The thermal and electrical efficiency of a custom-designed PV/T panel cooled by forced air circulation was investigated by experimental and computational fluid dynamics (CFD) analysis. Experiments were carried out with four different array configurations, under constant irradiation of 1100 W/m2 and 3 different air velocities (3.3 m/s, 3.9 m/s, and 4.5 m/s). The heat transfer surface area and forced air circulation are known to positively affect the total heat transfer, and therefore, it is foreseeable that an increased number of fins and higher air velocities will help maintain the electrical efficiency of the panel at higher levels. The main objective of this study is to determine the critical threshold for the abovementioned parameters as well as to show how important parameters, such as fin arrangement and consequent turbulent air flows, are for satisfying the heat removal needs. Highest efficiency was achieved with a 108 pc type 1 arrangement at 12.02% as expected. Nevertheless, while the 108 pc type 2 arrangement could maintain the electrical efficiency at 11.81%, a close level of 11.55% could be obtained with a 54 pc type 2 arrangement. Experimental results are compared with ANSYS Fluent program, and the effect of the number and arrangement of the fins on the efficiency of the panel has been shown.

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A B S T R A C TT he purpose of this study is to show the performance of hexagonal, square and cylindrical pin-fin arrays in improving heat transfer. In the present study, the thermal performance and pressure drop of the pin-fin heat exchanger are studied. The heat exchanger consists of cylindrical, hexagonal and square pin-fins. These types of pin-fins are capable of producing beneficial effects in transport enhancement and flow control. The pin-fins were arranged in an in-line manner. The relative longitudinal pitch (S L /D=2), and the relative transverse pitch were kept constant (S T /D=2). Air and water are used as working fluids in shell side and tube side, respectively. The inlet temperatures of air are between 50 and 90° C. The cold water entering the heat exchanger at the inner channel flows across the fin and flows out at the inner channel. Such pin-fins show potential for enhancing the heat transfer rate in pin-fin cross flow heat exchangers. Key Words:Thermal performance; Pressure drop; Cylindrical, Hexagonal and square ins I. Kotcioglu et. al./ Hittite J Sci Eng, 2014, 1 (1), [13][14][15][16][17][18][19][20] 14 N eeds for small-size and light-weight heat exchanger devices in power, process, computer and aerospace industries have resulted heat transfer surfaces. In order to enhance heat transfer between the flowing fluid and closely-spaced pin fins, in the case of pin-fin heat exchangers, pin-fins can be mounted on the channel surfaces.Jeng et al. [1] experimentally studied the pressure drop and heat transfer of a square pin-fin array in a rectangular channel by using the transient single-blow technique. The in-line square pin-fin array has smaller pressure drop than the in-line circular pin-fin array. The optimal inter-fin pitches of in-line square pin fin arrays are Xt = 2 and X L = 1.5, its Nu D * is around 20% higher than that of the in-line circular pin-fin array. Vanfossen [2] studied heat transfer by short pin-fins in staggered arrangements. According to their results, longer pin-fins transfer more heat than shorter pin-fins and the array-averaged heat transfer with eight rows of pin-fins slightly exceeds that with only four rows. Their results also established that the average heat transfer coefficient on the pin surface is around 35% larger than that on the end walls.Grannis and Sparrow [3] used the experiments to verify the accuracy of a numerical simulation of fluid flow through a diamond-shaped pin-fin array. They provided a correlation between the friction factor and the Reynolds number based on the results of numerical calculations.

Recently new and renewable energy sources began to become prominent as alternatives to fossil fuels. Among these are wind, solar, hydraulic, biomass, geothermal and wave energies. As for Turkey, the least accounted and less applied of these sources is wave energy. The government has established a short-term outlook on utilization of renewable energy sources, named "National Renewable Energy Action Plan" which is a part of Vision 2023 targets. Nonetheless, there is no planned utilization of and/or investment into wave energy in Turkey's agenda up to the year 2023. This might be mainly because of the complex structure of wave energy conversion systems, marine conditions, mechanical difficulties and high initial investment costs. However, this type of energy is environmentally friendly, cheap and clean, and a great potential is available especially in Turkey which is surrounded on three sides by sea. Although Turkey has neither coasts to oceans nor a long stretch of west coastline, which have the highest energetic waves thanks to the prevailing west-to-east winds; the Black Sea basin, as well as the southwestern Mediterranean region, may offer a good potential for development as an energetic regime, often comparable to oceanic sites in terms of wave heights, induced by strong wind patterns. In this study, wave energy potential in Turkey and recent studies made on determination of suitable sites for evaluation of wave energy in Turkey are discussed.