【 Weak current College 】 on positive pressure air study on calculation method of analysis (2)

3.2.1 most disadvantageous combination front chamber pressure air Q-in-front

Combined with the most negative before the Chamber pressure air, occurred in a door is closed, the second door m layer away.

A) through the air pathway of elevator door

-Arrow in the in-line between the square brackets as parallel relations; N — the number of elevators; n — the number of system floors; m-number of layers at the door, when n < 20 m = 2 when, when n ≥ 20, m = 3; Ad-elevator door area; Ap — the elevator shaft roof vent area; F2 — second door area (door width × high); kf-air partition coefficients.

B) elevator shaft combined circulation area of Az (1)

Kf=Ad/（A1+Ad）

-Aa (1) — a comprehensive series of branch, the circulation area; Az m2 (1)-condition 1 of the elevator shaft combined circulation area, m2; A1 — a door door product, m2; other symbol ibid.

C) each door and front room air

Q clearance = L2 + L3 (1)-L1 (1), m/s

L1（1）=α×A1×（P1-P2）1/2L2=α×A2×P21/2

L3（1）=α×Az（1）×P21/2/（n-m）

Α = 1.03375 in-; L2 — through the second door closes a door, from the combined front room leak into the aisle of the air leakage rate, m3/s; L3 (1) — through the elevator door front door combination from leaked to the elevator shaft of the air leakage rate, m3/s; L1 (1) — through a door door leakage from smoke to the stairs of the door and front room air leakage rate, m3/s; A1 — a door in the floor area, m2; A2 — second door of the door area, m2; P1 — smoke more pressure, the staircase; P2 — combined with 50Pa room top pressure, 25Pa; n-positive pressure ventilation system burden storey; other symbol ibid.

D) each door and front room air

Q open = Q21-L11-L31 (1), m/s

Q21=W1×F2W1=0.5m/sL11=α×A1×（P1-Pmin）1/2

-Q21 — through the second door open, door and front room from flowing into the aisle of the air flow, m3/s; L11 — through a door at the door, from the top pressure 50Pa stairways spilling to smoke a minimum residual pressure of the front door and Pmin room air leakage rate, m3/s; L31 (1) — through the elevator door, elevator shaft, from the top pressure before the closing share 25Pa leaked to maintain minimum residual pressure before the door and Pmin room air leakage rate, m3/s; Pmin — minimum residual pressure, 6Pa; other symbol ibid.

E) combined with the most negative before the Chamber pressure air

Q-ago = m×Q open + (n-m) × Q, m/s

3.2.2 smoke stairs most negative positive pressure air Q stairs

Smoke stairs most negative positive pressure air, takes place in the m-a door, when the second door is open.

Lt1（1）=α×A1×（P2-Pmin）1/2Qt1=W2×F1W2=0.7m/s

Q stairs = m×Qt1-(n-m) × Lt1 (1)

-Lt1 (1) — through a door at the door, the door of the residual pressure 25Pa leaked prior to the combination to maintain minimum residual pressure in the smoke of Pmin stairways of air leakage rate, m3/s; Qt1 — by the door and a door in front of room air flow, m3/s; other symbol ibid.

3.2.3 corresponding table 3 serial number 2 ~ 6, lack of space not much here, their calculation methods correspond to columns in the table 4 serial number 2 to 6. When no elevator N = 0, that is, as before. The ordinal number corresponding to table 4-1 ~ 6 smoke staircase and vestibule, combined with the most negative before the Chamber pressure air calculation method, the author series computer calculation procedure, its partial calculation results (left safety factor 1.25, flow units converted to m3/h) corresponds to the column in the table of eight numbers 1 to 6.

4, natural smoke exhaust smoke stairs, staircase, combined with the most negative before the Chamber pressure air calculation method

Natural smoke exhaust smoke stairs, staircase, combined with the most negative before the Chamber pressure air calculation methods listed in table 5. Part of the calculation results are listed in table 9.

5, smoke staircase (front rooms are not air) most negative positive pressure air calculation method

Smoke staircase (front rooms are not air) most negative positive pressure air calculation methods listed in table 6. Part of the calculation results are listed in table 10. This article in smoke stairs most adverse positive pressure air calculations, will close the first indoor residual pressure from 0Pa, such a positive pressure air calculated values more secure.

6, fire the elevator room's most negative positive pressure air calculation method

The elevator room fire most negative positive pressure air calculation methods listed in table 7. Part of the calculation results are listed in table 11.

7. closing remarks

Comprehensive table 8 ~ 11 of positive pressure air calculated value, you must open the door of the high-rise building different conditions, number of doors, wind speed, doors and door of geometric dimensions and the quantity, trapped in an elevator for serious engineering calculations.

Choose a) seriously high-rise building positive pressure air formula and calculation is very necessary. You cannot simply apply a formula, also deal with the effects of positive pressure air to conduct a comprehensive analysis of the factors, the selection of the correct calculation. In calculating the amount of air leaking door, opening the door of the air flow through the appropriate use of the doctrine ofOn the recommendation of the formula (1), (2), and to properly calculate the air pathway analysis for flow, integrated flow area.

B) tall buildings smoke staircase and vestibule, plus room and fire before the elevator room of positive pressure air, fire door dimensions, front room lift amount under the same conditions, by the door of the wind, the door width Max.

C) tall buildings smoke staircase and vestibule, plus room and fire before the elevator room of positive pressure air does not meet the regulations of section 8.3.2 requirement should not only be found on from construction quality, but also from a positive pressure air calculation for analysis.

D) in a positive pressure air introduced when calculating minimum residual pressure concept, you can make the calculation result is closer to the project's actual situation.

Reference documents

1GB50045 — 95 tall buildings design fire protection standard (2001 Edition)

2 Chen Tong Bao. Smoke control of high-rise building and former room stairwell pressurization calculation formula and the application. Ventilation and air conditioning. 1998, 28 (5): 9-12

3 duhong. Positive pressure air of a calculation method. Ventilation and air conditioning. 1996, 26 (3): 30-34

4 King yin. Tall buildings pressurization smoke control design discussion on several issues. Ventilation and air conditioning. 1994, 24 (3): 32-35

5 Chai huijuan, etc. HVAC design of high-rise building: Chapter III smoke control system design and specification for abroad. Beijing: China industry press 1995