U-20
CHAPTER 2
•
Lossnay Construction and Technology
5. Lossnay Energy Recovery Calculation
The following diagram shows the various air conditions when ventilation air is introduced through the Lossnay Core. If a
conventional sensible energy recovery unit is used alone and is assumed to have the same energy recovery efficiency as
Lossnay, the condition of the air supplied to the room is expressed by Point A in the figure. Point A shows that the air is very
humid in summer and very dry in winter.
The air supplied to the room with Lossnay is indicated by Point S in the figure. The air is precooled and dehumidified in the
summer, and preheated and humidified in the winter before it is introduced to the room.
iSA
iOA
tOA tSA
A
S
O
R
i
RA
iSA
iOA
tRA tRA
S
R
AO
t
SA tOA
XOA
XSA
XRA
XRA
XSA
XOA
iRA
The quantity of heat recovered by using the Lossnay Core can be calculated with the formula below:
Total heat recovered: q
T
=
γ
× Q × (i
OA
- i
SA
) [W]
=
γ
× Q × (i
OA
- i
RA
) ×
η
i
Where
Ventilation load
Lossnay Core energy recovery
Ventilation load
Lossnay Core energy recovery
Outdoor air
condition in
winter
Supply air condition of
the Lossnay
Supply air condition of
the Lossnay
Room air
condition
in summer
Outdoor air condition
in summer
Room air condition in winter
Dry bulb temperature (°F, °C)
<US unit>
γ = Specic weight of the air
under standard conditions 75 (Ib/ft
3
)
Q = Treated air volume (CFM)
t = Temperature (°F)
x = Absolute humidity (Ib/Ib’)
i = Enthalpy (Btu/Ib)
η = Energy recovery efficiency (%)
OA : Outdoor air
RA : Return air
SA : Supply air
<SI unit>
γ = Specic weight of the air
under standard conditions 1.2 (kg/m
3
)
Q = Treated air volume (m
3
/h)
t = Temperature (°C)
x = Absolute humidity (kg/kg’)
i = Enthalpy (kJ/kg)
η = Energy recovery efficiency (%)
OA : Outdoor air
RA : Return air
SA : Supply air
Enthalpy (Btu/Ib, kJ/kg)
Enthalpy (Btu/Ib, kJ/kg)
Absolute humidity
(Ib/Ib’, kg/kg’)
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