Embedded Based System For The Study Of Heats Of Mixing Of Binary Liquid Mixtures.pdf

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Journal of Science and Technology
Volume 1, Issue 1, December2016, PP 01-12
www.jst.org.in
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Embedded Based System For The Study Of Heats Of Mixing Of
Binary Liquid Mixtures
P.S.S Sushama1, K.Malakondaiah 2 , C.Nagaraja3
123(Department of Instrumentation and USIC, SKDU, Ananthapur, India)
______________________________________________________________________________________
Abstract : Studies of heats of reactions o f binary liquid mixtures are given a considerable importance in
understanding the nature of molecular interactions. Such studies mainly help to know the enthalpies of liquid
mixtures. The present study deals with design of a simple embedded b ased system for measuring heat of mixing
of binary liquid mixtures. The system consists of two units, cell assembly and data acquisition system. One of the
components of the binary mixture is taken into the cell, other component is injected in to the cell through
appropriate mechanical arrangement. The reaction on mixing causes the thermal changes which are sensed by
the thermal sensor, th at can be measured up to 10 -4oC. The entire unit is interfaced to LPC 2366 ARM based
controller (A less power consumption device made by philips). The ARM controller sends the data to the
Personal Computer through the serial port and software is developed to calculate enthalpy values. A
comparison of the results obtained with the literature data showed good agreement. The designed system can be
used as an alternative for the measuring heats of mixing of binary liquid mixtures. The paper deals with the
design aspects both hardware and software features of the system.
_______________________________________________________________________________________
Keywords - liquids, mixtures, ARM Processor, embedded
I. INTRODUCTION
Heat of mixing data for binary liquid systems is use ful for both chemists and engineers to know the
nature of the solutions and d esign the heat transfer equipment (heat exchangers). As the data of the non ideal
systems are very limited and the effect of temperature are very r arely has been investigated. Based on heat
transfer theory, the relations between the heat effect generated and the quantity measured in the calorimeter
known as the heat balance equation is established, which expresses the change of temperature directly as a
function of the heat produced in a calorimeter and is applied to design different types of calorimeters. A number
of calorimeter is available micro to macro and simple to complex in design. The calorimeters are d iffered by
their principle, heat flow calorimeter, Benson et. al.1 Picker flow calorimeter, Fortier and Benson2 in this type
of calorimeter excess heat capacities of mixtures of non -electrolytes were determined from vol umetric heat
capacity. Steady state and composition scanning differential flow micro calorimeters by Patrick Picker et. al.3,4
They developed two different flow micro calorimeters, one is of the adiabatic type and can be used to
measure ΔT mixing for liquid phase reactions, and other can be operated under either adiabatic or isothermal
conditions and serves for either gas or liquid phase investigations. The available commercial calorimeters like
Parr5,6 and ITC are sophisticated and very costly. Hence an attempt is made to design adiabatic micro
calorimeter which is simpler and versatile for a rapid and fairly accurate measurement of exothermic and
endothermic heats of mixing for binary liquid mixtures. The proposed system shows a new approach which is
attached with all t he advantages of a ny embedded based system in speed and compatibility. These
measurements assume a great significance because of diversified applications of these measurements i n
industries and R&D purposes.
II. MATERIALS AND METHODS
The chemicals used in the present work Carbon tetrachloride, n-hexane, Cyclohexane , Di mehyl
formamide, methyl-tert-butylethane (MTBE), Chlorobenzene, Nitrobenzene, Carbontettachloride are obtained
from M/s Fulka Ltd.,Bombay. Benzene (Spectroscopic grade) was obtained from M/s SD Fine Chemicals,
Boisar, India. Dimethoxyethane are obtained from SD Fine Chemicals, Boisar, India The chemicals used here
are used without any further purification. methyl-isobutyl ketone, methyl-ethylketone obtained from BDH Ltd.,
and dried over 4A molecular sieves for 4 5 days and purified by fractional distillation. Pure component
properties used to calculate excess enthalpies such as molecular weight, density and heat capacity are collected
and tabulated in Table 1. Measured density, boiling point and refractive index of the the compounds and
compared with literature values reported by Riddick et al7 and Ian M. Smallwood8 to ensure the purity of the
compounds. The data is tabulated in Table2. From Table2, it is found that the measured properties are in good
agreement with literature values9,10. The purity o f the compounds are checked and further confirmed by GC, a
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single sharp peak. The vibrator, Nokia 1100 (range is 500 milli volts to one volt) is used as a device to stir the
mixture inside the cell, the ARM7TDMI based LPC2366 controller (NXP Philips), 12V and 2Amp stepper
motor similar to that used in HP printer, constant current source REF200 and 5 k thermistor are purchased
from local electronic shop, Ahmedabad, India. Micro syringe (Borosil) of 10 ml capacity, Dewar flask (Eagle)
of 20 ml capacity are obtained from Ahmedabad, India. Insulating materials is Polytherific foam (PUF) from
M/s Bharathi Refrigeration systems from Ahmedabad, India.
The heats of mixing is calculated using the equation.
