Hobart HBA2G Rack Oven Report - FSTC · Browning Uniformity Tests ... 2-2 Cross section of a frozen apple pie ... Document the rack oven’s browning uniformity using white

Hobart Model HBA2G Gas Double-Rack Oven Performance Test

FSTC Report # 5011.06.14

Food Service Technology Center August 2006

Prepared by: David Zabrowski Greg Sorensen

Fisher-Nickel, Inc.

Prepared for: Pacific Gas & Electric Company

Customer Energy Efficiency Programs PO Box 770000

San Francisco, California 94177

© 2006 by Fisher-Nickel, inc. All rights reserved.

The information in this report is based on data generated at the Food Service Technology Center.

Acknowledgments

California consumers are not obligated to purchase any full service or other service not funded by this program. This program is funded by California utility ratepayers under the auspices of the California Public Utilities Commission.

Los consumidores en California no estan obligados a comprar servicios completos o adicionales que no esten cubiertos bajo este programa. Este programa esta financiado por los usuarios de servicios públicos en California bajo la jurisdiccion de la Comision de Servicios Públicos de California.

A Technical Advisory Group provides guidance to the Food Service Technology Center Project. Members include:

Applebee’s International Group

California Energy Commission (CEC)

Denny’s Corporation

East Bay Municipal Utility District

Enbridge Gas Distribution Inc.

EPA Energy Star

Gas Technology Institute (GTI)

In-N-Out Burger

National Restaurant Association

Safeway, Inc.

Southern California Edison

Underwriters Laboratories (UL)

University of California at Berkeley

University of California at Riverside

US Department of Energy, FEMP

Specific appreciation is extended to Hobart, for supplying the Food Service Technology Center with a model HBA2G gas roll-in rotating double-rack oven for controlled testing in the appliance laboratory.

Policy on the Use of Food Service Technology Center Test Results and Other Related Information

• Fisher-Nickel, inc. and the Food Service Technology Center

(FSTC) do not endorse particular products or services from any specific manufacturer or service provider.

• The FSTC is strongly committed to testing food service equipment using the best available scientific techniques and instrumentation.

• The FSTC is neutral as to fuel and energy source. It does not, in any way, encourage or promote the use of any fuel or energy source nor does it endorse any of the equipment tested at the FSTC.

• FSTC test results are made available to the general public through technical research reports and publications and are pro-tected under U.S. and international copyright laws.

• In the event that FSTC data are to be reported, quoted, or referred to in any way in publications, papers, brochures, advertising, or any other publicly available documents, the rules of copyright must be strictly followed, including written permission from Fisher-Nickel, inc. in advance and proper attribution to Fisher-Nickel, inc. and the Food Service Technology Center. In any such publication, sufficient text must be excerpted or quoted so as to give full and fair representation of findings as reported in the original documen-tation from FSTC.

Legal Notice

This report was prepared as a result of work sponsored by the California Public Utilities Commission (Commission). It does not necessarily represent the views of the Commission, its employees, or the State of California. The Commission, the State of California, its employees, contractors, and subcon-tractors make no warranty, express or implied, and assume no legal liability for the information in this report; nor does any party represent that the use of this information will not infringe upon privately owned rights. This report has not been approved or disapproved by the Commission nor has the Commis-sion passed upon the accuracy or adequacy of the information in this report.

Disclaimer

Neither Fisher-Nickel, inc. nor the Food Service Technology Center nor any of its employees makes any warranty, expressed or implied, or assumes any legal liability of responsibility for the accuracy, completeness, or usefulness of any data, information, method, product or process discloses in this docu-ment, or represents that its use will not infringe any privately-owned rights, including but not limited to, patents, trademarks, or copyrights.

Reference to specific products or manufacturers is not an endorsement of that product or manufacturer by Fisher-Nickel, inc., the Food Service Tech-nology Center or Pacific Gas & Electric Company (PG&E).

Retention of this consulting firm by PG&E to develop this report does not constitute endorsement by PG&E for any work performed other than that specified in the scope of this project.

Contents

5011.06.14 i Food Service Technology Center

Page Executive Summary ............................................................................... iii 1 Introduction ...................................................................................... 1-1 Background ................................................................................. 1-1 Objectives.................................................................................... 1-2 Appliance Description.................................................................. 1-2 2 Methods ............................................................................................ 2-1 Setup and Instrumentation .......................................................... 2-1 Energy Input Rate and Thermostat Calibration ........................... 2-1 Preheat and Idle Tests ................................................................ 2-2 Steam Performance Test............................................................. 2-3 Baking-Energy Efficiency Tests ................................................... 2-3 Browning Uniformity Tests........................................................... 2-5 Operating Cost Model.................................................................. 2-5 3 Results ............................................................................................. 3-1 Energy Input Rate and Thermostat Calibration ........................... 3-1 Preheat and Idle Rate Tests........................................................ 3-1 Steam Performance Test............................................................. 3-3 Baking Tests................................................................................ 3-4 Energy Cost Model ...................................................................... 3-7 4 Conclusions ..................................................................................... 4-1 5 References........................................................................................ 5-1 Appendix A: Glossary Appendix B: Appliance Specifications Appendix C: Results Reporting Sheets Appendix D: Baking-Energy Efficiency Data

List of Figures and Tables

5011.06.14 ii Food Service Technology Center

Page 1-1 The Hobart HBA2G ..................................................................... 1-3 2-1 The Hobart HBA2G instrumented for testing ............................... 2-2 2-2 Cross section of a frozen apple pie ............................................. 2-3 2-3 Thermocouple rig for measuring baked pie temperature ............. 2-4 3-1 HBA2G Preheat characteristics................................................... 3-2 3-2 HBA2G Steam production & repeatability.................................... 3-3 3-3 Cakes in top rack position ........................................................... 3-6 3-4 Cakes in 4th rack position from top .............................................. 3-6 3-5 Cakes in 11th rack position from top ............................................ 3-7 Page 1-1 Appliance Specifications.............................................................. 1-3 3-1 Input, Preheat and Idle Test Results ........................................... 3-2 3-2 Steam Performance Test Results................................................ 3-3 3-3 Frozen Apple Pie Test Results .................................................... 3-5 3-4 Annual Cost Model ...................................................................... 3-8

Figures

Tables

Executive Summary

5011.06.14 iii Food Service Technology Center

Roll-in rack ovens offer high volume production and even baking in a rela-tively compact footprint. A single rack oven typically accommodates 15 pans of product at a time, effectively replacing three full-size convection ovens; a double rack oven can bake 30 pans of product at a time. These large capacity ovens fill the requirements of high-volume retail and baking operations.

