Thermal Design Research Articles

Introduction to thermal control design process for CubeSats in Mexico

Abstract CubeSats are a popular type of spacecraft categorized as nanosatellites. In 1999, Professors first developed these devices at California Polytechnic State University and Stanford University to offer an affordable and accessible experience to students. Data information updated up to May 31st, 2023, shows that 2286 Nanosats have been launched, where 2105 were CubeSats. Moreover, 82 countries have nanosats, whereas Latin America has 44 CubeSat. The fact that Mexico just 5 launched 5 CubeSats is a consequence of the complicated space sector ecosystem in the nation that combines lack of funding and, more importantly, the absence of ¨know-how¨ design space missions from scratch. This manuscript reviews the system engineering methodology used to develop space missions, according to NASA discussing a particular methodology for CubeSat Missions. Next, a CubeSat data trend is shown, followed by a general description of its subsystems. Afterward, the design process activities of the Thermal Control Subsystem (TCS) based on the “NASA Systems Engineering Processes and Requirements” and “Thermal analysis handbook is described. The TCS is often underestimated and confused to implement. For this reason, a design methodology for the TCS accepted to Mexico context is proposed. Finally, the conclusions are presented.

Research on PCB layout optimization of vehicle controller based on electrothermal hybrid simulation

Abstract With the rapid development of the electronic industry, electronic equipment is more and more widely used in automobiles. The integration of electronic components on the Printed Circuit board (PCB) is getting higher and higher, the size is getting smaller and smaller, and the power is getting larger and larger, which leads to a sharp increase in the heat flow density of the whole PCB. The surface temperature of the chip is too high when it is working, which leads to a series of thermal failure problems. In order to improve the thermal characteristics between PCB and electronic components and improve the heat dissipation capability and reliability of PCB, this paper designed a vehicle controller PCB. PowerDC was used to conduct an electrothermal hybrid simulation analysis, and the temperature distribution of the whole board was obtained. Meanwhile, the structural layout of the PCB was optimized by increasing the heat dissipation hole, floor copper foil, and wiring width. Thus, the temperature of PCB and electronic components is reduced, which provides a vital reference for the thermal design of PCB.

Improve the thermal performance of precooler by enhancing the utilization of chemical heat sink: Refined design method and characteristic analysis

The chemical heat sink of the coolant plays a crucial role in enhancing the performance of the precooler, which affects the overall performance of the air-breathing precooled engines. The conventional thermal design method for precoolers cannot accurately evaluate the chemical heat sink of coolants. To address this crucial issue, this paper proposes a refined model that considers the chemical reaction processes of n-Decane, based on a two-dimensional discretization unit model and the plug flow reactor model incorporating molecular-level chemical reaction mechanisms. The validation of this model is conducted by comparing it with publicly accessible data and computational fluid dynamics simulations, thereby demonstrating its excellent accuracy. Subsequently, an analysis is conducted on the factors influencing the chemical heat sink release of the coolant within the precooler, and enhanced design criteria for optimizing chemical heat sink utilization are proposed. Building upon these considerations, the performance of a precooler with a design point of Mach number 5 under off-design conditions was analyzed. The findings indicate that employing rational design methods can enhance the chemical heat sink efficiency of endothermic fuels by 8.0%, along with a concurrent 10.3% increase in the total heat sink. This underscores the significance of considering the impact of the chemical heat sink of endothermic fuels in the design of precoolers. In the case presented in this paper, the contribution of the chemical heat sink to the total heat sink within the n-Decane precooler could reach 35.3%.

Australian East-West Radio Relay System Revisited: Thermal Design of Repeater Shelters

The Journal revisits two historic papers from 1971 covering the thermal design and environmental controls in repeater shelters of the Australian East-West radio relay system from Northam in Western Australia to Port Pirie in South Australia.

