et10sce1311 hot food holding cabinets fwe hlc-2125-5 final ho… · the insulated cabinet utilizes...

Design & Engineering Services

Hot Food Holding Cabinets Test for FWE HLC-2125-5 ET10SCE1311 Report

Prepared by:

Design & Engineering Services Customer Service Business Unit Southern California Edison

January 4, 2011

Hot Food Holding Cabinets Test for FWE HLC-2125-5 ET10SCE1311

Southern California Edison Page ii Design & Engineering Services January 2011

Acknowledgements

Southern California Edison’s Design & Engineering Services (DES) group is responsible for this project. It was developed as part of Southern California Edison’s Emerging Technology program under internal project number ET10SCE1310.1 DES project manager Neha Arora conducted this technology evaluation with overall guidance and management from Juan Menendez and Paul Delaney. For more information on this project, contact [email protected].

Disclaimer

This report was prepared by Southern California Edison (SCE) and funded by California utility customers under the auspices of the California Public Utilities Commission. Reproduction or distribution of the whole or any part of the contents of this document without the express written permission of SCE is prohibited. This work was performed with reasonable care and in accordance with professional standards. However, neither SCE nor any entity performing the work pursuant to SCE’s authority make any warranty or representation, expressed, or implied, with regard to this report, the merchantability or fitness for a particular purpose of the results of the work, or any analyses, or conclusions contained in this report. The results reflected in the work are generally representative of operating conditions; however, the results in any other situation may vary depending upon particular operating conditions.


Southern California Edison Page i Design & Engineering Services January 2011

ABBREVIATIONS AND ACRONYMS ASTM American Society for Testing and Materials

BTU British Thermal Unit

CFM Cubic Feet Per Minute

CT Current Transformers

DAS Data Acquisition System

F Fahrenheit

ft Feet

FTC Foodservice Technology Center

in Inches

kW Kilowatt

kWh Kilowatt Hour

lb Pound

NEMA National Electrical Manufacturers Association

SCE Southern California Edison

VAR Volt-Ampere Reactive


Southern California Edison Page ii Design & Engineering Services January 2011

FIGURES Figure 1. FWE HOT Food Holding Cabinet ........................................ 3

Figure 2. DAS Interface With National Instruments LabVIEW ............. 5

Figure 3. Cavity Thermocouple Installation ........................................ 7

Figure 4. Preheat Characteristics .................................................. 8

TABLES Table 1. Summary of FWE TST-16-EPL Hot Food Holding Cabinets ...... 1

Table 2. Energy Input Rate .......................................................... 8

Table 3. Preheat and Idle Energy Rate .......................................... 9

EQUATIONS EQUATION 1. ENERGY INPUT RATE ........................................................ 6

Equation 2. Energy Consumption (Idle Energy Rate) ....................... 6


Southern California Edison Page iii Design & Engineering Services January 2011

CONTENTS EXECUTIVE SUMMARY _______________________________________________ 1

INTRODUCTION ____________________________________________________ 2 Background ........................................................................... 2

Objective .............................................................................. 2

Appliance Evaluated ............................................................... 3

TEST METHODOLOGY _______________________________________________ 4 Laboratory and Instrumentation Description ............................... 4

Thermostat Calibration ............................................................ 5

Energy Input Rate .................................................................. 6

Preheat and Idle Energy Rate ................................................... 6

RESULTS _________________________________________________________ 7 Thermostat Calibration ............................................................ 7

Figure 3. Cavity Thermocouple Installation ................................... 7

Energy Input Rate .................................................................. 7

Preheat and Idle Energy Rate ................................................... 8

CONCLUSION ____________________________________________________ 10

APPENDIX A _____________________________________________________ 11

REFERENCES _____________________________________________________ 13


Southern California Edison Page 1 Design & Engineering Services January 2011

EXECUTIVE SUMMARY The hot food holding cabinet is widely used and is a versatile piece of equipment generally used in commercial kitchens. These cabinets are mostly used to; keep food at a safe serving temperature; keep serving plates warm, and to transport food for catering events. In addition, these hot food holding cabinets are lightweight for easy moving, yet strong enough for everyday use.

