Thermo-hydraulic performance and entropy generation of biologically synthesized silver/water-ethylene glycol nano-fluid flow inside a rifled tube using two-phase mixture model

ABSTRACT

In this paper, the two-phase mixture model is used to determine the influence of the number of ribs on the first-law and second-law performance features of the laminar forced convection flow of a biologically prepared silver/water-ethylene glycol nano-fluid (NF) in a rifled tube. The influence of the Reynolds number (Re), nanoparticle concentrations ($\mathit{\phi }$) on the outcomes are also evaluated. Two parameters of Performance Evaluation Criterion (PEC) and Figure of Merit (FOM) are defined to analyze the merit of using rifled tube and NF over the plain tube and water-ethylene glycol mixture (50:50 by volume) for the same Re and $\mathit{\phi }$. The results showed that the increase in the number of ribs is desirable from the first-law viewpoint and undesirable from the second-law viewpoint. It was found that for all the examined cases, the hydrothermal performance of the rifled tube is always better than the plain tube, and boosting the Re and decreasing the $\mathit{\phi }$ leads to an increase in FOM. Moreover, it was observed that the PEC for the six-head and eight-head rifled tubes is always greater than unity and for the two-head rifled tube is always less than unity.

KEYWORDS:

• Biological nano-fluid
• entropy generation
• heat transfer
• laminar flow
• pressure drop
• rifled tube

Nomenclatures

$c_p$	=	Specific heat capacity (J kg−1 K−1)
$d_p$	=	Nanoparticle diameter (m)
$D_h$	=	Hydraulic diameter of tube (m)
$f_{\mathit{drag}}$	=	Drag coefficient (-)
$\mathit{FOM}$	=	Figure of merit (-)
$\mathit{g}$	=	Gravitational acceleration (m s−2)
$\mathit{h}$	=	Convective heat transfer coefficient (W m−2 K−1)
$\mathit{k}$	=	Thermal conductivity (W m−1 K−1)
$\mathit{p}$	=	Wetted perimeter of tube (m)
$\mathit{P}$	=	Pressure (Pa)
$\mathit{PEC}$	=	Performance evaluation criterion (-)
$\mathit{q}{ }^{\mathrm{\prime \prime }}$	=	Heat flux (W m−2)
$\mathit{Re}$	=	Reynolds number (-)
${\dot{S}}_{\mathit{g},\mathit{f}}^{{ }^{\prime \prime \prime }}$	=	Local fluid friction irreversibility rate (W m−3 K−1)
${\dot{S}}_{\mathit{g},\mathit{f}}$	=	Global fluid friction irreversibility rate (W K−1)
${\dot{S}}_{\mathit{g},\mathit{t}}^{{ }^{\prime \prime \prime }}$	=	Local total irreversibility rate (W m−3 K−1)
${\dot{S}}_{\mathit{g},\mathit{th}}^{{ }^{\prime \prime \prime }}$	=	Local heat transfer irreversibility rate (W m−3 K−1)
${\dot{S}}_{\mathit{g},\mathit{th}}$	=	Global heat transfer irreversibility rate (W K−1)
$\mathit{T}$	=	Temperature (K)
$\mathit{V}$	=	Velocity (m s−1)
$V_{\mathit{dr}}$	=	Drift velocity (m s−1)
$V_{\mathit{in}}$	=	Inlet velocity (m s−1)
$V_{\mathit{pf}}$	=	Relative velocity (m s−1)
Greek letters	=
$\mathit{\phi }$	=	Volume concentration of nanofluid (%)
$\mathit{\mu }$	=	Viscosity (Pa s)
$\mathit{\rho }$	=	Density (kg m−3)
$\mathrm{\Delta }\mathit{P}$	=	Pressure drop (Pa)
Subscripts	=
$\mathit{bf}$	=	Base fluid
$\mathit{m}$	=	Nanofluid
$\mathit{p}$	=	Particle
$\mathit{pt}$	=	Plain tube
$\mathit{RT}$	=	Rifled tube

Additional information

Notes on contributors

Amin Shahsavar

Amin Shahsavar was born in Urmia, Iran in 1983. He received his Bachelors in Mechanical Engineering in 2007 from Urmia University, Iran, Master of Technology in Mechanical Engineering with specialization in Photovoltaic/thermal systems in 2009 from the Shahid Bahonar University of Kerman, Iran and Ph.D. in Mechanical Engineering with specialization in magnetic nanofluids in 2015 from the Isfahan University of Technology, Iran. Thereafter, he is currently an Assistant Professor in the department of Mechanical Engineering at the Kermanshah University of Technology, Iran. His research interests are renewable energy systems, nanofluids and electronics cooling.

Majid Jafari

Majid Jafari is a graduate of the Kermanshah University of Technology, where he studied Mechanical Engineering. He is currently working toward a Master's in Mechanical Engineering at Kermanshah University of Technology. For the last 3 years, his research has focused on the performance improvement of heat transfer systems.

Ighball Baniasad Askari

Ighball Baniasad Askari is an Assistant Professor in department of Mechanical Engineering University of Zabol, Iran. He has more than 10 years of experience conducting research on the topics of thermodynamics, heat transfer, and renewable energy systems. He received his PhD, MSc and BSc in Mechanical Engineering (Energy Conversion) from the Shahid Bahonar University of Kerman, Iran.  Applications of his research include Heat transfer, water desalination systems, solar thermal power plants, fuel cell technology, and other renewable energy systems.  He joined the University of Zabol as a teaching assistant professor where he is heavily involved in heat transfer, thermodynamics, air conditioning & refrigeration and renewable energy system education.

Fatih Selimefendigil

Fatih Selimefendigil is a Professor in the Department of Mechanical Engineering at Celal Bayar University, Manisa, Turkey. He completed his Ph.D. at the Technical University of Munich (Chair for Thermodynamics) in 2010. He worked in German Aerospace Center (DLR) and Department of Thermal Engineering and Desalination Technology at King Abdulaziz University, Saudi Arabia. His general research interests are nanotechnology applications, thermal energy storage, thermo-acoustic (instability, power generation and refrigeration), thermo- electric, heat transfer enhancement techniques, MHD flow, pulsating flow, model order reduction techniques in thermal engineering, system identification in heat transfer. He has published more than 120 SCI journal papers. He has 36 h-index with more than 3200 citations according to Scopus.