# Calculation method of exhaust air volume and fresh air volume

2021-01-12 09:19:03 16

Calculation method of fresh air volume I

According to the number of people that can be accommodated in the room: (applicable to divided, multiple small rooms)

Qm=N ×qm

N-number of people; (the number of people per unit area can be calculated according to the plot ratio of unit area, i.e. number of people = area × 0.8)

QM - fresh air volume, unit: ㎥ / h;

QM - the amount of fresh air required by each person (generally 30-50 ㎥ / person).

Calculation method of fresh air volume II

According to the percentage of fresh air in total supply air:

Q fresh air volume = q total air volume × 10-30% (suitable for large area)

The fresh air volume is 10% to 30% of the total supply air volume

Note: the total supply air volume is the sum of the supply air volume of multiple air conditioners carrying the cooling (heating) load of the air conditioning area.

Exhaust volume calculation

Exhaust volume calculation method 1

According to the number of air changes in the room: (applicable to divided, multiple small rooms)

Q exhaust volume = n × V

N - room ventilation rate

V - room volume

Exhaust volume calculation method 2 (applicable to large area)

80-90% of the new air volume is taken as the exhaust air volume

Q exhaust air volume = q fresh air volume × 80-90%

Case

1. The ceiling of a KTV entertainment place is 2.8m high, with 50 rooms, each with an area of 28 m2. Calculate the total new and exhaust air volume, and select the corresponding new and exhaust fans. KTV exhaust volume

The calculation is as follows:

Qxin = 20 × 50 × 50m3 / h = 50000m3 / h

Q row = 28 × 2.8 × 50 × 15m3 / h = 58800m3 / h

5 sets of bfp-10d for fresh air fan

The exhaust fans are 6 sets of 10000m3 / h fans.

2. The total air conditioning area of a shopping mall is 10000 m2, and the unit load is 150W / m2. Calculate the total new and exhaust air volume, and select the corresponding new and exhaust fans. Calculation of fresh air volume in shopping malls

Use the second calculation method

1. Calculate the cooling load of the whole shopping mall and select the VAV air conditioning unit;

2. Calculate the total supply air volume from the selected VAV air conditioning unit;

3. Calculate the new air volume according to the total air supply volume;

4. Calculate the exhaust volume according to the percentage of exhaust and fresh air. View My Stats