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Öğe Combustion, performance and emissions of a diesel power generator fueled with biodiesel-kerosene and biodiesel-kerosene-diesel blends(Elsevier, 2017-02-05) Bayındır, Hasan; Işık, Mehmet Zerrakki; Argunhan, Zeki; Yücel, Halit Lütfi; Aydın, HüseyinHigh percentages of biodiesel blends or neat biodiesel cannot be used in diesel engines due to high density and viscosity, and poor atomization properties that lead to some engine operational problems. Biodiesel was produced from canola oil by transesterification process. Test fuels were prepared by blending 80% of the biodiesel with 20% of kerosene (B80&K20) and 80% of the biodiesel with 10% of kerosene and 10% diesel fuel (B80&K10&D10). Fuels were used in a 4 cylinders diesel engine that was loaded with a generator. Combustion, performance and emission characteristics of the blend fuels and D2 in the diesel engine for certain loads of 3.6, 7.2 and 10.8 kW output power and 1500 rpm constant engine speed were experimented and deeply analyzed. It was found that kerosene contained blends had quite similar combustion characteristics with those of D2. Mass fuel consumption and Bscf were slightly increased for blend fuels. HC emissions slightly increased while NOx emissions considerably reduced for blends. It was resulted that high percentages of biodiesel can be a potential substitute for diesel fuel provided that it is used as blending fuel with certain amounts of kerosene.Öğe An experimental investigation of the effect of thermophysical properties on time lag and decrement factor for building elements(Gazi University, 2020-06-01) Oktay, Hasan; Yumrutaş, Recep; Argunhan, ZekiThe time lag (TL) and decrement factor (DF) are essential for the heat storage capabilities of building elements, which strictly depend on the thermophysical properties of the elements. Many investigations are presented in literature arguing to find the influence of each thermophysical property on TL and DF by keeping the other properties constant. This study aims to investigate the effect of each property on TL and DF, utilizing relationships between the measurement values of the thermophysical properties of wall materials. Therefore, first, 132 new concrete wall samples were produced, and their thermophysical properties were tested. Secondly, TL and DF values for each building element are computed from the solution of the problem by Complex Finite Fourier Transform (CFFT) technique. Finally, a multivariate regression analysis has been performed, and the variations of each thermophysical property versus TL and DF are presented, and also the findings are compared with literature. The results show that each property alone (keeping the other properties constant) is not adequate to identify the thermal inertia and thermal performance of a wall element. Besides, 87.3 % decrease in thermal diffusivity corresponds to 6.03 h increase in the value of TL and 88.8 % decrease in value of DF; respectively, for W1 wall assembly.Öğe Experimental investigation of solar stills integrated with solar water heating collectors(Türk Isı Bilimi ve Tekniği Derneği, 2017-10-31) Argunhan, Zeki; El, Emin; Yıldız, Cengiz; Çakmak, GülşahSolar still is a more practical way of obtaining clean water. In this study, we aimed to improve the efficiency of solar still systems and obtain distilled water at the same time. For this purpose, 5 different solar still systems were designed. Type 1; conventional solar still, Type 2; conventional solar still integrated with solar water heating collector and run via natural convection, Type 3; conventional solar still integrated with solar water heating collector and tubular heat exchanger and run via natural convection, Type 4; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via natural convection, Type 5; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via forced convection. In this study, the experiments were carried out on the parameters influencing the performance, the amount of distilled water obtained, and the efficiency of experiment settings designed in different types; and finally the results were presented. The amount of distilled water and efficiency of conventional solar still were 2389 ml and 51.47%, respectively. Maximum total amount of water and efficiency from natural convection systems were obtained from Type 4, and the values calculated were found as to be 5788 ml and 55.91%. Maximum amount of distilled water and the efficiency were obtained by utilizing forced convection system were found as to be 6068 ml and 58.99%, respectively.