Optimum Selection of Direct-Coupled Photovoltaic Pumping System in Solar Domestic Hot Water Systems

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Date
1997Author
Al-Ibrahim, Abdulrahman M.
Publisher
University of Wisconsin-Madison
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Show full item recordAbstract
The performance of photovoltaic powered pumps in direct and indirect solar domestic
hot water (PV-SDHW) systems has been studied. The direct PV-SDHW system employs
a photovoltaic array, a DC-motor, a centrifugal pump, a thermal collector, and a
storage tank. The indirect PV-SDHW system employs similar components to those in
the direct PV-SDHW system in addition to a heat exchanger to transfer the energy from
the collector-loop fluid to the tank-loop fluid. Both a forced convection heat
exchanger and a natural convection heat exchanger were investigated. The primary
objective of this thesis is to optimize the design and quantify the performance of PV-
SDHW systems.
The search methodology for an optimum PV-SDHW system has been performed in a
unique two-phase procedure. In phase one the goal is to find, among the possible PV
pumping systems' flow rate profiles, the profile that maximizes the performance of a
given SDHW system. In phase two the goal is to select the components of the PV
pumping system. Each combination of PV cells, DC-motor and pump exhibits a
unique flow rate profile. Therefore, the problem in this phase is to identify the PV
pumping system components that results in the best match to the optimum flow rate
profile found in phase one. This decoupling considerably eased the process of
optimal search. An analysis of actual flow rate profiles of PV pumping systems
showed that the optimum search can be restricted to the family of profiles represented
by a function dependent upon three parameters only.
A comparison is made between the performance of the optimum direct PV-SDHW
system and a conventional direct SDHW system operating under three control
schemes: an ON-OFF flow SDHW system operating at the manufacturer's
recommended constant flow rate, an ON-OFF flow SDHW system operating at the
optimum constant flow rate and a linear proportional flow SDHW system, with the
flow proportional to the solar radiation operating under an optimum proportionality.
It was found that the optimum direct PV-SDHW system was superior to the systems
with conventional control schemes.
Subject
Thesis (Ph.D.)--University of Wisconsin--Madison, 1997.
Dissertations Academic Mechanical Engineering.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7734Description
Under the supervision of Professors William Beckman and Sanford Klein; 215pp.
Citation
Al-Ibrahim, A.M. (1997). Optimum Selection of Direct-Coupled Photovoltaic Pumping System in Solar Domestic Hot Water Systems. Doctoral Dissertation, University of Wisconsin-Madison.