United States Air and Energy Engineering

Environmental Protection Research Laboratory

Agency Research Triangle Park, NC 27711

E AP Project Summary

Research and Development EPA/600/SR-95/028 March 1995

The report gives results of a study

that provided information regarding the

merits of using ammonia with a secondary brine loop for supermarket refrigeration systems. The ammonia systems were compared with an equivalent R-22 system. The models used in

the study are provided with the final

report.

This Project Summary was developed

by EPA’s Air and Energy Engineering

Research Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully

documented in a separate report of the

same title (see Project Report ordering

information at back).

The Program

The objectives of this project were to

quantify the advantages and disadvantages of using ammonia with a secondary

brine refrigerant compared to R-22 in supermarket refrigeration applications. These

objectives were achieved by numerical

experiments using simulations. Mechanistic models of refrigeration system compoInvestigation of Ammonia

Equipment Configurations for

Supermarket Applications

Timothy P. McDowell, Sanford A. Klein, and John W. Mitchell

nents were used, based on fundamental

principles, accepted heat transfer/pressure

drop correlations, and available manufacturers’ data. Available thermodynamic and

transport property data correlations for

ammonia and R-22 were used in the models. The parameters of these models were

varied to determine their effect on system

performance and locate optimum values.

A modular approach was used in which

each component was separately modeled

allowing simple changes in system configurations.

The combined component models resulted in a large set of coupled nonlinear

algebraic equations for the quasi-steady

systems that did not involve brine storage. The systems involved differential and

algebraic equations. These equations were

solved using the general-purpose simulation programs EES and TRNSYS. EES is

a robust nonlinear equation-solving program with built-in thermophysical property

data. TRNSYS is a sequential modular

simulation program that employs schemes

to solve coupled algebraic and differential

equations.
2

Timothy P. McDowell, Sanford A. Klein, and John W. Mitchell are with the University

of Wisconsin-Madison, Madison, WI 53706.

Evelyn Baskin is the EPA Project Officer (see below).

The complete report and diskette, entitled “Investigation of Ammonia Equipment

Configurations for Supermarket Applications,” (Order No. PB95-502555; Cost:

$90.00, subject to change) will be available only from:

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Telephone: 703-487-4650

The EPA Project Officer can be contacted at:

Air and Energy Engineering Research Laboratory

U.S. Environmental Protection Agency

Research Triangle Park, NC 27711

• •

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

EPA/600/SR-95/028

Official Business

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