C120-H007-08EN 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
24C (75.2F) 45% Setup condition
Temperature and
humidity of the air
coming out of the air
conditioner
18C (64.4F) 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) [Btu/(lbF)]
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 24C (75.2°F)
and 45% RH from the air-line diagram.
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