Thermal Control Strategy Research Articles

Temperature management of liquid-cooled fuel cells based on active disturbance rejection control

In the proton exchange membrane fuel cell (PEMFC) systems, the operating temperature affects the gas transport, reaction rate and water balance inside the PEMFC stack, thus affecting the output performance and lifetime of the stack. Therefore, it is necessary to study the thermal management methods and control strategies to maintain the stack temperature at the expected value. A thermal management system model of the PEMFC based on the electrochemical reaction and thermodynamics is established. This study proposes a novel active disturbance rejection controller (ADRC) to solve the problem of excessive temperature fluctuation of liquid-cooled stack with the dynamic load current changes. The simulation data show that compared with the PID, Fuzzy-PID and PSO-PID controllers for the cooling fan, the overshoot amount of the coolant inlet temperature with the ADRC is significantly reduced from 1.02 %, 0.77 % and 0.26 % to 0.07 %, and the integral of time absolute error (ITAE) is decreased from 5.299 × 104, 5.206 × 104 and 1.255 × 104 to 3.930 × 103, respectively. The degree of temperature fluctuation is reduced and the parasitic power does not significantly increase. Therefore, the ADRC proposed in this study improves the temperature control effect of the PEMFC stack, which is conducive to enhancing the stack performance.

Research on Temporal–Spatial Partition Control Strategies for Luminous and Thermal Environment in High Space of Gymnasiums

The lighting design of large-space buildings in gymnasiums can impact the indoor luminous and thermal environment, resulting in an uneven light and thermal distribution. This paper investigates the luminous and thermal environment control strategies for high spaces in gymnasiums, by simulating the luminous and thermal environment under different lighting forms and establishing a comprehensive evaluation model. The results show that the weights of the indoor luminous environment, thermal environment, and comprehensive energy consumption change with season and time under different lighting forms, which provides a basis for developing a temporal–spatial partition control strategy. The temporal–spatial partition control strategy is proposed for summer and winter, including the shading angle control under the lighting forms of south-facing side windows, west-facing side windows, and top skylights. Under summer conditions, the south-facing side windows have no shading from 8:00 to 10:00 and 14:00 to 16:00, and the shading angle is 0° from 10:00 to 14:00; the west-facing side windows have no shading from 8:00 to 14:00, the shading angle is 0° from 14:00 to 15:00, and the shading angle is 15° from 15:00 to 16:00; and the top skylight has a shade angle of 15° from 8:00 to 9:00, 30° from 9:00 to 11:00, 45° from 11:00 to 13:00, and no shade from 13:00 to 16:00. Under winter conditions, the south-facing side windows have no shading all day; the west-facing side windows have no shading from 8:00 to 14:00, and the shading angle is 30° from 14:00 to 16:00; and the top skylight has no shading from 8:00 to 13:00, a shading angle of 45° from 13:00 to 15:00, and a shading angle of 75° from 15:00 to 16:00. This paper provides a set of scientific and reasonable luminous and thermal environment regulation strategies for large-space buildings, which can help optimize the building energy consumption and improve the indoor environment quality.

Design and application of deployable heat radiator

Abstract Limited by the envelope size of the launch vehicle, comparing with the body-mounted radiator of the traditional spacecraft, the thermal control scheme based on single-phase fluid loop is proposed in order to improve the system-level heat dissipation. The thermal analysis model of the deployable heat radiator, including the spacecraft, is established. Through the comparative analysis of the fin parameter, infrared radiation effect, and working fluid selection, the heat dissipation efficiency of the radiator is improved, and the first flight application of the deployable heat radiator is realized. The research results show that in view of the GEO spacecraft’s bad external heat flow condition, the heat dissipation of a single radiator can reach 250W/m2 above; the method of using multiple deployable heat radiators can effectively solve the problem of insufficient heat dissipation capacity on the spacecraft.

