Condensation Control Experiences in a Building with Movable Sash.ppt

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1、1,Condensation Control Experiences in an“historic”Building with Movable Sash,2,What are your first thoughts when you consider ceiling radiant cooling panels?,$,Capacity,3,Requirement for Ceiling Radiant Cooling Panel Application,4,Site for the condensation control experiences:1900s Engineering Units

2、,5,3 of 12 36”X 96”single glazed movable sash serving the 40 x 80 lab,6,The Space as seen from inside,7,System Schematic,8,Size and extent of the major components in the system,9,Condensate control method,Maintain the panel inlet water temperature above the space DPT Condensate sensor is hard wired

3、into the power supply of the panel spring return control valve.,10,Field experience,student co-op?,The lab is used by a new(but just one)group of students per yearNear the beginning of the semester,I will address them on the systemand make just a few points.Leave the doors or windows open and radian

4、t cooling will be lostnot recommendedPiling things on top of the panels will cause the cooling to be reducednot recommendedSlicing the exterior duct insulation not a good idea,condensate may drip on you and your work.,11,Students response?,They never opened the windows or propped the doors open.The

5、condensation control was unchallengedAn instantaneous open door and window tests on a hot humid summer day thus ensued.,12,The data:,Windows opened,OA DPT,Room DPT,CHWT to panels,CHWT exceeds room DPT after 22 min,13,Extreme Condensation,after 8.5 hr.on a chilled panel intentionally held 14oF below

6、the space DPT,Isothermal,Fin,14,Control response:,Windows opened,Valve responds,Valve closed,Valve begins to modulate again to maintain CHWT at the space DPT,15,No Condensation on the panel after the test:,16,Very Slight Condensation on the chilled water supply pipe to the panel,17,What about the co

7、ntrols cost in a large movable sash building with many zones,Panel capacity control:CV,VT or VV,CTOur building used CV,VTA large multi zone building would likely use VV,CT to each zoneWhat happens then in large building if the windows go open?Monitor the window positionIf OA DPT exceeds space design

8、 close the modulating control valve.,18,Conclusion:,In the historic building with a large area of movable sash,condensation control was achieved easily,even when the space DPT was suddenly elevated by opening all of the doors and windows.The test was repeated many times,with the same outcome.The pas

9、sive fail safe sensor has yet to be activated under automatic control consequently no condensation problems,19,Oh,about capacity concerns,Rules of thumb:400 ft2/ton,or 30 Btu/hr-ft2Panel capacity,20-30 Btu/hr-ft2Conclusion,entire ceiling and perhaps some of the wall must be covered with panels.Whats

10、 the problem here?A large percentage of the design chiller load is OADOAS can take part of the space sensible and 100%of the space latent loadGenerally for low density occupancy spaces 50%ceiling need be in panelsVAV reality check:1 cfm/ft2 at 55F can do about 20 Btu/hr-ft2.,20,First cost must be hi

11、gher?,Reductions in first cost with DOAS/radiantLarge reduction in chiller size,and associated cooling towers,pumps etc.Ductwork is significantly reduced and VAV boxes eliminated.AHU is much smaller.More rentable space.Floor to floor dimensioncost savings in constructionAnd OP cost is reduced by 30 to 40 percent compared to VAV.,21,Finally,Terror resistance.The system would look schematically look like:,