CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS

4.1	 INTRODUCTION ........................................................................................................... 4­1
 

4.2	 TECHNOLOGIES THAT DO NOT AFFECT DAILY ENERGY
 

CONSUMPTION............................................................................................................. 4­2
 

4.2.1	 Higher Efficiency Expansion Valves................................................................... 4­2
 

4.2.2	 Condenser Fan Motor Controllers ....................................................................... 4­2
 

4.2.3	 Variable Speed Compressors............................................................................... 4­3
 

4.2.4	 Liquid­Suction Heat Exchangers......................................................................... 4­3
 

4.3	 SCREENED­OUT TECHNOLOGIES............................................................................ 4­3
 

4.3.1	 Thermoacoustic Refrigeration ............................................................................. 4­3
 

4.3.2	 Magnetic Refrigeration ........................................................................................ 4­4
 

4.3.3	 Electro­Hydrodynamic Enhanced Heat Transfer................................................. 4­4
 

4.3.4	 Copper Rotor Motors........................................................................................... 4­4
 

4.4	 REMAINING TECHNOLOGIES ................................................................................... 4­5
 

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CHAPTER 4. SCREENING ANALYSIS
 

4.1 INTRODUCTION
 

This chapter addresses the screening analysis that the U.S. Department of Energy

(DOE) conducted in support of the ongoing energy conservation standards rulemakings

for refrigerated bottled or canned beverage vending machines. These rulemakings are

mandated by the Energy Policy Act of 2005, and are effective for equipment

manufactured three years after the date of publication of a final rule establishing energy

conservation standards.

In the market and technology assessment (chapter 3), DOE presented an initial list

of technologies that can reduce the energy consumption of refrigerated beverage vending

machines. The goal of the screening analysis is to screen out technologies that will not

be considered further in the rulemaking analyses. Some of the technologies considered in

chapter 3 can reduce annual energy consumption under real­world conditions, but may

not reduce daily energy consumption (DEC), as measured by the American National

Standards Institute/American Society of Heating, Refrigerating and Air­Conditioning

Engineers (ANSI/ASHRAE) Standard 32.1–2004, Methods of Testing for Rating Vending

Machines for Bottled, Canned, and Other Sealed Beverages. DOE removed from

consideration those technologies that do not reduce DEC. DOE evaluated the remaining

technologies using the screening criteria set forth in the Energy Policy and Conservation

Act (EPCA). (42 U.S.C. 6311–6317)

Section 325(o) EPCA establishes criteria for prescribing new or amended

standards that are designed to achieve the maximum improvement in energy efficiency.

Further, EPCA directs the Secretary of Energy to determine whether a standard is

technologically feasible and economically justified. (42 U.S.C. 6295(o)(2)(A), as

directed by 42 U.S.C. 6316(a)(1)–(3)). EPCA also establishes guidelines for determining

whether a standard is economically justified. (42 U.S.C. 6295(o)(2)(B)) In view of the

EPCA requirements for determining whether a standard is technologically feasible and

economically justified, appendix A to subpart C of Title 10, Code of Federal Regulations,

Part 430 (10 CFR Part 430), “Procedures, Interpretations, and Policies for Consideration

of New or Revised Energy Conservation Standards for Consumer Products” (the Process

Rule), sets forth procedures to guide DOE in its consideration and promulgation of new

or revised efficiency standards. These procedures elaborate on the statutory criteria

provided in 42 U.S.C. 6295(o) and, in part, eliminate problematic technologies early in

the process of prescribing or amending an energy efficiency standard. In particular,

sections 4(b)(4) and 5(b) of the Process Rule provide guidance to DOE for making a

determination whether to eliminate from consideration any technology that presents

unacceptable problems with respect to the following criteria:

Technological feasibility. Technologies incorporated in commercial equipment

or in working prototypes will be considered technologically feasible.

