United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
 EPA/600/SR-95/028
March 1995
Investigation of Ammonia
Equipment  Configurations  for
Supermarket Applications


Timothy P. McDowell, Sanford A. Klein,  and John W. Mitchell
  The report gives results of a study
that provided information regarding the
merits of using ammonia with a sec-
ondary brine loop for supermarket re-
frigeration systems. The ammonia sys-
tems were  compared with an equiva-
lent 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  Tri-
angle Park, NC, to announce key find-
ings 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 disadvan-
tages of using ammonia with a secondary
brine refrigerant compared to R-22 in su-
permarket refrigeration  applications. These
objectives were  achieved by numerical
experiments using simulations. Mechanis-
tic models of refrigeration system compo-
 nents were used, based on fundamental
 principles, accepted heat transfer/pressure
 drop correlations, and available manufac-
 turers' data. Available thermodynamic and
 transport property data correlations  for
 ammonia and R-22 were used in the mod-
 els. 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 con-
 figurations.
   The combined component models  re-
 sulted in a large set of  coupled nonlinear
 algebraic equations for the quasi-steady
 systems that did not involve  brine stor-
 age. The systems involved differential and
 algebraic equations. These equations were
 solved using the general-purpose simula-
 tion programs EES and TRNSYS. EES is
 a robust nonlinear equation-solving pro-
 gram with built-in thermophysical property
 data.  TRNSYS is a sequential modular
 simulation program that employs schemes
 to solve coupled algebraic and differential
 equations.
                                               Printed on Recycled Paper

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   Timothy P. McDowell, SanfordA. Klein, and John W. Mitchell are with the University
     of Wisconsin-Madison, Madison, Wl 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

Official Business
Penalty for Private Use $300
      BULK RATE
POSTAGE & FEES PAID
         EPA
   PERMIT No. G-35
EPA/600/SR-95/028

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