Fuzzy Logic Control with Long Short-Term Memory Neural Network for Hydrogen Production Thermal Control System

In the development of decarbonization technologies and renewable energy, water electrolysis has emerged as a key technology. The efficiency of hydrogen production and its applications are significantly affected by power stability. Enhancing power stability not only improves hydrogen production efficiency and reduces maintenance costs but also ensures long-term reliable system operation. This study proposes a thermal control method that stabilizes hydrogen output by precisely adjusting the temperature of the electrolysis stack, thereby improving hydrogen production efficiency. Fluctuations in the electrolysis stack temperature can lead to instability in the hydrogen output and energy utilization, negatively affecting overall hydrogen production. To address this issue, this study introduces an innovative system architecture and a novel thermal control strategy combining fuzzy logic control with a long short-term memory neural network. This method predicts and adjusts the flow rate of chilled water to maintain the electrolysis stack temperature within a range of ±1 °C while sustaining a constant power output of 10 kW. This approach is crucial for ensuring system stability and maximizing hydrogen production efficiency. Long-term experiments have validated the effectiveness and reliability of this method, demonstrating that this thermal control strategy not only stabilizes the hydrogen production process but also increases the volume of hydrogen generated.

Numerical Investigation on the Influence of Substrate Board Thermal Conductivity on Electronic Component Temperature Regulation

This study presents a detailed numerical analysis of substrate boards made from various materials (FR-4, Si cladding, and Cu cladding) with nine electronic components mounted on them. Each component is subjected to different heat fluxes, and the analysis covers both natural convection (NC) and forced convection (FC) modes of heat transfer at air velocities of 4m/s and 6m/s. The findings reveal that at an air velocity of 6m/s, using a copper cladding board significantly lowers the temperatures of the electronic components by 340C to 540C compared to FR-4 and Si cladding boards. Additionally, the copper cladding reduces the required air-cooling velocity by 2m/s and achieves a temperature reduction for the IC chips ranging from 3.500C to 13.120C. It is recommended to use an air velocity of 4m/s with copper cladding to minimize fan power consumption while maintaining component temperatures below 1250C. These results provide crucial insights for thermal design engineers, aiding in the selection of appropriate substrate boards for effective thermal management of electronic components. The study emphasizes the benefits of copper cladding in distributing heat more uniformly, reducing energy consumption, and maintaining optimal operating temperatures. Furthermore, it suggests that placing high heat-dissipating components at inlet or outlet points can minimize thermal interactions and overall configuration temperatures. The research offers valuable guidance to the heat transfer community, particularly electronic thermal designers, by highlighting the importance of substrate material choice and component placement in enhancing the reliability and lifespan of integrated circuits (ICs). The comprehensive analysis and recommendations serve as a vital resource for optimizing thermal control strategies in electronic devices, ultimately contributing to improved performance and durability.

Thermal testing of corundum ceramics: Classical techniques for optical heating

The types of defects and ways of their formation in the production of tiles from corundum ceramics are considered. The integrity of tiles containing artificial defects has been investigated by the method of active thermal non-destructive testing using optical heating. Single- and double-sided thermal control schemes are applied, as well as various methods of software processing of thermograms. It has been established that the best results in detecting internal defects in ceramic tiles with a thickness of 10 mm during thermal stimulation using halogen lamps are obtained by the method of unilateral thermal testing.

Optimization and safety analysis for CO oxidative coupling reactor with co-current thermal management

The CO oxidative coupling with methyl nitrite (MN) to dimethyl oxalate (DMO) in syngas-based ethylene glycol (EG) process faces challenges in low conversion and capacity per unit. In this work, by using a rigorous reactor model and NSGA-II algorithm, Pareto solutions balancing production capacity and safety were obtained to compare thermal control schemes. Under the specified domain, the optimized co-current-flow scheme achieved a DMO yield of 1.0 gDMO/(gcat∙h), surpassing the conventional isothermal-coolant scheme (0.55 gDMO/(gcat∙h)), and even under conservative conditions, the co-current scheme achieves 43% enhancement in capacity. Subsequently, the dynamic behavior of co-current reactor was compared with the isothermal-coolant one in much depth on the conditions determined by optimization of both performance and sensitivity. The results show that the reactor with co-current scheme provides the operators with twice more time to rectify operational biases, and an alarm of the wrong-way behavior when GHSV and inlet temperature are changed.

