EURECA 2013 – EFFICIENT AIR-CONDITION UNIT BY USING NANO-REFRIGERANT
Efficient Air-Condition Unit By Using Nano-Refrigerant
Muhammad Abbas1, Rashmi G. Walvekar2, Mohammad Taghi Hajibeigy3, Farhood S. javadi4
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School of Engineering, Taylor’s University, Malaysia, 4Department of Mechanical Engineering, University of Malaya, Malaysia.
*Corresponding Author email: RashmiGangasa.Walvekar@taylors.edu.my
Al 2 O 3 nanoparticles were optimal. Hence, the power consumption
drops by 2.4% and COP increased by 4.4% [6].
Abstract— This research mainly focuses on CNT-based
nanolubricant in the refrigeration system. CNT Nanoparticles
introduced into the system through lubricant to improve its heat
transfer performance. A concentration of 0.01-0.1wt% of CNTPolyester Oil was tested along with suitability and environmental
friendly refrigerant R134a. Results show that CNT nanoparticle
concentration of 0.1wt% is optimal and gives highest heat transfer
enhancement and improve the coefficient of performance (COP)
by 4.2%.
Keywords— nanolubricant, refrigeration, heat transfer, coefficient of
performance, polyester oil.
2. Methodology
2.1. Preparation of Nano lubricants
CNT nanoparticles are added to refrigerant by dispersing in the host
lubricant POE (Poly Ester) in the compressor of the air-condition unit.
POE is widely used in the industry for refrigeration and air-condition.
CNT Nanoparticles with concentration of 0.01wt%, 0.05wt% and
0.1wt% were measured by digital weight balance. Each mass fraction
of nanoparticles is mixed with base lubricant and the amount of each
sample of nanolubricant prepared was 700 grams. Resultant
nanolubricant was homogenized for 15 minutes followed by
sonication for up to 4 hours using a water bath sonicator.
1. Introduction
Concept of Nano-lubricant came from the idea of Nano refrigerants
which are a relatively new category of refrigerants consist of a
conventional refrigerant with Nano-sized particles mostly (range
between 1nm to 100nm) suspended within them. Nano refrigerant is
also called Nanofluid; Nanofluid is famous because of its unique type
with remarkable thermal conductivity in refrigeration and airconditioning systems. Nanofluid was first proposed by Choi [1].
Carbon Nanotubes (CNT) are famous because of its great thermophysical properties and extremely high thermal conductivity reported
by researchers recently. Extensive research in the last two decades
shows that nanofluids are a new generation of heat transfer fluids. Due
to small size and large specific area of nanoparticles, nanofluids holds
superior properties such as high thermal conductivity, minimal
clogging in flow passage, long-term stability and homogeneity [2].
Refrigerants are widely used in refrigeration and air-conditioning
equipment in industries, offices and domestic & commercial buildings,
consuming huge amount of energy. Nano-refrigerants have potential to
enhance heat transfer rate thus making heat exchanger of airconditioning and refrigeration equipment compact. This, consequently,
will reduce energy consumption in these sectors along with reduction
in emission, global warming potential and greenhouse-gas effects [3].
CNT were observed to have relatively high thermal conductivity
(~3000W/mK) over other nanoparticles such as CuO, Al 2 O 3 , SiO 2
diamond and TiO 2 [4]. Patel et al.[5] used R113a as a base refrigerant
and significant evidences of performance improvement of the system
was observed in the extensive research using CNT nanoparticles. The
recent studies have found that the CNT based nanofluids have higher
thermal conductivity compared to conventional refrigerants [5].
Recently, several research studies conducted on a refrigeration system
using different refrigerants, lubricants and nanoparticles showed
significant reduction in power consumption and improvement in
coefficient of performance (COP) of the system. Sendil et al. [6] used
hydrocarbon refrigerant and mineral lubricant suspended with Al 2 O 3
nanoparticles and showed better lubrication and heat transfer
performance. Furthermore study shows that 60% R-134a and 0.1 wt %
2.2. Charging of the system
A Refrigeration laboratory unit (R713) purchased from P. A. Hilton
Ltd was used for the conduction of experiments for this research. First
of all, system was isolated from electricity. Existing refrigerant and
lubricant was evacuated from the system by the service ports provided
in the compressor using vacuum pump. 650gm of nanolubricant oil
was filled in the compressor through the service port. Then the
refrigerant gas of 550g in the system was recharged by using precision
electronic balance. The same procedure was followed for all mass
fractions of CNT nanoparticle in lubricant.
