1、2009 ASHRAE 161This paper is based on findings resulting from ASHRAE Research Project RP-1362.INTRODUCTIONThe capture and containment (C&C) exhaust ventilation rates for commercial cooking appliances currently published in the ASHRAE Applications Handbook, Kitchen Ventilation, Chapter 30 (ASHRAE, 20
2、05) were obtained through a consensus of industry representatives, including hood manu-facturers, appliance manufacturers, kitchen designers, and foodservice consultants. To support this consensus, the body of research regarding capture and containment to date has been significant. However, many app
3、liance types have not been documented and others need review. The test matrix for the ASHRAE RP-1362 work statement identified 20 addi-tional appliances to be tested with the goal of improving the heat gain information available in Table 5, Recommended Rates of Heat Gain from Typical Commercial Cook
4、ing Appli-ances, in Chapter 31 (ASHRAE, 2008) and provide expanded data for Chapter 30. To compliment the specified appliances, refrigeration equipment was added to the test matrix. The compilation of new capture and containment data, in parallel with new heat gain data, will support the efforts of
5、ASHRAE in providing engineers with better design guidelines for commercial kitchen ventilation systems. The information regarding the heat gain evaluation can be found in the technical paper titled Revised Heat Gain Rates from Typical Commer-cial Cooking Appliances from RP-1362 (Swierczyna, et al, 2
6、008), as well as in the main project report titled ASHRAE Research Project 1362 Revised Heat Gain and Capture and Containment Exhaust Rates from Typical Commercial Cook-ing Appliances (Swierczyna, et al, 2008).The capture and containment performance of the hooded equipment was characterized by the t
7、hreshold capture and containment exhaust airflow rate as determined in accordance with ASTM F1704-05 Standard Test Method for Capture and Containment Performance of Commercial Kitchen Exhaust Ventilation Systems (ASTM, 2005). The capture and contain-ment conditions were established for full-load coo
8、king condi-tions using two full-scale schlieren systems and one shadowgraph system that allow visualization of the thermal and cooking plumes in real time (Schmid, et al, 1997). Heavy-load cooking or simulation was conducted in accordance with the appropriate ASTM performance test methods or as othe
9、r-wise recommended and endorsed by the project monitoring sub-committee (PMS) (ASTM, 2008).In this paper, exhaust capture and containment rates are discussed. First, the data is summarized across all appliance duty classes. Then, the impact of side panels on capture and containment performance is pr
10、esented. Next, a more detailed review of the capture and containment results are presented by duty class, including the extra-heavy, heavy, medium, and light duty classes, as well as typically unhooded equipment that could operate as hooded equipment. Lastly, capture and containment exhaust rates th
11、at greatly differed from the rates established for the duty class are highlighted, along with potential duty class reclassification. EXPERIMENTAL DESIGNAppliance Specifications and CalibrationAppliances were specified and chosen according to Table 5, Recommended Rates of Heat Gain from Typical Comme
12、r-Capture and Containment Ventilation Rates for Commercial Kitchen Appliances Measured during RP-1362Paul Sobiski Rich Swierczyna Don Fisher, PEMember ASHRAE Associate Member ASHRAE Associate Member ASHRAEPaul Sobiski is a research engineer and Rich Swierczyna is a lab operations manager at the Arch
13、itectural Energy Corp., Commercial Kitchen Ventilation Laboratory, Wood Dale, IL. Don Fisher is CEO with Fisher-Nickel, Inc., San Ramon, CA.LO-09-012 (RP-1362) 2009, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions 200
14、9, vol. 115, part 2. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.162 ASHRAE Transactionscial Cooking Appliances. The appliances were calibrated according to the appropriate AST
15、M Standard Test Methods. In selected cases, derivatives of the test procedures, as approved by the PMS, were applied to the appliance under consider-ation. In other cases, the ASTM Standard Test Method did not exist and the calibration was performed to represent the typical operation of the applianc
16、e.Appliance/Hood RelationshipsThe horizontal distance from the hood to the appliance, typically referred to as hood overhang, may seem to be a straightforward measurement. However, variations are possi-ble. At the appliance, the overhang can be measured to the cooking surface or to the vertical surf
17、ace of the appliance. At the hood, the overhang can be measured to the outside edge of the hood, or the inside edge if there are performance-enhanc-ing features.The appliance was usually located in the right hand posi-tion of a three-appliance cook line. It was positioned under the 10-foot hood at a
