25-08-2017, 09:32 PM
Solar Water Heater Research Project: Collector Facing Horizontal Angle Orientation
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Introduction
Objective Our initial goal for this research project was to do design and build a passive thermosyphon solar water heating system capable of reaching an optimal temperature of 100F (38C) – 110F (43C). Additional, the system was designed to support a semester long study on the optimal position of the collector relative to the sun, along a horizontal angle (or azimuth), capable of producing the above stated temperatures. Background Research
The overall process of this research project required a fairly extensive amount of background research, mainly to uncover and utilize the past findings of others. The background research revealed articles discussing the step-by-step process of how to construct several types of passive solar water heaters and a thorough review of relevant terminology. This served as a great starting point for understanding some of the components of designing any type of passive system. There were discussions of the methods of insulating systems, orientation of the systems relative to the sun, as well as the important design elements needed for an efficient collector and storage tank to achieve optimal insolation. The background research revealed in-depth discussions on several variations of solar heating systems and clear explanations on some underlying principles of how these systems work including the associated properties of water and thermodynamics. Basically, this was a review of the physics at work in a thermosyphon system. There were also specific reviews of flat-plate collector designs (the type used here) including the dimensions of the many parts included in such a system.
Hypothesis
While the research team understands that past research clearly supports a generalized south-facing collector orientation, our hopes were to reveal a more specific optimal range of horizontal angles from which a flat-plate collector is most effective in capturing solar energy. While a true south-facing (0) collector may yield the highest levels of insolation, the research team believed there to be an optimal range of south-facing angles (-15 to +15) that would allow the collector to capture the same amount of radiation from the sun as if it were oriented in a true south-facing (0) direction. For the purposes of this experiment, true south will be given the value 0 (where east would be -90 and west +90).
System Design and Construction
The materials used in the construction of our passive solar water heater, their costs, and each item’s specific qualities and dimensions are listed in Fig. 2. Our system design was based upon the following factors: the team’s individual research on the web
and scientific databases, past student reports on similar projects, class discussions, and the availability and cost of materials.
Mechanisms and Design
There are other factors regarding the mechanisms of operation and system design that are important to discuss. First, the collector design held some interesting and unintended consequential effects. As was discussed in the above section entitled System Design and Construction and as seen in Fig. 4 above, the collector was an elongated version of the more conventional square-shaped collectors others chose to build. Our original intentions for this component of the design are explained above. However, what is important to consider is the possibility that this elongated collector may have allowed us to more accurately test the levels of insolation at varying angles along the horizon. That is, although the total surface area measured 1 square foot, only 6 inches (the width of the collector) of collector facing was available to capture solar energy. In addition, the depth of our collector may have also inhibited less direct sunrays to enter the collector by effectively blocking them out. Although this was an unintended consequence of our design, and may have been a factor in the water temperature never reaching our desired goal, this may be an important element for future researchers to consider.
Conclusion and Recommendations Conclusion
Overall, the most important aspect of this research project involved rethinking the relationship between humans and energy consumption. Our attempt to optimize a component of capturing solar energy for the purpose of heating water mostly illuminated one simple fact: the Sun’s energy, unless stored, is not consistently available 24 hours a day, year-long at any one place on Earth. However, the “needs” of humans living within industrialized societies currently dictates an ever-ready supply of energy with many of these sources quickly being depleted. Thus, it is important for the scientific community to optimize solar energy. However, perhaps it is most important for humans to rethink our energy consumption and relative “needs” in light of what sources are truly available long-term.