Yazarlar
- Cuce, Erdem(27)
- Cuce, Pinar Mert(22)
- Tozlu, Alperen(12)
- Guclu, Tamer(10)
- Karaali, Rabi(10)
- Imamoglu, Ilyas Kays(7)
- Isik, Cem(7)
- Ongan, Serdar(7)
- Aydin, Rahman(4)
- Hırca, Tuğçe(4)
- Karaali, R.(4)
- Keven, Arzu(4)
- Özahi, Emrah(4)
- Abusoglu, Aysegul(3)
- Ceviz, Mehmet Akif(3)
- Eryılmaz Türkkan, Gökçen(3)
- Kuziboev, Bekhzod(3)
- Serencam, Uğur(3)
- Tozlu, A.(3)
- Yıldırım, Ümit(3)
- Çakir, Uǧur(3)
- Çomakli, Kemal(3)
- Abuşoǧlu, A.(2)
- Afshari, Faraz(2)
- Aloui, F(2)
- Arslantürk, Cihat(2)
- Atabani, A.E.(2)
- Ayşegül, Çokgez Kuş(2)
- Dincer, I(2)
- Erol, Şahin(2)
- Guleryuz, Didem(2)
- Güler, Cüneyt(2)
- Güngör, Osman(2)
- Jomaa, Seifeddine(2)
- Kamiloğlu, Hakan Alper(2)
- Kemal, Çomakli(2)
- Köksal, Hüseyin(2)
- Niazkar, Majid(2)
- Ozahi, Emrah(2)
- Riffat, Saffa(2)
Yayınlar
- MakaleAçık Erişim2017Scopus SJRQ1Thermal performance assessment of a novel liquid desiccant-based evaporative cooling system: An experimental investigation
Cuce, Pinar Mert
Energy consumption in buildings due to heating, cooling and air conditioning (HVAC) systems has a steadily growing trend as a consequence of enhanced indoor thermal comfort conditions. The role of cooling in HVAC oriented energy consumption is remarkable especially in regions with extreme climatic conditions such as Africa and Middle East. In hot and arid climates, cooling demand is usually met by cost-effective evaporative cooling solutions. However, in hot and humid climates, evaporative cooling systems are not capable of providing cooling as the outdoor air is already almost saturated in most cases. Therefore in this research, a novel desiccant-based evaporative cooling system is presented. For different values of inlet supply air temperature and relative humidity provided by a standard environmental chamber, temperature and relative humidity values are measured experimentally at the inlet and outlet of dehumidification and humidification unit, respectively. Since the main purpose of the system developed is to provide cost-effective thermal comfort conditions especially in humid climates, dehumidification effectiveness is calculated for each case tested. The results indicate that the system provides attractive findings for temperate and humid climatic conditions, where stand-alone evaporative cooling systems are inconclusive. For a case of average inlet relative humidity of 94.7% and average inlet air temperature of 38.6 °C, the average outlet relative humidity and air temperature are determined to be 65.5% and 33.3 °C, respectively. An average of 5.3 °C reduction is achieved in supply air temperature as well as an average of 63.7% dehumidification effectiveness which is attractive and promising.
AtıfScopus35WoS32OpenAlex37
İncele - MakaleYalnız künye2017Scopus SJRQ1Role of airtightness in energy loss from windows: Experimental results from in-situ tests
Cuce, Erdem
The rate of air leakage related energy loss from glazed areas is unequivocal especially in older and poorly installed windows. Therefore, in this research, a comprehensive experimental investigation is done to analyse the importance of air leakage on overall heat transfer coefficient (U-value) of conventional air filled double glazed windows. The tests are conducted in a typical UK dwelling of Nottingham fitted with traditional air filled double glazed windows. One sash of the test window is sealed internally with a special transparent cover to provide excellent airtightness whereas the second window sash is left as it is to represent the ordinary case. The experiments are conducted in April 2016, and dynamic co-heating test methodology is applied to evaluate the rate of enhancement in the U-value of airtight window sash. The results indicate that the airtight window sash has a notably lower U-value compared to the ordinary window sash due to the impact of airtightness and reverse heat flux during noon time owing to the greenhouse effect between transparent cover and internal glazing. The overall U-value of ordinary window sash is found to be 2.67 W/m2K, whereas it is 1.79 W/m2K for airtight window sash. It is observed that about 33% of reduction in heat losses can be achieved via airtight windows.
