{"title":"Non-monotonic phase change front propagation during one-dimensional melting/solidification in the conduction-dominated regime","authors":"Emad Hasrati, Ankur Jain","doi":"10.1016/j.ijthermalsci.2025.109970","DOIUrl":"10.1016/j.ijthermalsci.2025.109970","url":null,"abstract":"<div><div>Development of theoretical techniques to model melting/solidification is important for a number of engineering problems. Using an approximate analytical technique, this work considers melting/solidification of a one-dimensional phase change material (PCM) with convective heat transfer boundary conditions at the two ends. Good agreement with past work under special conditions is shown. Assuming negligible buoyancy-driven convective heat transfer, it is shown that, under certain conditions, the phase change front may grow non-monotonically, i.e., beyond a peak value of the phase change front, there may be a reversal in the direction of the front propagation, before steady state is reached. It is shown that this retraction phenomenon is governed by the Stefan number, ratio of applied temperature differences, ratios of thermophysical properties, and Biot numbers associated with boundary conditions. The retraction phenomenon is explained on the basis of the competition between phase change front propagation and solid phase thermal diffusion. Retraction is shown to occur when the rate of propagation is much greater than the rate of diffusion. The retraction phenomenon investigated here is novel because most one-dimensional phase change problems proceed monotonically, and a reversal in the phase change direction does not commonly occur. In addition to the theoretical interest in non-monotonic phase change propagation, results from this work may also be helpful in improving the thermal performance of PCMs in practical engineering devices.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"217 ","pages":"Article 109970"},"PeriodicalIF":4.9,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenjuan Bai , Xijun Zhang , Chenyu Gao , Xinyue Zhao , Yan He , Yuanyuan Shang , Baohui Shi , Lingxiao Lu , Dianming Chu
{"title":"3D printing of CNTs-modified continuous carbon fiber composites driven by Joule-heat resin curing","authors":"Wenjuan Bai , Xijun Zhang , Chenyu Gao , Xinyue Zhao , Yan He , Yuanyuan Shang , Baohui Shi , Lingxiao Lu , Dianming Chu","doi":"10.1016/j.ijthermalsci.2025.110048","DOIUrl":"10.1016/j.ijthermalsci.2025.110048","url":null,"abstract":"<div><div>Amidst the growing scarcity of energy resources, we are committed to fully exploiting the capabilities of anisotropic materials present in nature. Additive manufacturing (3D printing) has surfaced as a promising avenue for this objective, particularly with the increasing adoption of continuous carbon fiber (CF) reinforced thermosetting resins, which exhibit superior strength-to-weight ratios compared to metallic materials. However, issues such as delamination and the intricacies of real-time curing and molding processes pose significant challenges in this domain. In this research, we introduce a method for Joule heat curing (JHC)-based 3D printing. Initially, a structure mimicking “tree roots” is established by grown carbon nanotubes (CNTs) at the CF interface through the thermotropic flash assembly (TFA) technique, resulting in a 39.8 % enhancement in interfacial shear strength. Additionally, precision precisely controlled Joule heat epoxy resin is utilized for rapid curing and improved adhesion, achieving an curing degree of 0.44. Ultimately, a manipulator facilitates free-forming capabilities. This process leads to substantial increases in interlaminar shear strength while maintaining tensile strength close to its original value. By directly applying “line energy” to the material, this methodology enables efficient regulation and utilization, yielding enhanced efficiency, energy conservation, and cost reduction.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110048"},"PeriodicalIF":4.9,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enpei Wang , Meng Zhao , Haopeng Shi , Hao Zhang , Yanhua Yang , Qinglong Wen
