- #1
redsox5
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I'm trying to calulate the efficency of a small hydrogen fuell cell that I built. I have all of the measurements, but I'm not coming up with a resonable effiency.
The power to electrolyze the water is the P IN.
3.25 W =2.5 V x 1.3Amps (.21 mA)
We measured the electrical power out finding the voltage and amperage.
P OUT = V x I
2.01 x 10^-4 W=.96 V x .00021 AMPS (.21 mA)
I caulcate the force to be 1.421 N
Then I take the electrical P Out and use it as the P IN for the car
the P IN for the car is the electrical P Out
and the P Out for the car is F x V
To find the % efficiency:
The avg velocity is .0198 m/s
For the car: (there is something wrong here since I'm getting more power out)
P in = 2.01 x 10^-4 W
P Out = F x V
2.81 x 10^-2 J = 1.421 N x .0198 m/s
I'm coming up with an unreasonable calculation
Isn't watts joules per second. Should I be including the time it took to electrolyze the water. I'm just using the formula i was given, but the units don't work out
Also I'm not sure if I'm calculating the force in th right way. We used a spring scale and my measurement was .160 kg. I'm I just supposed to multiply that by 9.8 m/s^2. I know that this way gives me Newtons, but the car isn't being affected by gravity anyways. If someone could look this over I'd appreciate it.
The power to electrolyze the water is the P IN.
3.25 W =2.5 V x 1.3Amps (.21 mA)
We measured the electrical power out finding the voltage and amperage.
P OUT = V x I
2.01 x 10^-4 W=.96 V x .00021 AMPS (.21 mA)
I caulcate the force to be 1.421 N
Then I take the electrical P Out and use it as the P IN for the car
the P IN for the car is the electrical P Out
and the P Out for the car is F x V
To find the % efficiency:
The avg velocity is .0198 m/s
For the car: (there is something wrong here since I'm getting more power out)
P in = 2.01 x 10^-4 W
P Out = F x V
2.81 x 10^-2 J = 1.421 N x .0198 m/s
I'm coming up with an unreasonable calculation
Isn't watts joules per second. Should I be including the time it took to electrolyze the water. I'm just using the formula i was given, but the units don't work out
Also I'm not sure if I'm calculating the force in th right way. We used a spring scale and my measurement was .160 kg. I'm I just supposed to multiply that by 9.8 m/s^2. I know that this way gives me Newtons, but the car isn't being affected by gravity anyways. If someone could look this over I'd appreciate it.