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Experimental study on HFC-161 mixture as analternative refrigerant to

R502Yongmei Xuan*, GuangmingChen

1

Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China

Received 7 January 2004; received in revised form 22 March 2004; accepted 5 April 2004

Abstract

Ternary near-azeotropic mixture of HFC-161 as an alternative refrigerant to R502 is firstly presented in this paper.Thephysical characteristics of this new refrigerant are similar to those of R502. Its environment performance is friendly. It has

anODP of zero and a GWP smaller than those of R502, R404A and R507. Without any modification to system components,drop-in experimental tests are performed on a vapor compression refrigeration plant with a reciprocating compressor, whichwasoriginally designed to use R404A, a major substitute for R502. Experimental results under two different ratedworkingconditions indicate that the pressure ratios of this new refrigerant are nearly equal to those of R404A. Under lower evaporative

temperature, its COP is almost equal to that of R404A and its discharge temperature is slightly higher than that of R404A,whileunder higher evaporative temperature, its COP is greater than that of R404A and its discharge temperature is lower than that of

the latter. This new refrigerant can achieve a high level of COP and can be considered as a promising retrofit refrigeranttoR502.q 2004 Elsevier Ltd and IIR. All rightsreserved.Keywords: Experiment; Compression system; Refrigerant; R-161; R-502; Performance; COP

Etude experimentale du melange HFC-161 entant que substitut du R-

502Mots-cle: Experimentation; Syste ` me a compression; Frigorige `ne; R-161; R-502; Performance; COP

1. Introduction ultraviolet solar radiation and eventually dangerous con-

sequences for our human beings. The discovery of the ozone

hole observed over the Antarctic led to a series ofWith the increasing recognition of environment protec-

conferences held by the UNEP (United Nations Environ-tion, a great deal of attention has been devoted to the

mentProgram)

[2] . And a lot of protocols, such as Montrealnegative environmental effect of CFCs andHCFCs. Protocol and its amendments, have been subscribed to callAs proposed by Molina and Rowland [1] ,

commonly for complete phasing-out of CFCs andHCFCs

[2].used CFCs and HCFCs are at the origin of ozonelayer Also, these refrigerants were found to cause the green-depletion, which leads to a lack of protection against

house effect or global warming which has unpredictable

consequences on earth thermal balance such as a rise of* Corresponding author. Tel.: 86-571-87951680; fax: 86-

ambient temperature. As regulated by the Kyoto Protocol571-87952464.

in 1997, CFCs is one of the controlled greenhouse effectE-mail address: [email protected] (Y. Xuan).

gases.1 Member of IIR Commission A1

0140-7007/$ - see front matter q 2004 Elsevier Ltd and IIR. All rights reserved.doi:10.1016/j.ijrefrig.2004.04.003


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R502, a key supermarket freezer refrigerant, is abinary

their GWP are high and are unsuitable with the guideline of

azeotropic mixture comprised of 48.8% HCFC-22and

environment protection.

51.2% CFC-115 on a mass basis. It has manyremarkable

In this work, an environmentally friendly newalternativeproperties, such as non- ammable, non-toxic, etc. It is a refrigerant is proposed and comparison experiments

very suitable working substance for vapor compression between this new refrigerant and R404A under twodifferentplants operating between condensing temperature of about rated working conditions were carried out to prove its

35 8C and evaporative temperature from 2 40 to 08C

[3] . potential as a promising substitute.

But from the viewpoint of ozone protection,R502contains large proportions of CFC-115, which ODP is

0.4[4] . HCFC-22, another composition of R502, has an ODPof0.05

5[4] , though much smaller than that of CFC-115, it

still3. Physical and environmental characteristics

has unfavorable effect to ozone layer. According to

Montreal Protocol and its amendments, CFC-115should

A new alternative refrigerant composed of HFC-

161,be phased out by the year 1996 in developed countries, and

HFC-125 and HFC-143a (10/45/45 wt%) is put forward.Inbefore 2010 in developing countries. The deadline

forconsideration of the ammability of HFC-161,non-HCFC-22 is 2020 and 2030, respectively. Furthermore,

theammable HFC-125 is added to suppress theammabilityGWP of R502 is considered to be 4500 times that of

COof HFC-161 while still giving thermodynamic

properties

2

over 100 years [4]. In consequence, much effort should bethat were reasonably similar to that ofR502.expended on finding suitable substitutes for R502. Physical and environmental characteristics of HFC-

161mixture, R502, R404A and R507 are calculatedbyREFPROP

[9].

Table 1 summarizes their basic physical characteristics2. Literatureoverview [4] . Fig.

