Matching Items (3)
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- All Subjects: Thermodynamics
- Creators: Milcarek, Ryan
Description
In these times of increasing industrialization, there arises a need for effective and energy efficient heat transfer/heat exchange devices. The focus nowadays is on identifying various methods and techniques which can aid the process of developing energy efficient devices. One of the most common heat transfer devices is a heat exchanger. Heat exchangers are an essential commodity to any industry and their efficiency can play an important role in making industries energy efficient and reduce the energy losses in the devices, in turn decreasing energy inputs to run the industry.
One of the ways in which we can improve the efficiency of heat exchangers is by applying ultrasonic energy to a heat exchanger. This research explores the possibility of introducing the external input of ultrasonic energy to increase the efficiency of the heat exchanger. This increase in efficiency can be estimated by calculating the parameters important for the characterization of a heat exchanger, which are effectiveness (ε) and overall heat transfer coefficient (U). These parameters are calculated for both the non-ultrasound and ultrasound conditions in the heat exchanger.
This a preliminary study of ultrasound and its effect on a conventional shell-and-coil heat exchanger. From the data obtained it can be inferred that the increase in effectiveness and overall heat transfer coefficient upon the application of ultrasound is 1% and 6.22% respectively.
One of the ways in which we can improve the efficiency of heat exchangers is by applying ultrasonic energy to a heat exchanger. This research explores the possibility of introducing the external input of ultrasonic energy to increase the efficiency of the heat exchanger. This increase in efficiency can be estimated by calculating the parameters important for the characterization of a heat exchanger, which are effectiveness (ε) and overall heat transfer coefficient (U). These parameters are calculated for both the non-ultrasound and ultrasound conditions in the heat exchanger.
This a preliminary study of ultrasound and its effect on a conventional shell-and-coil heat exchanger. From the data obtained it can be inferred that the increase in effectiveness and overall heat transfer coefficient upon the application of ultrasound is 1% and 6.22% respectively.
ContributorsAnnam, Roshan Sameer (Author) / Phelan, Patrick (Thesis advisor) / Rykaczewski, Konrad (Committee member) / Milcarek, Ryan (Committee member) / Arizona State University (Publisher)
Created2019
Description
Buildings release an abundance of waste heat that is left unused. Thermogalvaniccells (TGCs) can take advantage of waste heat to generate electricity with a low
temperature gradient. In this dissertation, I simulated the thermal transport of TGCs
containing different triply periodic minimal surface (TPMS) structures, compared it
to measured values and conducted a mesh convergence study to examine the viability
of the computational fluid dynamics (CFD) solutions. Natural convection effects are
one of the driving forces in TGCs. Using the Bousinesq approximation, I was able to
capture those effects in the CFD simulations as it accounts for the density variations
of the fluid. Upon simulating the TGC using the Schwarz P TPMS geometry, the
cathode temperature converged as I refined the mesh and approached the measured
value. As for the IWP TPMS structure, the solution converged as I refined the mesh,
despite having a deviation to the measured values. This was due to the abundance of
sharp regions along the walls of the TPMS that ANSYS had difficulty to accurately
model.
Furthermore, I simulated the TGCs using different boundary condition (BC) approximations to observe the cathode and anode temperatures as well as their overall
∆T across the cell. For the TGC containing the Schwarz P geometry, Case C (constant anode temperature BC with TPMS conduction) was the most accurate while
Case D (convection BC at anode with TPMS conduction) deviated from the measured
values, had the most accurate ∆T and was well within the uncertainty bounds of the
measured values. Larger temperature fluctuations were seen closer to the cathode
while the effects steadily decrease as the fluid approaches the anode.
Moreover, the TGC containing the IWP structures presented interesting results.
The main deviation was from the cathode temperatures because a higher temperature
readings meant that more cells in the fluid domain were prone to diverging, thereby
resulting in a higher calculated cathode temperature. Simulating the TGC with the
Schwarz P geometry produced satisfactory results while the TGC using the IWP
geometry deviated due to the software limitations. Finally, the effects of natural
convection and TPMS on TGCs were studied and it was found that the absence of
natural convection lead to a higher ∆T while the absence of TPMS resulted in a more
uniform temperature distribution throughout the domain
Contributorsalweqayyan, yousef (Author) / Phelan, Patrick (Thesis advisor) / Rykaczewski, Konrad (Committee member) / Milcarek, Ryan (Committee member) / Arizona State University (Publisher)
Created2021
Description
Energy storage technologies are essential to overcome the temporal variability in renewable energy. The primary aim of this thesis is to develop reactor solutions to better analyze the potential of thermochemical energy storage (TCES) using non-stoichiometric metal oxides, for the multi-day energy storage application. A TCES system consists of a reduction reactor and an insulated MOx storage bin. The reduction reactor heats (to ~ 1100 °C) and partially reduces the MOx, thereby adding sensible and chemical energy (i.e., charging it) under reduced pO2 environments (~10 Pa). Inert gas removes the oxygen generated during reduction. The storage bin holds the hot and partially reduced MOx (typically particles) until it is used in an energy recovery device (i.e., discharge). Irrespective of the reactor heat source (here electrical), or the particle-inert gas flows (here countercurrent), the thermal reduction temperature and inert gas (here N2) flow minimize when the process approaches reversibility, i.e., operates near equilibrium. This study specifically focuses on developing a reduction reactor based on the theoretical considerations for approaching reversibility along the reaction path. The proposed Zigzag flow reactor (ZFR) is capable of thermally reducing CAM28 particles at temperatures ~ 1000 °C under an O2 partial pressure ~ 10 Pa. The associated analytical and numerical models analyze the reaction equilibrium under a real (discrete) reaction path and the mass transfer kinetic conditions necessary to approach equilibrium. The discrete equilibrium model minimizes the exergy destroyed in a practical reactor and identifies methods of maximizing the energy storage density () and the exergetic efficiency. The mass transfer model analyzes the O2 N2 concentration boundary layers to recommend sizing considerations to maximize the reactor power density. Two functional ZFR prototypes, the -ZFR and the -ZFR, establish the proof of concept and achieved a reduction extent, Δδ = 0.071 with CAM28 at T~950 °C and pO2 = 10 Pa, 7x higher than a previous attempt in the literature. The -ZFR consistently achieved > 100 Wh/kg during >10 h. runtime and the -ZFR displayed an improved = 130 Wh/kg during >5 h. operation with CAM28. A techno-economic model of a grid-scale ZFR with an associated storage bin analyzes the cost of scaling the ZFR for grid energy storage requirements. The scaled ZFR capital costs contribute < 1% to the levelized cost of thermochemical energy storage, which ranges from 5-20 ¢/kWh depending on the storage temperature and storage duration.
ContributorsGhotkar, Rhushikesh (Author) / Milcarek, Ryan (Thesis advisor) / Ermanoski, Ivan (Committee member) / Phelan, Patrick (Committee member) / Wang, Liping (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2023