Optimized Local Exhaust Solution for Working Place

Transcription

1 Optimized Local Exhaust Solution for Working Place Case Study Dr. Daniel Gubler, AFC Air Flow Consulting AG Ventilation 2006 Conference Chicago, May 2006 AFC Air Flow Consulting AG Weinbergstrasse 72 CH-8006 Zürich T F info@afc.ch

2 Content Situation & Problem Description Ventilation Strategies CFD Modelling CFD Results Implementation Verification Conclusions

3 Workplace for Test Bench 3 cabins max. 6 workplaces for testing operations Work process produces CO Current: Mixing ventilation Air supply

4 Problems with Existing Solution Ventilation strategy with blowing and mixing leads to: Low capture efficiency Draft due to high air velocities Existing installation is aged, the mechanics of the supply air arms are not working properly Goal: Development of an optimized ventilation strategy Consider the working process and the capture efficiency! Achieve target levels

5 Basic Ventilation Strategies Mixing (High momentum) Displacement Piston Local Exhaust Contaminant Source High Concentration

6 Basic Concepts Blowing & Mixing (Current solution) Large exhaust Hood Local Exhaust Hood Customized exhaust hood Standard Product

7 Basic Concepts Mixing Ventilation Push Pull Ventilation Push Pull & Local Exhaust Hood Standard Product

8 Basic Concepts Push Pull Ventilation with high momentum

9 CFD Simulations 4 Basic Concepts evaluated for CFD Simulations V0: Blowing & mixing (Current) Reference Case V1: Local exhaust hood V2: Mixing ventilation V3: Push pull with wall exhaust (Low Momentum)

10 CFD Simulations V0: Blowing & mixing (Current) Airchange: 2 000m3/h Supply: 450m3/h CO Concentration (Steady State)

11 CFD Simulations V1: Local exhaust hood Room Airchange: 550/h Local Exhaust: m3/h CO Concentration (1 200m3/h)

12 CFD Simulations V2: Mixing Ventilation Airchange: m3/h Outlet Supply CO Concentration (3 000m3/h)

13 CFD Simulations V3: Push pull with wall exhaust (Low Momentum) Airchange: ca m3/h LF Device: 350 m3/h Outlet Supply CO Concentration

14 Conclusion 1 Mixing ventilation cannot achieve the target levels even at a very high air change rate Using blowing arms, the target levels are achieved but: Arm needs to be adjusted properly Comfort problems Huge air change rates Local exhaust arms give good results but have to be adjusted properly Push pull gives good results as well Push pull installation is too big! (Customer opinion) Optimization for Local Exhaust Hood

15 Optimization Local Exhaust Hood Variation of exhaust hood positions

16 Optimization Local Exhaust Hood Variation of exhaust hood design

17 Optimization Local Exhaust Hood All cases identical flow rates

18 Visualization

19 Capture Area Results for capture area simulation

20 Implementation

21 Smoke Test Off On On

22 CO Measurement 40cm CO Measurement in breathing zone

23 CO Measurement 40cm CO Measurement in breathing zone

24 CO Measurement 40cm CO Measurement in breathing zone

25 Conclusion 2 3D-CAD Models used for concept evaluation Operators involved in design process increased acceptance! Best ventilation strategy found by CFD Target levels achieved by CFD Optimization At breathing zone, reduction of CO concentration by a factor of >>100 Required air flow rate reduced to < 25% Reduced installation & running cost Cost of CFD simulations << Savings (Installation & Operation)

26 Questions Dr. Daniel Gubler, AFC Air Flow Consulting AG Ventilation 2006 Conference Chicago, May 2006 AFC Air Flow Consulting AG Weinbergstrasse 72 CH-8006 Zürich T F info@afc.ch