Sustainable Energy, SI Edition
2nd Edition
ISBN: 9781337672092
Author: DUNLAP, Richard A.
Publisher: Cengage Learning
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Problem 1/
A vertical glass cylinder contains 850 ml of water at 20 °C; the height of the water column is 70 cm. The water
and its container are heated to 70 °C. Assuming no evaporation, what will be the height of the water if the
coefficient of thermal expansion for the glass is 3.5 x 10-6/°C?
A small lake with volume 10,000 m3
has a stream flowing into it with flow
rate 100 m3/day
and a Toluene concentration of 1.0
mg/m3. A factory discharges 5 m3/
day into the lake with
Toluene concentration of 10 mg/m3 -
they want to increase effluent to 50
mg/m3. Toluene
decays at a rate of 0.01 day-1.
Assume steady-state and completely
mixed (CSTR).
a) How would this increase in
discharge concentration change the
lake concentration?
Answer: 0.73 mg/m3 before, 1.71 mg/
m3 after
b) Field studies show that the same
lake would be better represented by
dividing the lake
into two cells. The first cell having a
volume of 2,500m3 and the second
with 7,500m3.
How does this affect the estimate of
concentration leaving the lake?
Compare with one-
cell model.
Assume the factory continues to
discharge at 10 mg/m3 into the first
cell.
Question 3
A 2L, 4-stroke, 4-cylinder petrol engine has a power output of 113.9 kW at 5500 rpm and a maximum torque of 235 N-m at 3000 rpm. When the engine is maintained to run at 5500 rpm, the compression ratio and the
mechanical efficiency are measured to be 8.9 and 83.2%, respectively. Also, the volumetric efficiency is 93.1 %, and the indicated thermal efficiency is 43.76 %. The intake conditions are at 36.9 °C and 1.00 bar,
and the calorific value of the fuel is 44 MJ/kg
Determine the Air-Fuel ratio in kg/kgf at 5500 rpm.
Use four (4) decimal places in your solution and answer.
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