The project of Magdalena Gutiérrez: the poetics of living in the Atacama Desert. The four modes of climate management

This study addresses the issue of living in fragile ecological environments, such as oases in deserts. Currently, the oasis of San Pedro de Atacama is experiencing a decrease in its agricultural area due to urbanization and tourism, affecting the sustainability of traditional farming practices and putting at risk the ecological and cultural balance of this Atacamenian locale. The article presents sustainable design strategies for contemporary living in fragile environments, examining thermal qualities and climate control strategies applied to the “Workshop House” or Casa Taller of Magdalena Gutiérrez. Using the principles of Lisa Heschong and Eva Horn, the review also includes Reyner Banham's climate management modes. The methodology combines architectural and ethnographic analysis, structured in three stages: selection of works, construction of the conceptual framework, and analysis and systematization. Models, photographs, maps, and diagrams were used to contrast theories and thermal and cultural qualities with evidence from the work. Classification criteria included evaluating characteristics such as the degree of privacy of areas and rooms, ventilation, lighting, thermal insulation, and heating methods, with a binary rating employed for systematic evaluation. The results highlighted that Casa Taller manifests poetic living in the exteriority of the Atacama Desert, suggesting a vocation for community activities. The lighting qualities revealed a strategic design that maximizes controlled daylight, utilizing openings and skylights. It was concluded that the Casa Taller represents an expression of "Revisited Critical Regionalism." The "site-form" relationship is fundamental in this approach, balancing local techniques with cultural and natural surroundings. This work offers a sustainable model for living in fragile environments, where architectural design is appropriately integrated with the place’s climatic and cultural conditions.

Detailed modeling of droop-controlled multi-energy systems under unbalanced operation

Considering the residential sector, greenhouse gas emissions can be effectively reduced by the widespread deployment of distributed renewable energy sources (DRESs) in low-voltage (LV) electrical networks (ENs). Through the electrification and the integration of different energy systems, the exploitation of the locally generated renewable energy can be further increased, acting also as an efficient countermeasure to the technical challenges in ENs posed by the intermittent nature of DRESs. This work deals with the modeling of multi-energy systems (MESs) consisting of unbalanced ENs and district heating networks (DHNs), formulated based on existing EN and DHN models. The developed model is enhanced by the incorporation of a thermal droop control scheme into the controllable sources of DHN, i.e., heat pumps (HPs). The validity of the proposed model is assessed via time-series simulations on a MES composed of a benchmark unbalanced LV EN and a real DHN. It is shown that the integrated droop control scheme can act as a means towards overvoltage mitigation, temperature control and reduced MES losses, improving the operational reliability and exploitation of the DRES potential. Therefore, the proposed model could be useful for system operators and decision makers for the efficient planning and operation of MESs.

Optimizing Occupant Comfort in a Room Using the Predictive Control Model as a Thermal Control Strategy.

Thermal comfort strategies represent a very important aspect when it comes to achieving thermal comfort conditions. At the same time, recently, there has been a growing interest in user-centered building control concepts. Thus, this work focuses on developing a thermal control strategy that combines the restrictions related to achieving thermal comfort, expressed in terms of environmental parameters and specific factors of personal perception, with the objective of reducing energy consumption. This case study aims at implementing this strategy in a laboratory room located within the Technical University of Civil Engineering Bucharest. The strategy proposed by the authors is based on implementing a combination of a Model Predictive Control (MPC) model and a fuzzy system, which presents constraints related to the room occupancy level. Relevant observations regarding the parameterization of fuzzy systems are also highlighted.