The Hobart HBA2G double-rack oven features stainless steel interior and ex-terior construction, a 300,000 Btu/h in-shot burner system with a weldless tubular stainless steel heat exchanger, a self-contained steam generator and a digital control panel with the capability to store 99 separate menus.

The Food Service Technology Center (FSTC) tested the Hobart, Model HBA2G, gas-fired double-rack oven under controlled laboratory conditions. Rack oven performance is characterized by preheat duration and energy con-sumption, idle energy rate, steam performance, baking energy rate and effi-ciency, production capacity, and browning uniformity. The oven was tested using two different food products—frozen apple pies and white sheet cakes.

Oven steam performance is defined as the oven’s ability to consistently pro-vide sufficient steam for baking crusty breads. The steam performance of the Hobart HBA2G double rack oven was monitored over five successive steam cycles conducted at 15-minute intervals. The results of the steam performance are summarized in Figure ES-1.

Baking-energy efficiency is a measure of how much of the energy that an ap-pliance consumes is actually delivered to the frozen pies during the baking process. Baking-energy efficiency is therefore defined by the following rela-tionship:

× 100%E pies+ E pans E oven Baking-Energy Efficiency % =

Executive Summary

5011.06.14 iv Food Service Technology Center

A summary of the preheat, idle and baking test results is presented in Table ES-1.

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Table ES-1. Summary of the Hobart HBA2G Rack Oven Performance.

Rated Energy Input Rate (Btu/h) 300,000

Measured Energy Input Rate (Btu/h) 297,645

Preheat to 400°F:

Preheat Time (min) 22.3

Preheat Energy (Btu) 71,387

Idle Energy Rate @ 400°F (Btu/h) 32,320

Idle Fan/Control Energy Rate (kW) 1.07

Baking-Energy Efficiency (%) 55.7 ± 1.0

Production Capacity (lb/h) 287.6 ± 4.6

Figure ES-1. Hobart HBA2G steam performance.

Executive Summary

5011.06.14 v Food Service Technology Center

Hobart’s HBA2G double rack oven performed well during controlled labora-tory testing, exhibiting a competitive 55% baking-energy efficiency and a 288 lb/h production capacity. The oven’s consistent and repeatable steam genera-tion stands up to high-volume baking while delivering enough steam to ensure a quality baked product.

With the results obtained from the application of the laboratory test, the an-nual expenditures associated with its operation can be estimated. For this model, the rack oven was used to bake 1,200 pounds of food over a 12-hour day, with one preheat per day, 365 days a year. At $1.20/therm and $0.10/kWh, the Hobart HBA2G double rack oven would have an annual oper-ating cost of $4,044 under this scenario.

1 Introduction

5011.06.14 1-1 Food Service Technology Center

Dedicated to the advancement of the food service industry, the Food Service Technology Center (FSTC) has focused on the development of standard test methods for commercial food service equipment since 1987. The test meth-ods, approved and ratified by the American Society for Testing and Materials (ASTM), allow benchmarking of equipment such that users can make mean-ingful comparisons among available equipment choices.

The primary component of the FSTC is a 10,000 square-foot appliance labora-tory equipped with energy monitoring and data acquisition hardware, 60 lin-ear feet of canopy exhaust hoods integrated with utility distribution systems, appliance setup and storage areas, and a state-of-the-art demonstration and training facility. End-use customers and commercial appliance manufacturers consider the FSTC to be the national leader in commercial food service equipment testing and standards, sparking alliances with several major chain customers to date.

Roll-in rack ovens offer high volume production and even baking in a rela-tively compact footprint. A single rack oven typically accommodates 15 pans of product at a time, effectively replacing three full-size convection ovens; a double rack oven can bake 30 pans of product at a time. These large capacity ovens fill the requirements of high-volume retail and baking operations. They are also ideal for rethermalizing many products prepared in cook/chill systems as well as baking and roasting. The rack oven is capable of producing thou-sands of identical products or many diverse menu items within the same cook-ing cavity.

The glossary in Appendix A is provided so that the reader has a quick refer-ence to the terms used in this report.

Background

Introduction


The objective of this report is to examine the operation and performance of the Hobart, Model HBA2G, gas double-rack oven under the controlled labora-tory test conditions. The scope of this testing is as follows:

1. Verify that the rack oven is operating at the manufacturer’s rated energy input.

2. Determine the time and energy required to preheat the rack oven from room temperature to 400°F.

3. Determine the idle energy rate with the rack oven set to maintain 400°F in the baking chamber.

4. Characterize the rack oven’s ability to produce steam during successive baking cycles.

5. Document the rack oven’s browning uniformity using white sheet cakes.

6. Document the baking-energy consumption and baking-energy efficiency using frozen apple pies as the test product.

7. Determine the baking time and production capacity.

8. Estimate the annual operating cost for the rack oven using a standard cost model.

The Hobart HBA2G double-rack oven features stainless steel interior and ex-terior construction, a 300,000 Btu/h in-shot burner system with a weldless tubular stainless steel heat exchanger, a self-contained steam generator and a digital control panel. A single-point connection provides venting for the inte-grated eyebrow hood, burner system and oven cavity. The integrated hood is fully welded and can be connected as either a Type I (heat and vapor) installa-tion, or a Type II (grease) installation. The programmable controls have the capability to store 99 separate menus with up to four separate stages.

