Do the following problems from our textbook by Cengel (just this once, a copy of

Question

Do the following problems from our textbook by Cengel (just this once, a copy of these questions from the textbook is attached to end of this document). 1-8C 1-10C 1-12C 1-15 1-20 2-21E 2-24E Consider the flowchart on the reverse of this page. The original can be found at https://flowcharts.llnl.gov/. Based on the 2012 chart: Where percent of total US energy use is used to generate electricity? What percent of electricity is generated from fossil fuels? What percent of total US energy use goes to practical use (energy services)? Which of the four energy use sectors (pink boxes) has the least efficient energy conversion? Over a 24 hour period an industrial building has the following energy usage; a large freezer consumes 400 kWh. Electric lights and other equipment, which operate for 10 hours of the 24 hour period, consume at the rate of 120,000 Watts. A boiler heats the building and consumes 16 gallons of heating oil. Heating oil has a heat content at 20,000 BTU/gallon. Report the total energy use by the building over the 24 hour period in units of: kwh BTU kJ After Friday you can do Conservation of mass: Read Section 6-1 A tank initially (at t = 0) contains 1000 kg of water. Water flows into the tank at the constant of 10 kg/sec. Water flows out of the tank at a rate given by: m^dot_out =1 + 0.01t where t is in seconds and the rate is in kg/sec. This equation applies for t = 0 to t = 500 seconds. For example, when t =100 seconds the rate is 2 kg/sec. what is the rate that water accumulates in the tank when t = 250? How much water is in the tank at t = 250 How much water is in the tank at t = 500 se the differential form of mass balance and integrate to find m_cv, as a function of time.

Explanation / Answer

we know,
1 BTU = 1055 J

1 KWH = 3.6*10^6 J

1 W = 1 J/s

a) Total energy use by the building, E = 400 kWh + (10*60*60s)*(120000 J/s) + 16*120000 BTU

= 400 kWh + (10*60*60(120000) J + 16*120000*1055 J

= 400 KWh + (10*60*60*120000)/(3.6*10^6) KWh + 16*120000*1055/(3.6*10^6) kWh

= 2163 kWh

b) E = 2163*3.6*10^6 J

= 2163*3.6*10^6/(1055) BTU

= 7.38*10^6 BTU

c) E = 2163*2.6*10^6 J

= 2163*2.6*10^3 kJ

= 5.62*10^6 kJ

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