Browsing by Author "Yilmaz, Tuncay"

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Development of an Artificial Neural Network Model for the Prediction of the Performance of a Silica-Gel Desiccant Wheel
(Taylor & Francis inc, 2015) Uckan, Irfan; Yilmaz, Tuncay; Hurdogan, Ertac; Buyukalaca, Orhan
This work presents mathematical equations derived from Artificial Neural Networks (ANNs) for the estimation of dry bulb temperature and specific humidity at the outlet of a desiccant wheel to predict useful data for designers and engineers. The neural network model comprises five inputs and two output neurons that define the outlet conditions (dry bulb temperature and specific humidity) of a desiccant wheel. The results obtained by the ANN model are compared with the actual data by using input variables. The results show that the mean absolute percentage errors for dry bulb temperature and specific humidity are found to be 0.80% and 1.56% respectively; and the correlation coefficient (R) values obtained are approximately 0.986 for both output variables. The root mean square errors, which is another significant point in this study, are found to be 0.54% and 0.18% for dry bulb temperature and specific humidity respectively.
Effect of Operation Conditions on the Second Law Analysis of a Desiccant Cooling System
(Pergamon-elsevier Science Ltd, 2017) Uckan, Irfan; Yilmaz, Tuncay; Buyukalaca, Orhan
In order to evaluate the potential of a desiccant based evaporative air conditioning system, a second law analysis of the systems was investigated. In this work, a wide range of working parameters that are regeneration temperature from 90 degrees C to 110 degrees C, volume flow rate from 2000 m(3) to 4000 m(3) and ambient air conditions which are relative humidity, ambient air temperature and wet-bulb temperature is carried out for performance calculation of the system. It is observed from results that the Carnot COP and the thermal COP of the system varies vice versa during the day. The highest value of Camot COP and the thermal COP is about 25 and 0.62, respectively. Also, the cooling capacity has significant effect on the second law efficiency. The importance of this study shows that the second law analysis can provide useful information with respect to the theoretical upper limit of the system performance, which cannot be obtained from the first law of thermodynamic analysis alone. (C) 2016 Elsevier Ltd. All rights reserved.
Exergy Analysis of a Novel Configuration of Desiccant Based Evaporative Air Conditioning System
(Pergamon-elsevier Science Ltd, 2014) Uckan, Irfan; Yilmaz, Tuncay; Hurdogan, Ertac; Buyukalaca, Orhan
In this work, a process is developed for exergy analyses of a novel configuration of desiccant based an evaporative air conditioning system. The exergy transfer and destruction between the components of the system are defined for the average measured variables obtained from the experimental results. The exergy formulations are carried out to the experimental system using the data collected during a typical operation of the system. The exergy output, specific flow exergy, exergy destruction, exergy input and exergy efficiency are determined. Furthermore, the sustainability assessment and relative irreversibility of components are obtained. It is found that the exergy efficiency of the entire experimental unit is 40.7% at a reference temperature of 15 degrees C. It is also observed that the exergy efficiencies of the entire system varies between 56% and 25% for reference temperature of 0-30 degrees C, respectively. The effects of reference temperature on the performance of the studied system are investigated. Based on the investigation, it is seen that an exergy analysis can provide beneficial knowledge with respect to the theoretical upper limit of the system performance. (C) 2014 Elsevier Ltd. All rights reserved.
Experimental Investigation of a Novel Configuration of Desiccant Based Evaporative Air Conditioning System
(Pergamon-elsevier Science Ltd, 2013) Uckan, Irfan; Yilmaz, Tuncay; Hurdogan, Ertac; Buyukalaca, Orhan
A novel configuration of desiccant based evaporative cooling system for air conditioning application is developed and tested. At the beginning of the design stage of the system, an analysis is carried out in order to maximize the performance of the system. It is found based on configuration that outdoor air must be used for regeneration to increase performance of the system and so three air channels are used. Experiments are carried out to investigate the total performance of the system and performance of the components used during summer season in a hot and humid climate. Effectiveness values for both heat exchangers and evaporative coolers are calculated through this work. In addition to the cooling capacity, coefficient of performance (COP) and energy consumption of the system are also evaluated. Results show that the effectiveness for the heat exchangers and evaporative coolers are very high under different outdoor conditions. It is also shown from the results that indoor air conditions are in the range of thermal comfort zone defined by ASHRAE and expanded comfort zone for evaporative air conditioning applications. (C) 2012 Elsevier Ltd. All rights reserved.