Appliance specifications are listed in Table 1-1, and the manufacturer’s litera-ture is in Appendix B. The appliance is pictured in Figure 1-1.

Objectives

Appliance Description

Introduction


Table 1-1. Appliance Specifications.

Manufacturer Hobart

Model HBA2G

Generic Appliance Type Double-rack gas oven

Rated Input 300,000 Btu/h

Construction Stainless steel exterior and interior

Controls Solid-state programmable controls with a 99 different recipes

Pan Capacity (as tested) 30 full-size (18" x 26") sheet pans

External Dimensions (including hood)

72.0" x 92.5" x 99.5" (w×d×h)

Figure 1-1. The Hobart HBA2G.

2 Methods


In May 2005, the ASTM F26 Committee on food service equipment formed a task group to re-examine the procedures within the ASTM F2093-01 Standard Test Method for the Performance of Rack Ovens1. The task group was charged with simplifying the testing while improving the relevance of the re-sulting performance data. The procedures documented in this report and used for testing the Hobart HBA2G rack oven represent the task group’s recom-mendations to the F26 Committee for a revised version of the ASTM test method.

The double-rack oven was installed in accordance with the manufacturer’s instructions in a conditioned test space. The room was maintained at an ambi-ent condition of 75 ± 5°F during testing. Natural gas consumption was meas-ured with a positive displacement-type gas meter that generated a pulse for every 0.1 ft³ consumed. Motor and control energy were measured with a watt/watt-hour transducer that generated a pulse for each 10 Wh used. Water consumption was measured with an in-line flow sensor installed on the water inlet hose. Oven cavity temperature was monitored with 24 gauge, type K, Teflon insulated thermocouple wire located at the center of the pressure panel outlet. The transducer and thermocouples were connected to a computerized data acquisition unit that recorded data every 5 seconds. Figure 2-1 shows the Hobart double-rack oven instrumented with the data acquisition system.

The energy input rate was determined by turning the oven on and measuring the energy consumed from the time the oven first began operating until the time when the elements or steam generator first cycled off. The energy con-sumed and the time elapsed were used to calculate the maximum energy input

Setup and Instrumentation

Energy Input Rate and Thermostat Calibration

Methods


rate. Thermostat calibration was verified by allowing the oven to operate with the thermostat set to the specified operating temperature of 400°F for a period of one hour and then monitoring the oven cavity temperature for a period of thirty minutes. If the average oven temperature during the thirty minutes was more than 405°F or less than 395°F, the controls were adjusted, the oven was allowed to re-stabilize at the new temperature for a period of one hour, and the cavity temperature was again monitored for a period of thirty minutes. This process was repeated until the oven temperature was within 400 ± 5°F.

The preheat test recorded the time and energy required for the oven to in-crease the cavity temperature from 75 ± 5°F to a temperature of 390°F. Re-cording began when the oven was first turned on, so any time delay before the ignition of the burner was included in the test. Although the specified operat-

Figure 2-1. The Hobart HBA2G oven instrumented for testing.

Preheat and Idle Tests

Methods


ing temperature is 400°F, research at the Food Service Technology Center has indicated that a rack oven is sufficiently preheated and ready to cook when the oven temperature is within 10°F of the oven set point.

After the oven was preheated, it was allowed to stabilize for two hours, and then idle energy was monitored for a 3-hour period.

The steam performance test consisted of five successive baking cycles at 15-minute intervals. The rack oven was stabilized at 400°F for a minimum of two hours and the steam injection time set to manufacturer specifications for crusty bread. Water consumption and runoff were measured and recorded for each cycle. The amount of steam produced for each cycle was determined as the difference between the water into the oven and the runoff collected from the oven drain.

The baking-energy efficiency and production capacity tests consisted of bak-ing frozen apple pies on full-size sheet pans. The 10-inch ready-to-bake apple pies weighed an average of 3.10 ± 0.15 lb and consisted of a pre-cooked apple based filling (see Figure 2-2).

Three pies were placed on each baking pan and baked from 0 ± 5°F to an av-erage temperature of 185 ± 5°F. Baked pie temperature was measured using a

Steam Performance Test

Baking-Energy Efficiency Tests

Figure 2-2. Cross section of a frozen apple pie.

Methods


rig that held three thermocouples in a straight line across the diameter of the pie and fixed so that the sensing point could be easily located in the middle of the filling (Figure 2-3).

Energy imparted to the frozen pies is the sum of the energy required to raise their temperatures from 0°F to the endpoint (sensible energy), the energy re-quired to melt the frozen water in the pies (fusion energy), and the energy re-quired to vaporize a portion of the water contained in the pies (vaporization energy). The rack oven’s baking-energy efficiency is the amount of energy imparted to the pies, expressed as a percentage of the amount of energy con-sumed by the rack oven during the baking process.

The pie test was applied in triplicate and a statistical analysis of the results was performed to ensure that the reported baking-energy efficiency and pro-duction capacity results had an uncertainty of less than 10%.

Figure 2-3. Thermocouple rig for measuring baked pie temperature.

Methods


The rack oven’s browning uniformity was documented while baking white sheet cakes. For this test, the oven was loaded with 30 full-size sheet pans, each filled with 5 pounds of cake batter. The cakes were considered done when a wood skewer could be inserted into the cakes and removed without any particles adhering to it.

Appendix C contains the ASTM results reporting sheets for this oven.

The oven operating cost was calculated based on a combination of test data and assumptions about typical oven usage. This provides a standard method for estimating oven energy consumption based on ASTM performance test results. The examples contained in the operating cost model are for informa-tional purposes only, and should not be considered an absolute.

The model assumes that the rack oven was used to bake 1,200 pounds of food over a 12-hour day, with one preheat per day, 365 days a year. The idle (standby) time for the oven was determined by taking the difference between the total daily “on” time (12 hours) and the time spent baking and preheating.

