Presentation on theme: "Chilled Beams TROX USA for Laboratory HVAC Applications"— Presentation transcript:
1 Chilled Beams TROX USA for Laboratory HVAC Applications • • • • • • • • • • •TROX USA
2 Chilled Ceilings and Beams • • • • • • • • • • •Chilled Ceilings and BeamsEarly 1980’s198019902005Chilled CeilingsBuildings well insulated for heatingAdvent of personal computersNeed to remove heat from spaceLimited space availableChilled ceiling systems were first developed in Scandinavia in the 1970’s. Summer design conditions for this region were quite moderate and allowed buildings to use natural ventilation, however, they were very well insulated due to rigorous winter design (heating) requirements. This (heating) was accomplished from low level locations.The advent of personal computers caused significant heat build up due to the heavy insulation. Some means of removing that heat was required and existing buildings had little or no overhead space to accommodate air ducts. Chilled ceilings offered an ideal solution as they took very little space and were very efficient in the removal of the space heat.
3 Principle of Operation Chilled Ceiling Panels• • • • • • • • • • •CWS = 59 to 62ºFCWR = 62 to 66ºF55% Convective45% RadiantChilled ceilings transfer derive some 55% of their heat transfer through radiation from heat sources within the space. The human body’s heat transfer is about 70% radiant, while heat transfer equipment within the space is only 10 to 20% radiant. These systems therefore focus on the conditioning of the occupants while isolating much of the heat generated by the equipment and lighting.Chilled ceilings (and beams) usually employ supply water temperatures between 60 and 62F, (well above normal space dew points) to assure that condensation does not occur. They are also fitted with dew point monitoring or moisture sensing controls as a safety net.
4 Radiant Effect on Occupants Chilled Ceiling Panels• • • • • • • • • • •77° F74.5° FDry Bulb Temp.Effective Radiant Temp.It is generally acknowledged that the space temperature can be maintained some 2 to 3F warmer when chilled ceilings are used due to their radiant effect which is not measured by normal space temperature sensors.Another feature of chilled ceilings is that they are essentially self-regulating in that their return water temperature is a direct function of the heat sources in the space. If little or no sources are present the water simply return s at a lower temperature without sub-cooling the space resulting in far greater individual comfort control.
5 Chilled Ceiling Systems • • • • • • • • • • •Chilled Ceiling SystemsImproved thermal comfortTypically combined with displacement ventilation systemLow turbulence intensity decreases draft risksChilled ceiling systems offer excellent thermal comfort and space ventilation as they are typically combined with a low turbulence displacement ventilation system.Chilled ceiling systems rely on a separate air distribution system to ventilate and dehumidify the space.
6 Chilled Ceiling Systems • • • • • • • • • • •Chilled Ceiling SystemsImproved thermal comfortMinimal space requirementsNo additional space required in ceiling cavityEasy to install in retrofit applicationsChilled ceilings require only 6 to 8 inches of ceiling cavity depth.Due to the space allocation for lights, sprinkler heads and supply/return grilles the ratio of active area to gross ceiling area is usually a maximum of 75%. Therefore, the chilled ceiling capacity is about 18 BTUH/FT2.
7 Chilled Ceiling Systems • • • • • • • • • • •Chilled Ceiling SystemsImproved thermal comfortMinimal space requirementsLow energy cooling solutionHigh heat transfer efficiencies using waterLow transport costsChilled ceiling systems also offered a low energy solution. The heat transfer capacity is four times that of air on a weight basis.As transport costs are primarily dependent on volume flow rate, the horsepower required to transport cooling energy by means of air is 25 to 30 times that required to transport the same amount of energy by means of water!
8 Flow Cross Section Ratio • • • • • • • • • • •Cooling Capacity Comparison1 : 327Flow Cross Section Ratio18“ x 18“Air Duct1“ diameter Water PipeThis slide illustrates the efficiency of a hydronic HVAC delivery system to that of an all air strategy.The same cooling can be delivered in a 1” diameter pipe as that delivered by an 18” x 18” air duct!
9 Chilled Ceiling Systems • • • • • • • • • • •Chilled Ceiling SystemsImproved thermal comfortMinimal space requirementsLow energy cooling solutionLimited Cooling Capacity25 BTUH/FT2 of active panel18 BTUH/FT2 of floor area (based on 70% active ceiling)Despite the energy savings inherent to the chilled ceiling solution, their applicability is often limited by their cooling capacity.Chilled water temperatures must be maintained at or above the space dew point temperature to avoid condensation. Under such conditions, the cooling capacity of the chilled ceiling panels is limited to about 25 BTUH/ft2 of active panel. As lights, sprinklers and other elements must also be mounted in the ceiling chilled ceiling elements can only comprise about 70% of the total ceiling. This translates to about 18 BTUH/ft2 sensible cooling per square foot of floor area. As such chilled ceilings are not feasible for conditioning perimeter areas with large sensible cooling requirements.