Where T temperature difference, w i s weight and CP is hea t capacity of the components, C.C is cell
constant. Suffixes represent components 1 and 2 respectively. The pure co mponent data is collected from
literature is tabulated in Table2.
Table 1 Properties of pure components from literature value
Table 2 Comparison of properties of pure components
Sl.
No.
Name of
the
compoun
d
Mole
cular
weig
ht
Density
g/cc
Cp,
Cal/
mol/o
C
Chemical
Formula
Re
fer
en
ces
1
DMF
73
0.945
36
C4H10O2
5
2
MIBK
100
0.801
46
C6H12O
3
MEK
72
0.805
38
C4H10O
4
MTBE
88
0.741
44.8
C5H12O
5
Benzen
e
78
0.790
31
C6H6
6
Chloro
Benzen
e
113
1.106
35
C4H5cl
7
Nitro
benzen
e
123
1.204
44
C6H5NO2
8
Hexane
86
0.659
42.0
C6H14
9
Cyclo
hexane
84
0.778
36.4
C6H12
10
Ethanol
46
0.789
27
C6H5O
11
Water
18
0.998
18
H2O
12
Carbon
tetrachl
oride
154
1.580
32
CCl4
Sl.
N
o.
Name of
the
compoun
d
Density g/cc
Boiling point,
oC
Ref.
Expt.
Lit.
Expt.
Lit.
Expt.
Lit.
1
DMF
0.9453
0.945
152.6
153
1.4276
1.427
5
2
MIBK
0.8007
0.801
116.3
116
1.3945
1.394
3
MEK
0.8039
0.805
79.8
80
1.3772
1.377
4
MTBE
0.7402
0.741
55.2
55
1.3686
1.369
5
Benzene
0.7896
0.790
79.8
80
1.4978
1.498
6
ChloroBe
nzene
1.1062
1.106
131.7
132
1.5236
1.523
7
Nitro
benzene
1.2038
1.204
210.8
211
1.5488
1.550
8
Hexane
0.6578
0.659
69.4
69
1.3725
1.372
9
Cyclo
hexane
0.7782
0.778
80.6
81
1.4242
1.424
10
Ethanol
0.7886
0.789
78.2
78
1.3586
1.359
11
Water
0.9982
0.998
99.8
100
1.3323
1.332
12
Carbon
tetrachlor
ide
1.5796
1.580
75.6
76
1.4592
1.459
 
CCCwCwTH PP
E.
2211
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III. APPARATUS
The calor imeter was designed to operate adiabatically and to allow the heats of mixing at room
temperature to determine for the entire composition range. The designed system consists of two units. One is
calorimeter cell assembly and other is data acquisition system. The Cell design is as shown in fig.1.
The cell assembly consists of a test cell of 10 ml capacity inserted in a Dewar flask, which is insulated
with Polytherific foam material about 2 mm thickness. One of the components of binary mixture is taken into
the test cell and other component is added by means of dispensing unit. The dispensing unit consist of 12 V
stepper motor, gear rod, coupling and micro syringe. Syringe is taken and attache d to a gear rod. Stepper motor
is plugged to a 12 V power supply and interfaced to LPC 2366 ARM controller. T he syringe is connected to a
feed tube at one end and the other end is kept in to the cell inside Dewar flask. A 5 k thermistor was taken.
The thermistor is a glass covered probe with a resistance of 5 k at room temperature was sealed in the end of a
piece of glass tubing which carried the leads a out of the calorimeter. One o f the lead is connected to constant
current source REF200 and the other l ead is grounded to the power suppl y. The ther mistor is inserted in the
solution. Thermistor senses the temperature changes produced on adding second component to the other
component which was held in the calorimeter cell. The sensed voltages are sent to th e ADC channle2 of the port
pin 24 of ADC of LPC 2366 ARM controller and data is acquired from the PC through the serial port .A tiny
DC motor is taken and the leads are taken out and plugged to 900 mV power supply. A small glass tube is taken
and bended at the edge to act this as a stirrer. The glass tube is fixed to the tip of the motor. Stirr er runs at a very
low speed, so that the heat produced due to the stirrer is negligible. Here the designed tiny stirrer will not
produce any frictional heat while stirring.
Fig 1 Calorimeter Design
IV. EXPERIMENTAL PROCEDURE
The designed specification of calorimeter used for the measurement of heat of mixing for binary liquid
mixtures is as shown in Fig.1. First data point is obtained by taking known quantity (5 ml) of component 1 into
test cell and the 0.5 ml of component 2 is add ed through dispensing unit. A Vibrator is used to p rovide uniform
distribution of the component 2 into component 1 in the cell. The temperature change is recorded at every 5
seconds. Experiment is stopped after reaching thermal equilibrium, i.e., no temperature change. 0.5 ml of
component 2 is added to the mixture (5.5 ml) in the cell. The temperature change is recorded at ever y 5 seconds
and stopped after reaching thermal equilibrium. Th e procedure is rep eated till total amount of component 2
added is 5 ml with a 0.5 ml increment. . The temperature difference (T) is obtained by plotting time vs.
temperature. Up to 50% weight percent range is covered in this way. To obtain the data over e ntire composition