropriate morphological choices only; form and energy are thus linked in a tectonic fashion. A novel designsimulation process model that acknowledges both creative and analytic thinking is derived and discussed in the context of on-going integration attempts.

- by Irina M. Artemieva
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- Rheology, Density, Composition, Gravity

Climate change and rising energy costs necessitate a shift in how buildings that efficiently provide comfort are envisioned. With initiatives now aiming at bringing energy simulation into the mainstream of environmental design, the applicability of state-ofthe-art simulations in formally non-constrained creative production needs to be re-evaluated. To this end, a teaching experiment that includes multidomain simulations as drivers into the early architectural design process has been conducted; Master of Architecture students create a community centre with low energy use and high daylight utilization, presented in case studies. Performance increases are achieved by making appropriate morphological choices only; form and energy are thus linked in a tectonic fashion. A novel designsimulation process model that acknowledges both creative and analytic thinking is derived and discussed in the context of on-going integration attempts.

- by Farshad Nasrollahi
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- Architecture, Design Research, Design pedagogy, Energy Efficiency Buildings

—An analytic tool has been developed, which is able to calculate key machine parameters of a surface permanent magnet generator. These are found using analytic methods, and can be used as objective functions or constraints in optimization routines. The electrical machine modelled is a generator for use in a tidal turbine. Either a designer or an optimization program can choose up to 12 input parameters, including both slot and pole number. The multiphysics tool finds an appropriate winding layout; either a concentrated winding or a distributed winding design, and either single or double layer windings can be specified. Outputs include no load and armature reaction flux densities, machine temperatures, power factor, efficiency, weight and cost. With the presented analytic tool, it is possible to solve an optimization problem where the slot and pole combination is not fixed. The tool is used to find the machine parameters of one machine with distributed windings and one machine with concentrated windings, and a numerical solver is used to validate these numbers.

- by Astrid Røkke
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- Pm Machines, PMSM and PMSG Drives, Thermal Modeling, Magnetic Flux Analysis
- by vijaykumar R
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- Performance Studies, Mathematical Modeling, Solar PV, Thermal Modeling

The 2022 World Cup creates great opportunities for the country of Qatar, but also poses significant challenges. In this study the main challenge of maintaining thermal comfort conditions within the football arenas is presented, with respect to the heat stress index (HSI) and the aero-thermal comfort thresholds established for opened stadiums. Potential cooling strategies for delivering tolerant comfort levels are introduced, followed by their functional strengths and limitations for the hot-humid climate of Qatar. An estimation of the cooling load for semi-outdoor stadiums in Qatar is also presented. The results, produced by dynamic thermal modelling, indicated that a load of 115 MW h per game should be at least consumed in order to provide both indoor and outdoor thermal comfort conditions. Finally, the use of solar energy technologies for the generation of electricity and cooling are evaluated, based on their viability beyond the 2022 World Cup event, towards the nation's targets for sustainability and lasting legacy.

- by Dr. John Kaiser Calautit and +2
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- Computational Fluid Dynamics, Numerical Modeling, Climatic Changes, Heat Transfer
- by Tarun Huria and +1
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- Lithium Batteries, Lithium-Ion Battery, Hystersis Curve, State of Charge

Resilience of new and existing buildings to climate change is a key research issue. Climate change-related phenomena can considerably affect buildings mechanical and thermal-energy response by contributing to materials degradation and structural safety. Such an impact is even further exacerbated in historical constructions, more vulnerable to such events due to their ancient structure if compared to recent designs. The purpose of this paper is to propose an innovative, integrated, multidisciplinary methodology for assessing construction materials’ degradation in historic masonry buildings and its potential future evolution, providing a risk mapping accounting for interactions between climate change effects and structural damage. Such a replicable approach consists in (i) preliminary site inspections, (ii) damage and degradation surveys, (iii) development and calibration of numerical models predicting structural-thermal response and (iv) prediction of materials degradation accounting for future climate conditions and potential worsening of structural damage. The final output of the procedure is a hierarchical mapping of regions with different degradation severities, by identifying those where a specific type of degradation or damage insists but are likely stable and those where they are expected to get worse due to changes in future climate conditions or to a negative interaction between degradation and damage. The presented approach is applied to an iconic Italian monumental building, the Consoli Palace in Gubbio, where future climate scenarios up to 2080 are simulated according to the IPCC climate change predictions. Results highlight that thermal-energy and structural aspects need to be jointly considered in the preservation of surface materials of historic buildings exposed to climate change severity.

