R 22 REPLACEMENT REFRIGERANT
This invention relates to a refrigerant particularly but not exclusively for air
conditioning systems. The system relates especially to refrigerant compositions which
have to adverse effect on the atmospheric ozone layer and to compositions which can be
added to existing refrigerants which are compatible with lubricants commonly used in
refrigeration and air conditioning systems. The invention also relates to a method of
modifying refrigeration and air conditioning systems.
Chlorofluorocarbons (CFCs) eg CFC 11 and CFC 12 are stable, of low toxicity
and non-flammable providing low hazard working conditions used in refrigeration and air
cond. tioning systems. When released they penneate into the stratosphere and attack the
ozooe layer which protects the environment from damaging effects of ultraviolet rays. The
Montreal Preoticol, an international environmental agreement signed by over 160
countries, mandates the phase-out of CFCs according to an agreed timetable. This now
includes hydrochlorofluorocarbons (HCPCs) which also have an adverse effect on the
ozone layer.
R 22 is a chemical fluid and by far the largest HCFC refrigerant used globally in
refrigeration and air conditioning equipment R 22 has an Ozone Depletion Potential
(ODP) of approximately 5% of CFC 11. After CFCs have been phased out, the chlorine
content of R 22 will make it the largest ozone depteting substance in volumetric terms. R
22 is also the subject of a phase-out schedule under the Montreal Protocol. R 22 is
prohibited from use in new equipment in some countries.
Any replacement for HCFC 22 must have no ability to deplete ozone. The
compositions of the present invention do not include chlorine atoms and consequently they
will have no deleterious effect on the ozone layer while providing a similar performance as
a working fluid to R 22 in refrigeration apparatus.
Various terms have been used in patent literature to describe refrigerant mixtures.
These may be defined as follows:
Zeotrope: A fluid mixture whose vapour and liquid compositions are different at
a specified temperature.

Temptratare glide: If a zeolrapic liquid is distilled et constant ivessure its
iKMiiiid: point will increase. The change m boiling point firom tiie beginning of Ac
distil] ition uittil tbe point when a It^tkl phase has just d^q^ieared is called the
tenqperituie (^ide. Aslt(teisalsoohM(vedwh«ithesatuntedv^)oarofazeotr20%
Tbecoiqpositkms may be used as retrofit refirigenittiiiuaures. The composition
may ahia be used as extenders as diaomed below. The conqx»itions may be used in
semi-h'^rm^ic and hnmetic systems.
The prefiHied wwghts of R125 to R I34a are in fte ranges:
R125 60-80%
R134a 40-20%
A fOOK pn^cned mge is!
R125 60-78%
RI34a 40-22%
A moM prafiRied raiige is:
R125 64-76%
R134a 34-24%
These noq^es are prefeiTed for hennetkttdsemi-hennetic systems. The
comptKMoa may also be used in an open system. The prdnred weights in an open system
are in t:x ranges:
R125 57-78%
R134a 43-22%.
A more preferred range is:
R125 63-76%
R134« 33-24%
The itfoportkMi of R 125 used in an qien system may be up to 10%, pnfaMbly 4
to 5^ higher than in a harmetic or semi-hermetic system.
In a first aspect of tins invention no other refrigerant may be included in (he
mixta :¦ In i second isped, suitable for use as an R 22 extender, an additional refiigcrsiit
R 32 nay be added.
yrefiiwd h3fdrocarboiis additives are selected from tlw grai^) cmuisting of: 2-
metb}t propane, 2,2'diiiiethyliiropatte, butane, pentane, 2-niethylbutane, cyciopmtane,
iiexart. l-tadtij/lipGaltaat, 3-nietliy^)efit8nc, 2,2-diniethyibutane and metbylcyclopentane.
The b> droeaiboB addkive preftxably has a boiling point in the range 20 lo 4(rC. Use of
n-pentioe, cydepcBlaBe, isoiieQiaM aad mijmires thereof is pitfened. Use of n-pentane,
isopeitane or nixiWBi dMreof is eq»ad^ly preferred. Commercially avaiMile saturated
bydit :aiboa auMm ate wnkMe frooi cyclopeittane cmanMsreial grade from Phillips
Petro <>um bttcraaiional NV, Norpar 'S S n>pentane frmn Exxon Chemical and iso-pentane
QUli from ShellOwflucals.
