Filtern
Dokumenttyp
- Zeitschriftenartikel (10)
- Beitrag zu einem Tagungsband (3)
- Vortrag (2)
- Dissertation (1)
Sprache
- Englisch (16)
Schlagworte
- Fire (12)
- Insulation (8)
- LH2 (8)
- LNG (8)
- Multi-Layer Insulation (5)
- Safety (4)
- Cryogenic storage tank (3)
- Liquefied hydrogen (3)
- MLI (3)
- Tank (3)
Organisationseinheit der BAM
- 3 Gefahrgutumschließungen; Energiespeicher (16)
- 3.5 Sicherheit von Gasspeichern und Gefahrguttanks (9)
- 3.2 Sicherheit von Energiespeichern (8)
- 2 Prozess- und Anlagensicherheit (1)
- 2.1 Sicherheit von Energieträgern (1)
- 3.3 Sicherheit von Transportbehältern (1)
- 7 Bauwerkssicherheit (1)
- 7.3 Brandingenieurwesen (1)
The number of vehicles using or transporting cryogenic fuels such as Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG) increases fast in the land transportation sector. Does this also entail new risks? The storage of cryogenic fuels requires tanks with Thermal Super Insulations (TSI) to keep the fluid cold and limit the formation of boil-off gas. TSI has proven itself in some applications since the middle of the 20th century, but in the land transport sector they are still quite new, where accidents involving fires, collisions, and their combination are to be expected. This work focuses on investigating the behavior of different types of TSI while exposed to a heat source representing a fire. To this aim, a High-Temperature Thermal Vacuum Chamber (HTTVC) was applied, which allows the thermal loading of a thermal insulation material in a vacuum and measuring the heat flow transported through the TSI in parallel. In this study, the results of 6 samples are presented regarding 3 types of MLI, rock wool, perlites, and microspheres. The thermal exposure caused different effects on the samples. In practice, this can be connected to the rapid release of flammable gases as well as to a Boiling Liquid Expanding Vapour Explosion (BLEVE). These results are relevant for reducing the risks to people and infrastructures in the progressive establishment of tanks for cryogenic fluids in our industry and society. The data presented in the study can be used to improve the design of tanks and TSIs, the assessment of accident scenarios, and the development of measures for first responders.
Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG) establish themselves as important energy carriers in the transport sector. Its storage requires tanks with Thermal Super Insulations (TSI) to keep the transported fluid cold. TSI has proven itself in various applications over a long time, but not in the land transport sector, where accidents involving collisions, fires, and their combination are to be expected. The focus of this study is to investigate the behavior of different types of TSI when exposed to a heat source that represents a fire. Therefore, a High-Temperature Thermal Vacuum Chamber (HTTVC) was used that allows the thermal loading of thermal insulation material in a vacuum and measuring the heat flow through the TSI in parallel. Within this study, 5 samples were tested regarding 3 different types of MLI, rock wool, and perlites. The thermal exposure caused different effects on the samples. In practice, this can be connected to the rapid release of flammable gases as well as a Boiling Liquid Expanding Vapour Explosion (BLEVE). These results are relevant for the evaluation of accident scenarios, the improvement of TSI, and the development of emergency measures.
In the context of the growing global interest in hydrogen-based green energy, cryogenic tanks equipped with multi-layer insulation (MLI) are emerging as a leading solution for storing hydrogen in vehicles. The integrity of these systems might be threatened during fire exposure. This can trigger the degradation of the MLI materials and induce rapid pressurization of the tank with a high risk of catastrophic failure. In this work, a novel lumped model to simulate the thermal response of MLI-equipped cryogenic liquid hydrogen tanks is presented. The model integrates the accurate database “Coolprop” for hydrogen thermodynamic properties and sub-models for detailed simulation of MLI degradation, providing a realistic simulation of the experimental data obtained under normal operating conditions. The application of the model to several case studies considering different numbers of MLI layers and tank geometries demonstrates that aluminum-based MLI offers scarce protection in case of exposure to a hydrocarbon poolfire.