- by Abdul Arif
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- Finite Element Modeling, Friction Stir Welding, Ansys, Temperature Variation

Heating and cooling loads are the major reasons for energy use in buildings. Buildings are usually subject to schedules and set-points which are not optimized in response to the dynamic weather conditions, internal loads, and occupancy patterns. The thermal network model has been widely applied for realtime building load estimation, which is crucial for optimizing the operation of the HVAC system. However, there has been limited exploration of the capabilities of the thermal network model due to constraints imposed by the solution method adopted. In this paper, the exponential matrix method was adopted to simplify the state space equations and solve the thermal network model analytically. This enhances the applications of a simplified thermal network model for investigation of multiple scenarios of HVAC system operations and equipment sizing, and for more accurate estimation of heating and cooling loads.
This study also proves that the analytical solution method is symptotically stable regardless of time step. A typical office was used as a case study and the predicted building loads are compared with measured data and numerical results from EnergyPlus. For the case study, the model demonstrated better accuracy and is seen to be robust for thermal load estimation for cooling season.

Ancient Roman syntheses of Al-tobermorite in a 2000-year-old concrete block submerged in the Bay of Pozzuoli (Baianus Sinus), near Naples, have unique aluminum-rich and silica-poor compositions relative to hydrothermal geological occurrences. In relict lime clasts, the crystals have calcium contents that are similar to ideal tobermorite, 33 to 35 wt%, but the low-silica contents, 39 to 40 wt%, reflect Al3+ substitution for Si4+ in Q2(1Al), Q3(1Al), and Q3(2 Al) tetrahedral chain and branching sites. The Al-tobermorite has a double silicate chain structure with long chain lengths in the b [020] crystallographic direction, and wide interlayer spacing, 11.49 Å. Na+ and K+ partially balance Al3+ substitution for Si4+. Poorly crystalline calcium-aluminum-silicate-hydrate (C-A-S-H) cementitious binder in the dissolved perimeter of relict lime clasts has Ca/(Si+Al) = 0.79, nearly identical to the Al-tobermorite, but nanoscale heterogeneities with aluminum in both tetrahedral and octahedral coordination. The concrete is about 45 vol% glassy zeolitic tuff and 55 vol% hydrated lime-volcanic ash mortar; lime formed <10 wt% of the mix. Trace element studies confirm that the pyroclastic rock comes from Flegrean Fields volcanic district, as described in ancient Roman texts. An adiabatic thermal model of the 10 m2 by 5.7 m thick Baianus Sinus breakwater from heat evolved through hydration of lime and formation of C-A-S-H suggests maximum temperatures of 85 to 97 °C. Cooling to seawater temperatures occurred in two years. These elevated temperatures and the mineralizing effects of seawater and alkali- and alumina-rich volcanic ash appear to be critical to Al-tobermorite crystallization. The long-term stability of the Al-tobermorite provides a valuable context to improve future syntheses in innovative concretes with advanced properties using volcanic pozzolans.

- by Marie Jackson and +1
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- Cementitious Materials, Ancient Architecture and Construction History, Archeologia dei Campi Flegrei, Thermal Modeling
- by Davide Di Battista
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- Thermal Modeling, Advanced Engine Cooling System

- by Md Shamim Ahamed and +1
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- HVAC modelling, Thermal Modeling, Controlled Environment Agriculture

The induction machine, because of its robustness and low-cost, is commonly used in the industry. Nevertheless, as every type of electrical machine, this machine suffers of some limitations. The most important one is the working temperature which is the dimensioning parameter for the definition of the nominal working point and the machine lifetime. Due to a strong demand concerning thermal monitoring methods appeared in the industry sector. In this context, the adding of temperature sensors is not acceptable and the studied methods tend to use sensorless approaches such as observators or parameters estimators like the extended Kalman Filter (EKF). Then the important criteria are reliability, computational cost ad real time implementation.

