TY - GEN
T1 - Analysis and Design Optimization of Latent Heat Thermal Energy Storage System based on Phase Change Material Climate Modules
AU - Hassan, Hafiz Muhammad Adeel
PY - 2022/6/8
Y1 - 2022/6/8
N2 - Buildings worldwide (both residential and industrial) consume more than 40% of total
world energy consumption and they are responsible for approximately one-third of global
CO2 emissions. Free cooling of buildings using Phase Change Materials (PCMs) based
Thermal Energy Storage (TES) systems is one the most investigated techniques to improve
the energy efficiency of buildings. In this technique, a dedicated mass of the PCM is
employed in buildings either in stand-alone form or integrated with Heating, Ventilation
and Air Conditioning (HVAC) systems to improve the energy efficiency of the HVAC
systems for space cooling and heating applications. The main aim of this PhD research work is to investigate the development and
performance of a PCM based thermal energy storage system for its possible integration
with a commercially available decentral ventilation system VEX308. The work is divided
into experimental investigations and simulation work. In the start of the experimental
work, performance analysis of two thermal energy storage design configurations of a
research platform consisting of PCM storage plates has been done. The parameters
investigated are air flow distribution in the system and thermal performance of the PCM
storage. The design with smaller gap size between the PCM plates (1.5mm gap) provided
faster melting and solidification rates of the PCM and provided approximately 8.7% more
energy storage potential. Based on the results of research platform, a dual stack PCM
based thermal energy storage prototype (with two design configurations) has been
developed and tested for its possible integration with VEX308. Air flow distribution in two
PCM stacks and thermal performance of the PCM storage has been investigated. The flow
distribution during the charging and discharging cycles of the PCM for design 1 has been
found to be skewed towards first stack of PCM with a flow distribution of approximately
55%. While for design 2, stack 1 receives approximately 65% of the total air flow. The
energy storage rates for discharging and charging cycles are much larger at the beginning
of the experiments and decrease over time for both the designs. It takes around 3.4 hours
to completely melt/discharge and 3.1 hours to completely charge/solidify the energy
storage for the case of design 1. For design 2, it takes around 3.2 hours for completely melt
and approximately 3.0 hours to completely solidify the PCM. Both designs show almost
same average effectiveness values of 0.89. PCM phase segregation phenomenon was
noticed and investigated experimentally. The results showed that the segregated layers of
the PCM have almost same density, thermal conductivity and almost same phase change
temperatures.In simulations work, a 3D model 3-plate model of the PCM energy storage has been
developed and simulated to investigate pressure loss through the narrow gaps between
the PCM plates. The results of the simulations are validated with the experimental results.
The results show that there is a fair agreement between the simulation results and
experimental results at low and medium flow rates with relative deviation values less than
5%. In order to reduce the computational cost, a 3D sliced model from full 3-plate model
and a 2D simplified flow model have been developed. The reduced 2D model employs a
through-thickness resistance term in the Navier-Stokes equation which captures the
behaviour of fluid flow between parallel plates to producing same or nearly the same
results as the 3D model. A comparison of the results showed that the reduced 2D model
works fine for low velocities and larger channel heights with a relative deviation around
12%.
AB - Buildings worldwide (both residential and industrial) consume more than 40% of total
world energy consumption and they are responsible for approximately one-third of global
CO2 emissions. Free cooling of buildings using Phase Change Materials (PCMs) based
Thermal Energy Storage (TES) systems is one the most investigated techniques to improve
the energy efficiency of buildings. In this technique, a dedicated mass of the PCM is
employed in buildings either in stand-alone form or integrated with Heating, Ventilation
and Air Conditioning (HVAC) systems to improve the energy efficiency of the HVAC
systems for space cooling and heating applications. The main aim of this PhD research work is to investigate the development and
performance of a PCM based thermal energy storage system for its possible integration
with a commercially available decentral ventilation system VEX308. The work is divided
into experimental investigations and simulation work. In the start of the experimental
work, performance analysis of two thermal energy storage design configurations of a
research platform consisting of PCM storage plates has been done. The parameters
investigated are air flow distribution in the system and thermal performance of the PCM
storage. The design with smaller gap size between the PCM plates (1.5mm gap) provided
faster melting and solidification rates of the PCM and provided approximately 8.7% more
energy storage potential. Based on the results of research platform, a dual stack PCM
based thermal energy storage prototype (with two design configurations) has been
developed and tested for its possible integration with VEX308. Air flow distribution in two
PCM stacks and thermal performance of the PCM storage has been investigated. The flow
distribution during the charging and discharging cycles of the PCM for design 1 has been
found to be skewed towards first stack of PCM with a flow distribution of approximately
55%. While for design 2, stack 1 receives approximately 65% of the total air flow. The
energy storage rates for discharging and charging cycles are much larger at the beginning
of the experiments and decrease over time for both the designs. It takes around 3.4 hours
to completely melt/discharge and 3.1 hours to completely charge/solidify the energy
storage for the case of design 1. For design 2, it takes around 3.2 hours for completely melt
and approximately 3.0 hours to completely solidify the PCM. Both designs show almost
same average effectiveness values of 0.89. PCM phase segregation phenomenon was
noticed and investigated experimentally. The results showed that the segregated layers of
the PCM have almost same density, thermal conductivity and almost same phase change
temperatures.In simulations work, a 3D model 3-plate model of the PCM energy storage has been
developed and simulated to investigate pressure loss through the narrow gaps between
the PCM plates. The results of the simulations are validated with the experimental results.
The results show that there is a fair agreement between the simulation results and
experimental results at low and medium flow rates with relative deviation values less than
5%. In order to reduce the computational cost, a 3D sliced model from full 3-plate model
and a 2D simplified flow model have been developed. The reduced 2D model employs a
through-thickness resistance term in the Navier-Stokes equation which captures the
behaviour of fluid flow between parallel plates to producing same or nearly the same
results as the 3D model. A comparison of the results showed that the reduced 2D model
works fine for low velocities and larger channel heights with a relative deviation around
12%.
U2 - 10.21996/g1j8-sm11
DO - 10.21996/g1j8-sm11
M3 - Ph.D. thesis
PB - Syddansk Universitet. Det Tekniske Fakultet
ER -