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Öğe Numerical and experimental investigation of solar chimney power plant system performance(Taylor & Francis, 2020-03-15) Karakaya, Hakan; Durmuş, Aydın; Avcı, Ali SerkanA prototype of a solar chimney power plant was performed by modeling in this study. The performed prototype was experimentally confirmed. Temperature, velocity, and radiation values were measured to actualize the confirmation. Experimental data that were obtained to determine the performance of solar chimney whose prototype was actualized by the help of measured values were computationally analyzed. The geometry of a solar chimney in the analysis was bidimensionally (2D) drawn on an axis of symmetry. The numerical simulation was analyzed with computational fluid dynamics (CFD) method. Since analysis results show that there is turbulent flow in system (RNG), k-ɛ turbulence model was used. Continuity, momentum, and energy equations were applied to the solar chimney system via the finite volume method. Moreover, DO (discrete ordinates) model was inserted in analysis to evaluate the radiation effect in the collector area. In addition to all these, correlation results between SPSS 17 statistics program and data obtained were evaluated. Finally, with reference to the comparison between numerical and experimental results, data obtained and numerical data are close to each other; the prototype is applicable to the real systems.Öğe Numerical and experimental study of air flow by natural convection in a rectangular open cavity cooled top and bottom surfaces(Batman Üniversitesi, 2016-12-28) Karakaya, Hakan; Durmuş, AydınBu çalışma ile ilk olarak kapalı kübik hacmin ön yüzeyinin çevreye açılmasıyla kübik boşluk haline gelen hacimde, alt ve üst yüzeyinden soğutma sınır şartında, laminer durumda doğal taşınım deneysel ve teorik olarak araştırılmıştır. Elde edilen ölçümler Fluent 6.3 paket programı yardımı ile çözülmüş ve deneysel veriler ile karşılaştırılmıştır. Doğal taşınım şartlarını sağlayabilmek için bu deneysel çalışma ile 2x2x1,8m ebatlarında bir şartlandırma odası uygulamaya dahil edilmiştir. Ayrıca deney düzeneğinin giriş ağzı bu şartlandırma odasına verilmiştir. Son olarak bu çalışma ile sıcaklık değişimi, hız vektörleri ve akım fonksiyonu grafikleri elde edilmiştir. Buna ek olarak Nusselt sayısının zamana bağlı değişimi teorik ve deneysel çalışmalar sonucunda elde edilmiştir.Öğe Examination of energy capacities of hydroelectric power plants in Batman(Batman Üniversitesi, 2018) Karakaya, Hakan; Avcı, Ali Serkan; Kallioğlu, Mehmet Ali; Avcı, Ali Serkan; Durmuş, AydınÖğe Heat transfer and exergy loss in conical spring turbulators(Elsevier, 2013-05) Karakaya, Hakan; Durmuş, AydınIt would be misleading to consider only the construction costs of heat exchangers in their design because high service costs during their service life may also greatly increase total costs. Therefore energy saving aspects are very important in the design, construction and operation of the heat exchangers. For this reason, various active or passive methods have been sought to save energy by increasing the heat transfer coefficients in the cold and warm fluid sides in the heat exchangers. Conical spring turbulators (CST) are devised in this study. Performances of heat transfer and pressure drop in a pipe with the CST are experimentally examined for the CSTs’ angle (θ) of 30°, 45° and 60° in Reynolds number (Re) range of 10,000–34,000. Heat transfer, pressure loss and exergy analysis were made for the conditions with and without turbulators and compared to each other. Some empirical correlations expressing the results were also derived and discussed.Öğe Empirical calculation of the optimal tilt angle for solar collectors in northern hemisphere(Taylor & Francis, 2020-03) Karakaya, Hakan; Kallioğlu, Mehmet Ali; Durmuş, Aydın; Yılmaz, AdemPanel tilt angles (0°–90°) need to be in a proper position and location to get maximum productivity from solar energy. Values used in solar energy applications are generally computed by (global, diffuse, and direct) variation on horizontal surfaces calculated using isotropic sky and a mean albedo method. Being parallel to the available literature concerning such applications, this study focuses on the optimum solar panel angle. In this study, optimum solar panel angle value by months was determined for three sample provinces (Antalya, Kayseri, and Trabzon) first and North Hemisphere then. Capacity calculation of sample provinces was performed based on monthly, seasonal, and annual angle values and horizontal situation. Monthly and annual optimum angle values for Northern Hemisphere by 1° increase for between the latitudes of 1° N and 65° N. While the panel angle is at the highest level in autumn and winter (November-December-January and February) in annual process, the lowest angle is observed in spring and summer (May-June-July-August). Several different mathematical models have been developed for the sample provinces and Northern Hemisphere. While the variable of 12 different models that were developed for provinces is the Declination (δ) coefficient, the variable of 7 different models that were developed Northern Hemisphere is the latitude (Ø). Regional values in literature with estimation results of models were analyzed based on NASA and PVGIS data color scale. There was created a possibility of comparison by aligning all the optimum solar panel angle values of related location via a scale whose values vary by 1 and 10. Moreover, all the models were verified by statistical analysis methods. R2 (determination coefficient) in 19 different estimation equations is pretty close or equal to 1. However, the best among them is Eq. 32 (0.9979) for sample provinces and Eq. (33) (1) for the Northern Hemisphere; developed models are less-than-stellar. Other statistical data of these equations are MBE (−0.0616), RMSE (1.1176), t-sat (0.1830), Bias (1). For Eq. (32); MBE (1.96), RMSE (2.75), t-sat (8.13), MPE % (3.98), MAPE (5.87), SSRE (0.27), and RSE (0.06) for Eq. (33). The statistical analyzes indicate that all regression models are applicable in Turkey and Northern Hemisphere. Developed all correlations are recommended for academic and industrial users.Öğe Drying of sweet basil with solar air collectors(Elsevier, 2016-08) Karakaya, Hakan; Durmuş, Aydın; Fevzi, GülçimenIn this study, sweet basil was dried and its drying parameters were investigated experimentally and theoretically by using newly developed solar air collectors. Proper temperatures were chosen to dry sweet basil and experiments were carried out at different flow rates. At the end of drying experiments, it was determined that total mass of sweet basil decreased from 0.250 kg to 0.029 kg. In drying sweet basil, dimensionless moisture ratios were decreased rapidly to 300 min for 0.012 kg/s, 360 min for 0.026 kg/s, and 450 min for 0.033 kg/s. It was observed that the efficiency of collector was increased at the same rate with air flow changed between 29 and 63%. Among the models in the literature, Page Model was found to suit best for drying sweet basil. Furthermore, a novel mathematical model rendering more valid results for sweet basil and leafy products was developed.Öğe Investigation of efficiency and exergy loss in plate heat exchangers having spiral surface profiles(Energy Education Science and Technology Part A: Energy Science and Research, 2012-01) Karakaya, Hakan; Durmuş, AydınIt would be misleading to consider only the cost aspect of the design of a solar collector. High service costs increase total costs during the service life of solar collector. The most effective way to save energy is by increasing the efficiency in a solar collector by the heat transfer coefficient. In our study, three solar collectors that have (1,6 x 1,6 m2 ) dimensions shape area, have spiral reflective, different flow line length was made. According to the collector geometry, turbulence occurs in fluid flow and in this way heat transfer is increased. The results of the experiments were evaluated on the days with the same radiation. The efficiencies of these four collectors were compared to conventional flat-plate collectors. It was seen that heat transfer and pressure loss increased depending on shape and numbers of the absorbers.
