U-22
CHAPTER 3
•
General Technical Considerations
1. Lossnay Energy Recovery Effect
1.1 Comparing Ventilation Load of Various Ventilators
Examples of formulas that compare the energy recovered and ventilation load when ventilating with the Lossnay (total energy
recovery unit), a sensible energy recovery ventilation unit (sensible HRV), and a conventional ventilator unit are shown below.
(1) Cooling During Summer
Conditions
•
Model LGH-F600RX5-E
•
Energy recovery efficiency table (%)
(at 60Hz, high speed) (For summer)
•
Ventilation rate: 600 CFM
(specic gravity of air ρ = 0.0749 Ib/ft
3
)
•
Lossnay Unit
(Supply air diffuser temperature) tSA = 91.4°F – (91.4°F – 78.8°F) × 0.69 = 82.7°F
(Supply air diffuser enthalpy) hSA = 36.4 – (36.4 – 22.7) × 0.50 = 29.6 Btu/Ib
Heat recovered (36.4 – 29.6) × 0.0749 × 600 = 304.4 Btu/min = 5.4 kW
Ventilation load (29.6 – 22.7) × 0.0749 × 600 = 310.1 Btu/min = 5.5 kW
•
Sensible HRV Unit
(Supply air diffuser temperature) tSA = 91.4°F – (91.4°F – 78.8°F) × 0.69 = 82.7°F
(Supply air diffuser enthalpy) hSA = 34.5 Btu/Ib (from psychrometric chart)
Heat recovered (36.4 – 34.5) × 0.0749 × 600 = 85.4 Btu/min = 1.5 kW
Ventilation load (34.5 – 22.7) × 0.0749 × 600 = 530.3 Btu/min = 9.3 kW
[Calculated enthalpy recovery efficiency 85.4 ÷ (85.4 + 530.3) × 100 = 14%]
•
Conventional Ventilator Unit
If a conventional ventilator unit is used, the energy recovered will be 0 as the supply
air diffuser is equal to the outdoor air.
The ventilation load is:
(36.4 – 22.7) × 0.0749 × 600 = 620.2 Btu/min = 10.9 kW
Calculation Example Summer Conditions
Supply air
Room air
Indoor Unit
of
Air Conditioner
Lossnay
Unit
Sensible HRV
Unit
Conventional
Ventilator Unit
Dry bulb
temperature
Absolute
humidity
Relative
humidity
Enthalpy
78.8°F
82.7 82.7 91.4
0.0159 0.0203 0.0203
66.0 84 63
29.6 34.5 36.4
4.7 1.6 0
5.5 9.3 10.9
50 86 100
0.0105 Ib/Ib’
50%
22.7 Btu/Ib
Outdoor air
Exhaust air
Dry bulb
temperature
Absolute
humidity
Relative
humidity
Enthalpy
91.4°F
0.0203 Ib/Ib’
63%
36.4 Btu/Ib
Dry bulb temperature (°F)
Absolute humidity (Ib/Ib’)
Relative humidity (%)
Enthalpy (Btu/Ib)
Ventilation load (kW)
Ventilation load ratio (%)
Total energy recovered (kW)
* Calculated volume under conditions below.
Lossnay
Unit
Sensible HRV
Unit
Conventional
Ventilator Unit
Temperature
(Sensible Heat)
69 69 –
Enthalpy
(Total Heat)
50 14* –
iOA
iSA
iRA
36.4
29.6
22.7
tOA
91.4
tSA
82.7
tRA
78.8
R
S
AO
X
OA
0.0203
XSA
0.0159
XRA
0.0105
Absolute humidity (Ib/Ib’)
Room air condition in summer
Outdoor air condition
in summer
Supply air condition
of the Lossnay
Dry bulb temperature (°F)
Lossnay energy recovery
Ventilation load
Enthalpy
(Btu/Ib)
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