AtıfScopus60WoS59OpenAlex75İncele - MakaleAçık Erişim2017Scopus SJRQ2Efficiency improvement of gas turbine cogeneration systems; [Poboljšanje učinkovitosti kogeneracijskih sustava plinske turbine]
Karaali, Rabi; Öztürk, İlhan Tekin
In this study eight methods are evaluated for a gas turbine cogeneration cycle to improve the efficiency. These methods are increasing gas turbine inlet air temperature, cooling the inlet air of the compressor, air preheating, fuel preheating, increasing compressor inlet air pressure, increasing air excess rates, steam injection, and humidification of the inlet air of the compressor. These methods are studied in order to compare their effects on the performance of the systems. The effects of these methods on the exergetic efficiency depend on the kind of the cogeneration cycle. By combining recuperation, preheating fuel and steam injection methods high efficiency can be achieved. The combined methods give the best results under variable heat demands of the market. An appropriate combination of the efficiency improvement methods may increase the exergetic efficiency about 20 %. The results show that efficiency improvement methods must be applied together whenever it is possible.
AtıfScopus8WoS6OpenAlex15İncele - MakaleYalnız künye2017Scopus SJRQ1An accurate model for photovoltaic (PV) modules to determine electrical characteristics and thermodynamic performance parameters
Cuce, Erdem; Cuce, Pinar Mert; Karakas, Ibrahim Hakki; Bali, Tulin
Accurate and reliable modelling of photovoltaic (PV) modules is necessary for design and performance estimation of PV systems. Manufacturers of PV modules usually provide some basic electrical parameters specified at only one single operating condition, which is commonly known as standard test conditions (STCs). However, PV systems operate over a wide range of outdoor conditions, and the manufacturers’ reports do not cover sufficient information about how the PV modules react with respect to changes in the two most important environment-oriented conditions, which are solar intensity and operating cell temperature. In this respect, an accurate and reliable tool is required by designers to predict electrical characteristics and thermodynamic performance parameters of PV modules. Therefore in this research, a novel mathematical model is developed to determine solar intensity and cell temperature dependency of PV module parameters and thermodynamic efficiency figures. A simple one-diode model is proposed considering series resistance and shunt conductance. Mitsubishi PV-UJ225GA6 225 W polycrystalline silicon PV module and Kyocera KD205GH-2P 205 W multicrystal PV module are utilised for model assessment. Model results are compared with environmental chamber tests and manufacturers’ performance reports, and a very good agreement is achieved.
AtıfScopus97WoS85OpenAlex110İncele - BildiriAçık Erişim2017Scopus SJRQ3Thermodynamic performance assessment of different fluids in a typical organic Rankine cycle for usage in municipal solid waste power plant
Özahi, E.; Tozlu, A.; Abuşoǧlu, A.
This paper presents the energy and exergy analyses of some different organic fluids which can be used in an organic Rankine cycle adapted to a municipal solid waste power plant in the frame of energy recovery. The novelty of the study is to adapt a well-known organic Rankine cycle system theoretically to the existing municipal solid waste power plant where the exhaust gas with a temperature of almost 560 °C is sent to atmosphere causing both energy loss and air pollution, and also violating the related legislation. The efficient organic fluid that can be used in such a plant is estimated by means of the thermodynamic analyses. It is known that, in a typical municipal solid waste power plant, a considerable amount of energy is sent up from a plant chimney to the atmosphere. This waste energy can be utilized by using an adapted organic Rankine cycle system with a proper organic fluid. In this frame, some different organic fluids were examined and compared thermodynamically in this study. The optimal operation conditions of some organic fluids, R141b, isobutane, R245fa, n-pentane and n-hexane have been evaluated by means of ASPEN and EES software programs. The effects of the outlet temperature of heat source on the energetic and exergetic efficiencies and the net power output at a given pinch point temperature difference were investigated. It can be deduced from the analyses that n-hexane has the highest energetic and exergetic efficiencies at all outlet temperatures of the heat source such as 8.92% and 34.47% at 82.08°C, respectively. It can also be stated that the maximum net power output is obtained by using the organic fluid n-hexane.
AtıfScopus14WoS12OpenAlex13İncele - BildiriAçık Erişim2017Scopus SJRQ3Thermoeconomic analysis and assessment of Gaziantep municipal solid waste power plant
Tozlu, A.; Abuşoǧlu, A.; Özahi, E.
This paper presents a thermoeconomic analysis and assessment of a municipal solid waste power plant system in Gaziantep. The operation of an existing municipal solid waste power plant is described in detail and a thermoeconomical methodology based on exergoeconomic relations and specific exergy costing (SPECO) method is provided to allocate cost flows through subcomponents of the plant. SPECO method is based on a step by step procedure which begins from identification of energy and exergy values of all states defined in the present system through fuel (F) and product (P) approach and ends at the point of establishing related exergy based cost balance equations together with auxiliary equations. The actual exergy efficiency of the solid waste power plant is determined to be 47.84% which shows that 52.16% of the total exergy input to the plant is destroyed. The net electrical power output of the Gaziantep municipal solid waste power plant is 5.655 MW. The total cost rate of the power plant is evaluated as 18.44$/h as a result of thermoeconomic analyses.
