5B

- 1 APPENDIX 5 B

. ERA MODEL DESCRIPTION

5B .1 INTRODUCTION

The Energy

- efficient Refrigerator Analysis Program (ERA), formerly called the EPA Refrigerator Analysis Program, serves as an important tool in the engineering analysis, described in Chapter 5 of the TSD. Since its use in the 2011 residential refrigeration rulemaking, the Windows

- based ERA has undergone extensive analytical upgrades and now implements features that specifically facilitate cooled cabinet modeling. This appendix provides program operation guidance for the user. The program has its own interna l help utility to provide additional assistance to the user beyond the information provided in this appendix. Further information on the historical development of ERA can be found in Appendix 5B of the 2011 residential refrigeration Final Rule.

5B

. 2 WINDO WS VERSION OF ERA

User Interface

ERA uses a highly

- graphical interface, providing multiple options for selecting from the various cabinet and component choices. It is designed to guide the user carefully through the data input and editing process to ensur e data consistency. Prior to an actual simulation of the refrigeration appliance performance, the user is presented a summary of the selected design variables.

Cabinet Mode

ERA operates in one of four view modes: 1) cabinet design mode (shown in the image ), 2) cycle design mode, 3) simulation mode, and 4) reports mode. Each is characterized by its own sidebar, containing hotspots for selecting component or report options. The color of the sidebar provides an additional visual clue to highlight the particul ar mode that is current.

To define a new analysis, the user may either begin with a default set of design parameters and proceed through the editing process, or may read in an existing data file to be used as

- is or edited.5B

- 2 Each analysis must begin with a selection of the basic cabinet design parameters: cabinet category (shown on the desktop) and the overall dimensions of the unit. Once these basic choices have been made, the remaining categories of cabinet design data may be specified in any order. Dat a wizards, similar to those illustrated above for the stand

- alone programs, guide the user at each stage.

As each category of data is processed, a check mark is drawn on the sidebar to indicate the completeness of the editing progress. In some instances, special

- function dialogs may be summoned to assist in the preparation of an input value. For example, the i mage to the right shows a dialog used to calculate the effective resistivity of a cabinet wall that contains a vacuum panel or some equivalent high thermal resistance element.

Cycle Mode

Once the basic cabinet type has been selected, the user may spec ify the cycle parameters. This would begin with a selection of the basic cycle type (single evaporator, dual loop, dual evaporator, or Lorenz cycle). Once this choice has been made, a simple schematic of the chosen cycle category is displayed on the deskto p. The user may then continue to define the cycle parameters by clicking on the desktop to select the component of interest, or may use the sidebar or the drop

- down menu to select the next component to be defined. The displayed desktop image and its associ ated hotspots depend on the specific cycle category selected.5B

- 3 Simulation Mode

Prior to simulation of the cabinet loads and cycle behavior, the user is presented with a summary of the defined input. A data item can be selected for further editing by double

- clicking on the summary line displaying the item in the data review dialog. On ce the data has been reviewed and accepted, the user selects the Continue button to start the simulation.

Reports Mode

At the completion of the simulation (which is instantaneous for the cabinet loads), the program automatically switches to reports mo de and displays the results on the desktop. The example here shows the calculated cabinet loads. Results for the cycle analysis, overall performance parameters, or a more detailed summary, can be selected using the side

- bar or the drop

- down menu for report s.