1、714 ASHRAE TransactionsThis paper is based on findings resulting from ASHRAE Research Project RP-1480.ABSTRACTThe objective of ASHRAE 1480-RP was to expand thedatabase for the capture and containment requirements ofisland canopy hoods. The study investigated the performanceof four 10 ft long (3.05 m
2、) island canopy hood configurationsover standardized cooking equipment lines including: (1) a 4 ft(1.22 m) deep rear filter single-island, (2) a 6 ft (1.83 m) deepV-bank single-island, (3) an 8 ft (2.44 m) deep double-island,and (4) a 10 ft (3.05 m) deep double-island hood. More than 200configuratio
3、ns were tested, including the evaluation of sidepanels, replacement air strategies, and replacement air temper-atures. This paper provides an overview of the capture andcontainment performance for the two single-island canopyhoods. It was found that large appliance overhangs and well-balanced, low-v
4、elocity replacement air were critical for theoptimization of single-island canopy hood performance.INTRODUCTIONIsland canopy hoods, particularly single-island style,have become popular in foodservice operations that featuredisplay cooking. However, for a given line of appliances,industry experience
5、has shown that a single-island canopyhood requires a significantly higher exhaust rate than a wall-mounted canopy hood (FCSI 2006). While the databaseregarding the capture and containment performance of wall-mounted canopy hoods has become more robust (ASHRAE2003a) (PG&E 2010), the ASHRAE technical
6、committee onkitchen ventilation (TC 5.10) identified a lack of independentdata for island canopy hoods. The results from this TC 5.10sponsored research will be used to enhance kitchen ventilationsystem design guidelines in the Kitchen Ventilation chapter ofASHRAE HandbookHVAC Applications (ASHRAE 20
7、03b)and to revise the ASHRAE Standard 154 Ventilation forCommercial Cooking Operations (ASHRAE 2005). Two hundred and sixteen conditions were tested withinthe scope of this research project, of which one hundred andfifty eight were for the single-island hood configurations. Theprimary objectives of
8、this project were: (1) quantify thecapture and containment performance of four different islandcanopy hoods using ASTM F1704-05, Standard Test Methodfor Capture and Containment Performance of CommercialKitchen Exhaust Ventilation Systems (ASTM 2005), (2) inves-tigate the impact of hood design featur
9、es such side panels, and(3) investigate the impact of different replacement (makeup)air scenarios. While this technical paper focuses on the single-island canopy hood, data for both the single and double islandcanopy hood types can be found in the final report forASHRAE Research Project 1480 (Swierc
10、zyna, et al. 2010). Threshold capture and containment exhaust airflow rateswere determined in accordance with ASTM F1704-05, Stan-dard test method for capture and containment performance ofcommercial kitchen exhaust ventilation systems (ASTM2005). Capture and containment was validated using twoschli
11、eren systems and two shadowgraph systems, whichallowed real time visualization of the thermal and cookingplumes (Schmid et al. 1997). At the beginning of the project,heavy-load cooking was performed according to the appropri-ate ASTM Standard Test Methods, or as otherwise endorsedby the project moni
12、toring sub-committee (PMS) (ASTM1996, 1999a, 1999b). Then cooking simulations were estab-lished using the laboratorys visualization systems to ensure aCapture and Containment Ventilation Rates for Single-Island Canopy HoodsPaul A. Sobiski Richard T. Swierczyna Don R. Fisher, PEngMember ASHRAE Associ
13、ate Member ASHRAE Associate Member ASHRAEPaul A. Sobiski is a research engineer at Architectural Energy Corporation, Schaumburg, IL. Richard T. Swierczyna is a research engineerand Don R. Fisher is president and CEO of Fisher-Nickel, Inc., San Ramon, CA.LV-11-006 (RP-1480)2011. American Society of H
14、eating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior written permission.2
15、011 ASHRAE 715consistent effluent plume between actual and simulated cook-ing conditions. Once verified, simulated heavy-load cookingwas used for the duration of the project.EXPERIMENTAL DESIGNLaboratory LayoutThe commercial kitchen ventilation (CKV) laboratorywas equipped to accommodate the large i
16、sland canopy hoodsand the anticipated increase in the exhaust airflow. Fourteenfloor-mounted displacement diffusers provided up to9000 cfm (4250 L/s) of conditioned replacement air. Two airhandling units supplied the local replacement air devices, witha capacity that varied based on system static pr
17、essure. Theexhaust fan had a capacity of 9600 cfm (4530 L/s). To quantifythe air supplied to the laboratory, individual airflow measure-ment stations were installed before the two displacementventilation branches and before each local replacement airdevice. The layout of the laboratory, including th
