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CHAPTER 3
General Technical Considerations
1. Lossnay Heat Recovery Effect
1.1 Comparison of outdoor air load of various ventilators
Examples of formulas to compare the heat recovered and outdoor air load when ventilating with the Lossnay (total heat
recovery unit), sensible heat recovery ventilation (sensible HRV) and conventional ventilators are shown below.
(1) Cooling during summer
Conditions
Model LGH-50R type
(at 50Hz, high speed)
Ventilation rate: 500 m
(specific gravity of air ρ = 1.2 kg/m
Dry bulb temperature
Absolute humidity
Relative humidity
Enthalpy
Total heat recovered
Outdoor air load
Outdoor air load ratio
Dry bulb
Air
temperature
conditioner
Absolute
humidity
Relative
humidity
Enthalpy
Calculation example
Lossnay
(Supply air diffuser temperature) t
(Supply air diffuser enthalpy)
Heat recovered
Outdoor air load
Sensible HRV
(Supply air diffuser temperature) t
(Supply air diffuser enthalpy)
Heat recovered
Outdoor air load
[Calculated enthulpy recovery efficiency 3,480 ÷ (3,480 + 15,600) × 100 = 18.2]
Conventional ventilator
If a conventional ventilator is used, the heat recovered will be 0 as the supply air
diffuser is equal to the outdoor air.
The outdoor air load is:
(85.0 – 53.2) × 1.2 × 500 = 19,080 kJ/h = 5.3 kW
22
3
/h
3
)
Supply air
Lossnay
(°C)
27.6
(g/kg')
14.8
(%)
63
(kJ/kg)
65.4
(kW)
3.3
(kW)
2.0
(%)
38.5
Room air
26°C
10.5 g/kg'
50%
53.2 kJ/kg
= 33°C – (33°C – 26°C) × 0.77 = 27.6°C
SA
i
= 85.0 – (85.0 – 53.2) × 0.615 = 65.4 kJ/kg
SA
(85.0 – 65.4) × 1.2 × 500 = 11,760 kJ/h = 3.3 kW
(65.4 – 53.2) × 1.2 × 500 = 7,320 kJ/h = 2.0 kW
= 33°C – (33°C – 26°C) × 0.77 = 27.6°C
SA
i
= 79.2 kJ/kg (from psychrometric chart)
SA
(85.0 – 79.2) × 1.2 × 500 = 3,480 kJ/kg = 1.0kW
(79.2 – 53.2) × 1.2 × 500 = 15,600 kJ/H = 4.3 kW
Heat recovery efficiency table (%)
(For summer)
Lossnay
Temperature
(sensible heat)
Enthalpy
(total heat)
* Calculated volume under below conditions.
Conventional
Sensible HRV
ventilator
27.6
33
20.3
20.3
86
63
79.2
85.0
1.0
0
4.3
5.3
82
100
Sensible HRV
77
77
61.5
18.2*
Dry bulb
temperature
Absolute
humidity
Relative
humidity
Enthalpy
Summer conditions
85.0
i
OA
65.4
i
SA
53.2
i
RA
Dry bulb temperature (°C)
Conventional
ventilator
–
–
Exhaust air
Outdoor air
33°C
20.3 g/kg'
63%
85.0 kJ/kg
A
O
X
OA
0.0203
S
X
SA
0.0148
R
X
RA
0.0105
t
t
t
RA
SA
OA
26
27.6
33
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