{"title":"Critical heat flux prediction through machine learning model for narrow rectangular channels","authors":"Enpei Wang , Meng Zhao , Haopeng Shi , Hao Zhang , Yanhua Yang , Qinglong Wen","doi":"10.1016/j.ijthermalsci.2025.110050","DOIUrl":"10.1016/j.ijthermalsci.2025.110050","url":null,"abstract":"<div><div>Accurately predicting critical heat flux (CHF) is crucial for ensuring efficient energy transfer and safe operation in thermal system, particularly in narrow rectangular channels, which are favored for their superior thermo-hydraulic performance and compactness. This study compiles 660 experimental CHF data points from narrow rectangular channels under wide variety of operating conditions and evaluates existing CHF correlations. Four machine learning (ML) models—back-propagation (BP) neural networks, random forest (RF), support vector regression (SVR), and Long Short-Term Memory (LSTM) are employed to predict CHF using input parameters encompassing thermal-hydraulic and geometrical characteristics. The results indicate that the BP approach has a high level of performance, with a root-mean-square error (RMSE) of 38.37 and a mean absolute error (MAE) of 24.33. To further optimize the BP neural network, four metaheuristic algorithms—particle swarm optimization (PSO), genetic algorithms (GA), cuckoo search (CS), and ant colony algorithm (ACA) are applied. The GA optimization yields the most accurate predictions, achieving a RMSE of 33.53 and a MAE of 19.13. The trained GA-BP model exhibits robust performance in predicting CHF in narrow rectangular channels under varying pressure conditions.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110050"},"PeriodicalIF":4.9,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shizhe Liu , Chongguang Yue , Weihao Kong , Meng Yao , Jingyun Xue , Daqing Guang , Xiaoling Wang , Weiguang An
{"title":"The maximum ceiling temperature rise during moving train fire in subway tunnel: the influence of longitudinal ventilation","authors":"Shizhe Liu , Chongguang Yue , Weihao Kong , Meng Yao , Jingyun Xue , Daqing Guang , Xiaoling Wang , Weiguang An","doi":"10.1016/j.ijthermalsci.2025.110025","DOIUrl":"10.1016/j.ijthermalsci.2025.110025","url":null,"abstract":"<div><div>Longitudinal ventilation systems are extensively found in subway tunneling projects due to their low cost and superior smoke extraction capabilities. However, when a moving train in a tunnel is on fire, its fire characteristics, especially the temperature distribution characteristics, will be complicated by the simultaneous effects of longitudinal ventilation and piston wind. A series of scaled-down experiments were carried out to examine the ceiling temperature rise characteristics in this case. The characteristics of the tunnel flow field under the combined influence of piston wind and longitudinal ventilation are revealed, and it is discovered that the ventilation wind direction and wind velocity are the main factors controlling the dimensionless maximum airflow velocity. Ventilation velocity, fire power, and vehicle speed impact the variation in ceiling temperature rise by altering flame geometry, smoke flow, and heat accumulation time. Under the downwind condition, the maximum ceiling temperature rise for some scenarios increases and then decreases with increasing ventilation velocity. Under the upwind condition, owing to the significant overlapping enhancement effect of the annular gap flow field, the ceiling temperature rise value decreases monotonically with the increase of ventilation wind velocity and vehicle speed, and it is always lower than the safe value. It is recommended that the daily longitudinal ventilation wind velocity is less than 5.4 m/s, and the wind velocity can be increased in the later phase of the fire to optimize the safety evacuation and rescue conditions. A prediction model of ceiling temperature rise based on the dimensionless theorem is established by introducing the convective heat transfer intensity factor and the barrier effect factor. The cross-experiment results show that its prediction accuracy is high. The research results are helpful for monitoring and controlling tunnel fires and providing guidance for evacuation and rescue.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110025"},"PeriodicalIF":4.9,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shu-Yan Liu , Yu-Xing Peng , Yu Zhang , Kang Luo , Jian Wu , Hong-Liang Yi
