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Thermo, Volume 5, Issue 1 (March 2025) – 6 articles

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12 pages, 4884 KiB  
Article
Design and Implementation of Multi-Channel Temperature Measurement System of Thermal Test Chip Based on Diode Temperature-Sensitive Arrays
by Lina Ju, Peng Jiang, Xing Zhou, Ruiwen Liu, Yanmei Kong, Yuxin Ye, Binbin Jiao, Honglin Sun and Fan Wei
Thermo 2025, 5(1), 6; https://doi.org/10.3390/thermo5010006 - 12 Feb 2025
Viewed by 116
Abstract
When chips perform numerous computational tasks or process complex instructions, they generate substantial heat, potentially affecting their long-term reliability and performance. Thus, accurate and effective temperature measurement and management are crucial to ensuring chip performance and lifespan. This paper presents a multi-channel temperature [...] Read more.
When chips perform numerous computational tasks or process complex instructions, they generate substantial heat, potentially affecting their long-term reliability and performance. Thus, accurate and effective temperature measurement and management are crucial to ensuring chip performance and lifespan. This paper presents a multi-channel temperature measurement system based on a diode temperature-sensitive array thermal test chip (TTC). The thermal test chip accurately emulates the heat power and thermal distribution of the target chip, providing signal output through row and column address selection. The multi-channel temperature measurement system centers around a microcontroller and includes voltage signal acquisition circuits and host computer software. It enables temperature acquisition, storage, and real-time monitoring of 16 channels in a 4 × 4 array thermal test chip. During experiments, the system uses a constant current source to drive temperature-sensitive diodes, collects diode output voltage through multiplexers and high-precision amplification circuits, and converts analog signals to digital signals via a high-speed ADC. Data transmission occurs via the USB 2.0 protocol, with the host computer software handling data processing and real-time display. The test results indicate that the system accurately monitors chip temperature changes in both steady-state and transient thermal response tests, closely matching measurements from a semiconductor device analyzer, with an error of about 0.67%. Therefore, this multi-channel temperature measurement system demonstrates excellent accuracy and real-time monitoring capability, providing an effective solution for the thermal design and evaluation of high power density integrated circuits. Full article
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14 pages, 1583 KiB  
Article
Thermodynamic Model of a Gas Turbine Considering Atmospheric Conditions and Position of the IGVs
by Tarik Boushaki and Kacem Mansouri
Thermo 2025, 5(1), 5; https://doi.org/10.3390/thermo5010005 - 7 Feb 2025
Viewed by 273
Abstract
Gas turbines are widely used in power generation due to their efficiency, flexibility, and low environmental impact. Modeling, especially in thermodynamics, is crucial for the designer and operator of a gas turbine. An advanced and rigorous thermodynamic model is essential to accurately predict [...] Read more.
Gas turbines are widely used in power generation due to their efficiency, flexibility, and low environmental impact. Modeling, especially in thermodynamics, is crucial for the designer and operator of a gas turbine. An advanced and rigorous thermodynamic model is essential to accurately predict the performance of a gas turbine under on-design operating conditions, off-design or failure. Such models not only improve understanding of internal processes but also optimize performance and reliability in a wide variety of operational scenarios. This article presents the development of a thermodynamic model simulating the off-design performance of a gas turbine. The mathematical relationships established in this model allow for quick calculations while requiring a limited amount of data. Only nominal data are required, and some additional data are needed to calibrate the model on the turbine under study. A key feature of this model is the development of an innovative relationship that allows direct calculation of the mass flow of air entering the turbine and, thus, the performances of the turbine according to atmospheric conditions (such as pressure, temperature, and relative humidity) and the position of the compressor inlet guide vanes (IGV). The results of the simulations, obtained using code implemented in MATLAB (R2014a), demonstrate the efficiency of the model compared to experimental data. Indeed, the model relationships exhibit high determination coefficients (R2 > 0.95) and low root mean square errors (RMSE). Specifically, the simulation results for the air mass flow rate demonstrate a very high determination coefficient (R2 = 0.9796) and a low root mean square error (RMSE = 0.0213). Full article
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20 pages, 6372 KiB  
Article
Numerical Analysis of Transient Burn Injury Grading Through Coupled Heat Transfer and Damage Integral Modeling
by Chao Zhang, Xinbin Ma, Mengxi Li, Yubin Qiu, Moon Keun Kim and Jiying Liu
Thermo 2025, 5(1), 4; https://doi.org/10.3390/thermo5010004 - 4 Feb 2025
Viewed by 535
Abstract
The accurate assessment of parameters such as burn degree, volume, and depth is a prerequisite for the effective treatment of patients. However, as an unsteady heat transfer process, the temperature of the burn damage volume changes over time, and it is difficult to [...] Read more.