Assessment of internal and external disturbances on the fuzzy-based thermal control of a sub-scaled building testbed

This experimental study follows on our previous work on the development of robust fuzzy-based thermal control strategies of a multi-room sub-scaled building testbed. In the present analysis, the focus is placed on testing the robustness of the fuzzy controller under internal and external disturbances, as it deals with maintaining specific setpoint values of room temperatures. The testbed has eight rooms, distributed on two floors, with a cooling unit that supplies cool air to each room, and eight 40 W light bulbs serving as heat sources. T-type thermocouples gather the temperature data, and eight dampers deliver the airflow. The controller uses information about the difference between setpoint and actual temperatures, their derivative, and their cumulative integral. The fuzzy sets and if-then rules are built based on experimental data, and a Mamdani inference method is used to provide the inputs to the actuators. Results from experimental tests show that the fuzzy control strategy can handle the different types of disturbances while maintaining the room setpoints.

An intelligent thermal comfort control strategy for air conditioning of fuel cell vehicles

Thermal comfort is an important indicator for evaluating vehicle air conditioning, with many influencing factors, but traditional vehicle air conditioning control only take temperature as the control target, neglecting the passenger's actual thermal comfort situation, which cannot automatically adapt to the thermal comfort needs of different passengers. To address this issue, this paper establishes an air conditioning model based on a fuel cell vehicle (FCV) and proposes a control strategy based on thermal comfort, using deep reinforcement learning based on PPO algorithm to establish the control model. Which can automatically control the compressor and blower, this paper conducts simulation analysis under four different environmental conditions which including static and dynamic situations. The results show that when using the intelligent thermal comfort control strategy, the overall thermal sensation values of passengers are 0.006, 0.005, 0.033, and 0.102, respectively; which are 0.088, 0.333, 0.093, and 0.120 lower than the temperature-based control strategy, this proves that the control strategy proposed in this paper can achieve better thermal comfort for passengers.

Uncertainty-Aware Online Learning of Dynamic Thermal Control in Data Center with Imperfect Pretrained Models

The growing demand for cloud computing and storage necessitates the expansion of Data Centers, thereby increasing energy consumption and environmental footprint. The data-driven dynamic thermal control presents a promising solution to mitigate this issue, as it can offer improved thermal control strategies and address the intricate and stochastic nature of the thermal environment. Nonetheless, existing solutions typically exhibit deficiencies in terms of reliability and practicability. To this end, this paper proposes a feasible uncertainty-aware online learning method with reliable dynamics models and controllers. Specifically, Deep Learning models with the capacity for uncertainty quantification are employed to account for the imperfections in pre-trained models, hence providing reliable predictions. The Cross-Entropy Method and Monte Carlo trajectory sampling solve optimization problems while considering uncertainties. It is mathematically analyzed that the uncertainty quantified by the system dynamics model can be captured with sufficient trajectory samples, rendering a reliable controller. A practical framework is proposed and tested on a widely used Data Center model to mitigate the insufficient capacity of Deep Learning models to quantify uncertainties. The results demonstrate its superior performance during the initial training stage, achieving a 66% reduction in violations and 3.76% power savings compared to the default controller. Continuous active online learning enhances its adaptability, resulting in an 80% reduction in violations and a 6% energy saving. The thermal control strategies are thus improved by the proposed new solutions and insights.

Strategy to solve the thermal issue of ultra-wide bandgap semiconductor gallium oxide field effect transistor

Gallium Oxide (Ga2O3) holds significant potential for the next generation of electronic devices following SiC and GaN due to its ultra-wide bandgap of approximately 4.5 eV - 4.9 eV and high theoretical critical breakdown field strength of 8 MV/cm. Nonetheless, Ga2O3 has a naturally low thermal conductivity, resulting in limited device output performance and hindering Ga2O3 devices from reaching their full theoretical potential. In this study, we demonstrate that the appropriate thermal management strategy can solve the above challenges. By comparing the thermal control schemes including the Ga2O3 FET devices on the original substrate, the thinned Ga2O3 substrate, the high thermal conductivity substrate, the heat sink packaging, and the flip-chip packaging, it is demonstrated that the flip-chip model is the most effective strategy to improve the heat dissipation performance of the Ga2O3 device. By utilizing the appropriate carrier in flip-chip packaging, the temperature elevation of the device at 2 W/mm power density will be diminished by around 91% in contrast to the initial basic device. Furthermore, the output performance of the device demonstrates significant enhancement. This thermal management technique successfully resolves the severe heat dissipation issue prevalent in Ga2O3 devices and eliminates primary obstacles concerning the industrialization of Ga2O3 RF and power devices.

