Computer Drive User Manual

C120-H007-05EN 49
4.4 Thermal Load and Cooling Capacities
4.4.3 Underfloor ventilation air conditioning
Figure 4.9 shows the air condition for underfloor ventilation in a psychrometric chart.
Table 4.7 summarizes procedures for calculating the cooling capacities of an
underfloor-ventilation air conditioner, flow rate 220 m
3
/min (7770ft
3
/min).
The values in the table involve certain characteristic curve and psychrometric chart
read errors.
Figure 4.9 Air condition in a psychrometric chart (underfloor-ventilation air)
Table 4.7 Examples of underfloor-ventilation air conditioner cooling capacity
calculations (1/2)
Item Calculated value Calculation method
Temperature and
humidity at the inlet
24°C (75.2°F) 45% Setup condition
Temperature and
humidity of the air
coming out of the air
conditioner
18°C (64.4°F) 65% Setup condition
Air conditioner sensible
heat cooling capacity
(when calculated on the
basis of temperature
differences)
94.3 MJ/h (89400 Btu/h) at a flow
rate of 220 m
3
/min (7770ft
3
/min)
(T
1
- T
5
) × Specific heat × Flow rate/
Specific volume
=(24-18)(°C) × 1[KJ/(kg °C)] × 220 (m
3
/
min) × 60 (min/h) / 0.84 (m
3
/kg)
=(75.2-64.4)(°F) × 0.24[Btu/(lb⋅ °F)] ×
7770 (ft
3
/min) × 60 (min/h) / 13.5 (ft
3
/lb)
Enthalpy of the air at the
conditioner inlet
i
1
=45.4 kJ/kg
(19.5 Btu/lb)
Determine the enthalpy at 24°C (75.2°F)
and 45% RH from the air-line diagram.