These cabinets can be plugged into any wall outlet and sit on large wheels for easy mobility. The insulated cabinet utilizes magnetic door gaskets, auto door closers etc that provides additional energy saving attributes to these cabinets.

This project assesses the energy efficiency level of the FWE model number HLC2125-5-EPL hot food holding cabinet to determine an appliance baseline and a minimum energy efficiency level in order to qualify for the food service qualifying product list. This project also assesses the energy input rate, amount of energy consumed during holding cabinet preheating and idle energy rate. This test method was based on the reapproved version of ASTM F2140-01 (revised July 23, 2010) “Standard Test Method for Performance of Hot Food Holding Cabinets”.

Testing was performed at the Southern California Edison (SCE) Foodservice Technology Center (FTC) in Irwindale, CA. The test data provides key information to help determine the operation costs and the percentage of total kitchen productivity a single appliance can deliver.

Testing for the idle energy rate or energy consumption began after preheating the cabinet and stabilized at 150° Fahrenheit (F) for two hours after inserting sheet pans at a predetermined position in the cabinet. The preheat test is the measure of energy consumed by the equipment in order to reach a temperature of 150°F, from a room temperature of 75 ± 2.5°F. The idle energy test reports the energy required to maintain a 150°F setpoint for a period of three hours or ten thermal cycles (whichever is longer). Idle energy consumption can be used to calculate real-world energy usage of the equipment. Table 1 presents a summary of the test results.

TABLE 1. SUMMARY OF FWE HLC2125-5-EPL HOT FOOD HOLDING CABINETS

HOLDING CABINET

RESULTS

Nameplate Power (kW) 1.05 kW

Measured Power (kW) 1.04 kW

Percent Difference (%) 1.2%

Preheat Time (min.) 9.03 min

Preheat Energy (kWh) 0.154 kWh

Preheat Rate (°F/min) 8.51°F/min

Idle Energy Rate (kW) 0.10 kW

Idle Duty Cycle (%) 9.52 %

Interior Volume (ft3) 5.44 ft3

Idle Volume Efficiency (W/ft3) 18.38 W/ft3



INTRODUCTION The hot food holding cabinet is widely used and is a versatile piece of equipment generally used in commercial kitchens. These cabinets are mostly used to; keep food at a safe serving temperature; keep serving plates warm, and to transport food for catering events. In addition, these hot food-holding cabinets are lightweight for easy mobility, yet strong enough for everyday use.

These cabinets can be plugged into any wall outlet and use large wheels for easy mobility. The insulated cabinet uses magnetic door gaskets, and auto door closers that provide additional energy saving attributes.

This project assesses the energy input rate, amount of energy consumed during hot food holding cabinet preheating and idle energy rate. These parameters provide real world performance, providing end users with valuable information for purchasing and operating the hot food holding cabinets.

BACKGROUND Southern California Edison (SCE) is committed to the advancement of the food service industry and is part of a statewide team offering a food service qualifying product list. The qualifying product list identifies the most efficient commercial kitchen appliances within a specific appliance category. The qualifying appliances are eligible to receive incentives for their use. Currently, hot food holding cabinets are not listed in any of the appliance categories on the food service qualifying list.

OBJECTIVE This project examines the operation and performance of the FWE hot food holding cabinets. The operation and performance of the holding cabinet is evaluated using the American Society for Testing and Materials (ASTM) standard test methods. The intent of this project is to accurately record and represent the energy consumption of these cabinets for long and short-term thermal cycles. The testing examines the:

Energy Input Rate: The peak rate at which a hot food holding cabinet consumes energy, kilowatt (kW).

Preheat Energy: The amount of energy consumed, kilowatt hours (kWh), by the hot food holding cabinets while preheating its cavity from the ambient temperature to the specified thermostat setpoint, with the controls calibrated to the setpoint.

Preheat Rate: The average rate at which the holding cabinet’s cavity is heated from the room temperature to the predefined setpoint.

Preheat Time: Time required by the cabinet to preheat from the room temperature to the predefined setpoint.

Idle Energy Rate: The rate of energy consumed (kW) by the cabinets when empty that is required to maintain its cavity temperature at a specified thermostat setpoint.



