R12, R134a, and 152a: CORRELATION
OF THEIR THERMODYNAMIC PRO-
PERTIES AND COMPARISONS OF
PERFORMANCE INDICATORS
WHEN USED IN AN IDEAL
VAPOR-COMPRESSION
CYCLE
GAUDENCIO A. CATUBAO
NIDA A. CATUBAO
DIOSCORO Y. MANCAO, JR
Abstract
This research study presents the results ofa computer simulation of an ideal vapor-compression refrigeration cycle using R12 (anozone depleting refrigerant) and two non-CFCrefrigerants (R134a, and R152a) which areconsidered to be good replacements of R12. Thesimulation program incorporates explicitlycorrelated saturated and superheated propertiesof R12, R134a, and R152a..
Abstract (Continuation)
The simulation program was used to generate graphsshowing the relative performance of the refrigerantson the following performance indicators: a)volumetric flow rates at compression suction per tonof refrigeration, b) coefficient of performance (COP),c) horsepower per ton of refrigeration d) mass flowrate of refrigerant per ton of refrigeration, e)discharge pressure, f) discharge temperature, g)pressure ratio, and h) refrigerating effect. From thegraphs generated, analyses were made to determinethe potentiality of R134a and R152a as replacementsof R12 and to determine the most suitablereplacement of R12
Background of the Study
Availability of affordable microcomputers
Computer simulation to conduct experiments
The need to formulate equations representing tabulated properties
Availability of equations in textbooks
Objectives: (1/3)
To formulate explicit equations of the thermodynamic properties of R12, R134a, and R152a,
To develop a computer program that implements calculations of performance indicators of an ideal vapor compression refrigeration system,
To generate graphs showing the comparative performance of the three refrigerants on the following performance indicators:
Objectives (2/3)
a) volumetric flow rates
b) coefficient of performance
c) horse power per ton
d) mass flow rate per ton
e) discharge pressure
f) discharge temperature
g) pressure ratio and
h) refrigerating effect
Objectives (3/3)
Using the graphs generated, analyses were made to determine the suitability of using R134a or R152a as a replacement of R12.
Significance of the Study
The results of the study will benefit the following:
1. Students in Refrigeration – Can make use of the correlations in simulating an ideal vapor-compression cycle. The simulation program can be used to conduct experiments even without fabricating or building an actual system.
2. Refrigeration Specialist – Can make use of the graph generated as bases for choosing which refrigerant to use (R134a or 152a) as a replacement of R12 for a refrigeration system.
Computer Simulation Results
Evaporating Temperature, °C
Vo
lum
etr
ic F
low
Ra
te,
cu
.m./
se
c.
100-10-20-30-40
0.012
0.010
0.008
0.006
0.004
0.002
0.000
Variable
R152a
R12
R134a
Evaporating Temperature, °C
Co
eff
icie
nt
of
Pe
rfo
rma
nce
(C
OP
)
100-10-20-30-40
11
10
9
8
7
6
5
4
3
2
Variable
R-152a
R12
R-134a
Evaporating Temperature, °C
Pre
ssu
re R
ati
o
100-10-20-30-40
20
15
10
5
0
Variable
R-152a
R12
R-134a
Evaporating Temperature, °C
Ma
ss F
low
Pe
r To
n,
kg
/se
c.
100-10-20-30-40
0.040
0.035
0.030
0.025
0.020
0.015
Variable
R-152a
R12
R-134a
Evaporating Temperature, °C
Dis
ch
arg
e T
em
pe
ratu
re,
°C
100-10-20-30-40
70
65
60
55
50
45
40
Variable
R-152a
R12
R-134a
Evaporating Temperature, °C
Re
frig
era
tin
g E
ffe
ct,
kJ/
kg
100-10-20-30-40
260
240
220
200
180
160
140
120
100
Variable
R-152a
R12
R-134a
THANK YOU VERY MUCH
