1、138 2009 ASHRAEThis paper is based on findings resulting from ASHRAE Research Project RP-1362.ABSTRACTThe objective of ASHRAE RP-1362 was to refine and expand the database on the heat gain to space for commercial foodservice equipment and, where applicable for hooded appliances, report the exhaust v
2、entilation rates found using a 10-foot canopy hood. This paper provides an overview of the heat loads: radiant, sensible convective and latent from 83 appliances in 100 test conditions. The paper discusses these loads from typically unhooded and hooded appliances and their relationship to energy con
3、sumption, and uses the results to update the Heat Gain from Typical Commercial Cooking Appliances table in the ASHRAE Handbook of Fundamen-tals. INTRODUCTIONThe recommended heat gain values from typical commer-cial cooking appliances and ancillary kitchen equipment currently published in the ASHRAE
4、Fundamentals Handbook were obtained through ASHRAE 391-RP completed in 1984 (Alereza, 1984) and subsequently by Fisher (Fisher, 1998). Although a number of revisions have been made to Table 5, Recommended Rates of Heat Gain from Typical Commercial Cooking Appliances, in Chapter 30 (ASHRAE, 2005), th
5、ere remained concern with respect to the thoroughness and accu-racy of this information. As a result, the cooling loads currently specified for commercial kitchen HVAC systems may be difficult to estimate and potentially inaccurate.It was recognized that Table 5 did not provide a complete list of eq
6、uipment that may be specified in a commercial kitchen design. Thus, the test matrix for the ASHRAE 1362-RP (Swierczyna, 2008) identified 20 additional appliances to be tested with the goal of improving the information available in Table 5. To compliment the specified appliances, refriger-ation equip
7、ment was added to the test matrix.To improve the usability of the data, the heat gain values are reported in more relevant parameters for many equipment types. Similarly, the classification and reported heat gain of reach-in refrigerators and freezers should follow industry convention (e.g., single-
8、door, two-door, or three-door) rather than heat gain on a volumetric basis to be consistent with industry convention and design specifications.The objective of this ASHRAE research project was to refine and expand the database for heat gain to space from commercial foodservice equipment and, where a
9、pplicable for hooded appliances, report the exhaust ventilation rate required for capture and containment using the same test configuration used for heat gain testing. The primary goals of the study were to provide more reliable heat gain data, improve appliance categorization in Table 5, and improv
10、e the application guide-lines in the ASHRAE Handbook. A parallel goal was to report the exhaust ventilation rates found for each appliance (Sobiski, 2008). As a result, the engineer will have a more comprehensive understanding of the overall kitchen design, which will help to accurately calculate co
11、oling loads, design HVAC systems, and specify exhaust hoods.The research project undertook the testing of both hooded and un-hooded equipment types. For the hooded cooking appliances, the study determined the radiant heat gain to space during idle (ready-to-cook) conditions. For some equipment, the
12、heat gain was determined during representative usage, such as dishwashers washing dishes. For un-hooded appli-Revised Heat Gain Rates from Typical Commercial Cooking Appliances from RP-1362Rich Swierczyna Paul Sobiski Don Fisher, PEngAssociate Member ASHRAE Associate Member ASHRAE Associate Member A
13、SHRAERich Swierczyna is a lab operations manager and Paul Sobiski is a research engineer in the Commercial Kitchen Ventilation Laboratory at the Architectural Energy Corp., Wood Dale, IL. Don Fisher is CEO with Fisher-Nickel Inc., San Ramon, CA.LO-09-011 (RP-1362) 2009, American Society of Heating,
14、Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions 2009, 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.ASHRAE
15、 Transactions 139ances, where the kitchen air conditioning load is based on total enthalpy, the radiant and convective loads for the appliances were established, including the latent contribution. This paper presents the heat gain to space results for 83 appliances under 100 test conditions. The hea
16、t loads are discussed with respect to the appliances energy consumption rates and tabulated in a format similar to the existing Table 5, Recommended Rates of Heat Gain from Typical Commercial Cooking Appliances. EXPERIMENTAL DESIGNAppliance Specifications and CalibrationAppliances were specified and
17、 chosen according to Table 5, Recommended Rates of Heat Gain from Typical Commer-cial Cooking Appliances. The appliances were calibrated according to the appropriate ASTM Standard Test Methods. In selected cases, derivatives of the test procedures were applied to the appliance under consideration. I