Thermal performance and energy flow analysis of a PV/T coupled ground source heat pump system

Ground source heat pump (GSHP) system in cold regions will lead to a decrease in soil source temperature over the years after a long period of operation, and if no timely measures are taken, the system performance will get worse and worse, and even face the risk of shut down. The PV/T (photovoltaic/thermal) is an integrated energy supply system that can both improve the efficiency of solar energy utilization and weaken the soil temperature imbalance. In this paper, the thermal performance and year-round energy flow of the system are analyzed by the simulation model, and the effects of different soil thermal storage control strategies on the thermal storage performance in the transition season are explored. The results show that the coefficient of performance of the heat pump unit can reach 3.99 and 3.96 in the heating and cooling periods. The soil temperature only increases by 0.09 °C and 0.11 °C compared with the initial temperature after five and ten years of long-term system operation, respectively. In addition, after a comprehensive comparison of the thermal storage performance of different control strategies in the transition season, this study found that the temperature difference control strategy was superior to the time control strategy. Ultimately, the annual energy supply of the simulation system produces an additional 391.8 kWh of electricity in addition to meeting the energy demand for cooling, heating and power supply of the building, which realizes the zero-energy operation of the building.

Data Driven Type-2 Fuzzy Modeling and Control of Personalized Thermal Comfort

Since the room thermal comfort has high uncertainties, it is difficult but necessary to study the modeling and control of thermal comfort. This paper tries to solve the modeling and control problem for the room thermal comfort by utilizing the temperature and humidity data collected from the working or living room. Firstly, in order to discard the noisy data and to obtain the reasonable intervals for modeling the temperature and humidity, a statistic method based preprocessing strategy is presented. Secondly, the Gaussian interval type-2 fuzzy set models are constructed to depict the personalized temperature and humidity comfort by measuring the uncertainty degrees of the obtained intervals. Thirdly, a interval type-2 fuzzy method based control scheme is proposed to realize the personalized thermal comfort regulation. Finally, some experimental results are given. And, the results show that the proposed thermal comfort models and control scheme can not only recommend a reasonable temperature and humidity range, but also can realize the optimal thermal comfort control.

ControlPULP: A RISC-V On-Chip Parallel Power Controller for Many-Core HPC Processors with FPGA-Based Hardware-In-The-Loop Power and Thermal Emulation

High-performance computing (HPC) processors are nowadays integrated cyber-physical systems demanding complex and high-bandwidth closed-loop power and thermal control strategies. To efficiently satisfy real-time multi-input multi-output (MIMO) optimal power requirements, high-end processors integrate an on-die power controller system (PCS). While traditional PCSs are based on a simple microcontroller (MCU)-class core, more scalable and flexible PCS architectures are required to support advanced MIMO control algorithms for managing the ever-increasing number of cores, power states, and process, voltage, and temperature variability. This paper presents ControlPULP, an open-source, HW/SW RISC-V parallel PCS platform consisting of a single-core MCU with fast interrupt handling coupled with a scalable multi-core programmable cluster accelerator and a specialized DMA engine for the parallel acceleration of real-time power management policies. ControlPULP relies on FreeRTOS to schedule a reactive power control firmware (PCF) application layer. We demonstrate ControlPULP in a power management use-case targeting a next-generation 72-core HPC processor. We first show that the multi-core cluster accelerates the PCF, achieving 4.9x speedup compared to single-core execution, enabling more advanced power management algorithms within the control hyper-period at a shallow area overhead, about 0.1% the area of a modern HPC CPU die. We then assess the PCS and PCF by designing an FPGA-based, closed-loop emulation framework that leverages the heterogeneous SoCs paradigm, achieving DVFS tracking with a mean deviation within 3% the plant’s thermal design power (TDP) against a software-equivalent model-in-the-loop approach. Finally, we show that the proposed PCF compares favorably with an industry-grade control algorithm under computational-intensive workloads.