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Practicability to manufacture, install, and service. If mass production of a

technology in commercial equipment and reliable installation and servicing of the

technology could be achieved on the scale necessary to serve the relevant market at the

time of the effective date of the standard, then that technology will be considered

practicable to manufacture, install, and service.

Adverse impacts on equipment utility or equipment availability. If DOE

determines that a technology has significant adverse impact on the utility of the

equipment to significant subgroups of consumers, or result in the unavailability of any

covered equipment type with performance characteristics (including reliability), features,

sizes, capacities, and volumes that are substantially the same as equipment generally

available in the United States at the time, it will not be considered further.

Adverse impacts on health or safety. If DOE determines that a technology will

have significant adverse impacts on health or safety, it will not be considered further.

In sum, if DOE determines that a technology or combination of technologies has

unacceptable effects on the policies stated in section 5(b) of the Process Rule, those

technologies will be eliminated from consideration. If a particular technology fails to

meet one or more of the four criteria, it will be screened out. Section 4.3 below

documents the reasons for eliminating any technology.

4.2 TECHNOLOGIES THAT DO NOT AFFECT DAILY ENERGY

CONSUMPTION

As stated above, technologies that do not reduce DEC are not considered

beneficial in the context of this rulemaking. Therefore, DOE removed the following

technologies from consideration: higher efficiency expansion valves, condenser fan

motor controllers, variable speed compressors, and liquid­suction heat exchangers

(LSHXs).

4.2.1 Higher Efficiency Expansion Valves

Higher efficiency expansion valves can reduce the annual energy consumption of

refrigerated beverage vending machines by adapting to varying loads and ambient

conditions. Because ANSI/ASHRAE Standard 32.1–2004 is a steady­state test (i.e., there

are no changes in refrigerated­product loading or ambient conditions), there is no

opportunity for higher efficiency expansion valves to reduce DEC.

4.2.2 Condenser Fan Motor Controllers

Condenser fan motor controllers can adapt condenser operation to changing

ambient temperatures, and thereby reduce annual energy consumption of beverage

vending machines. However, because testing under the ANSI/ASHRAE Standard 32.1–

2004 test procedure is conducted at a constant temperature, there is no opportunity to

account for the effect of a condenser fan motor controller on DEC.

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4.2.3 Variable Speed Compressors

Variable speed compressors reduce energy consumption under real­world

conditions by matching their capacity to the refrigeration load, which can change due to

variations in ambient conditions and product loading. This technology therefore

eliminates the inefficiencies that occur due to mismatched capacity and load in a singlespeed compressor during part­load operation. Because the ANSI/ASHRAE Standard

32.1–2004 test procedure prescribes steady­state conditions, a variable speed compressor

undergoing this test would be limited to single­speed operation. The resulting energy

efficiency ratio would be no better than a properly sized single­speed compressor, so

there would be no appreciable energy savings. Similarly, under ANSI/ASHRAE

Standard 32.1–2004, the performance of a high­efficiency variable­speed compressor

would be comparable to a high­efficiency single­speed compressor.

4.2.4 Liquid­Suction Heat Exchangers

An LSHX is an indirect liquid­to­vapor heat transfer device that evaporates any

residual liquid refrigerant remaining in an evaporator discharge line, and thereby

minimizes the risk of liquid refrigerant carrying over to the compressor suction. In

general, LSHXs are installed in refrigeration systems to ensure proper system operation

and increasing system performance. Due to the combination of refrigerant type,

operating temperature, ambient conditions, and other factors, an LSHX does not

consistently reduce DEC, as measured by the ANSI/ASHRAE Standard 32.1–2004 test

procedure.

4.3 SCREENED­OUT TECHNOLOGIES

This section addresses the technologies that DOE screened out because they did

not meet the requirements of sections 4(a) and 5(b) of the Process Rule. DOE considered

the following four factors: (1) technological feasibility; (2) practicability to manufacture,

install, and service; (3) adverse impacts on equipment utility to consumers; and (4)

adverse impacts on health or safety. Four technologies were screened out:

thermoacoustic refrigeration, magnetic refrigeration, electro­hydrodynamic (EHD) heat

exchangers, and copper rotor motors.

