Mitsubishi Electric GUG-01SL-E Technical Manual page 49

Specification condition
(A) Outdoor air wet-bulb temperature
(B) Dx-coil inlet air dry-bulb temperature
(C) Air condition difference factor C
All of cooling specification for each Dx-coil unit are designed under above condition.
Therefore C ( = 1.02) is fixed value for all unit.
2-1
Designing condition
(D) Outdoor air wet-bulb temperature
(E) Dx-coil inlet air dry-bulb temperature
(F) Air condition difference factor C
(Find C from the graph on page 62. )
2-2
(G) Total air condition difference factor C
= C /C = (F) / (C) = 0.72 / 1.02
2-2 2-1
For the quick reference of air condition difference factor C
(3) Corrected refrigerant pipe length factor
(A) Refrigerant pipe length factor C
Same condition with Example 1-1.
(4) Adjusted Dx-coil unit capacity
(A) Dx-coil unit heating capacity on the specification
(B) Adjusted Dx-coil unit heating capacity
= (A) x C x C x C = 8.1 x 1.0 x 0.71 x 1.0 = 5.75
1 2 3
IV : Calculate the supply air conditions from Dx-coil unit
Enthalpy of supply air from Dx-coil : h
h : Enthalpy of Dx-coil inlet air
i
(equal to Lossnay outlet air) [kJ/kg(DA)]
C : Adjusted capacity of Dx-coil unit [kW]
a
Enthalpy of supply air from Dx-coil :
h = C / (ρ x Q / 3600) + h
o a f
= 5.75 / ( 1.2 x 1000 / 3600 ) + 29.2
Absolute humidity, the ratio of water weight against the unit weight of dry air, is unchanged during heating.
Supply air condition from Dx-coil can be read out by psychrometric chart.
STEP4. Comparison of Lossnay + Dx-coil unit capacity with required capacity
By calculations from STEP 1 to 3, the capacity of Lossnay + Dx-coil unit is summate as shown below.
Capacity calculation result
(A) Required cooling capacity
(B) Lossnay energy recovery
(C) Dx-coil heating capacity
(D) Lossnay + DX-coil unit system cooling capacity
= (B) + (C)
As a result, (D) is smaller than (A). Therefore, consider to add other heating equipment.
(In this example, air-conditioning equipment whose capacity is 12.8 kW ( 26.7 - 13.9 ) is necessary.)
9
Model selection and capacity calculation
CHAPTER
2-1
2-2
2
3
= C / (ρ x Q / 3600) + h
o a f
[kJ/kg(DA)]
i
Dry-bulb temperature
Wet-bulb temperature
Absolute humidity
Relative humidity
Enthalpy
6 WB
˚C
17.4˚CDB
1.02
– 3˚CWB
16.0˚CDB
0.72
0.71
, see the page 63.
2
1.0
8.1 kW
5.8
5.8 kW
[kJ/kg(DA)]
i
29.1 kJ/kg(DA)
5.8 kW
46.4 kJ/kg(DA)
Supply air from Dx-coil unit
[°C]
[°C]
[kg/kg(DA)]
[%]
[kJkg(DA)]
26.7 kW
8.1 kW
5.8 kW
13.9 kW
33.2
16.7
0.0051
16
46.4
46