APPLIANCE EVALUATED Figure 1 shows the FWE HLC-2125-5 hot food holding cabinet. It is comprised of heliarc welded, single unit, 20-gauge polished exterior stainless steel walls with 22- gauge stainless steel interior. The holding cabinet has a radiant heat system that includes an incoloy nickel-chromium alloy heating element. The holding cabinet has a maximum holding temperature of 190° Fahrenheit (F). The interior has a nominal depth of 28” (inches), a nominal width of 21.0” and a nominal height of 16.0”. The chamber doors are flush mounted, double pan, stainless steel doors that has 1” thick fiberglass insulation. The temperature control have temperature scale marked in ten degree increments from 90oF to 190oF, an operational range thermometer, power supply light and a thermostat cycling light. The FWE holding cabinet has a rated electrical input rate of 1.05 kW. Appliance specifications and the manufacturer's literature are included in Appendix A.

FIGURE 1. FWE HOT FOOD HOLDING CABINET



TEST METHODOLOGY Laboratory testing of the FWE hot food holding cabinet was performed according to the ASTM F2140-01(Reapproved 2007)- Revised July 23, 2010 test method for hot food holding cabinets.1 The test data provides key information to determine:

Energy input rate

Preheat energy

Preheat rate and time

Idle energy rate

LABORATORY AND INSTRUMENTATION DESCRIPTION Testing was performed at the SCE Foodservice Technology Center (FTC). The FTC is a 2,000 square-foot demonstration and equipment test center. The center is a part of the Customer Technology Application Center, located in Irwindale, CA. It is a certified ASTM and ENERGY STAR® testing laboratory. The FTC is capable of maintaining voltage regulation to ± 1 volt (V) on a 120-208V 3phase 4 Wire(W) system as well as a 120-240V split single phase, single and three-phase system. Receptacle configurations range from National Electrical Manufacturers Association (NEMA)-20R (20 amperes (A)/120V single-phase) to NEMA 4X and NEMA configuration FB11 (100A/208V/240V single-and three-phase) Receptacle. The FTC is also equipped with a Data Acquisition System (DAS), a National Instruments LabVIEW-based software pictured in Figure 2 used to monitor power (kW), amperage, voltage, power factor, frequency, and volt-ampere reactive (VAR) from all receptacles and display the results in a real-time graph during testing. The electrical consumption of the holding cabinet is logged in intervals of 1 second and the temperature data from 3 thermocouples is recorded. The interface also allows the user to configure the monitoring parameters and select specific monitoring hardware.



FIGURE 2. DAS INTERFACE WITH NATIONAL INSTRUMENTS LABVIEW

The DAS system is equipped with multi-functional digital transducers integrated serial current transformers (CTs) and voltage leads. The multi-functional digital transducer Data Stream RS485 detects power readings using CT and voltage inputs and has an accuracy of ± 0.5% over the full-scale readings. The CTs used in this project are accurate to 10% FS or better and have a frequency response ranging from 44 Hz to 3000 kHz. DAS system uses Omega K type thermocouples and connectors. The K type thermocouples can read a temperature range of -328°F to 2,282°F with accuracy of ± 2.2°F or 0.75% of temperature reading above 32°F and 2% of temperature reading below 32°F. A fiberglass insulated 24-gage K type thermocouple was used to determine the cavity temperature of the holding cabinet. The DAS system was calibrated in November 2009.

THERMOSTAT CALIBRATION Thermostat calibration is verified by installing a thermocouple in the geometric center of the cavity. Calibration is necessary since the placement of holding cabinet cavity temperature sensors can differ greatly between varying models and manufacturers. When performing a thermostat calibration, the holding cabinet stabilizes for one hour before taking readings of the cavity thermocouple. After the one-hour idle period, cavity temperatures are recorded at 30-second intervals for a minimum of 60 minutes. If the thermocouple reads an average temperature of 150 ± 5°F for a 60-minute period, then the thermostat is considered calibrated.



ENERGY INPUT RATE The energy input rate is used to confirm proper operation of the hot food holding cabinets and to ensure that all test results are determined at the same temperature. The energy input rate is the peak energy consumption of the cabinet while preheating the cabinet cavity from ambient temperature to a setpoint of 150°F. The peak energy consumption must be operating within 5% of the nameplate energy input rate. Energy input rate is calculated using EQUATION 1.