4.3.1 Thermoacoustic Refrigeration

Thermoacoustic refrigeration uses high­amplitude sound waves in a pressurized

gas to pump heat from one place to another. Because this technology is in the research

stage, DOE believes that it would not be practicable to manufacture, install, and service

this technology on the scale necessary to serve the relevant market at the time of the

effective date of the standard. Because this technology is in the research stage, DOE also

cannot assess whether thermoacoustic refrigeration will have any adverse impacts on

utility to significant subgroups of customers, result in the unavailability of any type of

refrigerated beverage vending machines, or present any significant adverse impacts on

health or safety.

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4.3.2 Magnetic Refrigeration

Magnetic refrigeration is a cooling technology that is based on the magnetocaloric

effect, in which a reversible change in temperature of a suitable material is caused by

exposing the material to a changing magnetic field. Magnetic refrigeration can be used to

attain extremely low temperatures and can be adapted to the cooling temperatures used in

common refrigerated beverage vending machines. However, DOE understands that

magnetic refrigeration is in the research stage and, therefore, believes that it would not be

practicable to manufacture, install, and service this technology on the scale and in the

timeframe necessary to serve the relevant market at the time of the effective date of the

standard. Because this technology is in the research stage, DOE also cannot assess

whether it will have any adverse impacts on utility to significant subgroups of customers,

result in the unavailability of any type of refrigerated beverage vending machines, or

present any significant adverse impacts on health or safety.

4.3.3 Electro­Hydrodynamic Enhanced Heat Transfer

EHD enhancement of heat transfer is the result of applying a high­voltage

electrostatic potential field across a heat transfer fluid, such as a refrigerant or refrigerant

mixture. The applied field destabilizes the thermal boundary layer, thereby producing

better mixing of the bulk fluid flow and increasing the net heat transfer coefficient. This

procedure appears to be more effective when applied to phase­change processes (e.g.,

boiling and condensation). Because EHD­enhanced heat transfer is in the research stage

and is not being used in commercially produced or sold refrigerated beverage vending

machines, DOE believes that it would not be practicable to manufacture, install, and

service this technology on the scale necessary to serve the relevant market at the time of

the effective date of the standard. Because this technology is in the research stage, DOE

also cannot assess whether it will have any adverse impacts on utility to significant

subgroups of customers, result in the unavailability of any type of beverage vending

machines, or present any adverse impacts on health or safety.

4.3.4 Copper Rotor Motors

Motor manufacturers have long known that substituting copper for die­cast

aluminum in rotors would significantly reduce motor losses and improve electrical

energy efficiency. However, manufacturing die­cast copper rotors requires specialized

equipment, significant investment, and proprietary know­how that are not yet suitable for

production of the millions of motors produced annually. DOE recognizes the advantages

of this significant advance in motor technology, but believes that it would not be

practicable to manufacture, install, and service copper rotor motors on the scale necessary

to serve the relevant market at the time of the effective date of the standard. Further,

DOE cannot assess whether the manufacture and use of copper rotor motors would have

any adverse impacts on the utility of refrigerated beverage vending machines to

significant subgroups of customers, result in the unavailability of any type of refrigerated

beverage vending machines, or present any significant adverse impacts on health or

safety.

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4.4 REMAINING TECHNOLOGIES

After eliminating those technologies that do not reduce DEC and do not meet the

requirements of sections 4(a) and 5(b) of the Process Rule, DOE is considering the

following technologies:

• higher efficiency lighting

• higher efficiency lighting ballasts

• higher efficiency evaporator fan motors

• evaporator fan motor controllers

• higher efficiency evaporator fan blades

• improved evaporator design

• low­pressure differential evaporators

• improved or thicker insulation

• defrost mechanism

• higher efficiency compressors

• improved condenser design

• higher efficiency condenser fan motors

• higher efficiency condenser fan blades

• improved glass pack design (for Class A machines)

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