Abstract
Solar parabolic trough collectors exploit solar energy for power generation in solar thermal power stations. These systems require long arrays of reflective troughs with absorber tube running along the axis of parabolic dish. A successful attempt to reduce the length of arrays was accomplished by experimentally analysing the modifications done in absorber tube. Two out of three tubes were fabricated and they were employed to obtain the performance parameters through experimentation conducted at VIT University, Vellore, India. Distilled water was used as the working fluid. Maximum efficiency of 39.12% was obtained at 451.6 W/m 2 of direct normal irradiance (DNI) for absorber tube with internal pin-fins and without glass tube (AFWG t ) compared to 8.15% obtained at same value of DNI and other conditions for simple absorber tube without glass cover (AWG t ). Cylindrical parabolic trough available at the university was utilized, providing the basis for designing and fabrication of the tubes. Plots for varying mass flow rate at interval of 10 minutes were made against instantaneous thermal efficiency and heat utilized, for direct normal irradiance vs. temperature difference across the tubes and instantaneous thermal efficiency. Through the experimentation conducted, better performance was procured compared to earlier works. Thus, the proposal infers that absorber tube with internal fins has good scope for its application, both domestically as well as industrially. It also calls for further research and development of proposed techniques so as to achieve better performance curves.
Highlights
As by Fernandez-Garcia et al (2010) [1] the concentrating systems can be classified into three major categories, point focus concentration, line focus concentration and linear concentration
Concentrating paraboloid concentrators are types of point focus concentrations, whereas parabolic trough collectors lies in category of line focus concentrators and Fresnel collectors lies in the category of linear collectors
As the experiments were conducted during the second phase of monsoon, intensified solar flux was not available compared to that obtained in summer season, affecting the performance curves of the proposed absorber tubes
Summary
As by Fernandez-Garcia et al (2010) [1] the concentrating systems can be classified into three major categories, point focus concentration, line focus concentration and linear concentration. Solar parabolic trough collector (SPTC) provides an effective way to harness solar energy providing “one-axis concentration” such that fluid flowing through the absorber tube, gains the concentrated energy and accomplish useful work. Researchers are working to optimize the operating performance of SPTC so that rapid heat transfer can take place and overall length of the trough collector can be reduced. Increase in the width of concentrating apparatus may result to unbalanced design and higher probability of back reflection of the incident solar radiations. To avoid such hindrances, requirement of precise tracking and high cost engrossment will be needed, which add some more minuses to the proposed design. Radiation thermal losses may increase with increase in coating temperature, results in development of high thermal stresses in the collector tube
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