Integrated manifold microchannels and near-junction cooling for enhanced thermal management in 3D heterogeneous packaging technology

The rapid advancement in electronic chip technology is driving the evolution of highly integrated and high-power configurations, which in turn imposes greater demands on thermal management. This study presents a novel approach to address the thermal management challenges associated with high-density integrated chips. By incorporating the near-junction cooling method into silicon-based chips, the thermal resistance during heat conduction is effectively reduced. To further enhance heat dissipation efficiency, we integrate manifold microchannels and near-junction cooling into an aluminum nitride ceramic substrate, creating a heterogeneous three-dimensional integrated chip. To verify the effectiveness of our approach, a thermal test chip and an aluminum nitride substrate with a manifold structure are meticulously prepared and packaged for experimental testing. Remarkably, the experimental results demonstrate that the heterogeneous integrated chip, featuring manifold microchannels, achieves an impressive heat dissipation capacity of 700 W/cm2 under normal operating temperature conditions. Additionally, sensitivity analysis and multi-objective optimization approach were employed, utilizing the Response Surface-Genetic Algorithm П(NSGAП), to optimize the manifold microchannels in the heterogeneous integrated chip. The optimization process yields significant improvements, reducing the total thermal resistance of the chip by 13.6 % and the maximum pressure drop by 68.5 %. These findings provide valuable theoretical insights and guidance for the thermal design of high heat flux integrated chips, and contribute to advance the design and development of high-performance integrated circuit systems.

Electro-thermal co-design of a variable pole toroidal induction motor

The United States Department of Energy targets an 88 % reduction in motor and power electronics volume by the year 2025 while minimizing or eliminating magnet usage. Induction machines are a magnet-free alternative with advantages such as low cost, high reliability, and capability of withstanding high short-term overload. To meet these societal goals, we develop an induction machine that uses an electro-thermal co-designed converter-integrated thermal management approach. The machine utilizes toroidal windings in the stator, and an 18-phase power converter to achieve 40 kW/L power density. An optimized jacket design was developed to enable the effective thermal management of the stator and integrated power electronics. The toroidal winding configuration provides advantages for thermal performance over conventional distributed windings due to an increased winding copper surface area without reducing slot-fill factor, thereby allowing for a higher stator density. The improved thermal performance of the toroidal winding design was verified using three-dimensional conjugate computational fluid dynamic simulations. A reduced-order transient model was then developed to generate torque-speed-temperature plots at various load conditions. The transient thermal analysis was extended to verify safe operation of the motor during a typical drive cycle for the desired application. The thermal design models developed in this work are robust and scalable to other motor sizes providing a framework for co-designing and developing thermal management systems for electric motors.

An intelligent data-driven investigation and optimization integrated with an eco-friendly thermal design approach for a marine diesel engine to study its waste-to-liquefied hydrogen generation potential

The waste heat generated by vehicles, especially heavy-duty engines, has motivated the current research to propose a novel thermal design for a ship's engine. Hence, the suggested system comprises an organic-flash power plant, a bi-evaporator cooling subsystem, a thermal desalination cycle, a water electrolysis-based hydrogen generation unit, and a Claude unit for liquefying hydrogen. The innovative aspects associated with the proposed design include utilizing a novel cascade heat recovery process aimed at reduced irreversibility for the engine's waste and the integration of bi-evaporator technology and Claude unit to facilitate the process of waste-to-liquefied hydrogen generation for a marine engine for improved handling. In addition, the research includes an intelligent study that comprehensively analyzes and optimizes the proposed system in terms of long-term sustainability and economic feasibility. For this purpose, a data-driven optimization technique is implemented using artificial neural networks in combination with multi-objective grey wolf optimization. The aims of the research encompass the optimization of the sustainability index and unit cost of liquefied hydrogen. The research findings indicate that the vapor generator’s terminal temperature difference exerts the most substantial influence on performance metrics, as evidenced by a mean sensitivity index of 0.368. Also, the mentioned objective functions exhibit values of 1.139 and 7.60 $/kg, respectively. Besides, the optimum exergy destruction rate is 124.3 kW, the total investment cost rate is 4.94 $/year, the specific cost of products is 74.87 /GJ, the payback period is 2.2 years, and the net present value is 7.48 M$.