Optimization of Thermal Control Design for Aerial Reflective Opto-Mechanical Structure.

To improve the adaptability of aerial reflective opto-mechanical structures (mainly including the primary mirror and secondary mirror) to low-temperature environments, typically below -40 °C, an optimized thermal control design, which includes passive insulation and temperature-negative feedback-variable power zone active heating, is proposed. Firstly, the relationship between conventional heating methods and the axial/radial temperature differences of mirrors with different shapes is analyzed. Based on the heat transfer analyses, it is pointed out that optimized thermal control design is necessary to ensure the temperature uniformity of the fused silica mirror, taking into account the temperature level when the aerial electro-optics system is working in low-temperature environments. By adjusting the input voltage based on the measured temperature, the heating power of the subregion is changed accordingly, so as to locally increase or decrease the temperature of the mirrors. The thermal control scheme ensures that the average temperature of the mirror fluctuates slowly and slightly around 20 °C. At the same time, the temperature differences within a mirror and between the primary mirror and the secondary mirror can be controlled within 5 °C. Thereby, the resolution of EO decreases by no more than 11.4%.

Developing a novel personal thermoelectric comfort system for improving indoor occupant’s thermal comfort

Personal comfort systems (PCSs), which target to condition only the occupied zones of indoor space, have received considerable interest due to their validity in thermal comfort improvement and building energy saving. Recently, the thermoelectric module (TEM) has been utilized in the design of PCS for its high reliability, small size and noise-free operation. However, the PCSs using the TEM generally lack the effective control strategy with occupant’s feedback, thus reducing their actual effectiveness on improving thermal comfort. In this paper, a novel personal thermoelectric comfort system (PTCS) is developed with a feedback control framework embedded into it. The PTCS is mainly composed of a thermoelectric conversion unit, a micro blower, control/drive modules and a tube network. A thermal comfort feedback control strategy is proposed for the PTCS. In this strategy, a thermal comfort feedback table is established based on offline experiments, and the tube outlet airflow velocity and temperature setpoints are obtained simultaneously through the table look-up method. Then, the neuron PID control algorithm and pulse width modulation (PWM) of voltage are adopted to adjust the tube outlet airflow velocity and temperature for tracking the obtained setpoints. Experimental results validate the effectiveness of the thermal comfort feedback control strategy. Thermal imaging results on human body demonstrate the availability of the developed PTCS. Performance comparison with other PCSs is also provided, which indicates the potential for practical applications.

Investigation of multifactorial effects on the thermal performance of battery pack inserted with multi-layer phase change materials

The safe and efficient power battery thermal management system (BTMS) is a prerequisite for the effectiveness and long service life of electric vehicles. So, a BTMS with inserted multi-layer phase change materials (PCMs) is proposed to enhance the safety and working performance of battery pack. Effects of PCM settings and operating conditions on the thermal performance of battery pack are discussed and analyzed. The results reveal that PCM cooling plays a significant role in the thermal management of battery pack, where the maximum temperature value and temperature difference of BTMS with multi-layer PCM #C are respectively reduced by 13.61 °C and 2.54 °C compared to battery pack without PCM. Besides, the coupling effects of multiple factors, that is, PCM permutation, the thickness and height of PCMs, and ambient temperature, on the heat dissipation of battery pack are discussed via orthogonal results analysis. The optimized multi-layer PCMs are obtained for the BTMS, i.e., Ps = 121, h1 = 5 mm and L = 6 mm, which achieves the lowest values of Tmax = 43.02 °C and ΔT = 3.37 °C at Tamb = 20 °C. It provides insights for optimizing thermal control strategies for the advancement of thermal management in electric vehicles, ultimately enhancing safety, performance, and longevity.