Browning Uniformity Tests

Operating Cost Model

3 Results


The energy input rate was measured and compared with the manufacturer’s nameplate value to ensure the rack oven was operating within its specified parameters. The measured energy input rate was 297,645 Btu/h, which was 0.8% lower than the nameplate rate of 300,000 Btu/h, but well within the 5% tolerance of the ASTM test method.

With the thermostat set to an indicated 400°F, the oven temperature at the pressure panel averaged 395°F. Therefore, testing was conducted with the thermostat at an indicated 405°F for all tests, with the exception of the sheet cake test, which was conducted at an indicated temperature of 330°F.

Preheat Energy and Time

The rack oven was instrumented with thermocouples located at the vertical center of each pressure panel in the air outlet to record the oven cavity tem-perature. After stabilizing the oven cavity at room temperature (75 ± 5°F) overnight, the oven was turned on and preheated to 400°F. Elapsed time and energy consumption were recorded during this preheat period. Any time that elapsed before the ignition of the burners was included in the test time. The oven reached 390°F in 22.3 minutes, while consuming 71,387 Btu. Figure 3-1 shows the rack oven’s energy consumption along with the baking cavity tem-perature during this preheat test.

Idle Energy Rate

The idle energy rate represents the energy required to maintain the set tem-perature, or the rack oven’s stand-by losses. After the rack oven had stabilized at 400°F for at least two hours, researchers monitored oven energy for an ad-

Energy Input Rate and Thermostat Calibration

Preheat and Idle Rate Tests

Results


ditional three hours. The idle energy rate during this period was 32,320 Btu/h. Table 3-1 summarizes the results of the input rate, preheat and idle tests.

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450

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44Time (min)

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450Te

mpe

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re (°

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Ene

rgy

Rat

e (k

Btu

/h)

Table 3-1. Input and Preheat and Idle Test Results.

Rated Energy Input Rate (Btu/h) 300,000

Measured Energy Input Rate (Btu/h) 297,645

Preheat to Operational Capacity:

Time (min) 22.3

Gas Energy Consumption (Btu) 71,387

Electric Energy Consumption (Wh) 526

Idle Energy Rate @ 400°F (Btu/h) 32,320

Idle Fan/Control Energy Rate (kW) 1.07

Figure 3-1. HBA2G preheat characteristics.

Results


The rack oven’s ability to produce steam repeatedly was determined by run-ning five successive steam cycles at 15-minute intervals. The interval was chosen as representative of a high-volume bakery baking 4-loads of bread per hour. Since many bakers consider ample steam at the start of the bake an es-sential requirement for a hard, shiny crust, the ability of the oven to produce sufficient steam from one bake cycle to the next is an important parameter to an operator. Table 3-2 and Figure 3-2 summarize the results of the steam per-formance tests.

Table 3-2. Steam Performance Test Results.

Cycle number 1 2 3 4 5

Water injection time (sec) 10 10 10 10 10

Volume of water delivered (gal) 0.57 0.55 0.56 0.57 0.56

Volume of Runoff (gal) 0.00 0.00 0.00 0.00 0.00

Volume of steam delivered (gal) 0.57 0.55 0.56 0.57 0.56

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Steam Performance Test

Figure 3-2. HBA-2G Steam produc-tion & repeatability.

Results


Two different food products were baked in the Hobart rack oven: frozen apple pies and sheet cakes. The frozen pies represented a heavy load on the oven due to large thermal mass, while the sheet cakes represented a medium load on the oven and provided distinct browning characteristics. Thirty full-size sheet pans were used for both sets of baking tests. Bake time, oven tempera-ture and oven energy consumption were monitored during these tests.

Pie Tests

The rack oven was tested with a full load (30 pans) of frozen apple pies. The pie test was designed to reflect a rack oven’s maximum performance. The large frozen load would drive down the cavity temperature and challenge the oven to recover after loading the pies. The Hobart double rack oven baked a full-load of pies in 55.0 minutes, while consuming 106,730 Btu.

Baking-energy efficiency is defined as the quantity of energy consumed by the food and pans expressed as a percentage of energy consumed by the oven during the cooking test:

Energy imparted into the pies was calculated by separating the various com-ponents of the apple pies (water, fat, solids) and determining the amount of heat absorbed by each component during the baking process. Baking-energy efficiency results for the frozen pie tests were 55.3%, 56.1% and 55.6%, yielding an uncertainty of 1.7% in the test results. Table 3-2 summarizes the results of the frozen pie tests. Appendix D contains a synopsis of test data for each replicate of the cooking tests.

Baking Tests

× 100%E pies + E pans E oven Baking-Energy Efficiency % =

Results


Table 3-3. Frozen Apple Pie Test Results.

Pies per Load 90

Bake Time (min) 55.0

Baking Energy Rate (Btu/h) 118,760

Fan/Control Energy Rate (kW) 1.28

Oven Energy Consumption (Btu/lb)

Production Capacity (lb/h) 287.6 ± 4.6

Baking-Energy Efficiency (%) 55.7 ± 1.0

Sheet Cake Test

White sheet cakes provide a visual indication of the temperature uniformity of an oven while baking. The bake time was experimentally determined so that the cakes were uniformly cooked while exhibiting the greatest possible differ-ences in color. In any oven, one can expect variations in color and texture from rack to rack, especially in the top location, since this area of the oven is usually the hottest. The final cook time that produced the most uniform batch of sheet cakes was determined to be 20.0 minutes. The results of the test are described below and visual representations of the browning are shown in Fig-ures 3-3 through 3-5.

Overall sheet cake browning was consistent from cake to cake. The first and third rack positions were slightly darker than the others. Uniformity across individual cakes was good, with minimal variation in color from center to corners. The photographs in Figures 3-3 through 3-5 show the cakes from the topmost position and two other rack positions that are indicative of the re-mainder of the set.

