Recent content by EnergyKitty

Homework Statement What size FPC is needed to supply a family's domestic hot water needs in March in Denver, CO? Assume 80 gallons per day are needed (1gal=8.3 lb.) for the water and that the collector-heat exchanger system has an average efficiency of 40%. The collector tilt angle is equal to...

No, not really. I think he used it because of the Btu conversion part. I think that requires the American system of lbs and Fahrenheit.

Ok so one of the kids in my class had this for the first question: 40 gallons * 8.3 lbs/gallons = 332 lbs 332lbs * 50 deg F = 16,600 Btu = 4.89 kW 4.89 kWh/20kW = 0.245 Hours or 14 minutes approximately

Here's How: Take the temperature in Fahrenheit subtract 32. Divide by 1.8. The result is degrees Celsius. 50-32=18/1.8=10

The first equation is 14.67 minutes. The second equation is 33.75 minutes. This from my professor which I still do not understand how to come up with this. Heat of vaporization is 540 calories per gram was given as information for the second question. For the first question I have done the...

I'm extremely confused. The answer that the professor gave me was 14.67 minutes. I keep ending up at 33.9 although I've used the equation in several ways. I converted 40 gallons to 33.8 kg and change of temp to 10 degrees Celsius. I'm not sure what to do now...

Homework Statement How long will it take to heat 40 gallons of water from 70°F to 120°F with a 20 kW immersion heater assuming no energy is lost the environment? Homework Equations It takes an electric tea kettle with 20°C water five minutes to reach boiling at 100°C. How long will it take for...