A dynamic three-dimensional volume element model (VEM) of a parabolic trough solar collector (PTC) comprising an outer glass cover,
annular space, absorber tube, and heat transfer fluid is studied with detail. The model is coupled with an existing semi-finite optical model
for the purpose of simulation and optimization. The spatial domain in the VEM is discretized with lumped control volumes (i.e., volume elements)
in cylindrical coordinates according to the predefined collector geometry. Therefore, the spatial dependency of the model is taken into account
without the need to solve partial differential equations. The proposed model combines principles of thermodynamics and heat transfer as well as
empirical heat transfer correlations, to simplify the modeling and expedite the computations. The resulting system of ordinary differential
equations is integrated in time, yielding temperature fields which can be visualized and assessed with scientific visualization tools. The
current model is validated with experimental data provided in the literature. The model was employed to evaluate the sensitivity of the
collector performance described by the first and second law efficiencies to receiver length, annulus gap spacing, concentration ratio, incidence
angle, inlet fluid temperature, and flow rate. This work also examined the effects of inlet fluid temperature and temperature differential on
dynamic collector performance in the transient case study. Results showed that the first law efficiency was most sensitive to the inlet fluid
temperature with the maximum variation of 30%, whereas the incidence angle and concentration ratio affected the second law efficiency the most
with the maximum variations of 375% and 300%, respectively. The effect of the remaining parameters were trivial in all cases. In the transient
analysis, higher temperature differential and lower inlet fluid temperature yielded higher total heat gain while the total exergy gain was
insensitive to both parameters. The first law efficiency should therefore be of greater importance than the second law efficiency in the control
of dynamic collector performance based on these two parameters. Furthermore, a sensitivity analysis of vemPTC is done with the Fourier amplitude
sensitivity testing (FAST) for selected nine parameters. Cover transmittance shows a highly sensitive parameter within the rest of the selected
parameters. After this sensitivity analysis, a multi-objective sensitivity analysis is studied for different heat transfer fluids such as
synthetic oils, molten salts, liquid metals, nanofluids, and gases. Sobol sampling method is used for a multi-objective sensitivity analysis of
different heat transfer fluids except for nanofluids, because it is more accurate to use a different methodology for sensitivity analysis of
nanofluids, due to the effects of specific parameters on both first and second law efficiency. The fluid inlet temperature is a common sensitive
parameter for almost all heat transfer fluids. Therefore, a multi-objective optimization study is done with four parameters and the results of
it are presented in Chapter Four. Moreover, Chapter Five shows enhancement of the efficiency of both traditional parabolic trough solar
collector (PTC) and transparent insulation material integrated PTC in both one and two dimensional model. Altering model types, operating
conditions, or making an assumption for some used correlations is studied in the last chapter of this dissertation. After comparing the 1D and
the 2D model, the results show that the most promising model type of PTC is the 2D model with TIM integrated one with correlation due to its
stability for predicted efficiency. That approved that simplifying the model types may affect the results even though sufficiently accurate
results are obtained with a simplified model. Temperature-dependent parameters should be selected for temperature sensitive variable in order to
reach precise results. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements
for the degree of Doctor of Philosophy. / Fall Semester 2018. / October 18, 2018. / Optimization, Parabolic trough solar collector, Renewable energy, Solar energy, Sustainable energy / Includes bibliographical references. / Juan C. Ordóñez, Professor Directing Dissertation; Hui Li, University Representative; Wei Guo, Committee
Member; Patrick J. Hollis, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_661211 |
| Contributors | Sensoy Cellat, Tugba Serpil (author), Ordóñez, Juan Carlos, 1973- (professor directing dissertation), Li, Hui, 1970- (university representative), Guo, Wei (committee member), Hollis, Patrick J. (committee member), Florida State University (degree granting institution), College of Engineering (degree granting college), Department of Mechanical Engineering (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (153 pages), computer, application/pdf |
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