Gels
·
2024
·Vol. 10
·期 11
·702
·
IF 5
Xiaoxu Wu,Kai Shen,Min Hu,Fang Zhou,Zikang Chen,Qiong Liu,Zijun Li,Zhi Li
The thermal safety of hydrophobic silica aerogels (SAs) is essential to thermal insulation applications. Herein, trimethylchlorosilane (TMCS), dimethyldichlorosilane (DMDCS), and methyltrichlorosilane (MTCS) were employed as surface modifiers to prepare three different methylsilyl-modified SAs (i.e., TSA, DSA, and MSA) and their combustion characteristics and thermal hazards were experimentally studied in detail. The cone calorimeter test found that the three SAs have similar combustion processes and the variations in ignition time and fire spread rate with the heat flux obey simple logarithmic and linear relationships, respectively. It further found that TSA has the most methylsilyl groups on silica skeletons and thus has the largest heat release, followed by DSA and MSA in turn, implying that TSA has the greatest fire hazard among the three SAs. These results further demonstrate that the type and quantity of methylsilyl groups on the skeletons of SAs significantly affect the thermal hazard of methylsilyl-modified SAs. In addition, the combustion mechanism of the methylsilyl-modified SAs is discussed. In total, this work experimentally studies the combustion characteristics of methylsilyl-modified SAs and compares their thermal hazards, clarifying the potential fire risk of methylsilyl-modified SAs in practical thermal insulation applications.
研究领域:
材料科学
·
消防安全
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2025
·
IF 19
Liangyuan Qi,Wei Cai,Tianyang Cui,Junwei Li,Lei Song,Zhou Gui,Bin Fei,Jixin Zhu,Yuan Hu,Weiyi Xing
Radiative cooling coatings demonstrate broad applicability on equipment surfaces, spanning spacecraft to precision instruments, for sub-ambient cooling. However, unlike conventional equipment relies on solar reflection and infrared emission for cooling, the heat-generating equipment relies on coupled thermal conduction and radiative cooling, representing a distinct heat transfer paradigm. This study introduces an innovative fire-safe radiative cooling-enhanced anisotropic thermal rectification coating (TRC) by leveraging the thermal rectification effect. The rectification mechanism stems from engineered thermal conductivity gradients with temperature-dependent anisotropy, where asymmetric phonon transport in multilayer architectures enables unidirectional heat flux control. Through the rational coupling of radiative cooling emitters at the cold terminal with thermal diodes, the TRC achieves unidirectional heat transfer enhancement through conduction-radiation coupling, demonstrating a thermal rectification coefficient of 1.78 and 3.1–3.4 °C daytime temperature reduction below ambient. Crucially, under concurrent solar irradiation and simulated heat-generating equipment (50 °C), TRC attains 6.8 °C maximum cooling enhancement. Notably, the TRC integrates gas-phase and condensed-phase flame retardant mechanisms to effectively mitigate the risk of thermal runaway in heat-generating devices. This multifunctional integration advances radiative cooling technology toward practical implementation in thermal-critical infrastructure, including power electronics thermal management and smart building systems.
研究领域:
热工程
·
材料科学
·
传热学
·
纳米技术
·
消防安全工程
·
应用物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
·
2015
·
IF 1.406
L. Zhang,W.D. Yu,X.H. Pan,J.J. Fang,M. Hua,F.M. Chen,J.C. Jiang
The exothermic oxidation of 3-methylpyridine with hydrogen peroxide was analyzed by Reaction Calorimeter (RC1e) in semi-batch operation. Heat releasing rate and heat conversion were studied at different operating conditions, such as reaction temperature, feeding rate, the amount of catalyst and so on. The thermal hazard assessment of the oxidation was derived from the calorimetric data, such as adiabatic temperature rise (ΔT ad ) and the maximum temperature of synthesis reaction (MTSR) in out of control conditions. Along with thermal decomposition of the product, the possibility of secondary decomposition under runaway conditions was analyzed by time to maximum rate (TMR ad ). Also, risk matrix was used to assess the risk of the reaction. Results indicated that with the increase of the reaction temperature, the reaction heat release rate increased, while reaction time and exotherm decreased. With the increase of feeding time, heat releasing rate decreased, but reaction time and exotherm increased. With the amount of the catalyst increased, heat releasing rate increased, reaction time decreased and exothermic heat increased. The risk matrix showed that when the reaction temperature was 70 °C, feeding time was 1 h, and the amount of catalyst was 10 g and 15 g, respectively, the reaction risk was high and must be reduced.
研究领域:
化学工程
·
安全科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Dan Wei,Kai Ma,Lei Ni,Ahmed Mebarki,Gang Fu,Juncheng Jiang
Traditional batch peroxyester synthesis processes pose a significant risk due to the presence of thermally unstable substances and highly exothermic nature of the reactions, highlighting the urgent need for a shift toward greener processes. With the aim to enhance safety of this process, a batch-to-flow transition was conducted, taking acid-catalyzed acylation of pivalic anhydride (PAn) with tert -butyl hydroperoxide (TBHP) to synthesize tert -butyl peroxypivalate (TBPP) as a case study. The acylation mechanism was investigated through density function theory calculation as well as in situ IR characterization. It was demonstrated that PAn first reacts with sulfuric acid to form pivalic acid sulfate, which subsequently undergoes nucleophilic attack by TBHP, yielding the corresponding peroxyester. The effects of process conditions, including reaction temperature, dosing rate, stirring rate and molar ratio, on thermal hazards in the semi-batch reactor was assessed. Under this mode, the processes which gained high yields (>90 %) showed unacceptable thermal runaway hazards. Then, the reaction was carried out under flow conditions. The process was optimized based on multi-objective Bayesian optimization. Through the batch-to-flow transition, it was showcased that the thermal runaway hazard could be reduced from severe (Class V) to moderate (Class II) along with a 74-fold increase in space-time yield. Furthermore, to distinguish the thermal risks quantitatively under different conditions in flow, a risk factor (R-factor) was proposed for the first time as a safety metric. With the application of R-factor, safety-oriented optimization in flow was made possible and sustainable synthesis processes could be realized.
研究领域:
化学工艺安全
·
流动化学
·
有机合成
·
反应工程
·
热分析
·
工艺优化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）