10 Chilled Ceilings and Beams • • • • • • • • • • •Chilled Ceilings and BeamsEarly 1990’s1980199020002005Chilled CeilingsPassive BeamsIncreased equipment loadsGreater occupant densitiesIn the 1980’s, chilled ceilings became popular throughout northern Europe. However, as the density of electronic equipment in offices increased it became obvious that chilled ceilings could not adequately cool perimeter spaces.In the early 1990’s passive chilled beams replaced chilled ceilings in these areas.Inadequate perimeter coolingTechnology revolution
11 • • • • • • • • • • •Passive Chilled BeamsCeiling manufacturers begin to sell high free area perforation panels competitivelyConvective coils replace ceiling panelsPassive beams rely on natural convection to transport warm air vertically to the beam location. The term “passive” is applied to beams which have no air connection, thus no mechanical means of inducing air through the coil.Passive beams may be either recessed or exposed. Exposed beams may be either surface mounted or pendant mounted.The cabinet encasing the beam can be customized to almost any appearance the architect might desire.
12 Passive Chilled Beams Concrete soffit • • • • • • • • • • • • • • • • • • • • • •Passive Chilled BeamsConcrete soffitChilled beams are also hydronic cooling solutions but their heat transfer is primarily (about 85%) convective.Instead of relying on a cool radiant surface, chilled beams circuit warm recirculated room air through a convective cooling coil.Warm air rising in the space pools at the lower level of the slab. This pooling causes the air to contact the chilled water coil. The cooled air then falls naturally into the space due to its negative buoyancy
13 Passive Chilled Beam Air Distribution Pattern • • • • • • • • • • • • • • • • • • • • • •Passive Chilled BeamAir Distribution PatternTypical air flow pattern for recessed and exposed passive chilled beams. This shows the ideal installation with under floor air distribution, high level distribution can be used but careful selection is required tp avoid there high level diffusers interfering with the passive chilled beams.
14 Passive Chilled Beams Exposed Beams Recessed Beams • • • • • • • • • • •Exposed BeamsPassive chilled beams can be either recessed (photo above left) or exposed (photo above right).When recessed beams are utilized, care must be taken to assure that the ceiling surface directly below and adjacent to the beam is of a sufficient free area to allow the air to pass through the surface. Usually this free area should be at least 50%.Recessed Beams
15 Passive Beam Components • • • • • • • • • • •Passive Beam ComponentsSupport RodsThis slide illustrates the mounting of an exposed beam.Heat Transfer CoilSeparation SkirtOptional Cabinet
16 H is between 4 and 12 in. Z should be ≥ 0.33B Passive Chilled BeamsInterior Area Installation• • • • • • • • • • •H is between 4 and 12 in Z should be ≥ 0.33BZHIn order to provide a sufficient path for the return and supply of the recirculated air, the recommendations in this slide should be observed.BB x 2
17 Passive Chilled Beams Perimeter Installation B B x 1.5 • • • • • • • • • • •When mounted adjacent to a perimeter wall, the inlet area of the beam may be reduced as the buoyancy of the rising air is typically greater.BB x 1.5
18 Passive Beam Installations • • • • • • • • • • •Passive Beam InstallationsThis project uses chilled ceilings for interior spaces while (recessed) passive beams are used in perimeter and conference areas.
19 Passive Beam Installations • • • • • • • • • • •Passive Beam InstallationsThis project is a credit card call center which uses exposed passive beams throughout. The space ventilation and dehumidification is affected by an underfloor air distribution system.
20 Chilled Ceilings and Beams • • • • • • • • • • •Chilled Ceilings and BeamsMid 1990’s1980199020002005Chilled CeilingsPassive BeamsActive BeamsLike chilled ceiling systems, passive beams required a separate air supply to dehumidify and ventilate the space.In the early 1980’s, contractors began to request that the air supply be integrated into the chilled beam so a separate air outlet was not required. This led to the development of active chilled beams.Continually increasing sensible loadsGreater occupant densitiesGypsum board tiles become commonCombine cooling and ventilation
21 Active Chilled Beams Concrete soffit Primary air supply • • • • • • • • • • •Active Chilled BeamsConcrete soffitPrimary air supplySuspended CeilingActive chilled beams discharge primary air through induction nozzles to induce room air over an integral heat transfer coil. Here it is reconditioned then mixed with the primary air stream for reintroduction to the space.The induction of the air through the coil significantly enhances the cooling capacity of the unit.