In this work we present the thermal behavior of a glow plug examined by thermal impedance
28 modeling. The circuit model is based on the analogy of thermal and electrical domains and
29 expresses the glow plug used in diesel engines to preheat the air-diesel fuel mixture. In this
30 study the circuit design, implementation and simulation of a glow plug for diesel engines are
31 illustrated. In order to verify this thermal model, two different glow plugs are produced. The
32 test results of the glow plugs produced within this study shows a complete agreement with the
33 simulation results. It is believed that this circuit based model will provide fast and reliable
34 simulations and will be beneficial in the industry to address different glow plug needs.
35 Keywords: Glow plug, Thermal modeling, Resistive element, Thermal imaging

- by Hidayet Günay
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- Thermal Modeling

This paper concerns the thermal investigation of a surface-mounted permanent-magnet synchronous motor designed for high-temperature aerospace actuation applications. A finite-element package was developed, enabling accurate 3-D transient thermal analysis by considering complex and unsymmetrical actuator housing configurations. Its validity was verified by measurements carried out at different duty cycles and operating conditions.

—The ever increasing need for cost-efficient, high-density power transmission brought to the fore applied superconductivity as an alternative worth investigating. Especially , high-temperature superconducting (HTS) dc cables emerge as a promising solution for bulk power transmission and their use in the near future is expected to be increased. HTS cables have the special characteristic of varying performance under different critical conditions, especially under different operating temperatures. Therefore, detailed thermal analysis of HTS cables representing thermodynamics and heat transfer for varying length and time is of significant importance. The analytical mathematical formulation presented in this paper solves heat transfer equations for a two-dimensional axisymmetric cable model and identifies temperature distribution over length and time. The analysis is conducted on a bipolar cable suggested by the Electric Power Research Institute for long-distance HTS dc transmission, while both steady-state and transient scenarios are examined.

Spoil tips are anthropogenic terrain structures built of leftover (coal) mining materials. They consist mostly of slate and sandstone or mudstone but also include coal and highly explosive coal dust. Coal soil tip fires cause an irreversible degradation to the environment. Government organizations notice the potential problem of spoil tip hazard and are looking for ways of fast monitoring of their temperature and inside structure. In order to test new monitoring methods an experimental was performed in the area of spoil tip of Lubelski Węgiel „Bogdanka” S.A. A survey consisted of creating a 3D discreet thermal model. This was done in order to look for potential fire areas. MASW (Multichannel analysis of surface wave) was done in order to find potential voids within the body of a tip. Existing data was digitalized and a 3D model of object’s outside and inside was produced. This article provides results of this survey and informs about advantages of such an approach.

- by Artur Dyczko
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- Geology, 3D visualisation, Poland, Coal Mining