Öğe Dimension and insulation thickness optimization of circular flat plate solar collectors(Energy Education Science and Technology, 2011) Argunhan, ZekiIn this study, expressions for optimum radius of a circular flat plate solar collector and the optimum insulation thickness distribution are derived by using the concept of solar gain, which maximizes the life-cycle savings. For the specified condition the optimum radius has been found as 2.14 m and the optimum insulation thickness distribution on back of collectors has been formulized. The insulation material thickness distribution has been determined by performing a detailed dimensional analysis; therefore heat loss is minimized, and results are presented in graphics.Öğe Experimental investigation of the effects of diesel-like fuel obtained from waste lubrication oil on engine performance and exhaust emission(Journals & Books, 2010-10) Argunhan, Zeki; Yumrutaş, Recep; Arpa, OrhanIn this study, effects of diesel-like fuel (DLF) on engine performance and exhaust emission are investigated experimentally. The DLF is produced from waste engine lubrication oil purified from dust, heavy carbon soot, metal particles, gum-type materials and other impurities. A fuel production system mainly consisting of a waste oil storage tank, filters, a reactor, oil pump, a product storage tank, thermostats and control panel is designed and manufactured. The DLF is produced by using the system and applying pyrolitic distillation method. Characteristics, performance and exhaust emissions tests of the produced DLF are carried out at the end of the production. The characteristic tests such as density, viscosity, flash point, heating value, sulfur content and distillation of the DLF sample are performed utilizing test equipments presented in motor laboratory of Mechanical Engineering Department, University of Gaziantep, Turkey. Performance and exhaust emission tests for the DLF are performed using diesel test engine. It is observed from the test results that about 60 cc out of each 100 cc of the waste oil are converted into the DLF. Characteristics and distillation temperatures of the DLF are close to those values of a typical diesel fuel sample. It is observed that the produced DLF can be used in diesel engines without any problem in terms of engine performance. The DLF increases torque, brake mean effective pressure, brake thermal efficiency and decreases brake specific fuel consumption of the engine for full power of operation.Öğe Second Law analysis in concentric heat exchangers with vortex flow generators(Energy Education Science and Technology, 2011) Argunhan, Zeki; Çakmak, Gülşah; Yıldız, Cengiz; Behçet, RasimIn the present study, the experimental results of heat transfer of a concentric tube heat exchanger were analyzed with respect to Second Law of Thermodynamics to reach the geometric optimal design of the heat exchangers. In order to increase the heat transfer, the vortex generators were placed in the entrance of the inner pipe of the heat exchanger. These vortex generators are 60 mm in diameter having six angled (55°, 65°, 75°, 90°) winglets. The winglets have one rectangular slot in each and are 2×7 mm in dimensions. Experiments were carried out with different Reynolds Numbers. Air as hot fluid and water as cold fluid were passed through the inner pipe and outer pipe of the concentric tube heat exchanger, respectively. The variations of the efficiency and Entropy Generation Number with respect to Reynolds Number are shown in graphics, and the results were discussed.Öğe Investigation of the thermal and acoustic performance of perlite- based building materials(European Journal of Technique (EJT), 2016-12) Oktay, Hasan; Argunhan, Zeki; Doğmuş, RecepPerlite is a siliceous volcanic glass that provides heat and sound insulation, whose volume can expand substantially under the effect of heat. Perlite ore is one of the most important mineral resources for Turkey where holds a large portion reserves in the world. Evaluation of perlite in building industry, which has advantages in terms of heat and sound insulation, will make an important contribution to the national economy. In this context, experimental investigations are performed for obtaining new concrete types with relatively high strength, low density and good thermal and acoustic properties for energy efficient buildings. For this purpose, 6 sets and different types of concrete samples were prepared with a constant watercement ratio, and normal aggregates replaced by expanded perlite aggregates at different volume fractions such as 10%, 20%, 30%, 40%, 50% and 60% of the total aggregate volume. Mechanical and thermal tests were all conducted and the hot disk method was used to establish thermal property values of concrete samples. The results of the experimental studies show that the compressive strength and density decreases, while highly increases the heat and sound insulation features with increasing in perlite content. As a result, it was found out that the reductions in thermal conductivity [Wm–1K–1] and ultrasonic pulse velocity [km/s] of the produced samples reached to 75% and 35%, respectively.