The accurate assessment of parameters such as burn degree, volume, and depth is a prerequisite for the effective treatment of patients. However, as an unsteady heat transfer process, the temperature of the burn damage volume changes over time, and it is difficult to accurately calculate the integral value of the damage, which is used to assess the burn degree. Therefore, it is impossible to accurately determine the location and volume of damage at all burn degrees. In this study, the C language is used to program a user-defined function of the burn damage integral formula, and the coupled numerical simulation method is used to calculate the heat transfer and damage in a high-temperature water burn process. Then, the temperature and burn damage integral value of each point can be determined to accurately assess and distinguish the burn degree in real time, and estimate the position distribution, volume size, and transient change trend of each burn degree. Under the working conditions selected in this paper, the heat source mainly affects the epidermis and dermis directly below, and has less influence on the area above, which is in convective heat transfer. The damage integral value is very sensitive to temperature, and the highest damage integral value caused by 373 K is two and four orders of magnitude higher than that of 363 K and 353 K, respectively. The increase in the heat source temperature caused the volume of a third-degree burn to increase rapidly in the early stage of injury, but the volume of second-degree and first-degree burns did not change much. After heating at 373 K for 15 s and delaying the action for 45 s, the volume of first-, second-, and third-degree burns accounted for 0.4, 2.9, and 1.9%, respectively, and the total volume of damage accounted for only 5.2% of the total volume. Full article
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19 pages, 1568 KiB  
Article
Energy and Exergy Analyses Applied to a Crop Plant System
by Heba Alzaben and Roydon Fraser
Thermo 2025, 5(1), 3; https://doi.org/10.3390/thermo5010003 - 30 Jan 2025
Viewed by 446
Abstract
The second law of thermodynamics investigates the quality of energy, or in other words exergy, described as the maximum useful to the dead-state work. The objective of this paper is to investigate the energy and exergy flows in a crop plant system in [...] Read more.
The second law of thermodynamics investigates the quality of energy, or in other words exergy, described as the maximum useful to the dead-state work. The objective of this paper is to investigate the energy and exergy flows in a crop plant system in order to identify the dominant flows and parameters (e.g., temperature) affecting crop plant development. The need for energy and exergy analyses arises from the hypothesis that crop stress can be detected via surface temperature measurements, as explained by the exergy destruction principle (EDP). Based on the proposed energy model, it is observed that radiation and transpiration terms govern all other terms. In addition, as a result of exergy analysis, it is observed that solar exergy governs all input and output terms. The results obtained from this study support the hypothesis that crop surface temperature can be utilized as an indicator to detect crop stress. Full article
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2 pages, 387 KiB  
Correction
Correction: Rabi’ et al. Packed Bed Thermal Energy Storage System: Parametric Study. Thermo 2024, 4, 295–314
by Ayah Marwan Rabi’, Jovana Radulovic and James M. Buick
Thermo 2025, 5(1), 2; https://doi.org/10.3390/thermo5010002 - 17 Jan 2025
Viewed by 230
Abstract
In the original publication [...] Full article
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19 pages, 4625 KiB  
Article
Optimal Design Parameters for Supercritical Steam Power Plants
by Victor-Eduard Cenușă and Ioana Opriș
Thermo 2025, 5(1), 1; https://doi.org/10.3390/thermo5010001 - 16 Jan 2025
Viewed by 714
Abstract
Steam thermal power plants represent important energy production systems. Within the energy mix, these could allow flexible generation and the use of hybrid systems by integrating renewables. The optimum design solution and parameters allow higher energy efficiency and lower environmental impact. This paper [...] Read more.
Steam thermal power plants represent important energy production systems. Within the energy mix, these could allow flexible generation and the use of hybrid systems by integrating renewables. The optimum design solution and parameters allow higher energy efficiency and lower environmental impact. This paper analyzes single reheat supercritical steam power plants design solutions using a genetic heuristic algorithm. A multi-objective optimization was made to find the Pareto frontier that allows the maximization of the thermal cycle net efficiency and minimization of the specific investment in the power plant equipment. The Pareto population was split and analyzed depending on the total number of preheaters. The mean values and the standard deviations were found for the objective functions and main parameters. For the thermal cycle schemes with eight preheaters, the average optimal thermal cycle efficiency is (48.09 ± 0.16)%. Adding a preheater increases the average optimal thermal cycle efficiency by 0.64%, but also increases the average optimum specific investments by 7%. It emphasized the importance of choosing a proper ratio between the reheating and the main steam pressure. Schemes with eight and nine preheaters have an average optimum value of 0.178 ± 0.021 and 0.220 ± 0.011, respectively. The results comply with data from the literature. Full article
(This article belongs to the Special Issue Innovative Technologies to Optimize Building Energy Performance)
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