EQUATION 1. ENERGY INPUT RATE

60Model E35input

Eq

t

Where:

qinput = measured peak energy input rate, (kW)

E = energy consumed during period of peak energy input, (kWh)

t = period of peak energy input, (min.)

PREHEAT AND IDLE ENERGY RATE The preheat test records the required amount of time and energy needed to raise the holding cabinet cavity temperature from ambient to a safe serving temperature. In this test, the holding cabinet was considered to at a safe serving temperature when the cavity reached 150°F. Once the cavity reached its setpoint of 150°F, it stabilizes for a period of two hours. After stabilization, the idle energy rate was taken by monitoring the consumption of the holding cabinet for a 3-hour period or ten thermal cycles (whichever is longer). The idle energy rate is the holding cabinets required rate of energy consumption (kW), when empty, needed to maintain its cavity temperature at a specified thermostat setpoint. The formula in EQUATION 2 calculates the idle energy rate.

Equation 2. Energy Consumption (Idle Energy Rate)

60idle

Eq

t

Where:

qidle = energy consumption (idle energy rate), (kW)

E = energy consumed during the test period, (kWh)

t = test period (min.)



RESULTS THERMOSTAT CALIBRATION The thermostat calibration reading was verified by installing a thermocouple in the geometric center of the cavity, as shown in FIGURE 3. While performing thermostat calibration, the holding cabinet was allowed to stabilize for 60 minutes before a one-hour average reading of the cavity thermocouple was taken. Data was recorded for one-hour, sampled every 30 seconds, and the resultant average temperature was 154.25°F. Because this result is within 5°F of 150°F, the cabinet’s thermostat was deemed properly calibrated.

Figure 3. Cavity Thermocouple Installation

ENERGY INPUT RATE The input rates were always checked to be within ± 5% of the manufacturers specifications before any tests were taken on any given day. TABLE 2 lists the results of the input rate, taken on each of the individual test days, and are calculated using EQUATION 1.



Table 2. Energy Input Rate

Holding Cabinet

Results Nameplate kW 1.05 kW

Measured kW 1.04 kW

Percent Difference (%) 1.2%

PREHEAT AND IDLE ENERGY RATE The holding cabinet was preheated from room temperature at the thermostat calibration temperature of 150°F. The cavity reached 150°F after 9.03 minutes while the cabinet consumed 0.154 kWh. The holding cabinet’s preheat curve is shown in FIGURE 4. The preheat curve shows that the heating elements never turned off or cycled while heating to the cavity setpoint.

Preheat Curve

70

80

90

100

110

120

130

140

150

0 1 2 3 4 5 6 7 8 9

Time (min)

Te

mp

era

ture

(°F

)

Figure 4. Preheat Characteristics



The holding cabinet was stabilized for two hours following the preheat test and then the energy demand was monitored for a three-hour period. The idle energy rate was 0.10 kW. The duty cycle, or percentage of the holding cabinet’s actual energy consumption rate compared to the 1.05 kW measured energy input rate was 9.52% during idle conditions. Results of preheat and idle tests are calculated using EQUATION 1 and are listed in TABLE 3.

Table 3. Preheat and Idle Energy Rate

Holding Cabinet

Results Preheat Time (min) 9.03 min.

Preheat Energy (kWh) 0.154 kWh

Preheat Rate (°F /min) 8.51 °F /min

Idle Energy Rate (kW) 0.10 kW

Idle Duty Cycle (%) 9.52%



CONCLUSION The following parameters of the FWE HLC-2125-5 holding cabinet were determined during testing:

Energy Input Rate: The maximum energy input rate recorded during the test was 1.04 kW.

Preheat Energy Rate: The holding cabinet took 9.03 minutes to reach the temperature of 150°F, yielding a preheat energy rate of 8.51°F/min.

Idle Energy Rate: The idle energy rate, the amount of energy required to maintain a 150°F setpoint, was recorded as 0.10kW.



APPENDIX A



REFERENCES

1 American Society for Testing and Materials, 2005. Standard Test Method for performance of

Hot Food Holding Cabinets. ASTM Designation F2140-01 (reapproved 2007)-Revised July 23, 2010. In Annual Book of ASTM Standards, West Conshohocken, PA

1 http://www.omega.com/temperature/z/pdf/z204-206.pdf

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