47
CHAPTER
9
Model selection and capacity calculation
STEP1
.
Calculation of required cooling capacity
Following calculations are just examples.
In the actual designing, please calculate in an appropriate way.
In this example, the outdoor and return air conditions are assumed that shown in the table below.
Example 2-1: Cooling for an school classroom by RA temperature control
I: Calculation of required ventilation air volume and selection of Lossnay unit
II: Calculation of cooling load to determine the required capacity
(A) Floor space
(B) Required fresh air rates
(C) Floor space per person
(D) The number of people per 1 m
2
= The reciprocal number of floor space per person
(E) The number of person in the floor
= (A) / (C) = 50 / 2
= (A) x (D) = 50 x 0.5
(F) Required fresh air volume
= (B) x (E) = 40 x 25
(G) Required static pressure
2 m
2
/person
40 m
3
/h·person
50 m
2
25 people
1000 m
3
/h
170 Pa
0.5 person/m
2
Adequate Lossnay model
LGH-100RVX-E
Dry Bulb Temp. Relative Humidity Wet Bulb Temp.
Enthalpy
Enthalpy Difference
Cooling
Outdoor Air
27 °C
50%
19.5 °C
55.4 kJ/kg (DA)
13.6 kJ/kg (DA)
Return Air
21 °C
53%
15 °C
41.8 kJ/kg (DA)
Ventilation load can be calculated by same formula as Example 1-1.
Ventilation load per unit area under above condition can be calculated as following
Ventilation load per unit area
In this example, other cooling loads are regarded as shown in the table below.
Calculate them in an appropriate way in the actual designing.
=
ρ
[kg/m
3
]
x n [person/m
2
] x V
f
[m
3
/h·person] x (h
O
- h
R
) [kJ/kg(DA)]
= 1.2 [kg/m
3
] x 0.5 [person/m
2
] x 40 [m
3
/h·person] x (55.4 - 41.8) [kJ/kg(DA)]
= 326.4 [kJ/h·m
2
]
= 90.7 [W/m
2
]
Load type
Load
Ventilation Air Load
90.7 W/m
2
Indoor Generated Heat
People
40.0 W/m
2
Lightning Equipment
20.0 W/m
2
Indoor Penatration Heat
36.3 W/m
2
Total
187.0 W/m
2
Required cooling capacity to make up for above cooling loads
= 187.0 [W/m
2
] × 50 [m
2
] =
9.4 [kW]
Summary of Contents for GUG-01SL-E
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