Relative piopoctioas of the peotaiw and butane components may be selected to
give ii total of OJI lo 5% of the ooopontions, preferably 2 to 4%, m xmdbig amoiitt of 4^ 10 3% t^butane in a coiiqiosmoii containing a total of 5^^
bydrc>::arboii. la oeaapoaitions widi lesa duw 5% ^lydrocarbon, for exanq>le 1% or 4%,
niad /ely laiger iHkie of butane: pefltane may be enq>loyed to minimise hydrocarfotm
build .ipeities:
(a) sttflteient solubilfty in the lubricant at die evaporator ten^iecature to
leduo: :ts vj|$cofity; and
(b) Sttffictent vdattUty to allow distillation from the hot Iwlmcant in the
comp: irssor ciaak case.
Hyvfaocvboos fidfil these rcsquHcmeots.
Refrigerant conyositions m accordance with this invmtion confer several
advantiges. R 125 has fire sivpfesstng cteractBcistics. The jxesence of R125 suitresses
thefli.inauAwI^of^refingonittmudwe. Thchigba'HFCcoatattaitf>lesiaoR;n-
pentaii: to beaddad to themiioure thartby in^Moving Ae sohibility prcqmties of the
ttixturs ¥ddi tra^ooal hduicairts. for example mineral aiui alkyi benzene oils.
Hw pc^cntnveittioo may oooftr a number of benefits in clecion,low«rdisdiaigeten9eratitte,and higher capacity.
The fffcseal iovcMioo m^ cci^far a nuii4)er of benefits in conqyanstm to the HFC
repUc cimrnt R407C including superior hydrocaibon oil retttni, better motor cooling in
henm tic compressors, louwr discharge lempa^ure and lower discharge pressure.
The inveaiioB is further desoibed by means of examples but not in any limitative
sense
EXAl.'?LEj
The perfMmances of five R125/Rl34a/peftt»e ctm^xMsitions were evaluated
using standard reoperation cycle analysis techniques in c»der to assess their suitability as
retfof I rq)lacemeiAs for R22 in h^mete or semi-hermetic systems The operating
condi ions, used for the analyses were cix»en as being typical of tliose conditions that are
found n air conditioning systems. SiiKC the blends were 7.eottt>pes the midpoints of their
tempc cature glides in the evaporator and condenser were chosen to define the temperatiue
limits c f the cycle. The same temperatures were also used to generate perforauuice data for
R22.
The pentane was present at 4% by weight based on the total wei^t of the
R125/t:134a btend. To simplify the calculation this small amouat of pentuie was omitted.
The fdhming refrigeiant corapociiioiis woe sulqecled to cycle analysis:
CONT^RESSOR
Electr i}sitioos 2,3 aad4 nieet the critoia set out above and dierefore satisfy die
reqiiittiaeots of dus inveotiwi.
EXAI>'[PLE2
The perfocmuices of five R125/R134a/pentane compositioos were evaluated
using s tandaid refrigeration cycle analysis techniques in order to assess their suitability as
retrof u rqslacements for R22 in qiea systems. The operating conditions, used for the
aaaly; :s were chosen as bong typical of diose conditions diat are fsiticHi cosqxisuig 56% R125: 44% R134a
3. A c(mq>oskkHi coi^xising 64% R125: 36% R134a
4. A composition caa^miag 76% R125: 24% RI34a
5. Acoaipo8itioaooiii|irisiiig80%R125:20%Rl34a
The feiiowii^ cyde conditioiu woe used in the analysis:
COOItNGDUTY IC kW
EVAI'DRATOR
Midpi) Jit fluid ev^iorationteiQpenKure 7.0 *C
Supcrbeating 5.0 'C
Sucti(4i lioe prassare drop (in saturated lciiq;)eniture) 1.3 "C
CONDENSER
Mtdpi>int flsid ooodaasiag tenpentute 45.0 *C
Subcculiag 5 OX
ExliMu4 line pfessme drop (in sanvHed tenfierature) 1.5 *C
UQLID LINE/SUCnON UNE HEAT EXCHANGER
Efficisncy 0.3
COMFRESSOR
Electiicmotmefitcwncy 0.85
On^4«ssor iseotnapic efiicieiicy 0.7
Coo^iressor volumetric efficiency 0.82
PAR^iSmC POWER
lodocrfaii 0.3 kW
OutdiHirfan 0.4 kW
Conticis O.I kW

Tbe results of analysii^ tbe perfonnances in an air-conditkNimg unit using these
opctBUng conditions are shown in T^rie 2. For comparison the performance of R22 is also
shown
All compositions have lower exhaust temperalures than R22 and are therefore
siqwiixcmdiisafiooust. However conyosition 5 is unaco^taMe because its ^chaust
press jre n more Am 2 bar above that of R22. Compotitioas 1 nd 2 are imacceptable
beeai.He their icfiigennt capaeitiet are less than 90% of tlMt of R22. The overall
performaooes of oon^ositiops 3 and 4 meet the criteria set out above and therefore satisfy
the n ({uiremeats of dus invention.