Results


Figure 3-3 Cakes in top rack position.

Figure 3-4. Cakes in 4th rack posi-tion from top.

Results


With the results obtained from the application of the laboratory test, the an-nual expenditures associated with its operation can be estimated. This guide can be used to project the operating cost of this rack oven based on the hours of operation, the amount of food produced, etc. Consumers can use this tool, along with the performance results to compare this appliance with other mod-els and manufacturers.

For this model, the rack oven was used to bake 1,200 pounds of food over a 12-hour day, with one preheat per day, 365 days a year. The idle (standby) time for the oven was determined by taking the difference between the total daily “on” time (12 hours) and the time spent baking and preheating. This ap-proach produces a more accurate estimate of the operating costs for the rack oven. Table 3-6 summarizes the energy consumption and associated operating cost for the Hobart HBA2G double rack oven under this scenario.

Figure 3-5. Cakes in 11th rack posi-tion from top.

Energy Cost Model

Results


Table 3-4. Annual Cost Model.

Gas (kBtu) a Electricity (kWh)

Daily Preheat Energy 71.4 0.53

Daily Idle Energy 241.1 7.98

Daily Cooking Energy 495.2 5.34

Total Daily Energy 807.7 13.85

Total Operating Cost ($/yr) b $4,044 a 1 kBtu = 1,000 Btu b Oven energy costs are based on $1.20/therm for gas and $0.10/kWh for electricity. (1 therm =100,000 Btu).

4 Conclusions


Hobart’s HBA2G double rack oven performed well during controlled labora-tory testing, exhibiting a competitive 55% baking-energy efficiency and a 288 lb/h production capacity. 2,3 The oven’s consistent and repeatable steam gen-eration stands up to high-volume baking while delivering enough steam to ensure a quality baked product.

The 2001 version of the ASTM test method for rack ovens specifies additional medium (15 pans) and light (2 pans) load tests. 1 After discussions with manu-facturers and end users, it was decided to eliminate these part-load tests since they were considered not representative of a typical real-world operation. Eliminating the unnecessary light and medium-load tests significantly short-ened the overall testing, while providing data that could be used to model oven energy consumption and cost.

Preheat and idle were simplified by reducing the stabilization time from 4 hours per the 2001 version of the ASTM test method to 2 hours. The Hobart oven was ready to bake in less than 20 minutes, consuming 71,387 Btu of natural gas and 0.53 kWh of fan energy. During idle at 400°F, the oven con-sumed 32,320 Btu/h and 1,100 watts for the fan.

With the results obtained from the application of the laboratory test, the an-nual expenditures associated with its operation can be estimated. For this model, the rack oven was used to bake 1,200 pounds of food over a 12-hour day, with one preheat per day, 365 days a year. At $1.20/therm and $0.10/kWh, the Hobart HBA2G double rack oven would have an annual oper-ating cost of $4,044 under this scenario.

Based on the results of testing the Hobart HBA2G double-rack oven, it is rec-ommended that the simplified test procedure used for testing the Hobart

Conclusions

5011.06.ro 4-2 Food Service Technology Center

HBA2G double rack oven replace the existing cumbersome procedure in the ASTM standard test method.

5 References


1. American Society for Testing and Materials, 2001. Standard Test Method for the Performance of Rack Ovens. ASTM Designation F2093–01. In annual book of ASTM Standards, West Conshohocken, PA.

2. Zabrowski, D., Sorensen, G., 2006. Lang BakerSeries® Gas Double-Rack Oven Performance Test. Food Service Technology Center Report 5011.06.04, March.

3. Zabrowski, D., Sorensen, G., 2006. Revent, Model 724U Gas Double-Rack Oven Performance Test. Food Service Technology Center Report 5011.06.07 draft, June.

A Glossary

5011.06.14 A-1 Food Service Technology Center

Baking Energy (kWh or kBtu)

The total energy consumed by an appliance as it is used to bake a specified food product.

Baking Energy Consumption Rate (kW or kBtu/h)

The average rate of energy consumption during the bak-ing period.

Baking-Energy Efficiency (%)

The quantity of energy input to the food product; ex-pressed as a percentage of the quantity of energy input to the appliance during the baking tests.

Duty Cycle (%) Load Factor

The average energy consumption rate (based on a speci-fied operating period for the appliance) expressed as a percentage of the measured energy input rate.

Duty Cycle = RateInput Energy Measured

Rate nConsumptioEnergy Average x 100

Energy Input Rate (kW or kBtu/h) Energy Consumption Rate Energy Rate

The peak rate at which an appliance will consume en-ergy, typically reflected during preheat. Heating Value (Btu/ft3) Heating Content

The quantity of heat (energy) generated by the combus-tion of fuel. For natural gas, this quantity varies depend-ing on the constituents of the gas.

Idle Energy Rate (kW or Btu/h) Idle Energy Input Rate Idle Rate

The rate of appliance energy consumption while it is “holding” or maintaining a stabilized operating condition or temperature. Idle Temperature (°F, Setting)

The temperature of the cooking cavity/surface (selected by the appliance operator or specified for a controlled test) that is maintained by the appliance under an idle condition. Idle Duty Cycle (%) Idle Energy Factor

The idle energy consumption rate expressed as a per-centage of the measured energy input rate.

Idle Duty Cycle = RateInput Energy MeasuredRate nConsumptioEnergy Idle

x 100

Measured Input Rate (kW or Btu/h) Measured Energy Input Rate Measured Peak Energy Input Rate

The maximum or peak rate at which an appliance con-sumes energy, typically reflected during appliance pre-heat (i.e., the period of operation when all burners or elements are “on”). Preheat Energy (kWh or Btu) Preheat Energy Consumption

The total amount of energy consumed by an appliance during the preheat period. Preheat Rate (°F/min)

The rate at which the oven cavity heats during a preheat.

