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 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 2. Relevant 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 3. 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.