{"title":"Effect of ion mobility on electro-thermal convection: Linear stability analysis and numerical simulation","authors":"Shu-Yan Liu , Yu-Xing Peng , Yu Zhang , Kang Luo , Jian Wu , Hong-Liang Yi","doi":"10.1016/j.ijthermalsci.2025.110033","DOIUrl":"10.1016/j.ijthermalsci.2025.110033","url":null,"abstract":"<div><div>In this work, a comprehensive investigation of Rayleigh-Bénard convection in an electric field is implemented based on linear stability analysis and numerical simulation. The effect of ion mobility represented by the ratio of negative and positive ion mobility (<em>K</em><sub><em>r</em></sub>) on the onset of flow instability and heat transfer enhancement is investigated. The stability analysis reveals that higher <em>K</em><sub><em>r</em></sub> values lead to a lower critical Rayleigh number (<em>Ra</em><sub>c</sub>), promoting earlier convection onset. A series of numerical simulations using the finite volume method with the EHD module is conducted across different <em>K</em><sub><em>r</em></sub> and <em>Ra</em> values, showing that a change in <em>K</em><sub><em>r</em></sub> not only initiates the flow without increasing the energy input, but also leads to the transition of the flow pattern and the structure of thermal plumes. Additionally, <em>K</em><sub><em>r</em></sub> significantly influences heat transfer efficiency: at <em>Ra</em> = 30000, increasing <em>K</em><sub><em>r</em></sub> from 1 to 10 leads to a 29 % increase in the Nusselt number (<em>Nu</em>). However, it is worth noting that the maximum velocity and heat transfer efficiency do not monotonically increase with <em>K</em><sub><em>r</em></sub>, suggesting that selecting an optimal working fluid is essential for practical applications. These findings highlight the critical role of ion mobility in driving convection and enhancing heat transfer in electro-thermal systems.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110033"},"PeriodicalIF":4.9,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhongxin Liu, Xuan Zhang, Long Zhang, Runmiao Gao, Han Shi, Zekang Zhen, Mengjie Song
{"title":"Effect of water temperature on ice melting characteristics under a bubbly flow","authors":"Zhongxin Liu, Xuan Zhang, Long Zhang, Runmiao Gao, Han Shi, Zekang Zhen, Mengjie Song","doi":"10.1016/j.ijthermalsci.2025.110034","DOIUrl":"10.1016/j.ijthermalsci.2025.110034","url":null,"abstract":"<div><div>Icing is widespread in the waters of cold regions, affecting the movement of ships, and effective de-icing methods are very necessary. The method of de-icing under a bubbly flow has the advantage of environmental protection and low energy consumption, and the effect of water temperature as a key factor deserves to be studied. An experimental set-up is designed to explore the ice melting process at different initial water temperatures ranging from 3–9 °C. Based on the experimental results, ice morphology, melting rate, heat transfer coefficient, and ice melting efficiency are analyzed. As the ice melts, a depression appears on the ice bottom surface and the depression profile gradually stabilizes with a change ratio of less than 10 %. The depression profiles at the same normalized time during under different water temperatures are almost identical, with a difference of less than 5 %. The melting rate decreases with increasing distance from the central axis in the beginning, while that in different locations gradually decreases to an almost equal constant due to the heat insulation of the remarkable bubble as the melting proceeds. The average melting rate in the height direction is linearly related to water temperature. The heat transfer coefficient is independent of water temperature. The heat transfer coefficient at each location of the ice bottom surface will gradually approach each other as melting proceeds. The findings are expected to be meaningful in the optimization of bubble de-icing systems.