22 Active Chilled Beam Air Distribution Pattern • • • • • • • • • • • • • • • • • • • • • •Active Chilled BeamAir Distribution PatternThe resultant space air diffusion is similar to that affected by a ceiling slot diffuser, that is a fully mixed system.
23 Active Chilled Beams Sensible loads up to 70 BTUH/FT2 • • • • • • • • • • •Active Chilled BeamsSensible loads up to 70 BTUH/FT2Primary air delivered at conventional (50 to 55ºF) temperatures at or near minimum ventilation flow rateCan be used with fiberglass ceiling tiles or without any ceilingActive beams have significantly higher cooling capacities than either passive beams or radiant ceilings.Due to their induction capabilities, active beams may also incorporate heating coils.TROX DID series ceiling induction diffusers are examples of active beams.
24 Active Beam Installation • • • • • • • • • • •Active Beam InstallationThis slide illustrates an installation of TROX DID 600 active beams in a trading area where sensible loads up to 100 BTUH/ft2 exist.
25 Active Beam Installation • • • • • • • • • • •Active Beam InstallationThis slide illustrates another view of the previous installation of TROX DID 600 active beams.
26 Comparative Energy Costs • • • • • • • • • • •Comparative Energy Costs$1.50Cost to chill waterCost to transport waterCost to cool airCost to transport airLEGEND$1.00$0.80Typical Annual HVAC Energy Cost ($/FT2)$0.48This slide illustrates the relative energy consumption of a hydronic cooling system (with either natural or forced ventilation) versus a VAV (all air) system.Chilled Ceiling with Natural VentilationPassive Beam with Displacement VentilationActive Chilled BeamVAV System
27 Active Chilled Beams For Laboratory HVAC Applications • • • • • • • • • • •199020002005Chilled CeilingsPassive BeamsActive BeamsRecently, several major engineering firms involved in laboratory design began to research the advantages of chilled beams when applied to laboratory spaces.Active Beams for Lab HVAC
28 Laboratory Design Issues • • • • • • • • • • •Laboratory Design IssuesSpace sensible heat gains of 60 to 70 BTUH/FT2Space ventilation requirements of 6 to 8 ACH-1Laboratories where chemicals and gases are present require 100% OAAll air systems require 18 to 22 ACH-1 to satisfy sensible loadAlthough the required number of air changes in make up air driven laboratories are often high due to a high density of fume hoods, most laboratories are not so densely populated.Many general use laboratories have very high sensible heat gains due to a large amount of electronic equipment and thermal processes. Sensible gains of 65 to 70 BTUH/ft2 are not uncommon. The ventilation rates for these laboratories are mandated at 6 to 8 ACH-1 but all of the ventilation air must be outside air due to the use of gases and chemicals within the space.In order to condition the space, all air systems (100% outside air) must supply 18 to 22 ACH-1, far more than the mandated ventilation rate. All of this air must be conditioned to 55˚F at the air handler before being delivered to the space.
29 Active Chilled Beams in a General Use Laboratory • • • • • • • • • • • • • • • • • • • • • •Active Chilled Beamsin a General Use LaboratorySensible Heat Gain = 65 BTUH/FT2Ventilation Rate = 8 ACH-18’ Active Beams12 CFM/LF44 ft.22 ft.TThis slide illustrates a laboratory with TROX DID 600 series chilled beams. The space sensible gain is 65 BTUH/ft2 and the mandated ventilation rate is 8 ACH-1.The piping and ductwork connections are also illustrated. Note that the installation requires a single space thermostat and chilled water valve and two constant air volume regulators.
30 Active Chilled Beams in a General Use Laboratory • • • • • • • • • • • • • • • • • • • • • •Active Chilled Beamsin a General Use LaboratorySensible Heat Gain = 65 BTUH/FT2All Air Solution = 18 ACH-1Ventilation Rate = 8 ACH-1Air-Water Solution = 8 ACH-18’ Active Beams12 CFM/LF44 ft.22 ft.12’ o.c.As the chilled beams are capable of removing about 60% of the space heat by means of their chilled water coil, the system is capable of conditioning the laboratory with an airflow rate equal to the specified minimum ventilation rate (8 ACH-1). In this case, only 45% of the total space sensible heat gain (5.25 tons) is removed by air while the remainder is removed by the chilled water coil within the beam.An all air system would have required an airflow rate of 18ACH-1 to accomplish the required space conditioning!
