Simulation Model of a Liquid Hydrogen Tank
Hällfors, Axel (2023)
Hällfors, Axel
2023
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20230906120705
https://urn.fi/URN:NBN:fi-fe20230906120705
Tiivistelmä
Construction Equipment, such as excavators and wheel loaders, holds great significance in construction and infrastructure projects worldwide. However, these machinery types predominantly rely on diesel-powered engines, which emit substantial amounts of greenhouse gases that contribute to climate change and air pollutants harmful to both human health and the local environment. To address these concerns, the need for alternative and cleaner fuels has become essential. Suggested alternatives are battery electric machinery, sustainable fuels, and hydrogen. While batteries are currently being introduced in urban and smaller construction equipment, their limited energy density poses challenges when applied to larger machinery due to their size and weight.
Alternatively, hydrogen offers the highest energy density per mass unit of any known chemical fuel and emits no direct emissions of greenhouse gases when utilized. However, at ambient conditions, hydrogen exists as a gas with a very low energy density per volume unit. To improve the volumetric energy density of hydrogen, it can be compressed at high pressures or transformed into a liquid state at cryogenic temperatures ranging from 13.8 to 33 Kelvin (-240 to -259 ⁰C). The key advantage of liquid hydrogen lies in its superior volumetric energy density compared to both compressed hydrogen and batteries.
However, the extremely low temperatures of liquid hydrogen present significant constraints on the storage vessel, and heat leakage from the ambient surroundings is inevitable. When heat enters the tank, it causes a portion of the liquid hydrogen to evaporate into gaseous hydrogen through a process known as boil-off. The resulting evaporated gas leads to an increase in pressure inside the tank, requiring the relief of gas into the atmosphere when the pressure exceeds the maximum allowable limit of the tank. This relief of gas results in direct hydrogen loss and gives rise to potential safety concerns. The management of boil-off and subsequent hydrogen relief represents the most significant challenge in the storage of liquid hydrogen.
A simulation model, developed in a Matlab/Simulink environment, has been designed to analyze the behavior and heat leakage of a liquid hydrogen tank. This model allows for the examination of how different factors influence temperature and pressure changes inside the tank, as well as the amount of boil-off and relieved gas when the tank is left unattended for a specific duration. Additionally, the model is employed to conduct case studies centered around duty cycles in two types of Volvo Construction Equipment machinery.
The results of the model, which align with the existing literature, indicate that factors such as the tank size, maximum pressure, insulation properties, and surrounding temperature significantly influence the storage of liquid hydrogen. Additionally, these results are compared to those obtained from an already existing simulation model of a liquid hydrogen tank, demonstrating mostly consistent outcomes.
The model will be utilized by Volvo Construction Equipment to simulate different scenarios for storing liquid hydrogen and conduct real-world testing to verify the results of the model. Further development can be made to the model in the future, to increase its credibility.
Alternatively, hydrogen offers the highest energy density per mass unit of any known chemical fuel and emits no direct emissions of greenhouse gases when utilized. However, at ambient conditions, hydrogen exists as a gas with a very low energy density per volume unit. To improve the volumetric energy density of hydrogen, it can be compressed at high pressures or transformed into a liquid state at cryogenic temperatures ranging from 13.8 to 33 Kelvin (-240 to -259 ⁰C). The key advantage of liquid hydrogen lies in its superior volumetric energy density compared to both compressed hydrogen and batteries.
However, the extremely low temperatures of liquid hydrogen present significant constraints on the storage vessel, and heat leakage from the ambient surroundings is inevitable. When heat enters the tank, it causes a portion of the liquid hydrogen to evaporate into gaseous hydrogen through a process known as boil-off. The resulting evaporated gas leads to an increase in pressure inside the tank, requiring the relief of gas into the atmosphere when the pressure exceeds the maximum allowable limit of the tank. This relief of gas results in direct hydrogen loss and gives rise to potential safety concerns. The management of boil-off and subsequent hydrogen relief represents the most significant challenge in the storage of liquid hydrogen.
A simulation model, developed in a Matlab/Simulink environment, has been designed to analyze the behavior and heat leakage of a liquid hydrogen tank. This model allows for the examination of how different factors influence temperature and pressure changes inside the tank, as well as the amount of boil-off and relieved gas when the tank is left unattended for a specific duration. Additionally, the model is employed to conduct case studies centered around duty cycles in two types of Volvo Construction Equipment machinery.
The results of the model, which align with the existing literature, indicate that factors such as the tank size, maximum pressure, insulation properties, and surrounding temperature significantly influence the storage of liquid hydrogen. Additionally, these results are compared to those obtained from an already existing simulation model of a liquid hydrogen tank, demonstrating mostly consistent outcomes.
The model will be utilized by Volvo Construction Equipment to simulate different scenarios for storing liquid hydrogen and conduct real-world testing to verify the results of the model. Further development can be made to the model in the future, to increase its credibility.