In the context of green energy transition, cryogenic tanks insulated by MLI and vacuum are emerging as a leading solution to store hydrogen in heavy-duty vehicles. However, the integrity of such tanks can be jeopardized by fire. In such a scenario, MLI materials degradation can occur, leaving the tank unprotected from the fire heat flux, with consequent rapid pressurization and a high risk of failure. This study presents a safety assessment of non-combustible MLI under fire exposure based on the estimation of the time to mechanical failure of the equipment. This is calculated through an innovative model that simulates the thermomechanical response of the tank, including the MLI thermal degradation and the pressure-relief valve (PRV) operation. The application to several case studies that consider a typical LH2 tank featuring a wide range of MLI configurations demonstrated the likelihood of failure in case of exposure to a hydrocarbon pool fire, providing also comprehensive insights into the impact of the insulation characteristics and operating conditions on the time to
failure.
In the context of green energy transition, cryogenic tanks featuring MLI systems are emerging as a leading solution to store hydrogen in heavy-duty vehicles. However, the integrity of such tanks can be jeopardized by fire. In such a scenario, MLI materials degradation can occur, leaving the tank unprotected from the fire heat flux, with consequent rapid pressurization and a high risk of failure. This study presents an assessment of aluminum-based MLI for liquid hydrogen cryogenic tanks under fire exposure based on the estimation of the time to mechanical failure of the equipment. This is calculated through an innovative model that simulates the thermomechanical response of the tank, including the MLI thermal degradation and the pressure-relief valve (PRV) operation. The application to several case studies that consider a typical LH2 tank featuring a wide range of MLI configurations demonstrated the likelihood of failure in case of exposure to a hydrocarbon pool fire, providing also comprehensive insights into the impact of the insulation characteristics and operating conditions on the time to failure.
In the ongoing energy transition, liquid hydrogen (LH₂) stored and transported in cryogenic tanks insulated with multilayer insulation (MLI) is emerging as a promising energy carrier with low environmental impact. To preserve the structural integrity of these systems under both normal and abnormal conditions represents a crucial challenge for their widespread adoption. Despite insulation, fire tests have shown LH₂ tanks may fail catastrophically under fire exposure. This was largely attributed to MLI degradation, leaving the tank unprotected. However, the few fire tests on LH₂ tanks and the lack of investigations into the MLI behaviour have constrained understanding of tank response to fire.
This work addresses these gaps by combining experimental and modelling efforts. The experimental activities characterized the high-temperature degradation and performances of MLI materials using both conventional methods and novel techniques. An innovative experimental apparatus was developed to impose fire-like thermal loads while measuring heat flux through the insulation. Test results revealed the pronounced degradation of MLI systems under typical fires. Complementary thermal analyses were performed to characterize degradation mechanisms at fire-like temperatures. Based on these insights, innovative MLI configurations with enhanced fire resistance were designed and tested.
The experimental dataset served as the benchmark to develop innovative heat-transfer and thermal-degradation models for MLI under fire exposure, obtaining accurate simulations of the experimental results. Thus, an original approach to the fire safety assessment of MLI-equipped LH2 tanks in fire scenarios was developed. A novel model integrating the high-temperature degradation of MLIs and the thermodynamic modelling of the tank load was coupled to specific key performance indicators. This was applied to a representative vehicle-scale LH₂ tanks under varying MLI configurations, operational conditions, and fire scenarios. The findings deliver crucial insights to support safer LH₂ tank designs, emergency response planning, and guide mitigation strategies for preserving tank integrity.