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110034"},"PeriodicalIF":4.9,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Flow boiling of water in a micro pin-fin heat sink at sub-atmospheric pressure","authors":"Wenjie Hu , Yunlong Qiu , Chuan Tong , Weifang Chen , Changju Wu","doi":"10.1016/j.ijthermalsci.2025.110032","DOIUrl":"10.1016/j.ijthermalsci.2025.110032","url":null,"abstract":"<div><div>Flow boiling of deionized water in a silicon-based micro pin-fin heat sink with sub-atmospheric outlet pressure are experimentally studied in this work. Experiments are conducted with a constant mass flow rate of 4 ml/min, a controlled outlet pressure ranging from 20 to 60 kPa, and effective heat flux up to 580 kW/m<sup>2</sup>. The inlet temperature is controlled at 20 K below the saturation temperature corresponding to the outlet pressure. The effects of sub-atmospheric outlet pressure on the flow boiling characteristics are investigated and discussed. It is found that lower sub-atmospheric outlet pressure leads to higher pressure drop due to the significant reduction in vapor phase density. When the outlet thermodynamic quality is about 0.27, the pressure drop is about 14.87 kPa at <em>P</em><sub><em>out</em></sub> = 20 kPa, while it is only 8.50 kPa at <em>P</em><sub><em>out</em></sub> = 60 kPa. In the meantime, the average heat transfer coefficient at <em>P</em><sub><em>out</em></sub> = 60 kPa is approximately twice that at <em>P</em><sub><em>out</em></sub> = 20 kPa. Besides, a decreasing tendency of wall temperature along the flow direction is observed, which is caused by the decreasing tendency of saturation temperature along the micro pin-fin heat sink. Under lower outlet pressure condition, the heat transfer performance degradation occurs earlier. The flow boiling visualization results show that the rapid expansion behavior of upstream bubbles and the evaporation of the thin liquid film in the downstream area are the main flow boiling behaviors in micro pin-fin heat sink under outlet sub-atmospheric pressure. The expansion of upstream bubbles is an important driving force for the replenishment of downstream liquid.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110032"},"PeriodicalIF":4.9,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haichao Wang , Yumeng Li , Hongyi Fang , Yuting Liao , Song Liu
{"title":"Research on the characteristics of turbine vane film cooling at low Reynolds numbers","authors":"Haichao Wang , Yumeng Li , Hongyi Fang , Yuting Liao , Song Liu","doi":"10.1016/j.ijthermalsci.2025.110015","DOIUrl":"10.1016/j.ijthermalsci.2025.110015","url":null,"abstract":"<div><div>Unmanned aerial vehicles and high-bypass-ratio engines typically operate at low Reynolds number(Re)conditions. It results in distinct film cooling characteristics for turbine vanes. This numerical study investigates the film cooling performance of four rows of film holes (S1 and S2 on the suction side, P1 and P2 on the pressure side) under low and high Re numbers (Re = 3.0 × 10<sup>4</sup>, 3.5 × 10<sup>5</sup>). The research focuses on the effects of blowing ratio (M = 0.2, 0.5, 1.0 for suction-side holes; M = 0.5, 1.0, 1.5 for pressure-side holes), mainstream turbulence intensity (Tu = 2.3 %, 15.7 %), and mainstream inlet Mach number (<em>Ma</em> = 0.0083, 0.15) on film cooling effectiveness and heat transfer coefficient ratios. The findings illustrate that, for suction-side film holes, when M = 0.2 and M = 0.5, the film cooling effectiveness at low Re number is significantly worse than at high Re number, but the difference decreases at larger blowing ratios (M = 1.0). Increasing mainstream Tu reduces the film cooling effectiveness at low Re number and increases the heat transfer coefficient ratio, whereas the opposite trend is observed at high Re number. At low Re number, the high <em>Ma</em> case increases the η values by 28–45 %, while this enhancement reverses at M = 1.0 at high Re number. For pressure-side film holes, the film cooling effectiveness at low Re number is poorer at small blowing ratios (M = 0.5), but superior at M = 1.0 and M = 1.5 compared to high Re number. An increase in Tu values leads to a decrease in the heat transfer coefficient ratio at both low and high Re numbers, although the response to turbulence intensity changes is less pronounced at low Re number. At both Re conditions, high <em>Ma</em> initially yields lower η than low <em>Ma</em> but eventually outperforms it. Overall, film cooling performance at low Re number is poorer and more sensitive to changes in turbulence intensity,yet demonstrates superior stability in film coverage across a wider range of applicable blowing ratios at a high <em>Ma</em> case.