1shows the comparison of their saturation vapor

pressure.Many studies have been concentrated on the research of

It can be observed from Table 1 and Fig.1

that the basicsubstitutes for R502. A considerable group of alternative

physical characteristics of this new ternary alternativecandidates for R502 have been put forward, such as R404A,

refrigerant such as boiling point, criticaltemperature,R402A, R402B, R408A, R407A, R403B, R507,

etc.

[3]. But

critical pressure and saturation vapor pressure are all similarat present there is no such unanimous solutions and none ofto those of R502, and can be used as a potential retrofit

these substitutes seems to be thebest substitutes. R404A andrefrigerant. It is environmentally acceptable too. Its ODPisR507 are two primary alternative refrigerants among

themzero, having no ozone depletion potential. Its GWP is71%[3,5,6

].

to that of R502, while the corresponding comparison ratiosR404A is a ternary near azeotropic mixture composedof

of R404A and R507 based on R502 are 84% and87%,HFC-125/HFC-143a/ HFC-134a, 44/52/4 wt%. As far as

therespectively. Its temperature glide is 0.38 8C, lower thanthatthermodynamic performance is concerned, its COP is a

littleof R404A (0.5 8C) and can be considered as anear-smaller than that of R502 in the working conditions of

lowazeotropicmixture.evaporative temperature while its discharge temperature is

lower than that of the latter and is a preferable alternative

refr igerant toR502

[7] .

R507 is a binary azeotropic refrigerant composedofHFC-125/HFC-143a, 50/50 wt%. Experimental results

indi-cate that it can be used as an alternative refrigerant to R502

in low evaporative temperature (245 to 0 8C). Polyesteroilshould be used in R507 systems. Though seldom used, R507

can be used in most R404A equipments [5] . For use in

refrigeration and air-conditioning units in low andmediumtemperature applications, similar operating parameters such

as compressor discharge temperature, pressure ratios and

coefficients of performance can be achieved in comparison

withR502

[6] . Experimental results indicate that theheattransfer coefficient of R507 is better than that of

R502[8].

But as far as the issue of environment protection is

concerned, the shortcomings of those above mentioned

refrigerants become evident. Although their ODP areall

Fig. 1. Saturation vapor pressure of R502, R404A, R507 and HFC-

zero and has no ozone depletion potential to the atmosphere, 161 mixture.


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Table 1

Physical and environmental characteristics of R502, R404A, R507 and HFC-161 mixture

R502 R404A R507 HFC-161mixture

Molecular weight (g/mol) 111.63 97.60 98.86 89.41

Critical temperature (8C) 80.7 72.1 70.9 76.4

Critical pressure (MPa) 4.02 3.74 3.79 4.01aBubble point (8C) 2 45.4 246.5 2 46.7 246.08

aDew point (8C) 2 45.4 246.0 2 46.7 245.70

Temperature glide (8C) 0 0.5 0 0.38

ODP 0.221 0 0 0

GWP 4500 3800 3900 3200

Safety group A1 A1 A1 /

a

Bubble point and dew point are saturation temperature under standard atmosphere pressure, 101.325 kPa.

4. Experimentalapparatus

The compressor used in this experiment is of reciprocat-

ing, piston, hermetically sealed type with a displacement

volume of 26.2cm

and is designed to work withR404A.

3An experimental set of vapor compression refrigeration

The condenser is shell and tube type while the subcooler iswas built up to investigate the performance of this new

tube-in-tube type. Both the condenser and the subcooler aresubstance and that of R404A. Fig.2

shows the schematic

water-cooled types. Calorimeter, the key part inthe

diagram of the refrigerationsystem. experiment, is a highly thermal insulation vessel. In

theThe set is composed of a compressor, a condenser, a

upside of the calorimeter there installed the evaporative coil.subcooler, a throttle valve, an evaporator installed in the

At the bottom of it there are electrical heaters submerged bycalorimeter, and some auxiliary and measuringdevices.There are two kinds of refrigerants in this

experimentalthe second refrigerant.

apparatus. One is the first refrigerant, whose properties are The temperatures and pressures of the refrigerant were

tested in the experiment. Another working substance is the measured at various locations in the experimental apparatus

second refrigerant, which is filled into calorimeter and

used

as shown in Fig.

2

, such as the inlet and outlet of the

as medium of heat transfer. compressor, condenser, subcooler and evaporator, etc.

Fig. 2. Schematic diagram of experimental apparatus.


