Environmental Engineering Reference
In-Depth Information
Table 34. ANOVA (heating and cooling mode)
Heating Mode
Cooling Mode
Factors
DoF
heat
DoF
cool
SS
V
%
SS
V
%
V
2
2
143416.55
71708.28
3.13
3144680.40
1572340.20
18.65
T
3
4
4360719.70
1453573.23
95.20
13361816.00
3340454.00
79.23
VxT
6
8
76221.97
12703.66
1.66
357099.39
44637.42
2.12
Error
0
0
0.00
0.00
0.00
0.00
0.00
0.00
Total
11
14
4580358.20
416396.20
100.00
16863596.00
1204542.60
100.00
Analysis of Results
Airflow Analysis
•
Cooling Mode
: its contribution is higher, around 18%. It is shown that, when the
airflow is increased, the total heat recovered rises, due to the increment of the film
coefficients: both the thermal coefficient, which characterises the sensible exchange,
as well as the mass coefficient linked to the latent exchange.
Temperature
•
Heating Mode
: this is the most contributory factor, with a very high percentage of
approximately 95%. This value is increased for the highest temperature differences
between both airstreams (supply and return). The behaviour of the system is clearly
shown, which goes from the positive values that characterize the heating mode to the
negative ones which represent the cooling mode. The transition between these
behaviours occurs near the temperature level 3 which corresponds to 15ºC.
•
Cooling mode
: this is the most contributory factor whose values are approximately
80%. In this factor, the effects produced by the temperature increments are cancelled
out by the sensible and latent heat recovered. The rising trend to negative values, the
continuity and the linearity that presents the evaporative cooler in this working mode
are clearly shown.
S
UMMARY
In Table 35 the main conclusions from the analysis performed are summarized.
The legend to understand the following table is: “x” means no contribution (negligible
contribution in terms of variance analysis), as well as the white squares. The light-grey
coloured squares represent a medium contributory percentage, and the ones in dark grey are
the most contributory squares, their effects were previously explained.
