(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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 T_{r}=50°C, T_{r}=60°C, T_{r}=70°C and T_{r}=80°C. What conclusions can you draw from your calculations?

Assume the following values:

G_{tn}=400 W/m^{2}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

U^{L}=5 W/m^{2}-K Overall loss coefficient including conduction, radiation and convection losses

T^{a}=20°C Temperature of the air

2. Relevant equations

I have too many equations and don't know what to do with them.

Q^{dot}_{u}=Q^{dot}_{in}-Q^{dot}_{loss}

Q=A_{r}U_{L}(T_{r}-T_{a})

eta = Q^{dot}_{u}/(A_{a}G_{t})

but I don't think G_{t}is anything.

and many more, but these seemed the most relevant

3. The attempt at a solution

m^{dot}= 80kg/3600s

Q^{dot}_{u}=m^{dot}c_{p}(T_{out}-T_{in})

=2330 W

Q^{dot}_{u}is in just about every equation, but in order to find the area of the plate, we need to know eta, I believe.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Flat plate solar collector

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**