Analytical design and computational fluid dynamics analysis for optimizing fixed ventilation systems for power transformer: Numerical study and experimental validation

Despite the recognized fact that power transformers (PT) are highly efficient technology, part of their electrical energy is counted as heat losses. Therefore, the cooling system is a critical factor in the life span and performance of the PTs, and hence the adopted thermal energy design can be strongly effective. This study revolves around the innovative development of a novel generation of fixed ventilation fans for PTs, achieved through Computational Fluid Dynamics (CFD) simulations and practical experiments. The proposed CFD model was developed adopting ANSYS FLUENT 19.2. The proposed CFD model was verified by comparing the numerical and experimental results of the cooling air temperature and velocity. A standard k-ε model was used to simulate the airflow of the investigated cooling system numerically. A thermal analysis of a four-sided power transformer was performed, and an analysis of the optimum position to install the cooling fan on the radiator was presented. The most effective number of used fans was also determined. The main results showed that two fans were found to be the best performance among the tested candidate alternatives. The two cooling fans’ size, material, and cover shape were also studied and added to the proposed model. Besides, the utilization of a thermoelectric generator was considered in this study in order to recycle some of the lost heat into output power. An experimental prototype mimicking the actual cooling system for the power transformer was designed and fabricated. Results showed that the selected material has achieved a high Calculated Factor of Safety (FoS) equal to 237, indicating that the utilization of the designed parts is of high safety.

Thermal design for enhanced temperature uniformity on spark plasma sintering device

Spark plasma sintering (SPS) is a widely used technique for sintering thermoelectric devices. In this process, the heat generated by Joule heating is primarily transferred to the die surface through radiative heat transfer, causing temperature non-uniformity within the specimen. These discrepancies in temperature distribution cause localized changes in the properties of the thermoelectric device, which presents significant engineering challenges in managing heat transfer during the sintering process. This study proposes a thermal design approach to reduce the temperature gradient within the specimen in the existing SPS device. The idea of the auxiliary heating system was evaluated using numerical simulation validated with experimental comparison. Design variables, heating power (an operating parameter) and heater depth (a geometric parameter), were chosen to balance the amount of Joule heating to the heat produced by the auxiliary heating system. The optimization process with sensitivity analysis led to the selection of an auxiliary heating system capable of reducing the temperature gradient within 61.1 K/m. This achievement allows for the sintering of thermoelectric devices with enhanced thermoelectric performance.

Quantitative assessment of thermal resistance in graphene field-effect transistors based on a phonon hydrodynamics and van der Waals coupling approach

In the progressive miniaturization of graphene field-effect transistors (GrFETs), pronounced thermal boundary resistance (TBR) and increasing ballistic-diffusive thermal resistance pose formidable challenges to thermal management. Quantitative analysis of thermal resistance is crucial for advancing efficient thermal designs in GrFETs using state-of-the-art technology. The inherently low-dimensional structure nature of graphene means that thermal conduction in GrFETs, governed by phonon hydrodynamic transport and van der Waals (vdW) interactions, cannot be accurately described by traditional Fourier's law-based models or the single-mode relaxation time approximation. This study introduces an innovative thermal simulation framework that addresses these challenges by incorporating phonon hydrodynamics equations and considering weak vdW coupling. Our findings indicate that thermal conduction in GrFETs is predominantly facilitated by flexural (ZA) phonons, and their thermal transport efficiency is significantly influenced by substrate perturbations. Specifically, the TBR in GrFETs is closely associated with the weak vdW coupling between ZA phonons and substrate atoms. Furthermore, this study employs dimensionless thermal resistance ratios and Knudsen numbers to explore the impact of silicon's geometric dimensions, heat source size, and ballistic phenomena on the substrate's thermal resistance. These insights provide substantial theoretical support for the development of efficient thermal management strategies in GrFETs.