Öğe The effect of rotary type turbulator placed in entrance of heat exchanger on heat transfer and frictional loss(Energy Education Science and Technology, 2011) Argunhan, Zeki; Behçet, Rasim; Yakut, Ali KemalIn this study, improving heat transfer in heat exchangers with paralel flow is gained by using swirl flow. For this purpose, a propeller type of turbulator was placed in the entrance of interior pipe of heat exchanger with paralel flow and the effect of turbulator on the heat transfer and friction losses in steady conditions was experimentally investigated. The effect of production of turbulance for improvement of heat transfer in interior pipe flows and the effects of turbulator on heat transfer and pressure drop are experimentally researched by placing a propeller type of turbulator at the entrance of heat exchanger to produce swirl air flow. In experiment setup, water was used as the fluid on which the heat was transferred and air was used as the fluid from which heat was transferred to the water. By usage of datas obtained from experimental measurements were calculated for Reynolds number ranging from 8000 to 24000 necessary relationships effet on heat transfer and pressure drop. In comparison with empty pipe it was seen that the heat transfer increased at range between 25,5%- 50,3% and the friction losses increased 5 times. Besides, by analyzing the system exergy, the dependence of non-dimensional exergy loss on Reynolds number was drawn to investigate whether this improvement technique is advantageous thermodynamically or not. When comparing the exergy losses in empty pipe and the pipe with a turbulator at approximately same Reynolds numbers, it was seen that exergy loss is 15% higher for empty pipe than that for the pipe with the turbulator. As a result of that information, the improvement technique was proved to be advantageous in thermodynamic manner too. By the usage of turbulator that results in the partial recovery of loss energy, it was proven that the improvement technique was thermodynamically advantageousÖğe Effect of swirl generators with different sized propeller on heat transfer enhancement(Energy Education Science and Technology, 2011) Argunhan, Zeki; Yıldız, Cengiz; Çakmak, GülşahIn this study, the swirl flow that is one of the passive methods is used for increasing the heat transfer coefficient in the concentric heat exchangers. For this purpose, propeller type swirl generators were prepared to test in the experiments. So, the effect of propellers placed in the inner pipe of the concentric heat exchangers on the heat transfer and pressure drop was investigated experimentally. Experiments were undertaken for the Reynolds Number range of 4000-12000 and for both parallel and counter-flow. It is shown that, the propellers rotated freely with the effect of fluid flowed in the inner pipe are swirling flow generator and they have improved heat transfer. In addition that up to 50% enhancements could be accomplished in heat transfer rates with the swirl generators compared to without the swirl generators. In the parallel flow mode, the enhancement was 10% lower than that of counter-flow at the same Reynolds number. On the other hand the pressure losses increase approximately 3 times more than the empty tube related to Reynolds numbers and propeller sizes. As an outcome of the study, the results showed that a rather smaller size but the same capacity heat exchanger could be proposed by using these elements imposing swirling to the fluid flowing through inner pipe.Öğe Effect of the air flow rate of blower on the performance of solar still(Türk Isı Bilimi ve Tekniği Derneği, 2015-06-01) Argunhan, Zeki; El, Emin; Yücel, Halit Lutfi; Çakmak, Gülşah; Yıldız, CengizSolar distillation is one of the important methods for water purification. This paper examines the performance of solar distillation system at different air flow rate. To increase the performance of distiller, artificial wind was created by fan and suitable wind speed was investigated to increase the amount of water distilled. The experiments were carried out in Elazığ climate conditions. In order to examine the effect of the wind speed on solar distillation system, two stills were manufactured with the size of 1000x1000 mm. One of them was the conventional still which was used as a reference. The other still was used to investigate experimentally the effect of the wind speed. Graphs were drawn for time-dependent changes in the amount of water distilled. It was found that that the productivity of the fan-still distiller was 14.7 % greater than that of a conventional still.
