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Öğe Building integrated solar air heating with waste heat utilization(Pergamon-Elsevier Science Ltd, 2018) Akhan, Hacer; Eryener, DoganA novel waste heat utilization system, which consists of transpired solar collector panels and capillary tube heat exchanger, is studied; its function principle is described, and its experimental performance is presented for the first time. A test unit of capillary tubes was installed at the solar wall air heater at the factory of an automotive company in Turkey in 2012. Capillary tubes utilized waste heat energy which is obtained from heat recovery unit of an air compressor. Thermal power output, ambient temperature, temperature rise, collector cavity temperatures, and water supply temperatures were monitored over the course of two winters. The results showed that capillary tubes can provide 15 degrees C temperature rise during night-time operation. The heat exchange effectiveness in air cavity is found to be maximum 0.7. The results also show that waste heat energy utilization can reach up to 85% depending on operating conditions.Öğe The effect of flow rate on small solar chimney performance(Taylor & Francis Inc, 2020) Kuscu, Hilmi; Eryener, DoganThe relationships between temperature rise, flow rate, and power output of turbine are presented for a small solar chimney unit. An experimental solar chimney system was constructed at Engineering Faculty of Trakya University in Turkey. Solar radiation, temperature rise, chimney inlet velocity, air flow rate, and power output were monitored. Solar chimney power output can be controlled by air flow management and maximum power point can be achieved for different operating conditions. Results showed that it is possible to obtain up to 50% more power output by using an air flow controller in solar chimney systems. Typical temperature rises for 400-600 W/m(2)solar radiation is found to be in the range of 12-15 degrees C. Power is changed in the range of 30-60 W according to different flow rates.Öğe Hybrid transpired solar collector updraft tower(Pergamon-Elsevier Science Ltd, 2018) Eryener, Dogan; Kuscu, HilmiA novel hybrid solar updraft tower prototype, which consists of photovoltaic panels and transpired solar collector, is studied, its function principle is described and its experimental performance is presented for the first time. A test unit of transpired solar collector updraft tower was installed at the campus of Trakya University Engineering Faculty in Edirne-Turkey in 2015. PV modules cover 42% of transpired solar collector area. PV and turbine power output, solar radiation, ambient temperature, temperature rise, collector cavity temperatures, and chimney velocities were monitored during 18 months. The results showed that hybrid solar updraft tower efficiency increased by about 2% in average compared to stand-alone PV system. The temperature rise in hybrid solar updraft tower is found to be 12-14 degrees C on the typical sunny day. Energy was produced continuously for 24 h. The results showed that solar utilization ranges from 60% to 80% during daytime.Öğe Nocturnal passive cooling by transpired solar collectors(Pergamon-Elsevier Science Ltd, 2021) Bokor, Balazs; Akhan, Hacer; Eryener, Dogan; Horvath, MiklosA novel use of the commercially available transpired solar collector is presented in the current paper. The reliable solar air heating system loses heat to the night sky if mounted on a building roof so it can be used as a passive cooling system based on thermal radiation. The collector plate cools down below ambient temperature and has the potential to cool the air as it is drawn through the perforations by a fan. A model has been elaborated for the cooling process based on heat transfer between the system components and energy balance equations. A method has been developed in order to choose the most suitable equivalent sky temperature model, as the radiative heat flow to the sky is the driving force of the cooling process and thus its accuracy is of utmost importance. The model has been validated by a series of field measurements carried out using a 5 m(2) setup in Edirne, Turkey. It has been found that the collector plate cools down up to 4.3 K below ambient temperature and it has the potential to cool air by up to 4.0 K. The system reached a maximum cooling performance of 66.5 W/m(2), while the average cooling performance was 34.6 W/m(2). It has been found that the collector plate cools down below ambient temperature an hour before sunset and does not reach ambient until one hour after sunrise under clear sky. A new Nusselt number correlation has been developed for the convection heat transfer between a perforated plate and the transpiring air flow.