COLD FRONT COOLING (cont’d):
The Barometric Damper may be controlled by natural pressure variations or, if motorised, by the control system, depending on
whether the Climate Wizard is required to function or not.
Cold Front Cooling means pre-cooling warm (hot) fresh air that is required by a refrigerated Air-Conditioning plant. Since
Climate Wizard cools fresh air down to almost the dewpoint and does not add any moisture, it is the ideal product to pre-cool the
fresh air. This low-cost pre-cooled air creates immediate energy savings for the building and it reduces the load on the refrigeration
equipment, thereby extending the life of the plant and saving capital outlay. It also enables load to be removed from the existing
over-stressed electrical power infrastructure, and especially so in heat-wave conditions.
First ascertain the quantity of fresh air of which the refrigerated Air Conditioning plant is capable. Match this quantity to the quantity
of air of the Climate Wizard will deliver. The maximum supply airflow of the 2 Climate Wizard models is:
CW-H10 approx. 800 L/sec at 200 Pa
CW-H15 approx. 1100 L/sec at 200 Pa
For customers who need to know the energy saving, the provides the Cooling Effect in kW of each
model at various ambient conditions.
Further reductions in energy consumption can be achieved when a portion of the return air is ducted via the Climate Wizard.
Maximising the use of return air can also open up further very viable possibilities for Climate Wizard in localities with extremely high
dewpoint temperatures. These are special cases and lie outside the scope of this Guide.
Sizing:
Psychrometric Chart, (Page 12)
WORKED EXAMPLES:
Commercial building inAdelaide,Australia, planning to use Lennox FGM200 RooftopA/C units.
Unit specs: 197 kW cooling capacity, input power 66 kW, 35000 cmh airflow. COP = 197 / 66 = 3.0
Total fresh air 25% of 35000 = 8750 cmh = 2430 L/sec. Use 2 x CW-H15
Climate 38°C Tdb and 10°C Tdew. CW-H15 Cooling Effect = 30.5 kW; input power = 2 x 1.8 kW,
A/C unit load becomes 197 - (2 x 30.5) = 136 kW; hence input power at 3.0 COP = 136/3 = 45 kW
Total system input power = 45 + (2 x 1.8) = 48.6 kW
Original system power = 66 kW
Supermarket in very hot city in Spain, planning to use Lennox FHK190 RooftopA/C units.
Unit specs: 208 kW cooling capacity, input power 75 kW, 33000 cmh airflow COP 208/75 = 2.8
Total fresh air 10% of 33000 = 3300 cmh = 917 L/sec Use CW-H15.
Climate 40°C Tdb, and 12°C Tdew. CW-H15 Cooling Effect = 31.6 kW ; input power 1.8kW
A/C unit load becomes 208 - 31.6 = 176.4 kW; hence input power at 2.8 COP = 176.4/2.8 = 63 kW
Total system input power = 63 + 1.8 = 64.8 kW
Original system power = 75 kW
Commercial Offices in Lyon, France, planning to use Lennox FGM200 RooftopA/C units.
Unit specs: 197 kW cooling capacity, input power 66 kW, 35000 cmh airflow. COP = 197 / 66 = 3.0
Total fresh air 20% of 35000 = 7000 cmh = 1944 L/sec. Use 2 x CW-H15
Climate 34°C Tdb and 11.7°C Tdew. CW-H15 Cooling Effect = 24.5 kW; input power = 2 x 1.8 kW
A/C unit load becomes 197 - (2 x 24.5) = 148 kW; hence input power at 3.0 COP = 148/3 = 49.3 kW
Total system input power = 49.3 + (2 x 1.8) = 52.9 kW
Original system power = 66 kW
Example 1:
Example 2:
Example 3:
Assume 25% fresh air.
Saving = 17.4 kW or about 26%.
Assume 10% fresh air.
Saving = 10.2 kW or about 14%.
Assume 20% fresh air.
Saving = 13.1 kW or about 20%.
8Indirect Evaporative Air Conditioner