18、 12.0-inch (305 mm) front overhang, and a 6.0-inch (153 mm) side overhang. The dimensions were measured from the edge of the hood to the cooking surface, in most cases. For appliances where this was not practical, such as ovens, the vertical skin of the appliance was used. Hood SpecificationsMost of
19、 the hooded appliances were evaluated under a wall-mounted canopy hood that measured 10 feet long by 4 feet deep by 2 feet tall (3.05 m by 1.22 m by 0.61 m). It was equipped with six 19.6-inch by 19.6-inch by 1.8 inch (498 mm by 498 mm by 46 mm) cyclone-type grease filters, and exhausted through a 3
20、6.0-inch by 12.0-inch (914 mm by 305 mm) exhaust collar. This collar transitioned to the existing 24.0-inch (610 mm) exhaust ductwork over a height of 36.0 inches (914 mm). To represent a generic application, the canopy hood was specified to have no performance-enhancing features such as flanges or
21、interior geometric features. The hood was equipped with open hems on three sides of the hood to accommodate the mounting of side panels or hood exten-sions. The front lower edge of the hood was located at 6.50 feet (1.98 m) above the finished floor. A 6.0-inch (153 mm) fascia was attached between th
22、e top of the hood and the suspended ceiling. To facilitate visualization along all edges of the hood, it was mounted to a clear back wall, which makes the hood appear to be without a back wall in photographs throughout the paper. A photograph of a typical setup is shown in Figure 1.Alternative hoods
23、 were used as needed to accommodate unique appliance dimensions. For appliances requiring a canopy hood greater than 4 feet (1.22 m) deep, a 1-foot (0.30 m) extension was added to the canopy hood. This modification provided a consistent hood design and quick-change capabil-ity, compared to removing
24、and installing alternative exhaust hoods. For appliances requiring a 5-foot (1.52 m) deep canopy hood but better tested on an individual basis, a 5 foot by 5-foot (1.52 m by 1.52 m) wall-mounted canopy hood was used. Appliances such as dishwashers and holding cabinets were well suited for this hood.
25、 In some cases, a 1-foot (0.30 m) rear filler panel was used to reduce the open area of the hood.Side Panel SpecificationsThe partial side panels measured 3 feet by 3 feet (0.91 m by 0.91 m) and tapered from the front upper corner to the lower rear corner, which resulted in a lower edge that was at
26、a 45 angle from the horizontal. The partial side panels were installed using interlocking hem joints at the hood and were sealed to the clear wall using foil tape. The installed side panels are shown in Figure 2.Makeup Air SpecificationsThe makeup (replacement) air for the exhaust hood under test wa
27、s supplied through a displacement ventilation system along the wall opposite to the front of the hood. All testing was performed with the displacement ventilation system as the sole replacement air supply for the laboratory. The design of this replacement air system provided a low-velocity air suppl
28、y, which has been proven to minimize the influence of replace-ment air on hood performance (Brohard et al, 2003). AIRFLOW VISUALIZATION SYSTEMSFocusing schlieren and shadowgraph systems were the primary tools used for airflow visualization. Schlieren systems visualize the refraction of light due to
29、air density changes. Using sophisticated optical technology, the labora-tory schlieren flow visualization system amplifies this effect for lower temperature differences, providing higher sensitivity and contrast than what is seen by the naked eye. Shadowgraph systems also make use of the schlieren e
30、ffect, providing simi-lar sensitivity but with less contrast than schlieren flow visu-alization systems. An example of schlieren imaging is shown in Figure 3.The repeatability of capture and containment measure-ments at the CKV laboratory was investigated and the error was found to be below 14% with
31、 a typical error of about 7%. Repeatability of the visualization systems was adversely affected as the ambient air and thermal plumes approached similar temperatures. This occurred with the presence of dilu-tion air, when thermal plume was relatively weak, or when the ambient conditions were above t
32、he normal operating range of 75 to 78 degrees Fahrenheit (24 to 26C).TEST PROCEDURESThe capture and containment determinations were made in accordance with ASTM F 1704-05 Standard Test Method for Capture and Containment Performance of Commercial Kitchen Exhaust Ventilation Systems. In selected cases
33、 deriv-atives of the test procedures, as approved by the PMS, were applied to the appliance under consideration.The phrase “hood capture and containment” is defined in ASTM F 1704-05 Standard Test Method for Capture and ASHRAE Transactions 163Figure 1 Wall canopy hood mounted to clear backwall over
34、 a typical appliance line.Figure 2 Partial side panels installed on wall canopy hood.164 ASHRAE TransactionsContainment Performance of Commercial Kitchen Exhaust Ventilation Systems as “the ability of the hood to capture and contain grease-laden cooking vapors, convective heat, and other products of