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Table 2

Specifications of measuring apparatus

Parameters Measuring apparatus Range Uncertainty

Temperature Platinum resistance thermometer (four wires) 2100 300 8C 0.18C

Pressure Precision manometer 0 0.4, 0 1.0, 0 2.5 Mpa 0.25%

Power Wattmeter 0 2.0, 0 4.0 kW 0.5%

Platinum resistance thermometers (four wires)were

During the experiments, make assurance that there is no

installed to measure the temperature and an electronic abnormal air ow around the experimentapparatus.digital universal meter is used to read the temperature. The In order to test the cycle performances of new refrigerant

suction and discharge pressures of compressor were read and those of R404A at rated working conditions, modulate

from a set of pressure gauges. Digital wattmeters were used the heating power to control the suction temperature of

to determine the electrical power input to the compressor compressor, adjust the opening degree of throttle valve to

and the heating power of the electrical heaters. control the o w rate of refrigerant, that is, to control the

suction pressure, adjust the ow rate of water in theTable 2 represents the specifications of measuring

condenser to control the discharge pressure, and adjustapparatus and their uncertainties reported by the

the ow rate of water in the subcooler to control themanufacturers.

subcooling temperature.During theexperiment, the second refrigerant was heated

When the system arrives at rated working condition byby the electrical heaters. Its vapor heats the main refrigerant

means of these above-mentioned methods and remainsin the evaporator upside, then condenses on the surface of

stable at thermal balance for a long enough time period,evaporator coils and returns to the bottom of calorimeter

record four successive groups of experimental data at timeafterward. The main refrigerant absorbs the heat and

interval of one hour. The period between the first recordevaporates. The compressor inhales the vapor of main

time and the fourth record time is called experimentalcycle.

refrigerant and compresses it to be high-temperature and

The deviations of experimental data during theexperimental

high-pressure gas. Then the gas is cooled and condensed

cycle are outlined in Table 4 .into liquid by water in the condenser, subcooled by water in

In consideration of the temperature difference existingthe subcooler, throttled by the throttle valve, and returns to between calorimeter and surrounding environment, heatevaporator in the end. Then begins a new circulation.

leakage coefficient was measured.When this system runs at stability, we can get the balance

First, turn off the inlet and outlet valve ofcalorimeter,

between electrical heating power and refrigerating capacity.

and regulate the electrical heating power to ensure that theThis is the principle of experiment, namely, theheating saturation temperature corresponding to the pressure of thepower of electrical heaters is equal to the cooling capacity of

second refrigerant is 15 8C higher than that of surroundingevaporator, if not considering the heat leakage.

environment. The temperature of the surrounding environ-

ment should be lower than 40 8C and its uctuation should

be smaller than ^1 8C. Be sure that the maximum shiftof

5. Experimentalprocedure heating power is ^1% and the pressure of the second

ref rigerant remains stable during the test. Record theAs R502 is now facing the fate of complete phasing out,

pressure data per hour. Also, at least four successive groupscycle performances of HFC-161 mixture werecompared

of data should be recorded. And the deviation of theirwith those of R404A, a main alternative refrigerant toR502.

corresponding saturation temperature should be smaller thanDrop-in experiments are carried out withoutany ^ 0.5 8C. The calculation equation of heat leakage

coeffi-modification to the experimental apparatus. Theexperiment

cient is outlined as follows.was started with R404A to set up the base reference for

further comparisons with new mixture under twoidenticalrated working conditions. The parameters of rated working h 2 1K Q WK 11

t 2 tconditions are outlined in Table 3 . p a

Table 3

Parameters of rated working conditions (unit: 8C)

Evaporative temperature Condensing temperature Suction temperature Subcooling temperature

Working condition 1 2 40 35 210 30

Working condition 2 2 23 43 5 38


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Table 4

Deviations of experimental data during the experimental cycle

Experimental parameters Maximum deviation between each measured data Maximum deviation between each measured data

and rated data and average data

Suction pressure ^1.0% ^0.5%

Discharge pressure ^1.0% ^0.5%

Suction temperature ^0.2 8C ^0.2 8C

Subcooling temperature ^0.2 8C ^0.2 8C

where, Q is electrical heating power. t is the average temperature ( 2 23 8 C), t he compressor p ower con-

h p

saturation temperature of the second refrigerant. And t is sumption of HFC-161 mixture (894 W) is alittle

a

the average temperature of environment. smaller than that of R404A (898 W), while the

coolingThe results show that the heat leakage is no more than capacity ( 1187 W ) is s till g reater than that o f thelatter5% that of cooling capacity of the system. Average the four (1152 W). Therefore, the COP of this newrefrigerantgroups of experimental data, and then modify them by the is greater than that of R404A.

obtained heat leakage coefficient, we got the finalexper-

(4) The discharge temperature of HFC-161mixtureimental results. The data reported in this paper have all been (115 8C) is h igher than that o f R404A (108 8C)

undermodified.

a lower evaporative temperature (240 8C), butitbecomes lower (104 8C) than that of the latter (1058C)when the evaporative temperature increases to

2 238C.

