PASCO TD-8564 THERMAL EFFICIENCY APPARATUS - Manual (Page 30)

Thermal Efficiency Apparatus 012-05443A
26
Experiment 2: Heat Engine Efficiency (Detailed Study)
Notes on Setup
➁
It may be necessary to prime the pump by sucking
on the output line briefly.
Sample Data
Mode T
h
(
°
C) T
c
(
°
C) V
h
I
h
V
w
V
s
Engine 57.9 3.5 10.00 2.02 0.890
Open 57.9 3.3 8.99 1.815 1.495
Calculated Values
Mode T
h
(K) T
c
(K) P
h
P
w
I
w
Engine 330.9 276.5 20.2 0.40 0.45
Open 330.9 276.3 16.3
Internal Resistance: r = 1.36
Ω
Results
Actual Adjusted Maximum
(Carnot) % Difference
Efficiency 1.96% 17.13% 16.44% -4.23%
Note that these results were obtained using slightly
lower initial voltage than recommended in the lab.
In general, mid-range temperatures give better
results than extremely large or small temperature
differences.
Answers to Questions
➀ If the temperature difference was decreased, the ef-
ficiency would also decrease.
➁ See experiment 1, question 5.
➂
For the hot reservoir,
∆
S/
∆
t was -0.061. For the
cold reservoir, it was 0.073. The total change in en-
tropy is positive. In any non-reversible process, the
entropy will increase.