31 Case Study Laboratory Design for Pharmaceutical Company • • • • • • • • • • •Case StudyLaboratory Design for Pharmaceutical CompanyLocation: St. Louis, MOOutdoor Design Conditions: 94DB/75WBLaboratory Space: 54,000 FT2Minimum Ventilation Rate: 8 ACH-1Space Sensible Heat Gain: 72 BTUH/FT2A major laboratory designer recently compared the use of active chilled beams to an all air (variable air volume system) for a pharmaceutical laboratory in St. Louis, MO.
32 Sensible Cooling Chiller System • • • • • • • • • • •Equipment RequirementsEquipmentConventional VAVActive Chilled BeamAir Handling Units180,000 CFM72,000 CFMCooling1,477 Tons587 TonsHeating21,617 lbs/hr8,588 lbs/hrDuct Distribution285,493 lbs.214,120 lbs.Control Points800Chilled Beams1,056Piping Distribution4,200 LFSensible Cooling Chiller System200 TonsThe chilled beam system allowed the airflow requirements to be reduced to 8 ACH-1 versus 20 ACH-1 required at design conditions for the VAV system. The air handler’s design refrigeration capacity was also reduced proportionally since a dedicated chiller was planned for the chilled water supply to the beams. The refrigeration capacity of the air handling unit for the VAV system was designed to handle the space load (332 tons) and the load (1145 tons) associated with conditioning the outside air(180,000 CFM) to 55˚F. The air handling unit for the chilled beam system was tasked with 40% of the space load (or 133 tons) plus the load (454 tons) of conditioning the outside air to 55˚F.The reduced airflow requirements of the chilled beams also resulted in a significant reduction in ductwork sizes. Approximately 33% savings in sheet metal was realized.The dedicated chiller was sized to handle 60% of the total space load (332 tons). It should also be noted that the operating efficiency of this chiller was enhanced some 40% due to the higher temperatures (50/56) of the supply and return chilled water!
33 Cooling Energy Requirement • • • • • • • • • • •Cooling Energy RequirementExample1000 FT2 LAB (10’ CLGS)TSHG = 70 BTUH/FT2VENTILATION = 8 ACH-18.07.06.0TOTAL ENERGY, ALL AIR SOLUTION5.04.0TOTAL COOLING ENERGY (kW)TOTAL ENERGY, AIR-WATER SOLUTION3.045%2.0The annual cooling energy savings of the chilled beams for this example averaged 45% less than that for the VAV system.Chilled beam air side cooling1.0Chilled beam water side cooling60657075808590OUTDOOR TEMPERATURE (°F)
34 Overall 35% Reduction in Energy Costs Energy ComparisonsCase Study, 93/75F Outdoor Design• • • • • • • • • • •Active Chilled Beam (Parallel Sensible Cooling)Reduced fan power – 32 % from Base VAVReduced cooling energy – 46 % from Base VAVReduced ductwork sizes – ACPH to 6-8 ACH-1Higher Pumping energy – 15% - Offset by other savingsHigher cooling system efficienciesOverall 35% Reduction in Energy CostsThe designer also estimated the fan energy use to be 32% less than that of the VAV system. The pumping energy was slightly higher but was a relatively insignificant part of the total energy usage.In summary, the designer identified the overall energy savings to be 35%.
35 Overall 25% Reduction in Energy Costs Energy ComparisonsModified for 80/64F Outdoor Design• • • • • • • • • • •Active Chilled Beam (Parallel Sensible Cooling)Reduced fan power – 32 % from Base VAVReduced cooling energy – 30 % from Base VAVReduced ductwork sizes – ACPH to 6-8 ACH-1Higher Pumping energy – 15% - Offset by other savingsHigher cooling system efficienciesOverall 25% Reduction in Energy CostsThe application of such a system in a mild climate (80/64F design), would result in a smaller (but still significant) cooling energy savings.In total, the overall energy savings would still be 25%.
36 Sensible Cooling Chiller System • • • • • • • • • • •Equipment RequirementsEquipmentConventional VAVActive Chilled BeamsAir Handling Units$2,264,335$899,610Cooling$1,627,799$646,717Heating$244,267$97,046Duct Distribution$1,481,709$1,111,282Control Points$1,200,000$1,140,000Chilled Beams$1,652,984Piping Distribution$266,444Sensible Cooling Chiller System$265,373Totals$6,818,109$6,079,456The equipment costs for the chilled beam system were also found to be less than that of a VAV system. Although the beams (including the chiller and piping system) themselves were quite expensive ($6,500 per ton of space cooling), the savings in the air handling unit and refrigeration plant far exceeded this cost.The overall cost of the chilled beam solution was about 10% below that of a VAV (all air) solution.
37 Chilled Ceilings and Beams • • • • • • • • • • •Chilled Ceilings and BeamsTROX USA
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