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
●
Heat recovery efficiency table (%)
(at 50Hz, high speed) (For summer)
●
Ventilation rate: 500 m
3
/h
(specific gravity of air
ρ
= 1.2 kg/m
3
)
22
CHAPTER 3 ● General Technical Considerations
Lossnay Sensible HRV
Conventional
ventilator
Temperature
77 77 –
(sensible heat)
Enthalpy
61.5 18.2* –
(total heat)
●
Lossnay
(Supply air diffuser temperature)
tSA = 33°C – (33°C – 26°C) × 0.77 = 27.6°C
(Supply air diffuser enthalpy)
iSA = 85.0 – (85.0 – 53.2) × 0.615 = 65.4 kJ/kg
Heat recovered
(85.0 – 65.4) × 1.2 × 500 = 11,760 kJ/h = 3.3 kW
Outdoor air load
(65.4 – 53.2) × 1.2 × 500 = 7,320 kJ/h = 2.0 kW
●
Sensible HRV
(Supply air diffuser temperature)
tSA = 33°C – (33°C – 26°C) × 0.77 = 27.6°C
(Supply air diffuser enthalpy)
iSA
=
79.2 kJ/kg (from psychrometric chart)
Heat recovered
(85.0 – 79.2) × 1.2 × 500 = 3,480 kJ/kg = 1.0kW
Outdoor air load
(79.2 – 53.2) × 1.2 × 500 = 15,600 kJ/H = 4.3 kW
[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
Calculation example Summer conditions
Absolute humidity (kg/kg’)
Room air condition in summer
Outdoor air condition
in summer
Supply air condition
of the Lossnay
Dry bulb temperature (°C)
Lossnay heat recovery
Outdoor air load
Enthalpy
(kJ/kg)
Supply air
Room air
Air
conditioner
Lossnay Sensible HRV
Conventional
ventilator
Dry bulb
temperature
Absolute
humidity
Relative
humidity
Enthalpy
26°C
27.6 27.6 33
14.8 20.3 20.3
63 86 63
65.4 79.2 85.0
3.3 1.0 0
2.0 4.3 5.3
38.5 82 100
10.5 g/kg’
50%
53.2 kJ/kg
Outdoor air
Exhaust air
Dry bulb
temperature
Absolute
humidity
Relative
humidity
Enthalpy
33°C
20.3 g/kg’
63%
85.0 kJ/kg
Dry bulb temperature (°C)
Absolute humidity (g/kg’)
Relative humidity (%)
Enthalpy (kJ/kg)
Outdoor air load (kW)
Outdoor air load ratio (%)
Total heat recovered (kW)
* Calculated volume under below conditions.
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