Vol.:(0123456789) 1 3
Journal of Thermal Analysis and Calorimetry
https://doi.org/10.1007/s10973-020-09884-5
Comparative performance evaluation of fy ash‑based hybrid
nanofuids in microchannel‑based direct absorption solar collector
Parag P. Thakur
1
· Tushar S. Khapane
1
· Shriram S. Sonawane
1
Received: 31 March 2020 / Accepted: 25 May 2020
© Akadémiai Kiadó, Budapest, Hungary 2020
Abstract
In this study, the performance of the hybrid nanofuid of alumina/fy ash-based nanofuid and silica/fy ash-based nanofuid
in the direct absorption solar collector is compared. SiO
2
, Fe
2
O
3
, Al
2
O
3
and CaO are main components of the fy ash. The
efect of diferent proportions of major components in fy ash and fow rate on the thermal and exergy efciency is studied.
Microchannel-based fat plate solar collector is used for the experimentation with a channel height of 800 microns. Experi-
ments are conducted to evaluate the thermal efciency, pumping power, performance evaluation criteria, entropy generation
rate and exergy efciency of fy ash-based nanofuids in direct absorption solar collector. The experimental results revealed
that the thermal efciency of the alumina/fy ash (80:20)-based nanofuid for direct absorption solar collector is 72.82%
while silica/fy ash (80:20) nanofuids showed 59.23% thermal efciency. Exergy efciency achieved by the alumina/fy ash
(80:20)-based nanofuids is 73%. This is signifcantly more than the silica/fy ash-based nanofuids. Silica/fy ash (80:20)-
based nanofuids achieved an exergy efciency of 68.09%. The study revealed that an increase in the concentration of alumina
in the fy-ash nanofuid will increase the thermophysical property and efciency of the nanofuid and an increase in the silica
concentration will lead to decrease in the thermophysical property and efciency of the fy ash-based nanofuid.
Keywords Solar collector · Fly ash · Metal oxides · Hybrid nanofuids · Microchannel
List of symbols
Qu Rate of useful energy gain (W)
m Mass fow rate (kg s
−1
)
C
p
Heat capacity of the nanofuids (J kg
−1
K
−1
)
T
o
Outlet fuid temperature of the solar collector
(°C)
η Collector efciency
F
R
Heat-removal factor
(τα) Absorption-transmittance product
I
T
Incident solar radiation (W m
−2
)
U
L
Overall loss coefcient of the solar collector
(W m
−2
K
−1
)
T
i
Inlet fuid temperature of the solar collector
(
0
C)
T
a
Ambient temperature (°C)
Ex Exergy rate (J Kg
−1
s
−1
)
k Thermal conductivity (W m
−1
k
−1
)
S
gen
Entropy generation rate (J kg
−1
K
−1
s
−1
)
ρ Density of fuid
μ Dynamic viscosity (Pa s
−1
)
Φ Particle volume fraction
f Friction factor
M Molecular weight
N Avogadro’s number
Abbreviation
DASC Direct absorption solar collector
ASHRAE American society for heating, refrigeration
and air conditioning engineers
IEA International energy agency
Re Reynolds number
PEC Performance evaluation criteria
Introduction
Nanofuids are the stable suspension of the nanomaterials in
the base fuid. Solids have several times higher thermal con-
ductivity compared to conventional fuids [1–3]. Thus, the
addition of the nanoparticles in the base fuid increases the
thermal properties like heat transfer coefcient and thermal
* Shriram S. Sonawane
shriramsonawane@gmail.com; sssonawane@che.vnit.ac.in
1
Department of Chemical Engineering, 206 Nano Resarch
Project Laboratory, Visvesvaraya National Institute
of Technology, Nagpur, MS 440010, India