Experimental investigation on jet impingement heat transfer analysis in a channel flow embedded with V-shaped patterned surface

ABSTRACT

Heating and cooling systems benefit from jet impingement as it increases efficiency while reducing operating costs. The combined methodology, integrating jet impingement and passive heat transfer through the use of roughened surfaces, offers significant potential for improving heat transfer. This research presents the results of an experimental study on a channel flow commonly used for air heating, known as a solar air heater (SAH), with impinging air on the heated surface. The surface is embedded with V-shaped ribs as turbulence promoters, and it receives a continuous heat flow of 1,000 W/m². Various design combinations were tested experimentally, including streamwise pitch ratio X/D_h = 0.866, spanwise pitch ratio Y/D_h = 0.866, jet diameter to hydraulic diameter ratio Dj/D_h = 0.065, and an angle of attack (α) ranging from 45° to 90°. During these experiments, the Re varied from 3,500 to 18,000. The optimal improvement was observed at values of X/D_h = Y/D_h = 0.866, D_j/D_h = 0.065, and α = 60°. This paper presents novel findings demonstrating that incorporating V-shaped rib patterns in SAHs can yield Nusselt numbers up to 5.2 times higher than those in smooth duct SAHs, offering substantial potential for enhanced energy efficiency. When the entering jet impacts and flows along the ribs of the absorber, the findings suggest that the V-shaped ribs accelerate the flow, resulting in enhanced heat transfer. All datasets were also analyzed for their thermo-hydraulic performance, with the maximum value recorded as 3.301 within the constraint range used in this analysis.

KEYWORDS:

• Jet impingement
• heat transfer
• coupled technique
• V-shaped ribs
• jet diameter

Nomenclature

STC	=	Solar thermal collector
SAH	=	Solar air heater
Cp	=	Specific heat in J/(kg K)
Dj	=	Diameter of the jet in mm
$\mathrm{\Delta }{\mathrm{P}}_{\mathrm{d}}$	=	Pressure drop across the duct in Pascal (Pa)
$D_h$	=	Hydraulic diameter in mm
$K$	=	Conductivity of air in W/(m·K)
$T_o$	=	Outlet temperature in °C
Re	=	Reynolds number
Nu	=	Nusselt number
Nus	=	Nusselt number for smooth
f	=	Friction factor
fs	=	Friction factor for smooth
$T_i$	=	Inlet temperature in °C
TEF	=	Thermohydraulic performance
$V$	=	Velocity of air in m/s
X/Dh	=	Streamwise pitch ratio
Y/Dh	=	Spanwise pitch ratio
Dj/Dh	=	Jet diameter to hydraulic diameter ratio
${\dot{m}}_a$	=	Mass flow rate of air in (kg/s)
Greek letters	=
${\rho }_a$	=	Density of air
${\upsilon }_a$	=	Kinematic viscosity of air

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Yashwant Singh Bisht

Yaswant Singh Bisht is working as an Assistant Professor in the Department of Mechanical Engineering, Uttaranchal Institute of Technology, Uttaranchal University Dehradun, India. He is doing research in the area thermal engineering, CFD.

S D Pandey

Dr. S D Pandey working as a Professor and Dean in Uttaranchal Institute of Technology, Uttaranchal University Dehradun, India. He has more than 15 years of research and teaching experience. He has guided many students and published many research articles in top-notch journals and conferences.

Sunil Chamoli

Dr. Sunil Chamoli, an Assistant Professor in Mechanical Engineering at GB Pant Institute of Engineering and Technology, Pauri Garhwal, has made significant contributions to academia. He has guided numerous UG, PG, and PhD students and published extensively in top-tier journals. His noteworthy achievement includes being recognized in the top 2% scientist list, a testament to his impactful work in the field.