Glossary

5011.06.14 A-2 Food Service Technology Center

Preheat Time (minute) Preheat Period

The time required for an appliance to heat from the am-bient room temperature (75 ± 5°F) to a specified (and calibrated) operating temperature or thermostat set point.

Production Capacity (lb/h)

The maximum production rate of an appliance while cooking a specified food product in accordance with the heavy-load cooking test.

Rated Energy Input Rate (kW, W or Btu/h, Btu/h) Input Rating (ANSI definition) Nameplate Energy Input Rate Rated Input

The maximum or peak rate at which an appliance con-sumes energy as rated by the manufacturer and specified on the nameplate.

Test Method

A definitive procedure for the identification, measure-ment, and evaluation of one or more qualities, character-istics, or properties of a material, product, system, or service that produces a test result. Typical Day

A sampled day of average appliance usage based on observations and/or operator interviews, used to develop an energy cost model for the appliance.

B Appliance Specifications

5011.06.14 B-1 Food Service Technology Center

Appendix B includes the product literature for the Hobart HBA2G gas-fired double-rack oven.

Item # _____________________________________

Quantity ___________________________________

C.S.I. Section 11400

F-40014 – HBA2G Double Rack Oven – Gas Page 1 of 2

HBA2G DOUBLE RACK OVEN – GAS701 S Ridge Avenue, Troy, OH 45374

1-888-4HOBART • www.hobartcorp.com

HB

A2G

DO

UB

LE R

AC

K O

VE

N – G

AS

MODEL❑ HBA2G – Double Rack Oven, Gas

OPTIONS

❑ Back-up control

❑ Propane gas

❑ Floor extender kit

❑ Shipped assembled (less canopy/steam system)

❑ Aluminum or stainless steel oven racks

❑ High output 350,000 BTU burner system

❑ Dual vent to provide for separate vent connection for hood and combustion flue

❑ Hood with grease filters (complies with NFPA 96 for Type I installations)

❑ Narrow viewing glass (10" W x 57.5" H)

❑ “C” style rack lift

❑ Kosher package

❑ 50 Hz available, consult factory for details

Specifications, Details and Dimensions on Back.

STANDARD FEATURES■ Advanced digital programmable control panel

includes: - Bake/steam timers - Cool-down mode - Vent mode - Four stage baking - Auto on/off control - Auto vent - 99 menus - Energy saving sleep mode

■ 300,000 BTU in-shot burner system

■ High-temp stainless steel tubular heat exchanger with weldless construction for longer life

■ Heavy duty rack lift includes high-temp bearings and slip clutch soft start rotation system

■ Stainless steel interior and exterior construction

■ Shipped in two main sections for ease of installation

■ Flush floor with patented adjustable floor construction provides easy access - no ramp required

■ Field reversible bake chamber door

■ Fully welded hood for Type II installation

■ Space saving 72" wide x 62" deep footprint (less canopy)

■ Wide viewing glass (21" W x 57.5" H) with triple pane glass for reduced heat loss and cooler working area in front of oven

■ Self-contained cast spherical steam system

■ Pre-plumbed gas and water lines

■ Built-in rollers and levelers for ease of installation

■ Single point 8" vent connection

■ Stainless steel “B” style rack lift

■ Capacity - two single racks or one double rack

■ One year parts/labor warranty

701 S Ridge Avenue, Troy, OH 453741-888-4HOBART • www.hobartcorp.com

Page 2 of 2 F-40014 – HBA2G Double Rack Oven – Gas

As continued product improvement is a policy of Hobart, specifications are subject to change without notice.

Printed On Recycled Paper

HBA2G DOUBLE RACK OVEN – GAS

F-40014 (REV. 3/06) LITHO IN U.S.A. (H-01)

SPECIFICATIONS

Front View Side View Top View

1. Water—1⁄2" NPT. Cold water @ 30 psi. (207 kPa) minimum @ 4.5 GPM (.29 liters/sec) flow rate.

2. Drain—Choose either rear or front drain and plug the drain connection that is not in use. Route to air-gap drain.

Rear drain: 3⁄4" FNPT; resides 5.5" from floor; Kit is provided to extend drain to left or right side of oven.

Front drain: 3⁄8" FNPT; resides 2" from floor.3. Gas—11⁄4" NPT. Connect Point

Gas Input Rate Supply Pressure(flowing)

StandardNatural Gas 300,000 BTU/hr.

(88 kJ/s)5-14" w.c.(1.25-3.5 kPa)

Propane Gas 300,000 BTU/hr.(88 kJ/s)

10-14" w.c.(2.5-3.5 kPa)

OptionalNatural Gas 350,000 BTU/hr.

(102 kJ/s)6-14" w.c.(1.5-3.5 kPa)

Propane Gas 350,000 BTU/hr.(102 kJ/s)

12-14" w.c.(3.0-3.5 kPa)

4. Electrical—2 supplies required. 1) 120/60/1. 20 amp dedicated circuit.

2) 208-230/60/3 4.4-4.2 amps 220/60/1 6.8 amps 460/60/3 2.1 amps 5. Hood Vent—8" diameter connection collar. Minimum 750 cfm

(21.3 m3/min) required with 0.6" w.c. (150 Pa) static pressure drop through hood. Hood is fully welded. Customer to supply duct and ventilator fan per local code. Air proving switch factory installed and integrated with burner system operation. Oven provided relay with max. 6.0 amp 1⁄3 H.P. @ 120V output for fan operation.

NOTES

1. The purchaser is responsible for all installation costs and for providing: Disposal of packing materials; labor to unload oven upon arrival; installation mechanics; and all local service connections including electricity, vents, gas, water and drain per local code. A factory technician or factory authorized installation technician must supervise and approve any installation. In order to validate the warranty, the start-up must be performed by an Authorized Servicer.

2. All services must comply with federal, state and local codes.3. CAUTION – To reduce the risk of fire, the appliance is to be

mounted on floors of non-combustible construction with non-combustible flooring and surface finish and with no combustible material against the underside thereof, or on non-combustible slabs or arches having no combustible material against the underside. IMPORTANT: Do not route utilities (wiring, plumbing, etc.) in or under the non-combustible floor beneath the oven.