Multilayer Insulation (MLI) is frequently used in vacuum conditions for the thermal insulation of cryogenic storage tanks. The severe consequences of the degradation of such materials in engulfing fire scenarios were recently evidenced by several large-scale experimental tests. In the present study, an innovative modelling approach was developed to assess the performance of heat transfer in polyester-based MLI materials for cryogenic applications under fire conditions. A specific layer-by-layer approach was integrated with an apparent kinetic thermal degradation model based on thermogravimetric analysis results. The modeling results provided a realistic simulation of the experimental data obtained by High-Temperature Thermal Vacuum Chamber tests reproducing fire exposure conditions. The model was then applied to assess the behavior of MLI systems for liquid hydrogen tanks in realistic fire scenarios. The results show that in intense fire scenarios degradation occurs rapidly, compromising the thermal insulation performances of the system within a few minutes.
The number of applications that demand zero-emission energy carriers, such as liquified hydrogen (LH2), is increasing worldwide. LH2 is typically transported or stored under cryogenic conditions. Storage in such conditions requires super thermal insulations which maintain very low boil-off for a prolonged time. Multi-Layer insulation (MLI) finds widespread use in cryogenic applications, designed to effectively restrict heat inleak towards cryogenic fluids. However, recent studies evidenced that exposure to high heat fluxes, such as in the event of a fire accident, can cause the thermal degradation of the insulation material, resulting in the severe collapse of its heat resistance performance. Therefore, the risk of rapid tank pressurization and its connection to the risk of BLEVE may be possible. This study proposes a numerical model to assess the performances of aluminum-based MLI materials under fire conditions. The model offers insights into the total heat transfer rate through the insulation, serving as a
Hydrogen is recognized as a keystone of the global energy transition, offering a clean, high-energy-density energy carrier ideal for storage and transportation. Among various storage options, liquid hydrogen (LH2) is especially advantageous for both mobile and stationary applications. However, ensuring the safety and performance of LH2 storage systems under extreme thermal conditions, such as fire exposure, remains an engineering challenge.
This study introduces an experimental framework, called the Cryogenic High-Temperature Thermal Vacuum Chamber (CHTTVC), designed to investigate the thermal-hydraulic response of vacuum-insulated cryogenic tanks under fire-like conditions. The apparatus enables evaluation of insulation performance, such as perlite and multilayer insulation (MLI), with a focus on thermal degradation, heat ingress, and vacuum stability.
Results indicate that combustible MLIs undergo substantial thermal degradation, leading to heat ingress rates of up to 6.5 kW and the formation of hazardous combustion by-products. In contrast, non-combustible MLIs and bulk insulation materials restrict heat ingress to approximately 3 kW while more effectively preserving vacuum integrity. Combustible MLIs also exhibit pronounced pressure increases in the evacuated section, reaching ∼6 × 104 Pa, nearly six times higher than those observed for non-combustible counterparts. Analysis of effective emissivity further reveals an enhancement in radiative heat transfer, approximately five times, for combustible MLIs following degradation. Additionally, marked thermal stratification develops under both nominal and extreme heat loads, with temperature gradients approaching 10 °C per 100 mm during sustained thermal exposure.
The safe use of liquid hydrogen as a clean fuel requires a deep understanding of its behaviour in accident scenarios. Among other scenarios, the possible involvement of cryogenic liquid hydrogen tanks in engulfing fires is of particular concern, due to the potentially severe consequences. This study proposes a computational fluid dynamic model suitable to simulate the behaviour of liquid hydrogen tanks equipped with multi-layer insulation (MLI) engulfed in fire. An original approach has been developed to assess the progressive degradation of the performance of the thermal insulation, that is crucial in determining the tank pressurization and failure. The model is validated against full-scale experimental fire tests. The outcomes of the model reproduce the progressive pressurization and the opening time of the pressure relief valve within 2 % error. The results demonstrate the importance of accounting for the dynamic evolution of the progressive degradation of the insulation when evaluating tank pressurization, and they highlight the limitations of empirical, simplified state-of-the-art approaches. Furthermore, the analysis evidences the key role of the fire temperature in governing tank response, stressing the need for proper fire characterization to support reliable modelling of fire scenarios and the development of emergency planning and mitigation strategies ensuring the structural integrity of liquid hydrogen tanks during fire attacks.