Laser cladding (LC) is a powder deposition technique which is used to deposit layers of clad material on a substrate to improve its surface properties. It has widespread application in structural repair, in particular, the repair of dies and molds used in the automobile industry. These molds and dies are subjected to cyclic thermo-mechanical loading and therefore undergo localized damage and wear. The final clad quality and integrity is influenced by various physical phenomena, namely, melt pool morphology, microstructure evolution and residual stress generation. Consequently, it is imperative to understand the physical phenomena influencing the process variables so as to develop a knowledge base for the usage of this process in repair based applications. The current study is focused on the development of a 3D finite element thermal model for powder injection laser cladding of CPM 9 V powder on H13 tool steel used extensively in repair of dies and molds. The thermal model incorporates deposition of clad elements via element birth technique along with uniform moving heat source and Gaussian powder distribution. The thermal model also takes into account, the attenuation of laser power due to laser-powder interaction and heat partition between the substrate and the powder. The temperature field predicted from thermal analysis was used to calculate the initial melt pool dimensions, taking into account the vaporization of clad elements. Furthermore, the thermal model predicts the final clad layer dimensions (clad height and width) by considering molten metal spreading via Tanner's Law. The clad characteristics (clad geometry, clad dilution and heat affected zone) are predicted with reasonable accuracy with prediction errors lying within ∼14% for most of the cases. The thermal model indicates a relatively strong dependence of interaction time on the heat penetration than that of laser intensity. The thermal model further predicts that the clad width increases with an increase in the laser power till it reaches a critical power and then it saturates. This critical laser power is capable of melting the entire injected powder material; hence, the width of the clad does not increase with power beyond this point.

- by Santanu Paul
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- Finite Element Methods, Heat Transfer, Additive Manufacturing, Lasers

Drilling through depleted zones in offshore deepwater prospects is becoming more common with ongoing production and field maturation, especially when deeper-lying, virgin-pressured reservoirs are explored and produced in later stages of field development. Some of the challenges associated with these depleted zones include severe mud loss and associated borehole problems, as well as troublesome cementing and poor zonal isolation. Artificially strengthening the wellbore is now becoming of crucial importance in order to successfully drill and cement deepwater wells in mature fields and any other wells with narrow drilling margins. In this paper, we introduce an innovative thermal wellbore strengthening (TWBS) technique to elevate the tangential stress (also known as the hoop stress) near the wellbore, and consequently increase the fracture gradient. A " thermal fluid " , consisting of a carrier mud with heat-releasing (" exothermic ") coated particles, has been designed to target depleted zones and release heat at exactly the right time to increase near-wellbore thermal stress, which directly elevates the near-wellbore tangential stress and in turn elevates the effective fracture gradient. Ultimately, this lowers the risk of lost circulation and improves the chance of successfully cementing and achieving zonal isolation. For instance, a TWBS treatment can be executed as an integral part of the cement job by using it in an extended spacer train for mud displacement, pumped directly prior to cement placement. The coated exothermic particles were designed such that they could release their " payload " via an extended time-release mechanism, to ensure that the heat release reaches the appropriate target location in the wellbore at the right time. The chemical systems, which are based on dissolving various hygroscopic salts in water, were tested and developed to heat up the wellbore and increase temperature up to 100 o C. This will potentially elevate the fracture gradient by several hundred psi, depending on formation properties. Details regarding the formulation and testing of the non-coated, coated particles, and the carrier fluid are discussed; as well as considerations for TWBS field application. In addition, a new computational heat transfer model was developed to calculate the temperature distribution within the rock formation and within the drillstring/work string and wellbore annulus, for a formation contacted by a fluid with particles that react in exothermic fashion. The new model calculates the transient temperature distribution, increase in near-wellbore stress, and fracture gradient for a given amount of heat generation by the fluid and temperature increase in the rock. It can assist with well design aspects of the proposed thermal wellbore strengthening technique, and is particularly helpful in estimating the downhole temperature variations and assessing its implications prior to job execution. Details of the model and results of several typical simulations are given herein.

- by Besmir Hoxha and +1
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- Thermal and Fluids, Wellbore Stability, Thermal Modeling, Petroleum Engineering

An accurate and real-time knowledge of temperatures in insulated-gate bipolar transistor modules is crucial for reliability analysis and thermal management of power electronic converters. For this purpose, this paper establishes an integrated thermal equivalent circuit model comprising self-heating thermal impedances and cross-heating thermal impedances to provide a temperature profile of the junction and solder joints during various operations and in the case of thermal aging. The thermal resistance and capacitance parameters of the thermal impedances are characterized in terms of different electro-thermal operating conditions and solder joints aging conditions with the help of three-dimensional finite element simulations. Also, the effect of the heatsink, which brings an uneven heat transfer coefficient distribution at the module baseplate, is investigated and modeled into the thermal impedances. The introduced thermal model can work even if the conditions change simultaneously. The accuracy of the model is verified by experiments and finite element simulations, all of which agree with negligible error unlike thermal models given in the datasheet and fixed-parameter thermal models.

