The importance of photovoltaic-thermal (PV / T) collector systems in renewable energy technologies is increasing for combined hybrid electrical heat applications. The efficiency of photovoltaic (PV) systems varies between 5-20%. On average, 15% of the solar radiation coming to the PV panel surface is converted to electrical energy and the remainder is lost. In this study, a PV/T collector was designed using two different fluids simultaneously and its efficiency was calculated numerically. PV/T collector systems are specifically designed for agricultural production and their advantages are discussed. In this study, numerical calculations of PV/T collector with a different design have been made. The results were compared with reference to another experimental study. Two different working fluids (air and water) were used in the calculations. The system where air is used as working fluid is called Mode 1 and the system where water is used is called Mode 2. It is aimed to achieve high heat transfer by using water pipes, air ducts and fins placed under PV panels. In this way, it is aimed to produce a more stable hot air and water. In addition, in order to investigate the effect of flow on the yield, different flow rates were calculated. As a result of the theoretical analyses and calculations made in consideration of literature, the total efficiencies of air flow mode (Mode 1) were calculated as 43.2%, 46,2% and 48.7% at 0.0067 kg/s, 0.0072 kg/s and 0.0077 kg/s mass flow rates, respectively. For water flow mode (Mode 2), these values computed as 52.81%, 53.83% and 55.04% at 0.023 kg/s, 0.036 kg/s and 0.054 kg/s mass flow rates, respectively. It was found that PV / T collector efficiency increased with increasing end flow. Designed collector system is preferable in terms of effective use of energy and it can be easily applicable in processes such as hot air-water preparation, drying and greenhouse heating.
In this study, two different industrial refrigerators were designed, manufactured and tested to analyze the impact of different types of fans (Type 1 and Type 2) used in industrial cooling systems on the performance of the cooling system. In order to test the fan performance and airflow effects, two axial fan configurations with different structures and different motor technology (EC and shaded-pole induction) were tested in two separate industrial refrigerator test rooms in accordance with TS EN ISO 23953-2 standards. R290 (Propane) was used as a refrigerant in the systems. The average temperature and relative humidity values of the environment where the experiment was conducted were measured as 25 °C and 60 % (Class 3), respectively. During the experiments, the total of 51.71 kWh energy was consumed in system 1, while the total of 54.22 kWh energy was consumed in system 2 and the difference between the energy consumption of the two systems was calculated as 4.85%. The average temperatures of the inlet and outlet of the evaporator of the system 1 and 2 were -21.57 °C, -18.97 °C and -23.43 °C, -20.94 °C, respectively. The average refrigerant temperatures for the system 1 and 2 were calculated as -24.65 °C, -26.44 °C, respectively. While the average coefficient of performance value of the type 1 system was 1.74, it was calculated as 1.54 for the type 2 cooling system. The average second-law efficiencies for the two cooling systems were calculated as 30.85 % and 29.81 %, respectively. In addition, the environmental economy analysis was carried out using the amount of CO2 that was prevented from emitting and the CO2 emission price calculated accordingly.
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