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• Analytical investigation has been studied of parallel flow solar air heater. • Thermal Efficiency of double flow conventional SAH and roughened SAH are compared. • It has been found that thermal efficiency of PFRSAH is nearly 8–10% more than the PFSSAH. • Optimum thermohydraulic efficiency nearly Reynolds number 29,000. • The parameters influencing the Nusselt number and friction factor are discussed. This paper deals with the theoretical analysis of a parallel flow solar air heater having an absorber plate roughened with arc shaped wires. The absorber plate that forms the upper and lower ducts is roughened on its upper side only. A mathematical model describing the fluid flow and heat transfer characteristics of such a parallel flow roughened absorber plate solar air heater has been developed to study the effects of various operating and systems parameters on thermal performance of the solar air heater. The governing energy equations have been solved by iterative method using computer codes in MATLAB. A comparison between the theoretical results obtained and experimental results available in the literature has been made which shows a good agreement between the results. The thermal efficiency of parallel flow roughened solar air heater has been found nearly 8–10% higher than the smooth parallel flow solar air heater operating under similar conditions. It has been found that based on the thermohydraulic efficiency criteria, parallel flow roughened solar air heater is not beneficial for higher Reynolds number (Re > 29000) as compared to solar air heater having smooth absorber plate and this fact can be considered for designing roughened parallel flow solar air heaters. [ABSTRACT FROM AUTHOR]

The solar collector is the heart of any solar energy collection system designed for operation in the low to medium temperature ranges. So, an efficient design of solar collector system, giving optimum performance is required. Though system performance is optimized by many different techniques, however, intelligent system design is an useful technique to optimize the efficiency of such systems. One of the intelligence techniques is Artificial Neural Network (ANN), and it is used in modeling, simulation and control of the system. ANN tool is faster and more accurate to solve complex and nonlinear problems as compared to other conventional techniques. ANN technique is applied in the field of Science, Engineering, Medicine, Defense, Business and Manufacturing etc. The main task of ANN tool is training of structure, which is done by collected experimental data of solar energy systems and in this method separate programming is not required as in other conventional methods. The aim of this study is to review the applications of ANN to predict the performance of solar energy collector and to identify the research gap for future work. Published research works presented in this paper, show that the ANN technique is very appropriate tool to predict the performance of solar collector systems [ABSTRACT FROM AUTHOR]

In the present paper, a comprehensive investigation on thermal and thermohydraulic performance of solar collector for heating air having circular wire rib roughness in the form of arc shape on the back side of absorber plate, has been carried out. A mathematical model incorporating the operating and system parameters has been developed and the results have been computed by using MATLAB for specified range of these parameters. A conventional solar air heater working under similar conditions has also been considered for the purpose of comparison. At rib height-to-duct hydraulic diameter ratio = 0.0422 and flow-attack-angle = 0.3333 the values of maximum thermal and effective efficiencies were found to be 79.84% and 75.24% respectively for the range of parameters used in the investigation. Further, the thermal efficiency, obtained in the present work has been compared with those obtained for other roughness geometries available in the literature for common roughness parameters and operating parameters to validate the results. Optimization of different parameters of wire roughness for optimum thermohydraulic (effective) efficiency of solar air heater duct has also been investigated. [ABSTRACT FROM AUTHOR]

In the present work, Artificial Neural Network (ANN) has been used to predict the thermal performance of unidirectional flow porous bed solar air heater. The ANN model was structured on the basis of data sets obtained from experiments and values of thermal efficiency of solar air heater. Four types of training functions are used in ANN model for training process with feed forward learning procedure. The aim of this work is to examine the performance and comparison of four training functions (TRAINCGP, TRAINSCG, TRAINLM and TRAINOSS) applied in training process of neural model. A comparison was based on the RMSE and R 2 . It was found that training function TRAINLM exhibits optimal result with the experimental data. [ABSTRACT FROM AUTHOR]

Exergy efficiency analysis is an useful method to evaluate overall performance of solar thermal systems as it takes into consideration of useful energy output and consequent pumping power requirement. In present work, an investigation on exergetic performance evaluation of solar air heater with arc-shaped wire rib roughened absorber plates has been made analytically by employing mathematical model and the results have been compared with a plane absorber plate solar air heater for similar operating conditions. The exergetic efficiency curves as a function of Reynolds number (Re) and temperature rise parameter (ΔT/I) for different roughness parameters have been plotted. The maximum enhancement in exergetic efficiency of roughened solar air heater as compared to smooth absorber plate solar air heater has been found as 56% corresponding to relative roughness height (e/D) = 0.0422. The design plots, exhibiting the optimum combination of roughness parameters, can be used to design arc shaped wire rib roughened solar air heater. [ABSTRACT FROM AUTHOR]