Measurement of isobaric specific heat of HCFC-123 in the liquid phase

203

Thermochimica Acta, 163 (1990) 203-210 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

MEASUREMENT OF ISOBARIC SPECIFIC HEAT OF HCFC-123 IN THE LIQUID PHASE

S. Nakagawa,

H. Sato, and K. Watanabe

Thermodynamics Laboratory Department of Mechanical Engineering Facuhy of Science and Technology Keio University 3-14-1, Hiyoshi Kohoku-ku, Yokohama 223 (Japan)

SUMMARY The isobaric

heat capacity,

CFC-11 has been measured

Cp, of HCFC-123 which is a prospective

by using a flow-calorimeter

values have been determined

at temperatures

0.5 MPa to 3.0 MPa. The uncertainty +2 kPa in pressure the experimental

alternative

to

in the liquid phase. Sixty-nine

Cp

from 276 K to 410 K and pressures

was estimated

and rt0.4 % in Cp, respectively.

from

being within e 10 mK in temperature, A Cp correlation

which is effective in

range has been also developed.

INTRODUCTION It is our

urgent

alternatives.

task

to

develop

HCFC-123(CHCI,CF,)

stratospherically

is one

of the

safe

prospective

CFC(chlorofluorocarbon) alternatives

to

CFC-11 (CCI,F) which has been widely used as a blowing agent and as a working turbo-compressor

driven refrigeration

isobaric heat capacity

machines

replace fluid for

and heat pumps. This paper reports the

data of liquid HCFC-123. The purity of HCFC-123 used in this study

was 99.83 wt%.

PRINCIPLE

AND APPARATUS

Isobaric

specific

performance agent,

but

heat

or heat transfer it is not

thermodynamic

easy

equation

is an

important

problems

for applications

to get the values

of state developed

reliable specific heat values are not determined phase,

especially

0040-6031/90/$03.50

property

at high pressures.

for

calculating

as a working

by predictions

thermodynamic fluid or a blowing

or calculations

on the basis of PV7 property theoretically

We selected

but experimentally

flow-calorimetry

0 1990 Elsevier Science Publishers B.V.

from

a

data. The most in the liquid

for determining

the

204 absolute values of specific heat of liquids.

This

compensate leakage

amount

of heat

already

isobaric

and

liquid

calorimeter

HFC-1 34at2J in

the

with

the

is shown

tubing

diameter

of

sheathed whose

9.35

stainless

outer

mm steel

at

outer tubing

heat flux to sample

fluid.

100

resistance

hermometer

in

and supplies Two

pump

in Fig. 1. A

is 1.6 mm is inserted

center

To vacuurr

The main part of

5.5 n microheater

diameter

for

of 50.4 % and 20.3

%, respectively.

SUS316

liquid.

heats

phases

uncertainties

n

platinum

thermometers

50 mm

I

sheath-

ed in SUS316 tubing whose outer diameter

shield

measured

specific

CFC-114(l)

Radiation

at various

rates of sample

have

their

can

by measuring

mass-flow We

the

method

Fig. 1. Cross-section

of the calorimeter.

is 1.6 mm are placed at

the center of 6.35 mm outer diameter

stainless

steel

tubing

inlet and outlet thermometers. explanation

of the present

The flow-calorimetry

as They were calibrated

apparatus

has been published

consists of three simultaneous

heat flux 6, and temperature

increment

according

to IPTS-68. A detailed

previouslyc3).

measurements;

mass-flow

LT. Specific heat Co is determined

rate fi,

by the following

relation:

C/J= Cj/ (rf~AT)

Equation temperature

(1) is true change

(1)

only

in the case

of an ideal

condition

without

due to sample liquid flowing. The heat leakage

heat

loss nor

is compensated

by

pe~orm~ng example

plural measurements

of measured

with different

rates. Figure 2 shows typical

Cp including heat loss versus reciprocal

the heat loss 0‘ into consideration,

Cp = 61 (r-hAT) +

mass-flow

of mass-flow rate. By taking

Eq. (1) becomes,

d,/ @AT).

where 0, will be eliminated

(2)

at the infinitely large mass-flow

rate, or by reducing

6, itself.

