TY - GEN A1 - Hajhariri, Aliasghar A1 - Eberwein, Robert A1 - Perrone, Luca Pakj A1 - Cozzani, Valerio A1 - Otremba, Frank A1 - Seidlitz, Holger T1 - Study the impact of spacer at thermal degradation process of MLI-based insulation in fire condition T2 - Journal of Loss Prevention in the Process Industries N2 - To reduce CO2 emissions, energy carriers such as hydrogen are considered to be a solution. Consumption of hydrogen as a fuel meets several limitations such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquified phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Different studies have been addressed the vulnerability of such insulation against high thermal loads e.g., in an accident engaging fire. Some of research works have highlighted the importance of considering the MLI thermal degradation focusing on its reflective layer. However, limited number of studies addressed the thermal degradation of spacer material and its effect on the overall heat flux. In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed that, as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Each individual spacer contributes to mitigating the radiative energy received by the measurement plate. Stacks of 20–50 spacers (this is the number of layers in commercial MLI systems applied for liquid hydrogen applications) can potentially reduce the thermal radiation by 1–2 orders of magnitude. An empirical correlation to predict a heat flux attenuation factor is proposed, which is useful for further numerical and analytical studies in the temperature range from ambient to 300 °C. KW - Liquefied hydrogen KW - Liquefied natural gas KW - Cryogenic storage tank KW - Thermal insulation KW - Multi-Layer Insulation KW - Microspheres KW - Perlite Y1 - 2024 U6 - https://doi.org/10.1016/j.jlp.2024.105461 SN - 0950-4230 VL - 92 SP - 240 EP - 248 PB - Elsevier BV ER - TY - GEN A1 - Hajhariri, Aliasghar A1 - Eberwein, Robert A1 - Camplese, Davide A1 - Scarponi, Giordano Emrys A1 - Cozzani, Valerio A1 - Otremba, Frank A1 - Seidlitz, Holger T1 - Non-Combustible MLI Based Insulation Behavior Under Fire Condition - Experimental and Numerical Investigation T2 - Process Safety and Environmental Protection N2 - 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 an indicator of the deterioration's impact on overall heat transfer. The proposed numerical model is validated against experimental data obtained by a High-Temperature Thermal Vacuum Chamber test facility that reproduces fire exposure conditions. The experiments conducted in this study underscore the emergence of pressure build-up within the insulation system, which contributes to increased gas conduction. Furthermore, it demonstrates that the spacer material is not entirely damaged under simulated fire conditions. The numerical calculation also underscores the significance of the modifications in material surface emissivity due to the deterioration process. The innovative approach proposed in this study thus paves the way for the development of improved tools aiming at the stationary and mobile cryogenic tanks behavior (e.g., LNG, LOX, LN2, and LH2) in fire accident scenarios. The model developed may, in perspective, be integrated into both CFD and lumped models for the calculation of the time to failure of cryogenic equipment under external fires. Therefore, this study offers valuable insights to improve the safety of processes and equipment for the storage of cryogenic fluids, thereby supporting emergency response planning in case of fire accidents. KW - Multi-Layer Insulation (MLI) KW - Cryogenic Vessels KW - Liquefied Hydrogen Y1 - 2024 U6 - https://doi.org/10.1016/j.psep.2024.11.037 SN - 0957-5820 VL - 193 SP - 403 EP - 420 PB - Elsevier BV ER - TY - GEN A1 - Seidlitz, Holger A1 - Hajhariri, Aliasghar A1 - Eberwein, Robert A1 - Perrone, Luca Pakj A1 - Cozzani, Valerio A1 - Otremba, Frank ED - Di Benedetto, Almerinda ED - Portarapillo, Maria T1 - Study the Impact of Spacer at Thermal Degradation Process of MLI-based Insulation in Fire Condition T2 - Proceedings of the 15th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions N2 - To reduce carbon dioxide emissions, energy carries such as hydrogen consider to be a solution. Consumption of hydrogen as a fuel meets several restrictions such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquid phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Some studies have been revealed vulnerability of this type of insulation against high heat flux, for instance a fire accident. Some investigations have been depicted the importance of consideration of the MLI thermal degradation in terms of its reflective layer. However, limited number of studies have been focused on the thermal degradation of spacer material and its effect on the overall heat flux. In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Moreover, the contribution of each individual spacer in all cases regarding the experimental temperature range is assessed to be around 8%. This value may increase to around 50% for glass paper and polyester spacers, and to around 25% for glass fleece spacers as the number of spacer layers increases up to six layers. To utilize the outcomes of the experiment later and integrate the results into numerical and CFD simulations, a model is proposed for the mentioned experimental temperature range up to 300°C to predict a heat flux attenuation factor. The model proposes a fitting factor that can reproduce the least square fitted line to the experimental data. KW - Multi-Layer Insulation (MLI) KW - Cryogenic KW - Liquid Hydrogen KW - Heat transfer Y1 - 2024 UR - https://zenodo.org/records/12621001 U6 - https://doi.org/10.5281/zenodo.12621001 SP - 744 EP - 755 CY - Napoli, Italy ER -