- by Mohsen Akbari
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- Thermal Engineering, Power Electronics, Aging, Semiconductors
- by Javier Gazzarri and +1
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- Kinetics, Lithium Batteries, Transport phenomena, Parameter estimation
- by Amr Mahir
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- Building Performance Simulation, Thermal Modeling

In response to the need to improve the energy efficiency of data centers (DCs), system designers now incorporate solutions such as continuous performance monitoring, automated diagnostics, and optimal control. While these solutions must ideally be able to predict transient conditions, in particular real time DC temperatures, existing forecasting methods are inadequate because they (1) make restrictive assumptions about system configurations, (2) are extremely time-consuming for real time applications, (3) are accurate only over limited time horizons, (4) fail to accurately model the effects of operating conditions, such as cooling unit operation conditions and server workloads, or (5) ignore important facets of the flow physics and heat transfer that can lead to large prediction errors in extrapolative predictions. To address these deficiencies, we develop a gray-box model that combines machine learning with the thermofluid transport equations relevant for a row-based cooled DC to predict transient temperatures in server CPUs and cold air inlet to the servers. An artificial neural network (ANN) embedded in the gray-box model predicts pressures, which provide inputs for the thermofluid transport equations that predict the spatio-temporal temperature distributions. The model is validated with experimental measurements for different (1) server workload distributions, (2) cooling unit set-point temperatures and (3) the airflow of the cooling units. This gray-box model exhibits superior performance compared to a conventional zonal temperature prediction model and an advanced black-box model that is based on a nonlinear autore-gressive exogenous model. An application of the gray-box model involves a case study to detect cooling unit fan failure in a row-based DC cooling system.

The microstructure directly influences the subsequent mechanical properties of materials. In the manufactured parts, the elaboration processes set the microstructure features such as phase types or the characteristics of defects and grains. In this light, this article aims to understand the evolution of the microstructure during the directed energy deposition (DED) manufacturing process of Ti6Al4V alloy. It sets out a new concept of time-phase transformation-block (TTB). This innovative segmentation of the temperature history in different blocks allows us to correlate the thermal histories computed by a 3D finite element (FE) thermal model and the final microstructure of a multilayered Ti6Al4V alloy obtained from the DED process. As a first step, a review of the state of the art on mechanisms that trigger solid-phase transformations of Ti6Al4V alloy is carried out. This shows the inadequacy of the current kinetic models to predict microstructure evolution during DED as multiple values are reported for transformation start temperatures. Secondly, a 3D finite element (FE) thermal simulation is developed and its results are validated against a Ti6Al4V part representative of repair technique using a DED process. The building strategy promotes the heat accumulation and the part exhibits heterogeneity of hardness and of the nature and the number of phases. Within the generated thermal field history, three points of interest (POI) representative of different microstructures are selected. An in-depth analysis of the thermal curves enables distinguishing solid-phase transformations according to their diffusive or displacive mechanisms. Coupled with the state of the art, this analysis highlights both the variable character of the critical points of transformations, and the different phase transformation mechanisms activated depending on the temperature value and on the heating or cooling rate. The validation of this approach is achieved by means of a thorough qualitative description of the evolution of the microstructure at each of the POI during DED process. The new TTB concept is thus shown to provide a flowchart basis to predict the final microstructure based on FE temperature fields.

