Organic Rankine Cycle (ORC) is a system that uses working fluids with hydrocarbon components instead of water and generates power from the heat recovery of different heat sources. In this study, the exergy analysis of a simple ORC, which produces electrical energy with the help a geothermal source (125°C), was performed. R123, R152a, R245fa and R600a were determined as the fluids to be used in the Cycle. In this analysis, which was carried out according to the pinch point temperature differences (5-20°C) in the evaporator, the exergy performance of the cycle components was evaluated for the geothermal resource unit flow rate and the variation of the exergy efficiency of the system was calculated. With the increase of the pinch point temperature difference in the evaporator, the decrease of the system’s exergy efficiency became maximal (11.7%) with the use of R152a as a refrigerant and the loss in the system’s exergy efficiency became minimal (9.03%) with the use of R123 as a refrigerant.

In this study, the performance of organic Rankine cycle (ORC), which produces electrical energy, was examined by using a geothermal resource with a temperature of 145°C. The fluids used in the system were determined as dry type fluids, and R142b, R227ea, R245fa, R600, and R600a were preferred as a working fluid. Within the scope of this study, energy and exergy analysis of the system was performed for different evaporator pressures (1000–2000 kPa). With the help of these analyses, the performances of the cycle elements were examined and the first and second law efficiencies of the system were compared for different refrigerants. Considering the selection of refrigerant, and evaporator pressure within the scope of this study, the first and second law efficiencies of the cycle have enhanced maximum of 4.86% and 19.78%, respectively.

Automobile radiator which is one of the vital components used for engine cooling in vehicles is expected to provide higher thermal performance without changing the exterior dimensions of the radiator with the development of engine technology. This situation necessitates changes in both design and operating parameters in the currently used radiator. In the present study, all fundamental parameters affecting the thermal and hydraulic performance of an automobile radiator are evaluated and optimized with statistical methods. Optimization study is carried out using Taguchi and ANOVA methods for two specified objective functions (heat transfer and pressure drop). The order of importance and impact rates for each design and operating parameter, the best and worst working conditions in terms of both target functions are determined. Air velocity, air inlet temperature, coolant inlet temperature, and fin pitch are found to be the most effective parameters on the heat transfer with a contribution ratio of 88%. The best and worst working conditions are obtained for the heat transfer and under these working conditions, they are calculated as 43.68 kW and 1.63 kW, respectively. When the system is examined in terms of the pressure drop, the results show that the coolant flowrate and tube height have a great impact with a contribution ratio of 67.04% and 32.06%, respectively. Lastly, the maximum and minimum pressure drop within the studied operating condition range is determined as 20.68 kPa and 0.12 kPa, respectively.

In this study, thermal insulation thickness used in the outer walls of buildings composing of different insulation applications having the same thermal resistance was optimized by considering condensation. The minimum insulation...