A Morris sensitivity analysis of an office building's thermal design parameters under climate change in sub-Saharan Africa

Sub-Saharan Africa faces severe overheating problems during hot periods due to substandardly constructed buildings and high-priced energy services. Global warming is expected to aggravate the situation. Although literature addresses the effects of climate change on buildings in different world regions, how it will impact the Sub-Saharan region is still being determined, particularly in terms of design parameters and how they will vary. This study assesses the influence of design parameters on the cooling energy demand of a small-scale office building in Lagos and Kano, Nigeria. A Morris sensitivity analysis was carried out to rank and compare the influence of different design parameters on energy consumption, determined using EnergyPlus for present-day typical weather and the SSP5-8.5 scenario. The future scenario was generated using the Future Weather Generator, a morphing tool. The results show that, in 2080, the cooling load will increase from 1551 kWh/a to 2612 kWh/a (68.4 %) in Kano and from 1931 kWh/a to 3093 kWh/a (60.1 %) in Lagos. The cooling load in Lagos will generally be higher than in Kano by 18.4 % (596 kWh/a). The results indicate that reductions in the thermal conductivity of the east wall and decreases in the solar absorptance of the east wall, roof, and west wall elements will be the most significant factors affecting cooling in Kano. In Lagos, reductions in the thermal conductivity of the east wall and decreases in solar absorptance of both the east wall and roof elements will be the most influential.

Development and experimental testing of an innovative nondestructive thermal sensor utilizing the thermal interrogation method for detecting leakage in water plastic pipes

Leak detection in water pipelines is still an important issue in real-world industrial systems. Thus, a new nondestructive thermal sensor design based on the thermal interrogation method has been developed to detect and estimate the real-time leaks in water plastic pipes without environmental interference. The proposed thermal interrogation method utilizes a combination of heat flux and temperature measurements on the upstream and downstream outside plastic pipe surfaces. These measurements are obtained by using heat flux sensors and thermocouples that are covered by thin-film polyimide electric heaters. The interrogation method approach delivers that at constant input heat flux, the difference in sensor temperature values is dependent on the leakage volume flow rates. The sensor was tested over a range of water leakage volume flow rate from 0.1 m3/h to 1.3 m3/h and a range of water temperature from 21 °C to 25 °C. The water leakage volume flow rates were correlated to the difference in temperature values between the upstream and downstream sensors. The measurement results reveal that this sensor can be used to detect and estimate the real-time water leakage volume flow rate with high accuracy and repeatability for plastic pipes.

Passive thermal control design and flight operation results of nano moon lander OMOTENASHI

OMOTENASHI is a 6U CubeSat launched by the first NASA SLS rocket. Its mission was to demonstrate that a CubeSat can make a semi-hard landing on the Moon. Tight resource constraints make it difficult to mount a heater and a radiator in a CubeSat, so passive thermal control is a prominent design feature of OMOTENASHI that resolves the technical difficulty. In November 2019, a thermal vacuum test was conducted. This paper discusses the thermal design and the test results. OMOTENASHI was launched by SLS rocket on November 16, 2022. After the SLS rocket separation, OMOTENASHI's attitude control malfunctioned so it could not generate power from its solar cells. Eventually, communications were lost and have not been restored. Brief telemetry data confirmed that the temperature monitor functioned correctly for 30 min. This paper reports the flight results of the thermal status during the first ground station pass. Also, a comparison between the analysis model and telemetry data is shown. Finally, based on its estimated trajectory, the future thermal profile of the spacecraft and the result of the search operation are discussed.

Lumped Parameter Thermal Network Modeling and Thermal Optimization Design of an Aerial Camera.

The quality of aerial remote sensing imaging is heavily impacted by the thermal distortions in optical cameras caused by temperature fluctuations. This paper introduces a lumped parameter thermal network (LPTN) model for the optical system of aerial cameras, aiming to serve as a guideline for their thermal design. By optimizing the thermal resistances associated with convection and radiation while considering the camera's unique internal architecture, this model endeavors to improve the accuracy of temperature predictions. Additionally, the proposed LPTN framework enables the establishment of a heat leakage network, which offers a detailed examination of heat leakage paths and rates. This analysis offers valuable insights into the thermal performance of the camera, thereby guiding the refinement of heating zones and the development of effective active control strategies. Operating at a total power consumption of 26 W, the thermal system adheres to the low-power limit. Experimental data from thermal tests indicate that the temperatures within the optical system are maintained consistently between 19 °C and 22 °C throughout the flight, with temperature gradients remaining below 3 °C, satisfying the temperature requirements. The proposed LPTN model exhibits swiftness and efficacy in determining thermal characteristics, significantly facilitating the thermal design process and ensuring optimal power allocation for aerial cameras.