Out of the many options available for thermal simulation of digital electronic systems, those based on solving an RC equivalent circuit of the thermal network are the most popular choice in the EDA community, as they provide a reasonable tradeoff between accuracy and complexity. HotSpot, in particular, has become the de-facto standard in these communities, although other simulators are also popular. These tools have many benefits, but they are relatively inefficient when performing thermal analysis for long simulation times, due to the occurrence of a large number of redundant computations intrinsic in the underlying models. This work shows how a standard description language, namely SystemC and its analog and mixed-signal (AMS) extension, can be used to successfully simulate the equivalent thermal network, by achieving accuracy comparable to existing simulators, yet with much better performance. Results show that SystemC-AMS thermal simulation can outpace HotSpot simulation by 10X to 90X, with speedup improving as the size of the thermal network increases, and negligible estimation error. As a further advantage, the adoption of the same language to describe functionality and temperature allows the simultaneous simulation of both dimensions with no co-simulation overhead, thus enhancing the overall design flow.

- by Yukai Chen
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- Electronic Design Automation, Thermal Analysis, Thermal Simulation, Thermal Modeling
- by Montserrat Torne and +1
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- Geology, Geochemistry, Geophysics, Potential Fields Geophysics

A three-dimensional thermal simulation investigation for the thermal management of GaN-on-SiC monolithic microwave integrated circuits (MMICs) of consisting multi-fingers (HEMTs) is presented. The purpose of this work is to demonstrate the utility and efficiency of the three-dimensional Transmission Line Matrix method (3D-TLM) in a thermal analysis of high power AlGaN/GaN heterostructures single gate and multi-fingers HEMT SSPA (solid state power amplifiers). The self-heating effects induce thermal cross-talk between individual fingers in multi-finger AlGaN/GaN that affect device performance and reliability. Gate-finger temperature differences only arise after a transient state, due to the beginning of thermal crosstalk which is attributed to the finite rate of heat diffusion between gate fingers. The TLM method accounts for the real geometrical structure and the non-linear thermal conductivities of GaN and SiC in order to improve the realistic calculations accuracy heat dissipation...

To assess power devices' reliability, it is crucial to have a relatively accurate thermal approach which provides valid temperature estimates. In this paper, a commercial Si IGBT and SiC MOSFET power modules are investigated. Also, the electric current-induced effects on bond wires and the correlation between the non-uniform temperature distribution and electrical conductivity of the sensitive constituent materials are studied. A more realistic active area of the die is defined by excluding inactive regions, i.e., the gate area, gate runners, and termination ring. Also, the electric current distribution among parallel bond wires attached to the dies' meta-lization pads is investigated. A comparison between an approach which includes all the above aspects with a conventional one where a thermal power with the same total value, but unifrom, is injected into the semiconductor dies is made, While an acceptable error is found for Si IGBTs, a very significant difference is observed in SiC MOSFETs.

Semiconductor devices are often the most vulnerable components of power electronics converters among which thermal failures are the most likely ones. Thus, more accurate but straightforward thermal models are needed to efficiently do actions such as lifetime prediction, thermal management, etc. This paper presents a Foster-type equivalent transient thermal model developed through finite element simulations for a commercial Si IGBT power module. Such thermal models can easily merge into circuit simulation programs and even can be employed as real-time temperature estimators. However, fixed thermal models may give large errors in different operating conditions. In addition, they become unable to satisfactorily estimate temperatures over time, because of the thermal aging phenomenon. Thus, in this study, the thermal model of the power module is developed to be adapted to different boundary conditions - ambient temperature, and cooling system – as well as thermal aging of solder joints, which is the most common failure in the power modules. Also, the thermal model features the effect of power loss, and the cross-coupling effect among nearby semiconductor dies. Comparisons with FEM verify the performance of the studied thermal model.

In this paper, a survey is conducted to examine the problem of estimating the states and parameters of an asynchronous machine when some of these measures are not available or the estimation approach is the best solution. The modeling is based on the theory of power dissipation; heat transfer and the rate of temperature increase the stator and the rotor, taking into account the effect of speed on trade. The first purpose of this article is displayed the effect of variable losses depending on the load and constant losses on the thermal behavior of asynchronous motor. According to the sensor's problems and the obtaining of the thermal information about the rotor, the second goal is the use of a sensorless method like the use of the EKF (extended Kalman filter), some simulation results are given and commented.

