Flat plate solar collector

In summary, the conversation discusses the need to size a flat plate collector in order to provide water for one hot shower per hour. The receiver temperature must be greater than 40°C and below 90°C, and the required area for the collector is determined for receiver temperatures of 50°C, 60°C, 70°C, and 80°C. The equations used include Qdotu=Qdotin-Qdotloss, Q=ArUL(Tr-Ta), and eta=Qdotu/(AaGt) among others. However, there is difficulty in determining the area of the plate due to the need to know eta, which requires knowing Qdotin and Qdotloss, but also requires knowing the area of the
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musicmar
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Homework Statement


We wish to size a flat plate collector to provide water for one hot shower per hour. We have determined that a shower uses 80 liters of 40°C water that has been heated from a 15°C supply line. The receiver temperature must be greater than the desired water temperature of 40°C and below 90°C to prevent the risk of pressure build up in the collector due to boiling. Determine the required area (Aa in m2) needed for the collector for the following receiver temperatures Tr=50°C, Tr=60°C, Tr=70°C and Tr=80°C. What conclusions can you draw from your calculations?

Assume the following values:

Gtn=400 W/m2 Total solar radiation on a surface normal to the sun’s beam
=30° Average angle of incidence between the normal to the collector and the beam
of the sun
=0.97 Receiver absorptivity
=0.87 Glass transmissivity
UL=5 W/m2-K Overall loss coefficient including conduction, radiation and convection losses
Ta=20°C Temperature of the air


Homework Equations


I have too many equations and don't know what to do with them.
Qdotu=Qdotin-Qdotloss

Q=ArUL(Tr-Ta)

eta = Qdotu/(AaGt)
but I don't think Gt is anything.

and many more, but these seemed the most relevant

The Attempt at a Solution



mdot = 80kg/3600s

Qdotu=mdotcp(Tout-Tin)

=2330 W

Qdotu is in just about every equation, but in order to find the area of the plate, we need to know eta, I believe.
 
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  • #2
But in order to find eta, I need to find Qdotin and Qdotloss, which requires knowing the area of the plate. It seems like a vicious cycle.
 

1. What is a flat plate solar collector?

A flat plate solar collector is a type of solar panel that is used to absorb sunlight and convert it into thermal energy. It typically consists of a flat, insulated panel with a series of tubes or channels running through it, which are filled with a heat transfer fluid. The sunlight is absorbed by the panel and heats up the fluid, which is then used to heat water or air for various applications.

2. How does a flat plate solar collector work?

A flat plate solar collector works by using a series of interconnected tubes or channels to circulate a heat transfer fluid, such as water or antifreeze, through a flat, insulated panel. The panel is coated with a dark, heat-absorbing material, which absorbs the sunlight and heats up the fluid as it passes through. The heated fluid is then used to transfer the thermal energy to water or air for use in heating systems or hot water systems.

3. What are the advantages of using a flat plate solar collector?

There are several advantages to using a flat plate solar collector. Firstly, they are relatively inexpensive and easy to manufacture compared to other types of solar panels. They also have a long lifespan and require minimal maintenance. Additionally, they can be used in a variety of applications, such as heating water for domestic use or providing heat for buildings, making them a versatile and sustainable energy source.

4. Are there any limitations to using a flat plate solar collector?

One limitation of using a flat plate solar collector is that they are most effective in areas with high levels of direct sunlight. They are also less efficient in colder climates, where the panels may be covered in snow or ice for extended periods of time. Additionally, they may not be suitable for large-scale energy production, as multiple panels would be needed to generate significant amounts of energy.

5. How can I maintain and care for a flat plate solar collector?

Maintaining a flat plate solar collector is relatively simple. It is important to regularly clean the panels to remove any dirt, dust, or debris that may block the sunlight. Additionally, the fluid in the tubes should be checked and replaced if necessary to ensure efficient heat transfer. It is also important to protect the panels from extreme weather conditions and make any necessary repairs or replacements to ensure they continue to function effectively.

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