Fujitsu AB* A12GATH, Design & Technical Manual

Page: 31 / 1124

3-2. METHOD OF CAPACITY CALCULATION
The capacity calculation method which takes the effects of air temperature, pipe length and
frosting/defrosting into consideration is shown below.
1. Calculate the estimated capacity of each indoor unit.
(1) Find
capacity of indoor unit at rated condition (TCin)r and at design temperature (TCin)d
[from 7. CAPACITY TABLE COOLING (INDOOR UNIT) or 8. CAPACITY TABLE HEATING (INDOOR UNIT)]
(2) Find the following compensation coefficient
[From 6. CAPACITY COMPENSATION COEFFICIENT].
„
●
Compensation coefficient of pipe length
„
●
Compensation coefficient of frosting/defrosting (Heating calculation only
)
(3) Calculate the estimated capacity of indoor unit (TCin)e.
COOLING:
Estimated capacity of indoor unit (TCin)e
= Capacity of indoor unit at design temperature (TCin)d
x Compensat
ion coefficient of pipe length
HEATING:
Estimated capacity of indoor unit (TCin)e
= Capacity of indoor unit at design temperature (TCin)d
x Compensation coefficient of pipe length
x Compensation coefficient of frosting/defrosting
2. Calculate the compensated capacity of outdoor unit.
(4) Find capacity of outdoor unit at rated condition (TCout)r
[From 2. MODEL LINE UP].
(5) Calculate total rated capacity of indoor units : ∑(TCin)r
and ratio to the rated capacity of outdoor unit : ∑(TCin)r / (TCout)r .
(6) Find capacity of outdoor unit at design temperature (TCout)d
[using result of (5) and 4. CAPACITY TABLE (OUTDOOR UNIT)].
(7) Calculate the compensated capacity of outdoor unit (TCout)c.
COOLING:
Compensated capacity of outdoor unit (TCout)c
= Capacity of outdoor unit at design temperature (TCout)d
x Compensation coe
fficient of pipe length
HEATING:
Compensated capacity of outdoor unit (TCout)c
= Capacity of outdoor unit at design temperature (TCout)d
x Compensation coefficient of pipe length
x Compensation coefficient of frosting/defrosting
3. Decide system capacity.
(8) Calculate total capacity of indoor units at design temperature ∑ (TCin)d.
(9) System capacity = the smaller one of (TCout)c and ∑ (TCin)d. • • • • • • • • (7) or (8)
4. Calculate actual capacity of each indoor unit.
(10) Calculate actual capacity of each indoor unit by dividing system capacity proportionally.
Actual capacity of indoor unit = (System capacity) x (Rated capacity of indoor unit) / (Total rated
capacity of indoor unit )
= (System capacity) x (TCin)r / ∑ (TCin)r • • • • • (9) x (1) / (5)
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