An Otto cycle engine is analyzed using the cold air standard method. Given the conditions at state 1, compression ratio (r), and
pressure ratio (rp). The specific heats for air are Cp = 1.0045 kJ/kg-K and Cv = 0.7175 kJ/kg-K.
T1 = 300K
P1 = 100 kPa
r = 10
rp = 1.65
a) Determine the temperature (K) at state 2.
b) Determine the pressure (kPa) at state 2.
c) Determine the pressure (kPa) at state 3.
d) Determine the temperature (K) at state 3.
e) Determine the temperature (K) at state 4.
f) Determine the pressure (kPa) at state 4.
g) Determine the net work output (kJ/kg/cycle) for the engine.
h) Determine the heat addition (kJ/kg/cycle) for the engine.
i) Determine the efficiency (%) of the engine.
Points will be given to answer showing all the work done to get right answer.
T1 = 300K
P1 = 100 kPa
r = 10
rp = 1.65
a) Determine the temperature (K) at state 2.
b) Determine the pressure (kPa) at state 2.
c) Determine the pressure (kPa) at state 3.
d) Determine the temperature (K) at state 3.
e) Determine the temperature (K) at state 4.
f) Determine the pressure (kPa) at state 4.
g) Determine the net work output (kJ/kg/cycle) for the engine.
h) Determine the heat addition (kJ/kg/cycle) for the engine.
i) Determine the efficiency (%) of the engine.
Points will be given to answer showing all the work done to get right answer.
1 answer:
You might be interested in
Answer:
You need a 120V to 24V commercial transformer (transformer 1:5), a 100 ohms resistance, a 1.5 K ohms resistance and a diode with a minimum forward current of 20 mA (could be 1N4148)
Step by step design:
- Because you have a 120V AC voltage supply you need an efficient way to reduce that voltage as much as possible before passing to the rectifier, for that I recommend a standard 120V to 24V transformer. 120 Vrms = 85 V and 24 Vrms = 17V = Vin
- Because 17V is not 15V you still need a voltage divider to step down that voltage, for that we use R1 = 100Ω and R2 = 1.3KΩ. You need to remember that more than 1 V is going to be in the diode, so for our calculation we need to consider it. Vf = (V*R2)/(R1+R2), V = Vin - 1 = 17-1 = 16V and Vf = 15, Choosing a fix resistance R1 = 100Ω and solving the equation we find R2 = 1.5KΩ
- Finally to select the diode you need to calculate two times the maximum current and that would be the forward current (If) of your diode. Imax = Vf/R2 = 10mA and If = 2*Imax = 20mA
Our circuit meet the average voltage (Va) specification:
Va = (15)/(pi) = 4.77V considering the diode voltage or 3.77V without considering it
