• Energy Research

Bu çalışmada kanola, soya ve atık ayçiçeği yağlarından baz katalizörlü transesterifikasyon reaksiyonu uygulanarak biyodizel üretilmiştir. Bu yağlardan üretilen biyodizeller TS-EN 14214 standarlarına uygun olduğu araştırılmıştır. Üretilen yakıtlar dizel yakıtla %5, %10 ve %20 oranlarında karıştırılarak üç silindirli direkt püskürtmeli bir dizel motorda test edilmiştir. Motor performans ve emisyon karekteristikleri dizel yakıt ile kıyaslanmıştır. Ayrıca biyodizel ve dizel yakıt kullanılması durumundaki elektrik üretim maliyetleri karşılaştırılmıştır. Deneysel sonuçlara göre; biyodizel karışımlarının dizel yakıt ile benzer özellikler gösterdiği tespit edilmiştir. Dizel yakıt içerisindeki biyodizel oranının artması ile özgül yakıt tüketiminde ve egzoz çıkış sıcaklığında artış gözlenmiştir. Motordaki biyodizel kullanımı dizel yakıt ile kıyaslandığında HC, CO, duman emisyonlarında düşüş, CO2, NOX ve O2 değerlerinde artış olduğu görülmüştür. Yapılan motor testleri sonucunda biyodizel ve karışım yakıtlarının dizel motorda yapısında değişiklik yapılmadan kullanılabilirliği sonucuna varılmıştır. Biyodizellerin yağlama özelliği olduğundan dolayı aşınmalar konusunda dizel yakıta kıyasla daha fayda sağladığı görülmüştür. Ayrıca hava kirliliğini azıltıcı etkisi olduğu için dizel motorlar için alternatif bir yakıt olacağı görülmüştür. Test yakıtları arasında en düşük üretim maliyetinin atık ayçiçeği yağı biyodizeli olduğu tespit edilmiştir. Dizel yakıt kullanımında 1 kW elektrik, 2.12 TL'ye üretilirken, %20 oranında atık ayçiçeği yağı biyodizeli (AAYB20) yakıtının kullanımında ise 1.99 TL bedel karşılığında üretilmiş olduğu tespit edilmiştir.

This article present a comparison of artificial neural network (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) applied for modelling a ground-coupled heat pump system (GCHP). The aim of this study is predicting system performance related to ground and air (condenser inlet and outlet) temperatures by using desired models. Performance forecasting is the precondition for the optimal design and energy-saving operation of air-conditioning systems. So obtained models will help the system designer to realize this precondition. The most suitable algorithm and neuron number in the hidden layer are found as Levenberg–Marquardt (LM) with seven neurons for ANN model whereas the most suitable membership function and number of membership functions are found as Gauss and two, respectively, for ANFIS model. The root-mean squared (RMS) value and the coefficient of variation in percent (cov) value are 0.0047 and 0.1363, respectively. The absolute fraction of variance (R2) is 0.9999 which can be considered as very promising. This paper shows the appropriateness of ANFIS for the quantitative modeling of GCHP systems.

In this study, for the first time in the literature, solar assisted cooler with misting system established on an arbor with an area of 24 m2and georeferenced in Elazig (38.6775° N, 39.1707° E), Turkey, is presented. Here, we present a system that reduces interior temperature of the arbor while increasing humidity. Also, the system generates required electricity with a solar photovoltaic module to power pressurized water pump through an inverter and stores it in a battery for use when there is no sunlight. The model of the photovoltaic module was implemented using a Matlab program. As a result of being an uncomplicated system, return on investment for the system is 3.7 years.