Öğe Nocturnal radiation: new opportunity in building cooling(Elsevier Science Bv, 2017) Bokor, Balazs; Kajtar, Laszlo; Eryener, DoganFree cooling systems are gaining increased attention as air conditioners are responsible for a remarkable amount of the electric peak load in summer. Several studies have shown that night ventilation of buildings reduces peak loads of the following day. However, their effect can be increased by a free cooling system based on nocturnal long wave radiation, which cools the air below ambient temperature. A perforated, corrugated metal plate which is used in transpired solar air heaters, functions as a radiating shield in this case. The air can reach temperatures below ambient as it passes the plate further increasing the free cooling's potential. A mathematical model has been set up to describe the cooling process. Based on governing equations diagrams are developed to show the correlation between the transpired radiant plate's temperature drop, as well as its cooling rate as a function of the long wave radiant heat flux and the air flow rate. Four European capitals are chosen to illustrate the cooling potential of nocturnal radiative air cooling. Building simulation is carried out using RETScreen 4 Clean Energy Project Analysis software. Results show that locations with drier climate reach higher nocturnal cooling performance as the moisture content of the atmosphere influences the radiant heat transfer. (C) 2017 The Authors. Published by Elsevier Ltd.Öğe PEM fuel cell performance with solar air preheating(Pergamon-Elsevier Science Ltd, 2020) Uzun, Alper; Bokor, Balazs; Eryener, DoganProton Exchange Membrane Fuel Cells (PEMFC) have proven to be a promising energy conversion technology in various power applications and since it was developed, it has been a potential alternative over fossil fuel-based engines and power plants, all of which produce harmful by-products. The inlet air coolant and reactants have an important effect on the performance degradation of the PEMFC and certain power outputs. In this work, a theoretical model of a PEM fuel cell with solar air heating system for the preheating hydrogen of PEM fuel cell to mitigate the performance degradation when the fuel cell operates in cold environment, is proposed and evaluated by using energy analysis. Considering these heating and energy losses of heat generation by hydrogen fuel cells, the idea of using transpired solar collectors (TSC) for air preheating to increase the inlet air temperature of the low-temperature fuel cell could be a potential development. The aim of the current article is applying solar air preheating for the hydrogen fuel cells system by applying TSC and analyzing system performance. Results aim to attention fellow scholars as well as industrial engineers in the deployment of solar air heating together with hydrogen fuel cell systems that could be useful for coping with fossil fuel-based power supply systems. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.Öğe Performance investigation of a solar updraft tower concept with downdraft windcatcher(Pergamon-Elsevier Science Ltd, 2023) Eryener, DoganIn this study, a novel solar updraft tower system that combines updraft and downdraft is examined, its functional principle is explained and its performance is presented. A prototype was built at Faculty of Engineering of Trakya University in Edirne Turkiye in 2017. The concept includes counter-rotating dual drag type vertical axis turbines, wind catchers, three prismatic diffuser towers and sloped transpired solar collector. The results showed that the downdraft wind catcher integration increased annual energy production by 8 times compared to a conventional solar updraft tower. In the diffuser-shaped downdraft tower, the incoming wind accelerated up to 2.5 times. The power potential, which is 160 W for the conventional system, becomes 83 kW at a wind speed of 10 m/s and a downdraft pressure coefficient of 1.0.Öğe The performance of first transpired solar collector installation in Turkey(Elsevier Science Bv, 2016) Eryener, Dogan; Akhan, HacerIn 2014, Turkey consumed 12 billion cubic meters of natural gas for space heating which accounts 26 percent of general natural gas consumption. Using several technologies to collect solar heat is one of the solutions to reduce the energy consumption in buildings. Among these technologies are transpired solar collectors, which are relatively new solar energy technology in Turkish energy market despite its wide and effective use in North America and Europe over the past 30 years to save energy in buildings by heating ventilation air using solar energy. In 2012, the first transpired solar collector on an industrial building was installed in Turkey, Cayirova. The installation on the south facing wall of PIMSA manufacturing building is a total of 770 m(2) with six large associated air handling units. This paper presents a review of the performance of the first transpired solar collector in Turkey. The energy drawn from solar collector and delivered to the building each month over the period of two years is monitored and analyzed. Results cover monitoring for the period of February 2013 - April 2013 and January 2014 - March 2014, when the transpired solar collector was operating. The monitoring system includes twenty-four thermocouples embedded in transpired solar collector with connected air handling units, two in the building, two outside on the wall and twenty-four automatic damper controllers all connected to a building management system. It has shown that transpired solar collector provides a significant amount of the heating required by the building. Heat outputs from transpired solar collector installation are also compared with the simulation outcomes of Retscreen solar air heating analysis software developed by the Canadian government. (C) 2016 The Authors. Published by Elsevier Ltd.