Saturated nucleate pool boiling of cryogenic fluids: Review of databases, assessment of existing models and correlations, and development of new universal correlation

The absence of a comprehensive and reliable nucleate pool boiling database for heat transfer coefficient (HTC) of cryogenic fluids is the driving force behind this study. Such a database is essential to evaluating the predictive accuracy of existing tools, including both models and correlations, and to pioneering the development of a new, more accurate predictive method. To address this need, a new Consolidated Cryogenic Nucleate Pool Boiling Database (comprised of 2908 data points) was compiled, with emphasis on HTC from flat horizontal and vertical surfaces, drawing from the broad literature resources available from across the globe. The database enabled a comprehensive assessment of prior models and correlations, and careful examination showed most of these tools yield unacceptably large errors in predicting the HTC data, especially for elevated pressures and large heat fluxes. Consequently, a new correlation is proposed for all cryogenic fluids combined, which is fine-tuned to outperform prior predictive tools, particularly for elevated pressures and large heat fluxes. The new correlation has a Mean Absolute Error (MAE) of 25.36 %, with 64.5 % of the predictions falling within ±30 % of the data and 87.2 % within ±50 %. This exceptional predictive capability positions the new correlation as a robust tool for both thermal design and performance assessment of a broad variety of devices and systems.

Investigating thermal transport across the AlN/diamond interface via the machine learning potential

Aluminum nitride (AlN) is an ultrawide-bandgap semiconductor with excellent potential for high-power applications. However, the heat dissipation issue remains a huge challenge for the use of AlN in high-power devices. A promising solution for this problem is to integrate AlN with the diamond heat sink. Therefore, interfacial thermal transport has become a significant bottleneck in thermal management. In this work, one neuroevolution potential is developed based on neural networks, which significantly improves the accuracy of predicting thermal properties compared to traditional potentials and address the issue of inaccurate thermal performance prediction of AlN/diamond heterostructures using traditional potentials. Molecular dynamics simulations based on NEP is adopted to investigate the crystal-orientation-dependent and interfacial-atom-dependent thermal boundary resistance of the AlN/diamond heterostructures after the interfacial bonding. Compared to bonding with Al and C atoms, the TBR decreases by approximately 50 % after bonding with N and C atoms at the interface. Especially for the AlN (0001)-N-diamond (100) heterostructure, the TBR is 0.95 m2·K·GW−1, very close to the theoretical limit of 0.8 m2·K·GW−1 through the diffuse mismatch model (DMM) theory. Finally, the insightful optimization strategies are proposed in this work which could pave the way for better thermal design and management of AlN/diamond heterostructures.

A field study of temperature field distribution characteristics of flat steel box girder and its influential environmental factors

As one of the mainstream girder types of long-span bridges, the flat steel box girder (FSBG) under thermal action has been one primary concern for bridge engineers and researchers. This research presents a field study of the temperature field distribution characteristics of FSBG and its influential environmental factors. To achieve this, an acquisition equipment that comprises of thermometers and environmental sensors is applied to a prototype cable-stayed bridge under construction, in which the structural temperature field of FSBG and the surrounding environmental data are collected and analyzed thoroughly. The results indicate that the vertical temperature distribution (VTD) in certain time instants exhibits significant variations and the maximum vertical temperature gradient can reach up to 27.9 °C. Despite of this, it is found that the VTD of FSBG can be covered by several current standards such as AASHTO standard and New Zealand standard. As for the transverse temperature distribution (TTD), it is found that both the variation and temperature difference of TTD in certain time instants are considerable, especially at the deck surface, which far exceed those of the TTD prescribed in current standards. This indicates that the TTD of FSBG should be seriously considered during the bridge design phase. Furthermore, the field study reveals that the wind speed has negative effect on the structural temperature of FSBG (when the air temperature is less than that of FSBG), while the solar radiation exerts positive effect on the structural temperature of FSBG. The outcome of this study can provide valuable references for thermal design, monitoring and control of long-span bridges employing FSBGs as bridge main girder.

