1、Air Flow Analysis in Pharmaceutical “Clean Rooms”,Patrick Phelps ( Flowsolve ) and Richard Rowe ( Clean Room Construction Ltd ),IPUC 8 - Luxembourg - May 2000,Air Flow Analysis in Pharmaceutical “Clean Rooms”,Industrial Context Health and Safety Issues Application to an Existing Room Application to
2、New Ventilation Designs Conclusions Experimental Verification,“Clean Rooms”,Areas concerned with the preparation, processing and packaging of pharmaceutical productsStrict codes of practice employed to eradicate risk of product contamination,“Clean Rooms”,Personnel access controlled 2-layer sterile
3、over-clothing Equipment sterilised before entry Strict cleansing procedures Particular attention to ventilation,Ventilation of “Clean Rooms”,Design and performance of air supply, filtration, and extraction arrangements must meet exacting standardsPositive pressure areas Use of Laminar Flow Units (LF
4、Us),“ Laminar Flow Units ”,Devices which deliver a controlled down-draught of re-filtered air over sensitive regions preparation areasprocessing areas packaging areas storage areas,Air Flow Analysis in Pharmaceutical “Clean Rooms”,CFD Application to Air Flow Analysis in “Clean Rooms”,ContextUpgrade
5、of ventilation system in a suite of “ clean rooms” at a UK pharmaceutical company,CFD Application to Air Flow Analysis in “Clean Rooms”,ObjectiveUse CFD to ensure exacting requirementscan be met , following installation of anumber of LFUs .,CFD Application to Air Flow Analysis in “Clean Rooms”,Works
6、cope3 rooms selected as representative examples of areas being upgraded Room 30 Room 23 Room 42,Modelling Considerations - 1,Irregular shaped domains Internal Obstructions to flow Cartesian grid employed K-e (Chen) turbulence model used Buoyancy important in transient (otherwise assume isothermal),M
7、odelling Considerations - 2,Dependent variables solved pressure, p lateral velocity component, U vertical velocity component, V Longitudinal velocity component, W Turbulence kinetic energy, k Turbulence energy dissipation rate, e residence time parameter, tres (temperature, T (for transient),Modelli
8、ng Considerations - 3,Boundary Conditions Air supply ducts prescribed sources of mass, momentum, turbulence and residence time Air Extract ducts specified fixed-pressure outlet sinks LFUs inlets and outlets specified as above,Representation of LFUs,Air flow in individual units not solved treated as
9、internal blockages in domain air discharged from base at prescribed rate matching intake from front face interactive updating of discharge residence time constant internal residence time assumed,Room 30,Small room - 4.94 x 5.94 x 2.92 m. Used for processing, filling and packaging of products Contain
10、s central plinth with filling-machine enclosure above Conveyor-linked trays outboard of enclosure, for containers & finished goods,Room 30 - “ Before ”,Room 30 Simulations,Steady flow patterns “ before ” LFUs in enclosure only Steady flow patterns “ after ” following fitment of 10 new LFUs 75,000 no
11、de 3-D model Distribution : 50 x 30 x 50,Room 30 - “ After ”,Room 30 Simulations,Objectives Check for “dead zones” ensure ventilation criteria met Criteria 25 Air changes per hour (residence time 144 seconds),Room 30 - Sectional Planes,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Ro
12、om 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ After ”,Room 30 - “ Before ”,Room 30 - “ Aft
13、er ”,Room 30 - “ Before ”,Room 30 - “ After ”,Complex flow paths between inlet and outlet Pattern complicated by LFU intake extraction flows air has to pass around central plinth and filling-machine enclosure air in near-side passage has to “run gauntlet” of LFUs,Room 30 Ventilation Summary (after r
14、efurbishment),Outflow-weighted residence time of 121 seconds meets client criterion “near” extract air considerably “older” than “far” extract air some “dead zones” still apparent evidence of entrainment into more than one unit,Room 30 Ventilation Summary (after refurbishment),“ Dead Zones ” - befor
15、e,“ Dead Zones ” - after,LFU intake times - 1,LFU Unit intake times - 2,LFU Unit intake times - 3,Units D1, D2, B2, C2, A1 receive considerably fresher air than their neighbours A2-A4, B2 and C1 Air entering A4 is 2.2 times older than that entering D1 Air leaving A4 exceeds air-change criterion en route to outlet,Conclusions,“Residence time” analysis concept adds considerable value to vector and contour plots in assessment of complex ventilation flows.,