AtıfScopus12WoS13OpenAlex16İncele - MakaleAçık Erişim2017Scopus SJRQ1An energy prediction algorithm for wind-powered wireless sensor networks with energy harvesting
Kosunalp, Selahattin
Energy harvesting (EH) from environmental energy sources has the potential to ensure unlimited, uncontrollable and unreliable energy for wireless sensor networks (WSNs), bringing a need to predict future energy availability for the effective utilization of the harvested energy. The majority of previous prediction approaches have exploited the diurnal cycle dividing the whole day into equal-length time slots in which predictions were carried out in each slot independently. This is not, however, efficient for wind energy as it exhibits non-controllable behaviour in that the amount of energy to be harvested varies over time. This paper proposes a novel approach to predict the wind energy for EH-WSNs depending on the energy generation profile of latest condition. The distinctive feature of the proposed approach is to consider the recent conditions in current-day, instead of past-day's energy generation profiles. The performance of the proposed algorithm is evaluated using real measurements in comparison with state-of-art approaches. Results show that the proposed strategy significantly outperforms the two popular energy predictors, EWMA and Pro-Energy.
AtıfScopus48WoS36OpenAlex51İncele - MakaleYalnız künye2017Scopus SJRQ2Solar Pond Window Technology for Energy-Efficient Retrofitting of Buildings: An Experimental and Numerical Investigation
Cuce, Erdem; Cuce, Pinar Mert
Windows are responsible for an important proportion of heat loss from building envelope due to inadequate insulative characteristics of traditional glazing products. In this respect, advanced glazing solutions are of vital importance to mitigate energy demand of buildings, thus to reduce carbon emissions. Therefore, in this research, a novel glazing technology called solar pond window is introduced, and it is numerically and experimentally investigated for different design configurations. The optimum design of this novel glazing covers four 5-mm-thick glass panes, two 20-mm-thick water layers, and one 20-mm-thick Krypton layer in the middle. The average heat transfer coefficient (U-value) of the optimum case is found to be about 0.40 W/m 2 K. If air is used as insulative gas in the interlayer, the U-value of the glazing is determined to be around 0.90 W/m 2 K, which is still competitive with the U-value range of argon-filled triple-glazed windows with low-e coatings. The fabrication cost of the optimum design of solar pond window is around €120/m 2. Overall, solar pond window technology is a cost-effective and energy-efficient glazing, which has a great potential to be the future of fenestration products as well as being capable of meeting the latest building fabric standards.
AtıfScopus10WoS7OpenAlex9İncele - BildiriYayıncıda açık erişim2016Scopus SJRQ4Exergy analysis of a combined power and cooling cycle
Karaali, R.
Ammonia-water power cycles are important for efficient utilization of low temperature heat sources such as geothermal, solar, waste heat sources, etc. For some special conditions ammonia-water power cycle is an important and economical option. This paper presents an exergetic analysis of a combined power and cooling cycle that uses ammonia-water mixture as working fluid. Such cycles, use solar or geothermal energy or waste heat energy from a conventional power cycle. Ammonia-water power cycle can be used as independent cycles to provide power output and cooling. For a range (25-55 Bar) of boiler pressure the performance of the combined power and cooling cycle is investigated. The exergy of the boiler is very low compared to its energy. There is a boiling process and a heat transfer process at low temperature, both of which destruct the energy given to the boiler, so that the energy efficiency is low; however the exergy efficiency is higher than the energy efficiency. Increasing the turbine inlet pressure decreases the energy and exergy efficiencies.
AtıfScopus13WoS12OpenAlex75İncele - MakaleAçık Erişim2016Scopus SJRQ1A novel roof type heat recovery panel for low-carbon buildings: An experimental investigation
Cuce, Pinar Mert; Cuce, Erdem; Riffat, Saffa
Energy saving and its efficient utilization is of prime interest in today's world due to the limited energy resources and growing significance of environmental issues. Despite the intensive efforts to narrow the gap between conventional energy sources (wood, coal, gas, oil, etc.) and renewables, renewable energy resources currently supply only about 14% of total world energy demand. In this regard, energy management and optimization are considered compulsory as much as the clean energy generation. Recent works indicate that the buildings play a significant role on global energy consumption. They are responsible for about 40% of global energy demand. Among the different building types, domestic buildings have the largest share with 63% and most of energy is utilized for heating, ventilation and air conditioning (HVAC) systems in those buildings. Energy consumption levels of buildings can be notably reduced through waste heat recovery in HVAC systems. There are several attempts in literature addressing the possibility of decreasing energy consumption of buildings via waste heat recovery technologies. The heat recovery technologies are cost effective and user friendly applications. The use of heat recovery systems aims at mitigating the energy consumption for HVAC applications as well as the greenhouse gas emissions, and hence decreasing the adverse effects of global warming on the Earth. It is well-documented in literature that the heat recovery systems are very promising for domestic applications. In this paper, experimental results of a novel heat recovery system developed for low-carbon buildings are presented. The proposed heat recovery system consists of a plate-type heat exchanger, blower fans and ducts. The parallel-flow arrangement is used to run the system. The system is designed as under roof application. The aim of the system is to recover waste heat and to preheat fresh air using stale air. The experiments of the system are carried out in winter season in Kent, UK. The study aims to investigate the coefficient of performance (COP) of the system as well as the heat recovery efficiency. The results show that the heat recovery efficiency of the proposed system is around 89% while the COP is 4.5. The proposed system can be used in both winter and summer conditions without requiring additional work. Its labor cost is extremely low, so it is cost-effective and user friendly.