18、n other cases, where the ASTM Standard Test Method did not exist, the calibration was performed to represent the typical operation of the appliance.Hood SpecificationsMost hooded appliances were evaluated in the rightmost position under a wall-mounted canopy hood that measured 10.0 feet long by 4.0
19、feet deep by 2.0 feet tall (3.05 m by 1.22 m by 0.61 m). The front lower edge of the hood was located at 6.5 feet (1.98 m) above the finished floor. Alternative hoods were used as needed to accommodate unique appliance dimensions. For appliances requiring a canopy hood greater than 4.0 feet (1.22 m)
20、 deep, a 1.0-foot (0.30 m) extension was added to the canopy hood. For appliances requiring a 5.0-foot (1.52 m) deep canopy hood but better tested on an individual basis, a 5.0 foot by 5.0 foot (1.52 m by 1.52 m) wall-mounted canopy hood was used. Appliances such as dishwashers and holding cabinets
21、were well suited for this hood. In some cases, a 1.0-foot (0.30 m) rear filler panel was used to reduce the open area of the hood. The setup of the 10.0-foot hood is shown in Figure 1, the 5.0-foot hood is shown in Figure 2, and the 2-foot hood setup is shown in Figure 3.Airflow Visualization System
22、sFocusing schlieren and shadowgraph systems were the primary tools used for airflow visualization (Sobiski, 2008). Airflow visualization was necessary to verify complete capture and containment of the thermal plume from the appli-ance and the accurate measurement of the generated loads. The airflow
23、rate used in the testing was the minimum rate to capture and contain the thermal plume while not disturbing the natural convection of the plume.TEST PROCEDURESThe heat gain to space determinations were made in accordance with ASTM F 2474-05 Standard Test Method for Heat Gain to Space Performance of
24、Commercial Kitchen Exhaust Ventilation/Appliance Systems (ASTM, 2005). Figure 1 10.0-foot by 4.0-foot wall canopy hood mounted to clear backwall with steam kettle under test.140 ASHRAE TransactionsFigure 2 5.0-foot by 5.0-foot wall canopy hood with door-type dishwasher under test.Figure 3 2.0-foot b
25、y 2.0-foot canopy hood with coffee brewer under test.ASHRAE Transactions 141The precision of the reported heat gain was within the speci-fications of 15%; values that calculated less than zero were reported as zeroHooded EquipmentHeat gain from hooded appliances is transferred primarily to the kitch
26、en space by radiation. Heat gain to space was measured indirectly using an energy balance protocol, where the radiant load was calculated as the difference between the energy consumed by the appliance and the energy removed by the exhaust system and food product. The energy balance as defined by AST
27、M 2474-05 is shown in Equation (1).Eappliance+ Emua= Eexhaust air+ Eheat gain+ Efood(if applicable) (1)In commercial kitchens, appliances are typically turned on at the beginning of each day and are not turned off until closing time. Although the appliances are “up to temperature” 100% of the time,
28、they may be used to cook food less than 25% of the time, even in high-volume restaurants. Therefore, idle heat gain measurement provides a good estimate for the cool-ing load from the hooded appliances. More precise analysis can be had and a load profile constructed if cooking heat gain values are a
29、vailable for hooded equipment, along with an activity log from the kitchen. When the cost, time, and level of effort was considered, along with the percentage of time appli-ances typically operate during the day, cooking heat gain test-ing for hooded appliances was considered to be well beyond the s
30、cope of this project and beyond typical commercial kitchen load calculations.The heat gain testing procedure is very time-intensive. Before the first heat gain test of the day was performed, the hood airflow was set to the required rate. The appliance was turned on Figure 4 Energy balance schematic
31、for heat gain calculations.Figure 5 Photograph of typical heat gain measurement test.142 ASHRAE Transactionsand allowed to stabilize to the specified operating temperature. The appliance/hood system was then operated for an additional period to ensure stabilization of the laboratory, hood, ductwork,
32、 and equipment temperatures. Following stabilization, each idle heat gain test usually required a minimum of one hour for a non-thermostatically controlled appliance and two hours for a ther-mostatically controlled appliance to generate reliable data. The schematic for hooded appliance heat gain tes
33、ting and the energy balance boundary conditions are shown in Figure 4. A photo-graph of a cook line during heat gain testing is shown in Figure 5.For some low-input equipment, more than one of the same appliance was needed to improve the heat gain accuracy. For most other cases, the exhaust airflow
