建筑给排水_外文文献翻译1

本科毕业设计

外文文献及译文

文献、资料题目：Sealed building drainage

and vent systems

文献、资料来源：国道数据库

文献、资料发表（出版）日期：2005.9.12院（部）：市政与环境工程学院

专业：给水排水工程

班级：

姓名：

学号：

指导教师：

翻译日期： 2012.06

外文文献：

Sealed building drainage and vent systems

—an application of active air pressure transient control and suppression Abstract

The introduction of sealed building drainage and vent systems is considered a viable proposition for complex buildings due to the use of active pressure transient control and suppression in the form of air admittance valves and positive air pressure attenuators coupled with the interconnection of the network's vertical stacks.

This paper presents a simulation based on a four-stack network that illustrates flow mechanisms within the pipework following both appliance discharge generated, and sewer imposed, transients. This simulation identifies the role of the active air pressure control devices in maintaining system pressures at levels that do not deplete trap seals.

Further simulation exercises would be necessary to provide proof of concept, and it would be advantageous to parallel these with laboratory, and possibly site, trials for validation purposes. Despite this caution the initial results are highly encouraging and are sufficient to confirm the potential to provide definite benefits in terms of enhanced system security as well as increased reliability and reduced installation and material costs.

Keywords: Active control; Trap retention; Transient propagation

Nomenclature

C+-——characteristic equations

c——wave speed, m/s

D——branch or stack diameter, m

f——friction factor, UK definition via Darcy Δh=4fLu2/2Dg

g——acceleration due to gravity, m/s2

K——loss coefficient

L——pipe length, m

p——air pressure, N/m2

t——time, s

u——mean air velocity, m/s

x——distance, m

γ——ratio specific heats

Δh——head loss, m

Δp——pressure difference, N/m2

Δt——time step, s

Δx——internodal length, m

ρ——density, kg/m3

Article Outline

Nomenclature

1. Introduction—air pressure transient control and suppression

2. Mathematical basis for the simulation of transient propagation in multi-stack building drainage networks

3. Role of diversity in system operation

4. Simulation of the operation of a multi-stack sealed building drainage and vent system

5. Simulation sign conventions

6. Water discharge to the network

7. Surcharge at base of stack 1

8. Sewer imposed transients

9. Trap seal oscillation and retention

10. Conclusion—viability of a sealed building drainage and vent system

1.Air pressure transients generated within building drainage and vent systems as a natural consequence of system operation may be responsible for trap seal depletion and cross contamination of habitable space [1]. Traditional modes of trap seal protection, based on the Victorian engineer's obsession with odour exclusion [2], [3] and [4], depend predominantly on passive solutions where reliance is placed on cross connections and vertical stacks vented to atmosphere [5] and [6]. This approach, while both proven and traditional, has inherent weaknesses, including the remoteness of the vent terminations [7], leading to delays in the arrival of relieving reflections, and the multiplicity of open roof level stack terminations inherent within complex buildings. The complexity of the vent system required also has significant cost and space implications [8].

The development of air admittance valves (AAVs) over the past two decades provides the designer with a means of alleviating negative transients generated as random appliance discharges contribute to the time dependent water-flow conditions within the system. AAVs represent an active control solution as they respond directly to the local pressure conditions, opening as pressure