THERMAL MECHANICAL ANALYSES OF COMPRESSED AIR ENERGY STORAGE PILE FOUNDATIONS
Loading...
Date
2021-05
Authors
Bimaganbetova, Madina
Journal Title
Journal ISSN
Volume Title
Publisher
Nazarbayev University School of Engineering and Digital Sciences
Abstract
Nowadays, renewable energy has become a widely accepted energy source due to the
growing interest in environmental issues such as air pollution and greenhouse gas emissions.
However, it highly depends on the day and night cycle and has an intermittent nature. Thus,
ways of storing the extra energy generated by renewable energy have been developed including
pumped hydroelectric, compressed air, solar batteries, and thermal energy storage. An energy
storage pile foundation system is being developed through a multidisciplinary research project.
The main idea of the proposed system is to store extra energy in hollowed pile foundations by
utilizing compressed air energy storage technology.
In previous studies, structural responses of the energy storage pile foundations under
internal air pressure were evaluated. These studies were based on an assumption of completely
cooling air down to the ambient temperature before entering the pile foundation for storage.
This assumption may require additional resources due to the efficiency of the cooling process.
Another option is to keep the storage air temperature higher than the ambient temperature,
which can be achieved by controlling the cooling process. As a result, thermal mechanical
loading will be induced to the pile foundation. However, the stress states in the pile section that
originated from the thermal loading are different from the stress states that originated from the
internal air pressure. Therefore, it is necessary to investigate the structural response of the pile
foundation under the combined air pressure and thermal mechanical loading. This thesis focuses on analytical investigations of structural responses of the energy
storage pile foundations under combined loadings from the internal air pressure and
temperature changes. To conduct this study, two steps of analytical research work were
performed. In the first step, non-steady state thermal analyses were conducted to identify the
temperature distributions inside the pile section. In the second step, the temperature distribution,
obtained from the first step, was used as thermal loadings forstatic thermal mechanical analyses
to evaluate the structural responses of the pile. The analyses were performed using general finite
element software, Abaqus CAE. Several pile designs with different parameters were studied.
These parameters include the geometry of the piles, spacing between them, level of cooling, the
thermal expansion coefficient of the pile, and inner diameter of the pile.
From the analytical results, it has been found that the maximum tensile stress originated
from the internal air pressure can be reduced by introducing an appropriate level of thermal
mechanical loading. The appropriate level can be achieved by adjusting the storage temperature. Moreover, by limiting the days of continuous usage of the energy storage pile, the thermal
mechanical loading can eliminate the state where the entire concrete section is under pure
tension, which has been a critical issue for the pile under the internal air pressure. Design
recommendations regarding the optimum storage temperature and the number of days of
continuous usage were made as follows: the appropriate range of storage temperature lies
between 31.5°C to 34°C; it is recommended to pause the air storage one day for every 5-14
days depending on the pile section sizes to avoid the entire pile section transiting to a pure
tension state.
Description
Keywords
energy storage systems, extra energy, Research Subject Categories::TECHNOLOGY, Type of access: Embargo, air storage
Citation
Bimaganbetova, M. (2021). Thermal Mechanical Analyses of Compressed Air Energy Storage Pile Foundations (Unpublished master's thesis). Nazarbayev University, Nur-Sultan, Kazakhstan