Optimization of Geothermal Heat Pump Systems for Sustainable Urban Development in Southeast Asia

This study examines the optimization of ground source heat pump (GSHP) systems and energy piles for sustainable urban development, focusing on Southeast Asia. GSHPs, which utilize geothermal energy for indoor HVAC needs, offer a sustainable alternative to traditional systems by utilizing consistent subsurface temperatures for heating and cooling. The study highlights the importance of understanding thermal movement within the soil, especially in soft marine clays prevalent in Southeast Asia, to improve GSHP system efficiency. Using a one-dimensional finite difference model, the study examines the effects of soil thermal conductivity and density on system performance. The results show that GSHP systems, especially when integrated with energy piles, significantly reduce electricity consumption and greenhouse gas emissions, underscoring their potential to mitigate the urban heat island effect in densely populated areas. Despite challenges posed by the region’s hot and humid climate, which could affect long-term effectiveness, the study highlights the need for further study, including field experiments and advanced modeling techniques, to optimize GSHP configurations and fully exploit geothermal energy in urban environments. The study’s insights into soil thermal dynamics and system design optimization contribute to advancing sustainable urban infrastructure development.

Heat-Dissipation Design and 3D Printing of Ternary Silver Chalcogenide-Based Thermoelectric Legs for Enhancing Power Generation Performance.

Thermoelectric devices have received significant attention because of their potential for sustainable energy recovery. In these devices, a thermal design that optimizes heat transfer and dissipation is crucial for maximizing the power output. Heat dissipation generally requires external active or passive cooling devices, which often suffer from inevitable heat loss and heavy systems. Herein, the design of heat-sink integrated thermoelectric legs is proposed to enhance heat dissipation without external cooling devices, realized by finite element model simulation and 3D printing of ternary silver chalcogenide-based thermoelectric materials. Owing to the self-induced surface charges of the synthesized AgBiSe2 (n-type) and AgSbTe2 (p-type) particles, these particle-based colloidal inks exhibited high viscoelasticity, which enables the creation of complex heat-dissipation architectures via 3D printing. Power generators made from 3D-printed heat-dissipating legs exhibit higher temperature differences and output power than traditional cuboids, offering a new strategy for enhancing thermoelectric power generation.

Micro-structured lateral thermal lens for increased output power and narrowed beam divergence in kilowatt-class 9xx nm diode laser bars

Local temperature non-uniformity is a critical limit to power in large-area semiconductor lasers, playing a larger role than the conversion efficiency and temperature sensitivity in the most efficient modern devices. For the specific case of kilowatt-level edge-emitting diode laser bars, we demonstrate that laterally re-distributing current locally within each emitter using a customized micro-structuring of the electrical contact can flatten the thermal profile, based on the thermal design using COMSOL. The concept is demonstrated experimentally in adapted bars that contain eight broad-area emitters, each having wide (∼1100 μm) stripes and a 4 mm long resonator. Each emitter in the laser bar has an electrical contact layer that is electrically structured into parallel sub-contacts using implantation, essential to prevent lateral lasing, implemented here with a period of 29 μm. The width of the individual sub-contacts is narrowed in the device center and then monotonically increased toward the emitter edges to collect a higher proportion of heat at the edges, for a fivefold reduction in the thermal lens, despite a significant (20%) overall increase in electrical and thermal resistance. Two performance benefits are observed. First, the slope varies more slowly with average temperature, recovering (here) around half of the efficiency penalty from in-stripe temperature non-uniformity, and hence increasing the power conversion efficiency at 800 W optical output power by around 5%. Second, the lateral far field (95% power content) is narrowed by around 2° at 800 W optical output power, corresponding to a reduction of around half of the thermal contribution.