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110015"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Condensation and boiling in the entrance region of horizontal and inclined smooth tubes","authors":"Vasyl Ruzaikin, Ivan Lukashov, Andrii Breus","doi":"10.1016/j.ijthermalsci.2025.110031","DOIUrl":"10.1016/j.ijthermalsci.2025.110031","url":null,"abstract":"<div><div>This manuscript presents the results of an experimental investigation into ammonia condensation and boiling in the entrance region of horizontal and inclined smooth tubes with an inner diameter (ID) of 11 mm. The study was conducted under saturation temperatures ranging from 55 °C to 65 °C, mass velocities between 60 and 120 kg m<sup>−2</sup> s<sup>−1</sup>, and vapour qualities from 0.1 to 0.7. Two-phase flow pattern transitions were also examined using a transparent tube of ID 7.5 mm, equipped with ID 2 mm throttling orifice. Perturbation lengths were quantitatively evaluated for saturation temperatures between 35 °C and 55 °C, mass velocities of 80–160 kg m<sup>−2</sup> s<sup>−1</sup>, and vapour qualities from 0.1 to 0.7. The results indicate that perturbation length is primarily determined by the initial two-phase flow pattern. The perturbation length remains unaffected by variations in saturation temperature, mass velocity, or vapour quality within the given flow pattern. In horizontal flow, the perturbation length does not exceed 23 hydraulic diameters (D) for stratified-wavy flows, and 15D for annular and annular-wavy flows. For vertical upflow, plug and churn flow regimes exhibit perturbation lengths of up to 24D, whereas annular and annular-wavy patterns remain stable beyond 20D. An L-junction does not significantly affect the flow pattern beyond a distance of 12D. In the entrance region, average condensation heat transfer coefficients (HTCs) are generally lower than those in the fully developed region at low mass velocities (<120 kg m<sup>−2</sup> s<sup>−1</sup>) and vapour qualities (<0.7). For boiling, performance in the entrance region is comparable to that in the fully developed region at low mass velocities. However, at higher mass velocities (120 kg m<sup>−2</sup> s<sup>−1</sup>), a slight reduction in boiling HTCs—approximately 10 %—was observed, which can be explained by the suppression of the nucleate boiling mechanism.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110031"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hongsheng Xu, Heng Yu, Fukai Chu, Zhandong Wang, Weizhao Hu, Lei Song, Yuan Hu
{"title":"Effect of sub-atmospheric pressure on combustion and pyrolysis behavior of flame-retardant polyethylene","authors":"Hongsheng Xu, Heng Yu, Fukai Chu, Zhandong Wang, Weizhao Hu, Lei Song, Yuan Hu","doi":"10.1016/j.ijthermalsci.2025.110028","DOIUrl":"10.1016/j.ijthermalsci.2025.110028","url":null,"abstract":"<div><div>With the rapid increase in the number of cruise aircraft and high-altitude greenhouses, internal electrical cables and polyethylene films are often exposed to low-pressure environments. However, current flame-retardant designs for polyethylene do not sufficiently account for the effects of low-pressure conditions, under which the combustion behavior and flame-retardant effectiveness may change significantly, leading to a considerable risk of functional failure. This study systematically investigates the combustion and pyrolysis mechanisms of low-density polyethylene (LDPE) with varying intumescent flame retardant (FR) contents in a pressure range of 55 kPa–101 kPa. The findings reveal that FR significantly enhances char formation under sub-atmospheric pressures, reducing ignition time compared to pure LDPE. Decreased pressure leads to a marked increase in heat release rate (HRR) and a reduction in CO emissions, as measured by a cone calorimeter in a low-pressure chamber. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) further reveals that low-pressure promotes the generation of more alkene and a higher proportion of long-chain pyrolysis products. Intumescent FR effectively reduce HRR, decrease CO production, and minimize the formation of saturated hydrocarbons under low-pressure conditions, while enhancing the char formation. Among these, a 35 wt% FR shows the best performance. However, ammonium polyphosphate, a common flame retardant, tends to make the material more susceptible to ignition. This work enhances the understanding of fire dynamics in low-pressure environments and provides a scientific foundation for designing safer, flame-retardant polyethylene materials tailored for sub-atmospheric applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110028"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}