4. For proper installation, floor should be level within 1⁄8" per foot not to exceed 3⁄4". Floor anchors require minimum of 1" thick solid floor substrate.

5. Minimum clearances to combustible construction: 0 inches from sides and back; 18" from top (99.5"). 10 feet minimum ceiling height for service access and filt up for installation.

6. Ventilator fan is required. Consult local authorities to determine whether TYPE 1 (grease) or TYPE 2 (vapor) duct will be required. Hood connection suitable for connection to Type B vent, except when products of baking are grease laden.

7. Actual weight: 3,520 lbs.; Shipping weight: 4,150 lbs. (freight class 70)

SECTION W x D x H (CRATED) PALLET WGT./CU. FT. W x D x H (ACTUAL)Heating 70" x 107" x 48" 2046 lb. / 203.7 36" x 62" x 104"Bake 70" x 107" x 48" 1488 lb. / 203.7 36" x 62" x 104"Hood 22" x 97" x 41" 345 lb. / 46.0 18" x 72" x 31"Door 11" x 78" x 50" 265 lb. / 23.5 44.5" x 5" x 74"

DETAILS AND DIMENSIONSHighest Point on Oven—104.0" (264.2 cm)

1 Water

2 Drain

3 Gas

4 Electrical

5 Hood Vent

C Results Reporting Sheets

5011.06.14 C-1 Food Service Technology Center

Manufacturer: Hobart Model: HBA2G Date: January 2006 Test Rack Oven

Description of operational characteristics:

The Hobart HBA2G double-rack oven features stainless steel interior and exterior construction, a 300,000 Btu/h in-shot burner system with a weldless tubular stainless steel heat exchanger, an integrated eyebrow hood with a sin-gle- point exhaust connection, a heavy-duty rack lift mechanism, and a programmable digital control panel. The program- able controls have the capability to store 99 separate menus with up to four stages. Description of steam generator:

Steam is produced using a self-contained cast spherical steam system. Cold water is sprayed onto the hot iron mass and immediately flashed into steam.

Apparatus

√ Check if testing apparatus conformed to specifications in Section 6. Energy Input Rate

Gas Heating Value (Btu/ft3) 1019 Measured (Btu) 297,645 Rated (Btu) 300,000 Percent Difference between Measured and Rated (%) 0.8 Thermostat Calibration

As-Received: Oven Temperature Control Setting (°F) 400 Oven Cavity Temperature (°F) 395 As-Adjusted: Oven Temperature Control Setting (°F) 405 Oven Cavity Temperature (°F) 400

Results Reporting Sheets


Preheat Energy and Time

Gas Heating Value (Btu/ft3) 1013 Starting Temperature (°F) 71.0 Energy Consumption (Btu) 71,387 Electric Energy Consumption (Wh) 526 Duration (min) 22.3 Preheat Rate (°F/min) 14.3

0

50

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44Time (min)

0

50

100

150

200

250

300

350

400

450

Tem

pera

ture

(°F)

Gas

Ene

rgy

Rat

e (k

Btu

/h)

Preheat Curve Idle Energy Rate

Gas Heating Value (Btu/ft3) 1030 Idle Energy Rate (Btu/h) 32,320 Electric Energy Rate (kW) 1.07



Browning Uniformity (White Sheet Cakes)

Description of sheet cake browning:

Overall sheet cake browning was consistent from cake to cake. The first and third rack positions were slightly darker

than the others. Uniformity across individual cakes was good, with minimal variation in color from center to corners.

Gas Heating Value (Btu/ft3) 1017 Initial Cake Temperature (°F) 68.6 Final Cake Temperature (°F) 196.4 Sheet Cake Bake Time (min) 20.0 Sheet Cake Baking Energy (Btu) 37,840 Electric Energy (Wh) 440

The following photographs show the cakes from the topmost position and two other rack positions that are indicative of

the remainder of the set.

Rack Position: 1st (Top)



Rack Position: 4th from Top

Rack Position: 11th from Top



Steam Performance:

Cycle #1 Cycle #2 Cycle #3 Cycle #4 Cycle #5

Water injection time (sec) 10 10 10 10 10

Volume of water delivered per cycle (gal) 0.57 0.55 0.56 0.57 0.56

Volume of Runoff per cycle (gal) 0.00 0.00 0.00 0.00 0.00

Volume of steam delivered each cycle

(gal)

0.57 0.55 0.56 0.57 0.56

Baking Energy Efficiency, Baking Energy Rate and Production Capacity

Gas Heating Value (Btu/ft3) 1025.3 Baking Time (min) 55.0 Production Capacity (lbs/h) 287.6 ± 4.6 Energy To Food (Btu/lb) 224 Baking Energy Rate (Btu/h) 118,760 Electric Energy Rate (kW) 1.28 Energy per Pound of Food Cooked (Btu/lb) 428 Baking Energy Efficiency (%) 55.7 ± 1.0

D Baking-Energy Efficiency Data

5011.06.14 D-1 Food Service Technology Center

Table D-1. Specific Heat and Latent Heat.

