United States
                  Environmental Protection
                  Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
                  Research and Development
EPA/600/SR-98/015
February 1998
&EPA      Project  Summary

                  Effect of Lubricant
                  Contamination on  the
                  Performance and  Reliability of
                  Heat  Pumps Charged with
                  R-407c
                  S. A. Fitzhenry, W. V. Payne, and D. L. O'Neal
                   The report gives results of the devel-
                  opment of new data that can be used
                  to determine the effect of mineral oil
                  contamination on the reliability of a heat
                  pump system operating with a  new
                  hydrofluorocarbon (HFC) mixture and
                  polyol ester (POE) lubricant, to assess
                  any  performance degradation due to
                  mineral oil contamination in retrofit ap-
                  plications, and to examine the impact
                  of water contamination on the retrofit
                  system. (NOTE: In heat pump refriger-
                  ant retrofit applications in the field, er-
                  rors can occur that can have an impact
                  on  subsequent equipment perfor-
                  mance.)
                   As the result of the premature failure
                  of one of the units, the long term reli-
                  ability of contaminated systems  was
                  not determined. Future investigation
                  should reexamine this issue. The ef-
                  fects on performance of various levels
                  of mineral oil contamination were not
                  significant, so further investigation at
                  specific conditions of interest may be
                  justified. The effects of water contami-
                  nation could  be more significant. The
                  increase  in total acid number could
                  have potentially led to increased
                  amounts of trace metals in the system
                  as the acid attacked the system com-
                  ponents. A more long term study would
                  be necessary to determine if there were
                  any long term effects of water contami-
                  nation that did not appear during this
                  15-week trial.
                   This Project Summary was developed
                  by the National Risk Management Re-
                  search Laboratory's Air Pollution Pre-
                  vention and Control Division, 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).

 Introduction
  Chlorofluorocarbons  (CFCs)  and
 hydrochlorofluorocarbons (HCFCs) are two
 major categories of refrigerants that con-
 tain chlorine. These chlorine- containing
 refrigerants have been found to be strato-
 spheric-ozone-depleting chemicals, and
 their use must be discontinued as required
 by international agreement and U.S. law.
 HCFC-22, a medium pressure refrigerant
 used in heating, cooling, and refrigeration
 applications,  is scheduled to be phased
 out of production and must be replaced.
 During the past several years, industry
 and government researchers have begun
 to develop and test  new refrigerants for
 replacing HCFC-22 in air conditioners, heat
 pumps, and other applications.  Currently,
 no  pure  non-flammable refrigerant has
 been identified as an acceptable replace-
 ment for HCFC-22. However, several suit-
 able    zeotropic    mixtures    of
 hydrofluorocarbons  (HFCs) have been
 identified.  Most notably, the  mixture of
 HFC-32,  HFC-125, and HFC-134a  in the
 proportions of 23/25/52 wt %  (industry-
 designated as refrigerant (R)-407c) is the
 refrigerant most likely to replace HCFC-
 22 in retrofit applications.
  In retrofit applications, where HCFC-22
 in a heat pump or air  conditioner is re-
 placed with R-407c in the field, errors can
 occur which can have an impact on sub-
 sequent  equipment  performance.  When

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using R-407c,  a polyol ester (POE) lubri-
cant must be used,  requiring the removal
of both the HCFC-22 refrigerant and the
associated mineral  oil  lubricant from the
system. It is  possible that  the existing
mineral  oil might not be totally cleaned
out of the system and remains as a con-
taminant in the new R-407c/POE system,
affecting  performance. Another  problem
could arise because the POE lubricant is
highly hygroscopic.  If care is not taken
during  the replacement of the  lubricant,
moisture could  enter the system with the
introduction of the lubricant and  degrade
performance and equipment life.
  The objectives of  this research were to
develop new data that could  be used to
determine the effect of mineral oil  con-
tamination on the reliability of a heat pump
system operating with the new HFC mix-
ture and  POE lubricant,  to  assess  any
performance degradation due to mineral
oil  contamination in retrofit applications,
and to examine the  impact of water con-
tamination on a system charged with the
replacement fluid and synthetic  POE lu-
bricant.