34、was limited to the area over the single appliance being tested by blocking filters on the inac-tive section of the hood. This modification reduced the airflow rate and increased the temperature rise from the room to the exhaust airstream, thus improving the accuracy of the measured heat gain. To ens
35、ure valid results, sensitivity testing was performed to minimize the airflow and maximize the tempera-ture rise in the exhaust air stream while maintaining capture and containment of the plume. A photograph showing the hood with a portion of the filters blocked is shown in Figure 6.Un-Hooded Equipme
36、ntFor hooded appliances, the energy balance protocol assumes that 100% of the convective load was exhausted with the cooking effluent. For un-hooded appliances, the convective load from the appliances put a sensible and latent load, in addi-tion to the radiant load, on the kitchen space. For this pr
37、oject, all appliances were tested under a canopy exhaust hood in order to capture, contain, and measure the convective load. The exhaust system was instrumented to measure the airflow, dry bulb temperature, and dew point temperature. With these measurements, the sensible and latent load was calculat
38、ed for each appliance. The test setup to measure the radiant and convective split from un-hooded equipment is shown as a photograph in Figure 7 and a schematic in Figure 8.CalculationsThe energy balance on Figure 8 yields:For the sensible radiant load:Eappliance+ Emua Eexhaust Eradiation Efood(if ap
39、plicable)= 0 (2)OrEradiation = Eappliance+ Emua Eexhaust Efood(if applicable) (3)Where:Emuais the energy in the makeup air streamEexhaustis the energy in the exhaust air streamEapplianceis the energy consumption of the applianceEfoodis the energy required to cook the foodFor the convective load:In I
40、Pqsensible convective load= 1.08 Qexh(Tdb-exh Tdb-mua) (4a)qlatent load= 4840 Qexh(Wexh Wmua) (5a)Figure 6 Exhaust hood with filter bank partially blocked.ASHRAE Transactions 143for SIqsensible convective load= 1.23 Qexh(Tdb-exh Tdb-mua)(4b)qlatent load= 3010 Qexh(Wexh Wmua)(5b)Where:qsensible conve
41、ctiveloadis the sensible convective heat load generated by the appliance in Btu/h (W)qlatent loadis the latent heat load generated by the appliance in Btu/h (W)Qexhis the volumetric flow rate of the exhaust air stream in cfm (L/s)Tdb-muathe dry bulb temperature of the makeup air stream in F (C)Tdb-e
42、xhis the dry bulb temperature of the exhaust air stream in F (C)Wmuais the humidity ratio of the makeup air stream in pound of water per pound of dry air (kg/kg)Wexhis the humidity ratio of the exhaust air stream in pound of water per pound of dry air (kg/kg)HEAT GAIN TO SPACE RESULTSHeat gain to sp
43、ace was measured during idle conditions for most hooded appliances. For unhooded equipment, heat gain to space was usually measured during idle and cooking conditions. In addition, sensitivity testing was performed on some appliances to investigate different operating conditions. The project generat
44、ed a significant amount of heat gain data with the appliances at idle conditions. The majority of Figure 7 Test setup to measure radiant and convective loads from uh-hooded equipment.Figure 8 Energy balance schematic for heat gain calculations including radiant and convective loads from un-hooded eq
45、uipment.144 ASHRAE Transactionsappliances were shown to have heat gain values below 2,000 Btu/h (586 W). Sixteen appliances were at or below detectable limits, as indicated with a reported heat gain to space value of zero. The majority of the sixteen appliances used water, such as dishwashers, steam
46、 kettles, steamers, rethermalizers, pasta cookers, and drawer warmers, at various operating modes with cooking surface or skin temperatures below 212F (100C). Eight appliances were measured with heat gain to space values ranging from 8,000 to 14,900 Btu/h (2,345 to 4,367 W), which were the highest h
47、eat gain values measured during the project. These eight appliances included broilers or ranges, at various operating configurations.When the sensible heat gain values were sorted by measured appliance energy consumption rate, the generally accepted trend of higher energy consuming appliances having
48、 a higher measured heat gain was not well supported, since many exceptions to this trend existed. For instance, the gas overfired broiler was measured as having the fourth-highest energy consumption rate at 87,900 Btu/h (25,761 W), and was rated at 100,000 Btu/h (29,307 W) (nameplate). However, a he
49、at gain of 2,500 Btu/h (733 W) was measured, which is significantly lower than the heat gain measured for other appli-ances with similar energy consumption rates. A graph of the data is shown in Figures 9 and 10.HEAT GAIN TO SPACE AS A FUNCTION OF APPLIANCE ENERGY CONSUMPTION RATE FOR GAS APPLIANCESThe regression of sensible radiant heat gain versus appliance consumption rate represents the radiation factor, Fr=q sensible/q idle energy consumption, as shown for gas appli-ances in Figure 11. The correlation is 0.69 for a radiation factor of 0.11. The outliers were test co