This paper reports on a modelling study of new solar air heater (SAH) system efficiency by using least-squares support vector machine (LS-SVM) method. In this study, a device for inserting an absorbing plate made of aluminium cans into the double-pass channel in a flat-plate SAH. A SAH system is a multi-variable system that is hard to model by conventional methods. As regards the LS-SVM, it has a superior capability for generalization, and this capability is independent on the dimensionality of the input data. In this study, a LS-SVM based method was intended to adopt SAH system for efficient modelling. For modelling, different mass flow rates in flow duct and collector types are used and then for obtaining the optimum LS-SVM parameters, such as regularization parameter, and optimum kernel function and parameters, several tests have been carried out. The performance of the proposed methodology was evaluated by using several statistical validation parameters. It is found that root mean squared error (RMSE) value is 0.0024, the coefficient of multiple determinations (R^2) value is 0.9997 and coefficient of variation (cov) value is 2.1194 for the proposed radial basis function (RBF)-kernel LS-SVM method at 0.03kg/s air mass flow rate. It is found that RMSE value is 0.0135, R^2 value is 0.9991 and cov value is 2.9868 for the proposed RBF-kernel LS-SVM method at 0.05kg/s air mass flow rate. Comparison between predicted and experimental results indicates that the proposed LS-SVM model can be used for estimating the efficiency of SAHs with reasonable accuracy.

Abstract The objective of this study is to show the temperature distribution development in the borehole of the ground-coupled heat pump systems (GCHPs) with time. The time interval for the study is 48 h. The vertical GCHP system using R-22 as refrigerant has a three single U-tube ground heat exchanger (GHE) made of polyethylene pipe with a 40 mm outside diameter. The GHE was placed in a vertical borehole (VB) with 30 (VB1), 60 (VB2) and 90 (VB3) m depths and 150 mm diameters. The experimental results were obtained in cooling and heating seasons of 2006–2007. A two-dimensional finite element model (FEM) was developed to simulate temperature distribution development in the soil surrounding the GHEs of GCHPs operating in the cooling and the heating modes. The finite element modelling of the GCHP system was performed using the ANSYS code. The FEM incorporated pipes, the grout and the surrounding formation. From the cases studied, this approach appears to be the most promising for estimation the temperature distribution response of GHEs to thermal loading.

Abstract The goal of the present study is to validate the cooling performance of a ground-coupled heat pump system established in Firat University, Elazig (38.41°N, 39.14°E), Turkey. The cooling load of the test room was 3.1 kW at design conditions. The experimental results were obtained from June to September in cooling season of 2003. The ground heat exchanger was used, and it was buried with in 2 m depth trench. The average cooling performance coefficient of the system (COP overall ) was obtained to be 2.01. The results obtained from experimental measurement showed that these systems could be used safely, reliably and efficiently at the lowest possible cost for Elazig, Turkey climatic conditions. Especially, the seasonal energy efficiency ratio (SEER) of this system is moderate at longer-term testing.

Abstract In this study, performance experiments and economic analysis of a horizontal ground source heat pump (GSHP) system have been performed. The horizontal GSHP system connected to a test room, Elazig (38.41°N, 39.14°E), Turkey, was designed and constructed for space heating. The heating and cooling loads of the test room were 2.5 and 3.1 kW at design conditions, respectively. The performance was determined experimentally under real operational conditions. The experimental results were obtained from 7 November 2002 to 3 May 2003 in the heating season of 2002–2003. A detailed cost analysis was presented and payback periods when substituting for different local fuel/power sources were determined. The GSHP system was compared to conventional heating methods (electric resistance, fuel oil, liquid petrol gas, coal, oil and natural gas) in the economical analysis using an annualised life cycle cost method. It was shown that the GSHP system offers economic advantages over the mentioned first five conventional heating methods. However, it is not an economic alternative system to natural gas.

In this study, experiments were performed to find out how the thermal performance of a two-phase thermosyphon solar collector was affected by using different refrigerants. Three identical small-scale solar water heating systems, using refrigerants R-134a, R407C, and R410A, were constructed and tested side-by-side under various environmental and load conditions. The performance of the system under clear-sky conditions has been investigated with and without water load. Detailed temperature distributions and cumulative collection efficiencies were determined and presented. The experimental results were compared to the results found in the literature and they showed good agreement.