Results
  The first set of tests examined the long
term reliability of a  heat pump  operating
with an alternate refrigerant when the unit
has mineral oil contaminant present. Two
identical heat pump  units were compared:
one operated with HCFC-22 and mineral
oil,  and  the other used R-407c  and  POE
with 11.9% mineral  oil contaminant.  The
two units were first  tested  in an environ-
mental chamber to obtain a reference  per-
formance  level  for each. They were then
to be operated under uncontrolled ambi-
ent conditions  in semi-continuous cycle
for a  year to simulate long  term perfor-
mance.  Unfortunately, due to the prema-
ture  failure  of  the  compressor for  the
HCFC-22  unit after 3  months, only  ap-
proximately 20% of the test cycles were
completed, and project time did not allow
for restarting  the test with a new set of
heat pumps. The compressor from the R-
407c unit was examined and showed nor-
mal wear  for the length of time that the
unit had been in operation. Operating data
are presented for both units.
  In the second set of tests,  performance
data were collected  on two  identical heat
pump units  to  determine  the  effect  on
performance of mineral oil contamination.
Each unit was tested with R-407c refriger-
ant and POE lubricant. Increased levels
of mineral oil contamination, up to 25% by
weight, were  introduced into the system
to characterize any performance degrada-
tion as a result of the contamination. Tests
were conducted for both heating and cool-
ing  modes. Overall,  the results showed
that mineral oil contamination had mini-
mal effect on the performance (capacity
and efficiency) of the heat pumps. Most of
the data for  capacity  and  efficiency  for
different contamination levels were within
the uncertainty of  the measurements.
There did not appear  to be a definitive
trend between performance and contami-
nation level.
  The final phase of the project examined
the effects of water contamination in the
lubricant on the  reliability of a unit charged
with R-407c and POE  lubricant.  Identical
units were charged  with R-407c refriger-
ant and POE lubricant. One  unit was left
as dry as  possible, while the  second  unit
was contaminated with 1200 ppm of mois-
ture. The units  were operated  continu-
ously in the cooling mode for 15 weeks.
Analysis  of  the  lubricant extracted  from
the units showed little to no increase in
the three metals (iron, copper, and  zinc)
tested in the study. The total acid number
in  the water contaminated unit showed a
general  increase. This increase in  acid
number could  have potentially led to  in-
creased amounts of the trace  metals  as
the acid attacked system components.

Conclusions
  As the result of the premature failure of
one of the units in the long term reliability
study, reliability of contaminated  systems
was  not determined. Future investigation
should reexamine the long term reliability
of a  unit operating with an alternative re-
frigerant when mineral oil contaminant is
present. The potential exists for  systems
to  become  contaminated  with mineral  oil
during retrofit operations. Although the ef-
fects on performance of various levels of
mineral oil contamination were not signifi-
cant, the effects varied between heating
and  cooling tests at various  test condi-
tions, so further investigation at specific
conditions of interest may  be justified. The
effects of water contamination could  be
more significant. The increase in total acid
number could  have potentially led to  in-
creased amounts of trace metals in the
system as the acid  attacked the system
components. A longer term study would
be necessary to determine if  there  were
any long term effects of water contamina-
tion that  did not  appear  during  this 15-
week trial.

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   S. Fitzhenry, V. Payne, andD. O'Neal are with the Dept. of Mechanical Engineering,
     Texas A&M University, College Station, TX 77843.
   Robert V. Hendriks is the EPA Project Officer (see below).
   The complete report, entitled "Effects of Lubricant Contamination on the Perfor-
     mance and Reliability of Heat Pumps Charged with R-407c," (Order No. PB98-
     127079; Cost: $31.00, 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 Pollution Prevention and Control Division
          National Risk Management Research Laboratory
          U. S. Environmental Protection Agency
          Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management Research (G-72)
Cincinnati, OH 45268

Official Business
Penalty for Private Use $300
      BULK RATE
POSTAGE & FEES PAID
         EPA
   PERMIT No. G-35
EPA/600/SR-98/015

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