18、e airflowvisualization systems, is shown in Figure 1.Airflow Visualization SystemsSchlieren and shadowgraph systems were the primarytools used for airflow visualization. Schlieren systems visual-ize the refraction of light due to air density changes. Usingsophisticated optical technology, the labora
19、tory schlieren flowvisualization system amplifies this effect for lower tempera-ture differences, providing higher sensitivity and contrast thanwhat is seen by the naked eye. Shadowgraph systems alsomake use of the schlieren effect, providing similar sensitivitybut with less contrast than schlieren
20、flow visualizationsystems. An example of schlieren imaging is shown inFigure 2. In addition to the schlieren and shadowgraph systems,theatrical fog distributed from tubular manifolds was used tovisualize the appliance thermal plume near the cookingsurface. This method was especially useful for evalu
21、ating thelocal replacement air devices, because the seeded plume couldbe traced in locations that were challenging for the visualiza-tion systems. An image of the smoke manifold in use with theheavy-duty appliance line, rear filter hood, and high-flowperforated supply plenum (PPS) replacement air sy
22、stem inoperation is shown in Figure 3. Appliance Specifications and CalibrationThe cooking appliances selected to challenge theexhaust hoods under test represented three appliance dutyclasses as defined in ASHRAE Standard 154 (ASHRAE2005). These appliances included the gas broiler from theheavy-duty
23、 class, the gas fryer from the medium-duty class,and the full-size electric convection oven from the light-dutyclass (ASTM 2005). For the two single-island hoodsdiscussed in this technical paper, two appliance lines wereevaluated: 1) a heavy-duty line consisting of three broilersand 2) a combination
24、-duty line consisting of a two-vat fryer,broiler, and full-size oven. Figure 1 Laboratory layout.716 ASHRAE TransactionsThe appliances were calibrated according to ASTM Stan-dard Test Methods (ASTM 2004). The two-vat fryers andbroilers each operated at equivalent ASTM full-load cookingconditions and
25、 the full-size convection ovens used ice loads tocause continuous element operation. Then, simulations wereestablished using the laboratorys visualization systems toensure a consistent effluent plume between actual and simu-lated cooking conditions, which was consistent with priorresearch during ASH
26、RAE RP-1202 (ASHRAE 2005). Simu-lation of the ASTM-specified cooking conditions wasachieved for the fryers by using a calibrated water boil togenerate a thermal plume that matched the plume from cook-ing shoestring potatoes. Simulated cooking for the broilerswas achieved by simply increasing gas pre
27、ssure to the burners,which produced a thermal plume of volume and strength thatmatched the plume from cooking hamburger patties. Sincethere was no difference in required exhaust rate for the full-size electric convection oven during idle and cook conditions,the ovens idled during testing. This simul
28、ated cooking strategygreatly improved testing by creating a constant effluent chal-lenge, improving repeatability and reducing laboratory timeand product cost. The specifications for the appliances usedare shown in Table 1. Appliance/Hood RelationshipThe horizontal distance from the inside lower edg
29、e ofcommercial canopy-type hoods to the edge of the top horizon-tal surface of the appliance on all open sides is referred to as“overhang” by the International Mechanical Code, section507.12 (ICC 2009). While this definition may seem to be astraightforward measurement, variations may be found andsho
30、uld be noted. Discrepancies include measuring to theappliance cook surface rather than the edge of the top hori-zontal surface, and measuring to the outside of the hood ratherthan the inside, especially when there is a lip or flange presenton the hood. For this study, the appliance was usually posi-
31、tioned with the cooking surface centered front-to-rear underthe hood and at a 6.0 in. (150 mm) side overhang. Hood SpecificationsThe two single-island hoods were installed with the loweredge of the hood at 6.5 ft (1.98 m) above the finished floor. Torepresent a generic application, the hoods had no
32、performanceenhancing features such as flanges or other geometricFigure 2 Example of schlieren images showing both spilland capture-and-containment.Figure 3 Smoke manifold in use with rear-filter single-island hood, heavy-duty line and high-flowperforated perimeter supply (PPS) in operationfront and
33、rear edge views.Table 1. Appliance Specifications3 ft Underfired Gas Broiler Full-Size Electric Convection Oven 2-Vat Gas FryerCapacity 58.4 in.2(37,700 mm2) cook surface 8.6 ft3(0.24 m3) cook cavity Two 50 lb. (23 kg) fry vatsInput 96,000 Btu/h (28.1 kW) 12.1 kW (41,300 Btu/h) 160,000 Btu/h (46.9 k
34、W)Height 37.0 in. (940 mm) 57.3 in. (1454 mm) 45.3 in. (1149 mm)Width 34.0 in. (867 mm) 40.0 in. (1016 mm) 31.3 in. (787 mm)Depth 33.0 in. (838 mm) 40.5 in. (1029 mm) 28.5 in. (724 mm)2011 ASHRAE 717features. To accommodate the mounting of side panels, thehoods were equipped with open hems along the