The heat loss appears as a slope of the lines in Fig. 2.

0 Fig.

2. Relation between the measured specific heat reciprocal of mass-flow rate, h-l, in flow-calorimetry. The temperature

measurements

because

AT was controlled always

mass-flow increment between without

the maximum

by

without

measu~ng heating

rate as those

by microheater

of measurements

by microheater.

liquid flowing

difference

between

the

associated

with heating.

This process compensates

was outlet and

The temperature differences

with heating

the temperature temperature

and

pressure,

from the sum of those temperature in both cases of the processes

increment change

inlet

at the same temperature,

and other effects. The maximum

inlet and outlet thermometers at higher temperatures.

the heat flux 6. The temperature

temperature

inlet and outlet thermometers

to sample

and

flow rate was 0.16 g/s. The temperature

LITin Eq. (1) was determined

heating

CpexP,

due to sample iiquid flowing was very small in the present

to be 5 K by regulating

monitored

thermometers

change

values,

change

change

and due

between

in the case of the process without heating was about 40 mK

206

Metering pump

(b) T

AC

Sampling l13 vessel 8

(e) 3 11

Needle valve T I#-#\ Q

3-way valve

Fig. 3. Flow assembly.

A schematic

diagram

in the system completely by a metering

of flow assembly

is shown in Fig. 3. The sample

in the liquid phase. The sample liquid is circulated

pump (a), where the pulsation

due to the metering

means of the metallic bellows installed in sampling

(9. The sample pressure is controlled metallic bellows the sampling

r5

difference

is installed

mK at a required of sampling

in the system

pump is absorbed

vessel (g) and accumulators,

by means of the pressure

of nitrogen

(9 through calorimeter

in a thermostated temperature.

(b) and

(b) to

(c) and needle valve (d).

bath where the temperature

The mass-flow

by

gas filled in

(b). The sample fluid flows from the accumulator

vessel (g) or accumulator

The calorimeter within

of accumulator

fluid is filled

rate is determined

is controlled from mass

vessel (g) placed on a digital balance and the time period.

MEASUREMENTS The measurements

were performed

at temperatures

from 275.65

K to 410 K and

207

0

2

Fig. 4. The present

pressures

from

measured

Cp values,

plotted

against

determined

Cp measurements

8 rfr' (s g-1)

at reciprocal

of various

10

mass-flow

rates.

0.5 MPa to 3.0 MPa. In order to know the effect of heat loss in the 138 data were measured

the reciprocals

of mass-flow

from the 138 measurements.

than 2 IO mK in temperature 2 10 mK in temperature, determined

6

4

increment,

at various

mass-flow

rates which were

rate in Fig. 4. Sixty-nine

final results were

The uncertainty

of the measurements

~0.02 % in heat flux, 20.2 % in mass-flow rate, and

and +2 kPa in pressure, respectively.

Cp values is concluded

is better

The overall uncertainty

of

to be better than 20.4 %. These results are plotted in

Fig. 5.

DISCUSSIONS Figure 4 shows the present measurements The specific heat values do not depend in the present the uncertainty

measurements

of mass-flow

rate.

upon the mass-flow rates which means heat loss

is small enough

of ~0.4 % as discussed

against the reciprocal

above.

to determine

the specific heat values with

208

A correlation

was developed

on the basis of the data measured

in the liquid phase

by least squares fitting with simple polynomials;

Cp = A(T)P

A(T ) =

(3)

+ B(T)

a, /(I - Tr ) + a2 /(l - Tr )".5 - Tr )'.5+ b, /(1 - Tr ) + b3 /(I - Tr )".5

B(T ) = b, /(l

a, = -0.005177

a, =

b, =

b2 = -0.4027

0.05824

0.007561 b, =

1.1235

where P and Tr denote pressure in MPa and temperature Cp is given

in kJ/(kg

K). The critical temperature

Tanikawa et al.t41 Equation(S)

of Tr = T / Tc, respectively,

Tc is 456.86

is effective in a range of temperatures

K which

reported

between

and by

275.65 K and

1.35 g+ 1.30 b 3 Q o

4

HCFC-123

4 4 410 K

1.25 ----@+---@400

K

1.20 1.15 1.10 1.05 1 .oo

b

-4-----P----~ 275.65

K

0.95 0.0

Fig. 5. Experimental HCFC-123.