6. Experimentalresults

Cycle performances, such as pressur e ratio, power

consumption of the compressor, cooling capacity, discharge 7. Conclusions

temperature and COP, are measured under twodifferentrated working conditions. Table 5 summarizes the

exper-

Ternary mixture of HFC-161, HFC-125 and HFC-

143a isimental results. firstly presented as a promising alternative refrigerant to

As can be seen from the experimental results, this new R502 in this paper. The performances of R404A andthisalternative refrigerant has the following characteristics. new mixture are compared in a vapor compressor refriger-ation set under two different rated working conditions.

As far as its physical and environmental characteristics(1) The operating pressure ratios of HFC-161 mixtureare are concerned, as well as the comparison

experimentalnearly equal to those of R404A under these two

results, we got the following conclusions.different evaporative temperatures.

(2) Under operating conditions of lower evaporative

temperature (240 8C), the cooling capacity ofHFC-

(1) Basic physical properties of this new mixture, suchas161 mixture (445 W) is a little greater than that

ofboiling point, critical temperature, criticalpressureR404A (434 W), and the compressor power

consump-and saturation vapor pressure are similar to those of

tion of the former (566 W) is also slightly greaterthan

R502, and can be used as a retrofitrefrigerant.that of the latter (547 W). Accordingly, the COPs

of(2) Its environment properties are friendly. Its ODP iszerothese two refrigerants are almost the same. and GWP is smaller than those of R502, R404A

and(3) Under working conditions of higher evaporative R507.

Table 5

Cycle performances of HFC-161 mixture and R404A at rated working conditions

Cycle performance Working condition 1 Working condition 2

HFC-161mixture R404A HFC-161mixture R404A

Pressure ratio 11.81 11.82 7.11 7.13

Compressor power (W) 566.2 546.7 894.3 898.4

Cooling capacity (W) 445.3 434.3 1187.3 1152.3

COP 0.79 0.79 1.33 1.28

Discharge temperature (8C) 114.52 108.45 103.69 105.45


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(3) Belonging to near azeotropic mixture, itstemperature

methanes chlorine catalyzed destruction of ozone, Nature 249

(1974) 810 812.glide is smaller than that ofR404A. [2] R.L. Powell, CFC phase-out: have we met the challenge?,(4) Operating pressure ratios are nearly equal to those of

J Fluorine Chem 114 (2002) 237 250.R404A under the above two rated evaporative

[3] C. Aprea, R. Mastrullo, et al., Behaviour and performances oftemperatures.

R502 alternative working uids in refrigerating plants, Int J(5) Under lower evaporative temperature, its COPis

Refrigeration 19 (1996) 257 263.almost equal to that of R404A and its discharge

[4] J.M. Calm, G.C. Hourahan, Refrigerant data summary, Engnrtemperature is slightly higher than that of R404A, Syst 18 (2001) 74 78.while under higher evaporative temperature, its COPis

[5] R. Camporese, G. Bigolaro, et al., Experimental evaluation of

greater than that of R404A and its discharge refrigerant mixtures as substitutes for CFC-12 and R502, Int JRefrigeration 20 (1997) 22 31.temperature is lower than that of the latter.

[6] R. Doring, H. Buchwald, et al., Results of experimental and(6) This new alternative refrigerant can achieve ahigher theoretical studies of the azeotropic refrigerant R507, Int Jvalue of COP under the above two evaporative

Refrigeration 20 (1997) 78 84.temperatures.

[7] J.W. Linton, Some performance measurements of four long(7) Ternary mixture of HFC-161, HFC-125 and HFC-143a

term R502 replacements in a test facility containing a scrollcan be used as a promising alternative refrigerant to

compressor. In 19th International Congress of Refrigeration,R502.

proceedings volume IVb; 1995, p. 898 905.

[8] S.M. Sami, M. Fontaine, Prediction of condensation character-

istics of alternatives to R-502 inside air-refrigerant enhanced

surface tubing, Appl Thermal Engng 20 (2000) 199 212.References [9] E.W. Lemmon, M.O. Mclinden, et al., Reference uid

thermodynamic and transport properties, National Institute of

[1] M.J. Molina, F.S. Rowland, Stratosphere sink for chloro uoro- Standard Technology (NIST), 2003.


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