The perfbnnances of five RI2S/RI34a^pent«ie coaapositioBs were cvaluatod
usi^ itandaid i«fif%ctalioa cyde MHifyets tecluiciues the in oider to assess their suitability
as relr)& rqriaoeMaitfs for R22 in heroidlic or semi-hermetic systems not fitted witti a
Itquic! iine/nictioa line heat exchanger. The operating conditioBs, used for the analyses
were chosen as bei^ typicid of ^lose oooditions ^lat are found in air ccMRIiti(ming systems.
Since tfie bleiids were zeottopes the mk^KMiits of their tanpeiature ^ides in the evaporator
and ccndeaier were ^osen to define tbc tempentfure WaiSs of the cycle. The same
tonp^ratuies were also used to generate perfonaaoce data for R22.
The peotMe was pcescitt an 4% by weight based on tbe toul wei^t of the
R]25/R134a bloxl To simplify the calcutati (in saluiMedieinperite 1.5 *C
CONDENSER
Midf oint fluid ooodnisiog taap&i^but 4f .0 °C
Subccoliag 5 0*C
Eidiai^rtlineprossiiiesitions 3 and 4 rneet the criteria set out above and therefore satisfy
the uquirements of this invention.

EXA^iPLE 4
The perfbnnances of two RI2S/R134a/pentane C(»i|M»itions weK evaluated
using standard lefi^eiMion cycle andysis techniques in oider to assess their suitability as
extern bars for R22 m bmnetic or saiu4ieniietic systems. The opeiatiiig conditioos selected
for Hh' analyses are typieai of those coDditions found in air oondUtioniag i^Mens. Since
the bl«Mds vMMVzaotrqpas the nudtwiBts of their ten^ientfttre i^ides in Ibe evapcNrator and
cottdet;ser were chosen to define the temperature limits of the cycle and were also used to
geneni e the perfonaance of R22 for conqufison.
The pe^aae was present at 4H by weight based on the Krtal weight of the
R125/fvt34a blead. To aa^lify the cateul^ion diis small amount of peatane was omitted.
Hie folhiwiBf R22 exteoder coo^Mwitmns were nds^edtd to cycle analysis:
1. Acoin|N»itioncoiqprisio^64%Rl2$:36% R134a.
2. A cooqwation comprismg 44% R12S: Sti% RI34a.
To estaWisfa the affects on unit performance resuhuig fiom successive dilutiint fliud ev^Kwatioii tempentaat 7.0 "C
Siqietreating 5.0 'C
SuctK>: 1 line pressure drop (in saturated temperature) 1.5 "C
CO> l>ENSER
Milint fluid coodensing temperature AS.CC
Sidxooling 5.0'C
Exhi.iist line premve drop (in satiuited tempenmire) 1.5 •c
UQ.TDUNB
Electric motor efficiency 0.85
Coni|M'essor isottrofMc efficiency 0.7
Coniinressor votunelric efficiency 0.82
PAI14SITIC POWER
Indcxx- fao 03 kW
Outioorfiu 0.4 kW
CoDt-ols O.IkW
AU ccmifM^ioK have kmw exlttust teie|>eratures dun R22 ami are Uierefore
swp'iior on ttiif aocouiL
Coii4>osition 1 ptovidet a oooiiog capmdty gieater than 90% of tfaet of R22 over
the whole of Ae dihiiioo range. Btaocjs containing nK^re than 45% R22 have capacities
equdl to or better ten that of R22. Hie CC^ (system) is withia 2% of that of R22 over the
vAuf e of die dilirtion range. This c(Mnpositi containing down to 20% of R22. Its COP (system) is essentially the same as that of
KLl over the whole of the dilution range. This eonq»ositi'3rfan 0.4 kW
CoDbols 0.1 kW
All Mends coataiiui^ the extcaxler have lower exhrast tempentures than R22 and
there:'i)re VBMBt the iwpitreinaata of diis qieeificaiioa. The OCMP (^stem) is essentially
equal o that of R22 over the wbis are typical of Uiose conditions found in air conditi X isentrcqiiic effteiency 0.7
Compres { jt volumetric effictency 0.82
PARASrnC POWER
Indo:>t fan 0.3
OuU:c<>r fan 0.4 kW
C