1.0

2.0 Pressure

data and the correlation for the isobaric

3.0 (MPa)

specific

heat

of liquid

209

400 K and pressures is estimated

up to 3 MPa. The uncertainty

better than 20.6 %. Equation

Fig. 5. The Cp values of saturated pressures

reported

of calculated

(3) is compared

Cp values from Eq. (3)

with the experimental

liquid HCFC-123 calculated

data in

from Eq. (3) at the vapor

by Piao et a1.r5Jare also given in Fig. 5 and these values are compared

with those of CFC-11 c6Jin Fig. 6 for the practical use of HCFC-123 as an alternative

fluid

to CFC-11.

I

1.35

h k

1.30

’

m

1.25

-

y

1.20

*

a -

1.15

-

op

1.10

.

1.05

-

0.95

-

0.90

./

I

I

I

CFC-11

0.85

, 260

1

280

300

320

340

360

380

Temperature Fig. 6. Comparison of the present correlation for HCFC-123 the saturation states.

400

420

(K) with that of CFC-11 c6)at

CONCLUSION Isobaric

specific

temperatures estimated

of

HCFC-123

were

from 275.65 K to 410 K and pressures

uncertainty

temperatures developed.

heats

between

of 20.4 275.65

The uncertainty

than 20.6 %.

%. The correlation

measured

liquid

phase

at

from 0.5 MPa to 3.0 MPa with the which

is effective

K and 400 K, and pressures

of calculated

in the

in the

range

of

up to 3 MPa was also

specific heat values from the correlation

is better

210

ACKNOWLEDGMENTS We acknowledge

the assistance

Atsusi Saitoh in the development for Scientific Science

Research

of Hideo Miyahara in the present measurements

of this apparatus.

Fund in 1989(Project

and Culture of Japan and a support

We are indebted

No.01603022) of Tokyo

and

to the Grant-in-Aid

of the Ministry of Education,

Electric Power Co., Ltd. We are

also grateful to Asahi Glass Co., Ltd., Japan, for kindly furnishing the sample of HCFC-123.

REFERENCES 1

2 3

4

5

6

H. Sato, N. Sakate, M. Ashizawa, M. Uematsu, and K. Watanabe, Measurement of the isobaric specific heat capacity for liquid dichlorotetrafluoroethane(R 114), Proc. 1987 ASME-JSME Therm. Eng. Joint Conf., 4 (1987) 351-358. A. Saitoh, H. Sato, and K. Watanabe, Isobaric heat capacity data for liquid HFC134a, submitted to J. Chem. Eng. Data, (1989). A. Saitoh, H. Sato, and K. Watanabe, A new apparatus for the measurement of the isobaric heat capacity of liquid refrigerants, Int. J. of Thermophys., 1O(3) (1989) 649659. S. Tanikawa, Y. Kabata, H. Sato, and K. Watanabe, Measurements of the vaporliquid coexistence curve in the critical region of HCFC-123, Proc. 2nd Asian Thermophys. Prop. (1989) 513-518. C.-C. Piao, H. Sato, and K. Watanabe, Measurements of the saturated vapor pressure and PVT property of HCFC-123, to be presented at the 1989 JAR Ann. Conf. (1989). A. F. Benning, Ft. C. McHarness, W. H. Markwood, Jr., and W. J. Smith, Heat of three fluorochloromethanes and capacity of the liquid and vapor trifluorotrichloroethane, Int. Eng. Chem., 32(7) (1940) 976-980.