Specific Heat (Btu/lb, °F) Apple Pies 0.63 Aluminum (Sheet pans) 0.20

Latent Heat (Btu/lb) Fusion, Water 144 Vaporization, Water 970

Baking-Energy Efficiency Data


Table D-1. Full-Load Pie Test Data

Replication 1 Replication 2 Replication 3

Measured Values Bake Time (min) 55.0 55.0 55.0 Oven Energy Consumption (Btu) 110,738 106,817 109,031 Fan/Control Energy Consumption (Wh) 1,176 1,178 1,153

Initial Temperature of Frozen Pies (°F) 0.3 3.4 -0.8

Final Temperature of Baked Pies (°F) 185.3 182.9 180.2

Weight of Sheet Pans (lb) 106.3 106.4 106.3

Initial Weight of Raw Frozen Pies (lb) 477.9 476.9 480.2

Final Weight of Baked Pies (lb) 469.2 468.2 471.8

Initial Moisture Content of the Apple Pies (%) 53.7 53.7 53.7

Calculated Values Initial Weight of Water (lb) 141.5 140.9 142.7

Weight Loss During Baking (lb) 8.7 8.6 8.4

Sensible Heat (Btu) 30,695 29,645 30,276

Latent – Heat of Fusion (Btu) 20,379 20,285 20,545

Latent – Heat of Vaporization (Btu) 8,439 8,381 8,167

Total Energy to Food (Btu) 59,513 58,311 58,989 Energy to Food (Btu/lb) 226 222 222 Energy to Pans (Btu) 3,933 3,820 3,848

Total Energy Consumed by the Rack Oven (Btu) 114,752 110,837 112,966 Energy to Oven (Btu/lb of food produced) 436 423 425

Results Baking Energy Rate (Btu/h) 120,805 116,527 118,943 Fan/Control Energy Rate (kW) 1.28 1.29 1.26 Baking-Energy Efficiency (%) 55.3 56.1 55.6 Production Capacity (lb/h) 287.3 286 289.6

Baking-Energy Efficiency Data


Table D-2. Baking-Energy Efficiency and Production Capacity Statistics.

Baking-Energy Efficiency Production Capacity

Replicate #1 55.3 287.3

Replicate #2 56.1 286.0

Replicate #3 55.6 289.6 Average 55.7 287.6 Standard Deviation 0.38 1.86

Absolute Uncertainty 0.95 4.60

Percent Uncertainty 1.7 1.60

E Energy Cost Model

5011.06.14 E-1 Food Service Technology Center

Appliance test results are useful not only for benchmarking appliance performance, but also for estimating

appliance energy consumption. The following procedure is a guideline for estimating rack oven energy con-

sumption based on data obtained from applying the appropriate test method.

The intent of this Appendix is to present a standard method for estimating oven energy consumption based

on ASTM performance test results. The examples contained herein are for information only and should not be

considered an absolute. To obtain an accurate estimate of energy consumption for a particular operation, pa-

rameters specific to that operation should be used (e.g., operating time, and amount of food cooked under

heavy-, medium-, and light-loads).

The appropriate oven performance parameters are obtained from section 11 in the test method.

The calculation will proceed as follows: First, determine the appliance operating time and total number of

preheats. Then estimate the quantity of food baked during the day. Calculate the energy due to baking, using

full-load equivalent baking hours and calculate the idle energy consumption. The total daily energy is the sum

of these components plus the preheat energy. For simplicity, it is assumed that subsequent preheats require the

same time and energy as the first preheat of the day.

Application of the test method to the Hobart HBA2G gas rack oven yielded the following results:

Energy Cost Model


Table E.1: Hobart HBA2G Gas Double-Rack Oven Test Results.

Preheat Time 22.3 min Preheat Energy 71,387 Btu + 0.53 kWh Idle Energy Rate 32,320 Btu/h + 1.07 kW Heavy-Load Baking Energy Rate 118,760 Btu/h + 1.28 kW Heavy-Load Production Capacity 288 lb/h

Step 1—The following appliance operation is assumed:

Table E.2: Oven Operation Assumptions.

Operating Time 12 h Number of Preheats 1 preheat Total Amount of Food Cooked 1,200 lb

Step 2—Calculate the total heavy-load baking energy.

The total time cooking heavy-loads is as follows:

PC

Wht = ,

lb/h 288lb 1,200

ht = ,

th = 4.17 h

The total heavy-load energy consumption is then calculated as follows:

Egas,h = qgas,h × th, Eelec,h = qelec,h × th,

Egas,h = 118,760 Btu/h × 4.17 h, Eelec,h = 1.28 kW × 4.17 h,

Egas,h = 495,229 Btu Eelec,h = 5.34 kWh

Energy Cost Model


Step 3—Calculate the total idle time and energy consumption.

The total idle time is determined as follows:

60tn pp×

−−= honi ttt ,

min/h 60

min 22.3preheat 1h 4.17h 12.0it ×−−=

ti = 7.46 h

The idle energy consumption is then calculated as follows:

Egas,i = qgas,i × ti, Eelec,i = qelec,i × ti,

Egas,i = 32,320 Btu/h × 7.46 h Eelec,i = 1.07 kW × 7.46 h

Egas,i = 241,107 Btu Eelec,i = 7.98 kWh

Step 4—The total daily energy consumption is calculated as follows:

Egas,daily = Egas,h + Egas,i + np × Egas,p,

Egas,daily = 495,229 Btu + 241,107 Btu +1 × 71,387 Btu

Egas,daily = 807,723 Btu/day = 8.08 therms/day

Eelec,daily = Eelec,h + Eelec,i + np × Eelec,p,

Eelec,daily = 5.34 kWh +7.98 kWh +1 × 0.53 kWh

Eelec,daily = 13.85 kWh/day

Step 5—Calculate the average demand as follows:

q Et

avgelec daily

on=

,,

h 12.0

kWh 13.85avgq = ,

qavg = 1.15 kW

Energy Cost Model


Step 6—The estimated yearly appliance energy cost may be determined as follows:

op

thermBtu

dailygas, gasyearlygas, d C

100,000

E r ×= ×

yrdays

thermBtudayBtu

therm$

yearly gas, 365 100,000

807,723 $1.20 C ××=

$3,538 C yearly gas, =

opdailyelec,elecyearly elec, d E r C ××=

yrdays

daykWh kWh

$yearly elec, C 36513.85$0.10 ××=

$506 yearly elec,C =

Documents

Hobart HBA2G Rack Oven Report - FSTC · Browning Uniformity Tests ... 2-2 Cross section of a frozen apple pie ... Document the rack oven’s browning uniformity using white