2.3. Performance Test
The performance test was conducted for all samples of CNT-Lubricant
oil mixture of 650gm and pure R-134a of 550g, which are treated as
the basis for comparison with other results. In order to obtain
repeatability each experiment was conducted 3 times.
3. Results and Discussions
To evaluate the efficiency of refrigeration cycle is the main objective
of this research and it is expressed in terms of coefficient of
performance (COP). The main purpose of refrigerator or air-condition
is to remove heat, Q L from the refrigerate space. In order to
accomplish the heat removal it requires a work input W net.in [7]. Then
COP of a refrigerator can be expressed as in equation 1.
Table 1. Temperature and Enthalpy reading in 3 different regions of
refrigeration cycle with different concentration of nanoparticles.
ToC
h kJ
1
87
Pure
18.86
260.99
POE Oil with CNT and without CNT
0.01%
0.05%
0.1%
18.85
19.26
19.68
260.98
261.2
261.42
EURECA 2013 – EFFICIENT AIR-CONDITION UNIT BY USING NANO-REFRIGERANT
2
72.73
280.68
69.28
280.34
70.5
280.5
73.1
280.68
Fig. 1
CNT concentration in Lubricant vs. Coefficient of
Performance COP
3
10.83
190.05
10.91
189.98
10.58
190.25
10.43
190.37
Fig. 1 illustrates that higher the concentration of CNT higher will be
the efficiency of the system. However, more research need to be
carried out to determine the optimum concentration of CNT
nanoparticle which can show highest efficiency.
COP
3.60
3.66
3.67
3.757
4. Conclusions
Addition of CNT nanoparticles into POE lubricant reveals
improvement in coefficient of performance (COP) of the refrigeration
system. Using nanoparticles reduce the power consumption and cost
effective. COP of the system increase with increase of CNT weight
percent in base lubricant. The highest COP value obtained was 3.757
at 0.1% of CNT.
Apart from that, Preparation of homogeneous suspension remains a
technical challenge since the nanoparticles always form aggregates
due to very strong van der Waals interactions.
Table 1 show that there are three readings for each nanoparticle
concentration in lubricant. Reading 1 and 2 are the inlet and outlet
temperature of the compressor unit and reading 3 is in the evaporation
region of the system where heat has been rejected thus, temperature
drops in this region.
Temperature readings converted to enthalpy values by using saturated
refrigerant R-134a - Temperature Table. Therefore, enthalpy values of
these three regions were used to calculate heat rejection from the
system and work input to the system. Hence, COP was calculated
using equation 1 as shown in section 3.1 below.
Acknowledgment
First, I would like to thanks to Taylor’s University for providing me
the platform for the research and all the facilities in the laboratory.
Secondly, I would like to thanks to University of Malaya for their
assistance during my research and I really admire their commitment
for the enhancement of the technology.
3.1. Formulas and Equations
The coefficient of performance of the refrigeration cycle can be
calculated by using the equation 1.
References
(1)
[1] Choi SUS. 1995. Enhancing thermal conductivity of fluids with
nanoparticles. In Developments and Applications of Non-Newtonian
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New York: The American Society of Mechanical Engineers; 1995:99.
[2] Chandrasekar, M., Suresh, S. & Chandra Bose, A. 2010.
Experimental investigations and theoretical determination of thermal
conductivity and viscosity of AL2O3/water nanofluid. Experimental
Thermal and Fluid science. 34(2):210-216.
[3] I.M. Mahbuhul, R. Saidur and M.A. Amalina. 2011. Pressure drop
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83M:2931–2933.
[6] D. Sendil Kumar, R. Elansezhian. 2012. Experimental Study on
Al2O3-R134a Nano Refrigerant in Refrigeration System: International
Journal of Modern Engineering Research (IJMER) Vol. 2, Issue. 5.
pp-3927-3929
[7] Yunus A. Cengel, Michael A. Boles. 2007. Thermodynamics an
Engineering Approach. Sixth Edition. McGraw Hill.
where,
Q is the heat supplied to or removed from the reservoir.
W is the work done by the compressor.
Data reveals that, when nanoparticles are introduced in the open
(reciprocating compressor or driven belt compressor) it travels into the
whole system along with refrigerant due to miscibility between
refrigerant and lubricant oil. Therefore, CNT nanoparticles improved
the heat transfer performance of the system because of its remarkable
thermo-physical properties due to their large surface area.
COP is related to power consumed by the system, higher the COP of
the system lesser the power consumption of the system. It was found
that, as the concentration of the CNT in lubricant increases the COP
will also increase. Highest COP value was obtained at 0.1wt%, which
was highest nanoparticle composition of this study.
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