35、 cooking processes”. Hood capture refers to the products getting into the hood reservoir from the area under the hood, while containment refers to these products staying in the hood reservoir and not spilling out into the space adjacent to the hood. The phrase “minimum capture and containment” is de
36、fined as “the conditions of hood operation in which mini-mum exhaust flow rates are just sufficient to capture and contain the products generated by the appliance in idle and heavy-load cooking conditions, or at any intermediate prescribed load condition.”During the capture and containment tests, th
37、e exhaust flow rate was reduced until spillage of the thermal plume was observed. The exhaust flow rate was then increased in fine increments until full capture and containment was achieved for the given condition. The exhaust flow rate at this condition is referred to as the threshold exhaust airfl
38、ow rate for complete capture and containment, or threshold capture and contain-ment rate. This value is the lowest and most repeatable airflow rate for making direct comparisons across various scenarios.ASHRAE Research Project 1202 Effect of Appliance Diversity and Position on Commercial Kitchen Hoo
39、d Perfor-mance utilized a 10-foot (3.05 m) wall-mounted canopy hood that evaluated hood performance for a variety of combinations of light-, medium- and heavy-duty appliances in different positions under the hood (ASHRAE, 2005). The research found the capture and containment exhaust rate for an appl
40、i-ance (e.g., broiler) in the end position of the 10-foot hood was nearly the same as the exhaust rate for three similar-duty appli-ances (e.g., three broilers) filling the space under the same hood. The hood performance and required exhaust rate was most dependent on redirecting the thermal plume o
41、f the end appliance towards the lower edge of the hood, independent of the number of appliances or the additional thermal challenge they created. Because of the variety of appliance sizes tested for this project, it was proposed to determine the capture and contain-ment exhaust flow rates for the “h
42、ooded” appliances under a 10-foot (3.05 m) wall-mounted canopy hood at the end posi-tion of the cook line, with the other appliances turned off. This appliance layout was also similar to the layout used to test hood capture and containment according to Underwriters Laboratory UL710 protocol, Exhaust
43、 Hoods for Commercial Cooking Equipment (Underwriters Laboratories, 2008). The test setup for the capture and containment evaluation with the test appliance positioned at the end of the 10-foot (3.05 m) hood and the three flow visualization systems is shown in Figure 4.Figure 3 Example of Schlieren
44、images at exhaust rates for spill and capture.ASHRAE Transactions 165CAPTURE AND CONTAINMENT TEST RESULTS AND DISCUSSIONThe exhaust rates required for full capture and contain-ment of the plume from each appliance during this project ranged from 20 to 520 cfm/foot (31 to 805 (L/s)/m). While most cap
45、ture and containment testing was performed during cooking conditions, some sensitivity testing was performed to evaluate operational changes, such as lid up compared to lid down for a steam kettle, or hickory briquettes compared to mesquite lumps for a sold fuel broiler, as well as idle compared to
46、cooking for other selected appliances.It was found that the capture and containment rate better correlated to the operating conditions, or cooking process of each appliance, rather than the duty rating. For instance, four appliances, including the light-duty gas conveyor oven, the typically unhooded
47、 under counter dishwasher, the light-duty 40-gallon (151 L), and the light-duty 60-gallon (227 L) gas steam kettles, represent the four highest required capture and containment rates. Yet, the heavy-duty electric and gas sala-manders required the lowest and forth lowest capture and containment rates
48、 respectively. Likewise, if the steam kettles were covered while boiling water, rather than uncovered, the capture and containment rate was reduced. For the 60-gallon (227 L) gas kettle, the rate was reduced from 500 to 330 cfm/ft (774 to 511 (L/s)/m). For the 40-gallon (151 L) gas kettle, the rate
49、 reduced from 490 to 350 cfm/ft (759 to 542 (L/s)/m). Appliances that seem almost identical when compared on paper may have greatly different capture and containment requirements. For example, two light-duty electric convection ovens from two manufacturers were tested. One oven had a nameplate energy input of 12.1 kW, an interior cavity volume of 10.2 cubic feet (0.29 cubic meters), and required 90 cfm/ft (139 (L/s)/m) for proper capture and containment. Another electric convection oven was larger, but could possibly be substituted for the other in a cook line if a few inches of extra spa
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