35、 left and rightsides. In order to view the thermal plume flow patterns in thehood reservoir, the sides of the hoods were transparent plastic.Rear Filter, Single-Island Canopy HoodThe rear filter single-island canopy hood measured10.0 ft long by 4.0 ft deep by 2.0 ft high (3.05 by 1.22 by0.61 m). It
36、was equipped with six 19.6 by 19.6 by 1.8 in. (500by 500 by 55 mm) baffle-type grease filters, and exhaustedthrough a 36.0 by 14.0 in. (915 by 355 mm) exhaust collar.This collar attached to the laboratorys 24.0 in. (610 mm)round exhaust ductwork through a transition. While the rear-filter canopy hoo
37、d is typically applied in wall-mounted instal-lations, it is also used for island applications. The test setup isas shown in Figure 4 (note the theater smoke manifold alongthe cooking surface). V-bank, Single-Island Canopy HoodThe V-bank filter, single-island canopy hood measured10.0 ft long by 6.0
38、ft deep by 2.0 ft high (3.05 by 1.83 by0.61 m). It was equipped with twelve 19.6 by 19.6 by 1.8 in.(500 by 500 by 55 mm) baffle-type grease filters. The 8.0 in.(205 mm) flat bottom of the filter bank was positioned 4.0 in.(100 mm) above the lower edge of the hood. The exhaust collarmeasured 36.0 by
39、14.0 in. (915 by 355 mm) and attached to thelaboratorys 24.0 in. (610 mm) round exhaust ductworkthrough a transition. V-bank style canopy hoods are generallyrecommend by manufacturers for single-island applications.The V-bank hood test setup is shown in Figure 5. Side Panel SpecificationsThe effect
40、of side panels was investigated using threepartial panel configurations, along with an appliance exten-sion. Side panel #1 was a tapered side panel, which measured42.0 in. (1065 mm) tall, 36.0 in. (915 mm) wide at the top, and28.0 in. (710 mm) wide at the bottom. Side panel #2 was asmall skirt, whic
41、h measured 8.0 in. (205 mm) tall, 48.0 in.(1220 mm) wide at the top, and 40.0 in. (1015 mm) wide at thebottom. Side panel #3 was a triangular shaped side panel,measuring 42.0 in. (1065 mm) tall, 36.0 in. (915 mm) wide atthe top, and tapered to a point at the bottom. The applianceextension, designate
42、d as side panel #4, actually rested on theappliance line, rather than being fastened to the hood. Theappliance extension was 24.0 in. (610 mm) tall, ran along theentire rear of the broiler line, and came forward 32.0 in.(815 mm) on the left and right sides of the appliance line. Theside panel config
43、urations are shown in Figure 6. Replacement Air SpecificationsTo maintain a zero pressure differential between insideand outside the laboratory, replacement (makeup) air wassupplied at a volume equal to the amount of air beingexhausted through the hood. Displacement DiffusersFor the baseline configu
44、rations, 100% of the replacementair was supplied through the displacement diffusers. When alocal replacement air strategy was being investigated, thedifference between the local replacement air and exhaust airflow was delivered to the room through the displacementdiffusers. The displacement diffuser
45、s were located as far awayas possible from the hood, with seven to the front of the hoodand seven to the rear of the hood. The diffusers were balancedleft-to-right across each system and each system was thenbalanced to ensure balanced airflow from both sides of thelaboratory. The intention was to pr
46、ovide a low-velocity airsupply, which minimized the influence that the replacementair had on hood performance. Figure 4 Rear-filter island canopy hood over heavy-dutyappliance line.Figure 5 V-bank island canopy hood over combination-duty appliance line.718 ASHRAE TransactionsCeiling DiffusersTwo 4-w
47、ay ceiling diffusers and two perforated ceilingdiffusers were used as part of the local replacement air inves-tigation. For direct comparison, each type of ceiling diffuserwas installed in the same two locations and then replaced withthe alternative diffuser type. Each diffuser was 24.0 by 24.0 in.(
48、610 by 610 mm), was connected to a 12.0 in. (305 mm) diam-eter duct, and was mounted 8.0 ft (2.44 m) above the floor. Onediffuser was located on the right side of the hood, with thecenter of the diffuser centered front-to-rear with the hood and18.8 in. (480 mm) from the side of the hood. Another dif
49、fuserwas located at the front of the hood, with the center of thediffuser located 24.0 in. (610 mm) from the right side of thehood and either 24.0 or 48.0 in. (610 or 1220 mm) from thefront of the hood. Gaps between the hood and diffusers werefilled in with either a suspended ceiling or a disabled perfo-rated perimeter supply. Perforated Perimeter SupplyFour perforated perimeter supply (PPS) plenums wereused as part of the local replacement air investigation. Eachwas 12.0 in. (305 mm) deep by 6.0 in. (150 mm) tall, with10.0 ft (3.05 m) of active PPS across the front and rear of theho
