Mitsubishi Electric Lossnay LGH-F1200RX5-E, Техническое руководство

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U-13
CHAPTER 1
•
Ventilation for Healthy Living
5.3 Ventilation Load During Heating
•
Classification of Heating Load
During heating, the heat generated by occupants and electrical equipment in the room can be subtracted from the heating load.
If the warming-up time at the start of heating is short, however, the generated heat may be ignored in some cases.
Percentage of Load
•
Heating Load Per Unit Area
When the ventilation air volume per occupant is 15 CFM (25 m
3
/h), and the number of occupants per 1 ft
2
is 0.0186 (1 m
2
is 0.2), the heating load will be approximately 12.4 W/ft
2
(133.7 W/m
2
).
•
Internal Heat Loss
In terms of load classification, the internal heat loss is the value of the ventilation air load subtracted from the approximate
heating load.
Internal heat loss = 12.4 W/ft
2
– 5.2 W/ft
2
= 7.2 W/ft
2
(133.7 W/m
2
– 56.0 W/m
2
= 77.7 W/m
2
)
•
Ventilation Load
Standard design air conditions in Tokyo
Conditions: Middle south-facing floor of a typical office building.
<US unit>
When the load per 1 ft
2
of floor area with a ventilation volume of 15 CFM·occupant is calculated with the air conditions
detailed above, the following is obtained:
Ventilation air load = 0.749 Ib/ft
3
× 0.0186 occupants/ft
2
× 15 CFM·occupant × 14.4 Btu/Ib = 0.30 Btu/min·ft
2
(5.2 W/ft
2
)
<SI unit>
When the load per 1 m
2
of floor area with a ventilation volume of 25 m
3
/h·occupant is calculated with the air conditions
detailed above, the following is obtained:
Ventilation air load = 1.2 kg/m
3
× 0.2 occupants/m
2
× 25 m
3
/h·occupant × 33.5 kJ/kg = 201.0 kJ/h·m
2
(56 W/m
2
)
The Lossnay recuperates approximately 70% of the ventilation load and saves on approximately 30% of the total load.
Ventilation
air load 41.9%
5.2 W/ft 2
(56.0 W/m
2
)
Indoor heat
loss 58.1%
7.2 W/ft 2
(77.7 W/m
2
)
12.4 W/ft
2
(133.7 W/m 2 )
Class Heat Load
(a)
Indoor heat
loss
Heat escaping from walls (q
WS
)
Heat escaping from glass (q
GS
)
Heat loss from conduction and convection (q
GS
)
Accumulated heat load in walls (q
SS
)
(b)
Ventilation
load Sensible heat (q
FS
)
Latent heat (q
FL
)
Type of Load Load
Ventilation Air Load 5.2 W/ft 2 (56.0 W/m 2 )
Internal Heat 7.2 W/ft
2
(77.7 W/m
2
)
Total 12.4 W/ft 2 (133.7 W/m 2 )
Dry Bulb Temp. Relative Humidity Wet Bulb Temp. Enthalpy Enthalpy Difference
Heating
Outdoor Air 32 °F (0 °C) 50% 26.6 °F (–3 °C) 2.1 Btu/Ib (5.0 kJ/kg)
14.4 Btu/Ib (33.5 kJ/kg)
Indoor Air 68 °F (20 °C) 50% 56.7 °F (13.7 °C) 16.6 Btu/Ib (38.5 kJ/kg)