Experimental investigation in a solar parabolic trough collector with optimized secondary optics

ABSTRACT

In the present study, experimental investigation of parabolic trough collector is carried out as per ASHRAE 93-1986 standard. In this study, two different case of receiver involving conventional absorber as standard model and optimized secondary optics absorber as proposed model. The heat transfer fluid used for the analysis is distilled water. The important performance parameters such as temperature variation, thermal efficiency, exergy efficiency, and pump work are explored and illustrated. Based on the results, the heating time and cooling time constants obtained for the proposed model are 110 and 115 s, respectively, which shows that the proposed model stabilizes quickly than the standard model. It is observed from the result that the proposed model attained a maximum thermal and exergy efficiency of 73.2 and 48.77%, respectively, which is 14.19 and 9.5% higher than that of the standard model. The electricity generation costs obtained for the proposed model and the standard model are Rs. 3.74/kWh and Rs. 5.71/kWh, respectively.

KEYWORDS:

• Cost analysis
• optimized secondary optics
• parabolic trough collector
• thermal efficiency
• time constant

Nomenclature

$Q_u$	=	The amount of useful heat delivered (W)
$\dot{m}$	=	Mass flow rate of heat transfer fluid (kg/s)
$C_p$	=	Specific heat capacity of heat transfer fluid (J/kgK)
$T_{0\mathit{utlet}}$	=	Outlet temperature of heat transfer fluid (K)
$T_{\mathit{inlet}}$	=	Inlet temperature of heat transfer fluid (K)
$A_a$	=	Aperture area (m2)
$I_b$	=	Solar beam radiation (W/m2)
$Q_{\mathit{S}}$	=	Total incident solar energy (W)
$T_{\mathit{am}}$	=	Ambient temperature (K)
${\eta }_{\mathit{th}}$	=	Thermal efficiency (%)
${\eta }_{\mathit{ex}}$	=	Exergy efficiency (%)
$E_u$	=	Useful exergy (W)
$E_s$	=	Exergy supplied (W)
$T_{\mathit{sun}}$	=	Sun temperature is 5,770 K
$\mathrm{\Delta P}$	=	Pressure drop (Pa)
$I_g$	=	Hourly global radiation (W/m2)
$I_{\mathit{bn}}$	=	Hourly beam radiation in the direction of the rays (W/m2)
${\theta }_z$	=	Zenith angle
$I_d$	=	Hourly diffuse radiation (W/m2)
$C_{\mathit{ic}}$	=	Initial cost (Rs.)
$\mathit{i}$	=	Rate of interest (%)
$\mathit{n}$	=	Number of years
Rs.	=	Indian rupees
$C_{\mathit{o}\text{ampm}}$	=	Operation and maintenance cost (Rs.)
$C_{Q_u}$	=	Cost of electricity generated (Rs./kWh)
$\mathit{dd}{H}_2\mathit{O}$	=	Double-distilled water
$\mathit{CR}$	=	Concentration ratio

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Ashokkumar Shyam

Dr. Ashokkumar Shyam is a Lecturer in the Department of Mechanical Engineering, Sakthi Polytechnic College, Sakthi Nagar, Erode, India. His research area includes CFD, solar energy and concentrated solar thermal technologies.

Kalilur Rahiman Arshad Ahmed

Dr. Kalilur Rahiman Arshad Ahmed is a Teaching Fellow in the Institute for Energy Studies, Department of Mechanical Engineering, Anna University, Chennai, India. His research area includes Heat transfer, CFD, solar energy and concentrated solar thermal technologies.

Selvarasan Iniyan

Dr. Selvarasan Iniyan is a Retired Professor in the Institute for Energy Studies, Department of Mechanical Engineering, Anna University, Chennai, India. His research area includes wind energy, solar energy, energy forecasting and energy planning.

Ranko Goic

Dr. Ranko Goic is a Professor in the Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture. His research area includes wind energy, solar energy and other renewable energy technologies.