Öğe The Potential of Solar Air Heating in the Turkish Industrial Sector(Budapest Univ Technology Economics, 2019) Bokor, Balazs; Akhan, Hacer; Eryener, Dogan; Kajtar, LaszloTranspired solar collector (TSC) systems are simple solutions for the preheating of ventilation air with solar energy. Their performance is a function of several environmental factors, so the climatic conditions of the location play an important role. In this paper, the effect of different climatic zones on the thermal performance of the TSC is investigated. To exclude other sources of influence, the same reference industrial building is examined in four Turkish locations (Antalya, Istanbul, Ankara and Sivas) representing different climatic conditions. RETScreen simulation is carried out for all four regions to obtain the drop of conventional heating requirement in case absorber azimuth of 0 degrees, 45 degrees and 90 degrees. To illustrate the performance, temperature rise, heating energy savings and annual solar fraction are presented. Generally, it can be stated that a location with cold climate and high solar radiation at the same time benefits most from the use of a TSC system. A mathematical correlation has been found showing the solar fraction's dependence on solar radiation and heating degree days. Finally, simulation results have been compared to a set of measurement data from an industrial building's TSC system near Istanbul.Öğe Theoretical and experimental analysis on the passive cooling effect of transpired solar collectors(Elsevier Science Sa, 2017) Bokor, Balazs; Akhan, Hacer; Eryener, Dogan; Kajtar, LaszloThe present study provides results about the experimental performance of the transpired solar collector's passive cooling effect for the first time. In order to see the cooling performance of the transpired solar collector, a slope-adjustable experimental setup was built on the campus of Trakya University, Engineering Faculty, Edirne, Turkey. Solar radiation, ambient temperature, absorber temperature, cavity and back plate temperatures were monitored during summer period for different collector tilts. A physical and a mathematical model have been created to describe the heat transfer processes in the collector. The models were used to evaluate the measured data. It has been found that a natural airflow comes to be through the perforated plate, which acts similarly as in open-end double layer roofs. This airflow discharges the heat from the plenum decoupling the back plate from the exposed perforated plate. The temperature of the back plate, which represents the roof under the transpired collector, is significantly lower compared to that of the exposed roof on a typical sunny day. Similarly, the heat gain of the back plate is remarkably lower than the solar radiation received on the exposed roof. It has been found that the passive cooling effect of the transpired solar collector is increasing with rising intensity of radiation, as the heat transfer coefficient between the plenum and the back plate decreases with increasing solar radiation. Due to the natural character of the airflow in the plenum, wind heat losses are strongly dependent on the airflow's characteristics. Convective losses of the perforated plate have been defined by using two methods energy balance equations and a referenced heat loss correlation. (C) 2017 Elsevier B.V. All rights reserved.Öğe Thermal performance of a transpired solar collector updraft tower(Pergamon-Elsevier Science Ltd, 2017) Eryener, Dogan; Hollick, John; Kuscu, HilmiA novel solar updraft tower prototype, which consists of transpired solar collector, is studied, its function principle is described and its experimental thermal performance is presented for the first time. A test unit of transpired solar collector updraft tower was installed at the campus of Trakya University Engineering Faculty in Edirne-Turkey in 2014. Solar radiation, ambient temperature, collector cavity temperatures, and chimney velocities were monitored during summer and winter period. The results showed that transpired solar collector efficiency ranges from 60% to 80%. The maximum temperature rise in the collector area is found to be 16-18 degrees C on the typical sunny day. Compared to conventional solar tower glazed collectors, three times higher efficiency is obtained. With increased thermal efficiency, large solar collector areas for solar towers can be reduced in half or less. (C) 2017 Elsevier Ltd. All rights reserved.
