In the master's thesis, we modeled the uncontrolled release of propane, methane, and hydrogen into the environment using the ALOHA and Phast software programs. The use of ALOHA and Phast represents an effective approach in assessing the consequences of potential accidents, as well as in preliminary spatial planning and the design of adequate safety measures that can prevent accidents or the recurrence of modeled incidents in the future. When modeling the uncontrolled releases of propane, methane and hydrogen, we used the same input data in both programs to ensure the comparability of the obtained results. The key variables included the type of hazardous substance, the quantity of the hazardous substance, the energy value of the hazardous substance, and meteorological data for both typical summer and winter conditions. The choice of an appropriate program depends on the objectives of the analysis, the availability of input data, and the required response time.
We found that Phast allows for the simultaneous display of results from multiple model scenarios, while ALOHA does not support the concurrent presentation of results for several scenarios. In the case of a release of hazardous substances from a reservoir, where the substance does not ignite, the horizontal component of the gas clouds is larger than the vertical component, meaning that all gas clouds are more horizontally than vertically oriented in relation to the terrain surface. The impact zones (flammability zone, thermal radiation zone) for the modeled predictions of propane cover a larger area than those for methane, though neither of these extends beyond the distances reached in the modeled predictions of uncontrolled hydrogen release. The impact zones for propane and methane (based on identical mass and energy value predictions) are smaller for summer conditions than for winter conditions, but the impact zones for hydrogen expand further under the meteorological conditions typical for winter time.
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