- by Hacene Mellah and +1
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- Kalman Filtering, Induction Motor, Thermal Modeling

Peak shaving is a relatively new approach aimed at increasing the primary energy efficiency in District Heating Systems. This is mainly performed using thermal storage units that can be charged when the thermal request is small, usually at night, and discharged to cover peak requests. Thermal storage typically allows one increasing the utilization of waste heat, renewables and cogeneration systems while reducing the use of boilers. An alternative option to conventional thermal storage is " virtual storage ". This consists in modifying the thermal request profiles of buildings in order to reduce their contributions in peak hours. Such modifications rely on the thermal capacity of buildings in order to comply with end-user requirements on the internal temperatures. The analysis of possible operational strategies should be performed using an integrated simulation, which considers both the thermos-fluid dynamic behavior of the network and the thermal behavior of the buildings. In this paper, a physical tool specifically conceived for the analysis of peak shaving in large networks through virtual storage is presented and applied to a portion of the Turin district heating network. Detailed information about thermal requests of buildings obtained from a pervasive metering system is used in order to characterize their behavior. This piece of information is then adopted for constraining and checking possible different operational strategies. Two different scenarios are analyzed and compared with current operation in terms of primary energy consumption, showing that primary energy savings of the order of 5% can be achieved without affecting the comfort perceived by the users.

The building technology class “Parametric Design” simultaneously teaches thermal and daylight performance simulation to novice users, usually Master of Architecture students. Own buildings are created, analysed and geometrically modified during the design process, resulting in structures that are energetically pre-optimized. It is shown that energy demand and daylight utilization can be significantly improved while taking into account formal considerations. Departing from a design process model that gives preference to either engineering or design thinking, multi-modal decision-making is diagnosed to be mediated by hybrid or multivalent representations, necessitating a shift in how inter-domain design knowledge flows might be understood. Opposed to purely linear or iterative process assumptions, a fluent state model of interconnected domains of analytic inquiry is proposed.

- by Max C Doelling
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- Architectural Engineering, Architecture, Design Methods, Design Research

A one dimensional steady state thermal analytical model has
been developed to study the heat transfer and temperature distributions
in a quartz ampoule filled with MoO3 powder. The
source heat generation inside the ampoule is released from the
high neutron flux (1.4 · 1014 neutrons/cm2s) interaction with
MoO3. Natural and forced convections heat transfer boundary
conditions are adopted during the irradiation process. The
peak temperatures in MoO3 powder and quartz are calculated
and compared with their melting temperatures to ensure the irradiation
safety criteria.

- by Amr Abdelhady
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- Neutron Flux, Thermal Modeling, Neutron Irradiation Effect, Research Reactor

As the smart-grid realization is becoming more pragmatic, the analysis on transactive energy systems (TESs) is also getting more substantial. Bidirectional DC-DC converter (BDDC) is the energy flow driver for a TES connected electric vehicles (EVs) and energy storage systems (ESSs). In this work, we have performed a detailed thermal and efficiency analysis of Silicon (Si), Silicon Carbide (SiC), and Si-SiC hybrid half-bridge commercial power modules for BDDC. Considering the power modules' operating junction temperature as 85% of the rated maximum value, the optimum switching frequency (OSF) for Si, hybrid, and SiC modules is evaluated as 4, 10.5, and 27.5 kHz, respectively. For the full load OSF operation, the required heatsink maximum thermal resistance is estimated as 0.037, 0.040, and 0.080 °C/W, respectively and the SiC MOSFET module shows the highest efficiency of 99%. The BDDC simulation is performed in PLECS, which comprises a control block for bi-directional power operation and the estimated thermal management.

- by Md Multan Biswas and +1
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- Electric Vehicles, Wide Bandgap Semiconductors, Silicon Carbide, Dc-Dc Converters

by Artemieva I.M. and Mooney W.D.

- by Irina M. Artemieva
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- Geophysics, Precambrian Geology, Kimberlites, Heat Flow