AtıfScopus28WoS23OpenAlex31İncele - MakaleAçık Erişim2016Scopus SJRQ1Novel glazing technologies to mitigate energy consumption in low-carbon buildings: A comparative experimental investigation
Cuce, Erdem; Cuce, Pinar Mert; Riffat, Saffa
Buildings play a key role in total world energy consumption as a consequence of poor thermal insulation characteristics of facade materials. Among the elements of a typical building envelope, windows are responsible for the greatest energy loss because of their notably high overall heat transfer coefficients. About 60% of heat loss through the building fabric can be attributed to the glazed areas. In this respect, novel cost-effective glazing technologies are needed to mitigate energy consumption, and thus to achieve the latest targets toward low/zero carbon buildings. Therefore in this study, three unique glazing products called vacuum tube window, heat insulation solar glass and solar pond window which have recently been developed at the University of Nottingham are introduced, and thermal performance analysis of each glazing technology is done through a comparative experimental investigation for the first time in literature. Standardized co-heating test methodology is performed, and overall heat transfer coefficient (U-value) is determined for each glazing product following the tests carried out in a calibrated environmental chamber. The research essentially aims at developing cost-effective solutions to mitigate energy consumption because of windows. The results indicate that each glazing technology provides very promising U-values which are incomparable with conventional commercial glazing products. Among the samples tested, the lowest U-value is obtained from the vacuum tube window by 0.40W/m2K, which corresponds to five times better thermal insulation ability compared to standard air filled double glazed windows.
AtıfScopus35WoS33OpenAlex37İncele - Derleme MakaleYalnız künye2016Scopus SJRQ1Vacuum glazing for highly insulating windows: Recent developments and future prospects
Cuce, Erdem; Cuce, Pinar Mert
A comprehensive review of vacuum glazing technology from state-of-the-art developments to future prospects has been presented. The review has been conducted in a thematic way in order to allow an easier comparison, discussion and evaluation of the findings. First, a thorough overview of historical development of vacuum glazing has been given. Then, numerous experimental, theoretical, numerical and simulation works on the scope have been evaluated and the characteristic results from the said works have been analyzed. Commercial vacuum glazing products in market have been assessed in terms of several performance parameters such as overall heat transfer coefficient, visible light transmittance, solar heat gain coefficient and cost. Techno-economic and environmental aspects of vacuum glazing technology have also been discussed. It can be concluded from the results that overall heat transfer coefficient of a vacuum glazing can be reduced up to 0.20 W/m2K through optimized integrations with low-e coatings. The incomparable U-value range of vacuum glazing enables significant mitigation in energy consumption levels and greenhouse gas emissions. Retrofitting 25.6 million homes in the UK with vacuum glazing can provide a carbon abatement of about 40 million tonnes a year, which is very promising.
AtıfScopus138WoS117OpenAlex148İncele - Derleme MakaleYalnız künye2016Scopus SJRQ1Toward multi-functional PV glazing technologies in low/zero carbon buildings: Heat insulation solar glass - Latest developments and future prospects
Cuce, Erdem
Heat insulation solar glass (HISG) is a recently developed multi-functional photovoltaic (PV) glazing technology to mitigate energy consumption of buildings and to provide optimum thermal comfort conditions to occupants. In essence, HISG represents an improved transparent amorphous silicon (a-Si) PV module prepared with several optimized coatings and structures. HISG differs from conventional PV glazing products by having some characteristic features such as thermal insulation, sound absorption, self-cleaning and notable energy saving. In addition, HISG has a 100% UV blocking rate and remarkably low shading coefficient, which provides desired lighting related thermal comfort conditions for indoor environments. HISG is also competitive with conventional double glazed products in market in terms of fabrication cost. In this respect, it is highly expected that HISG has a strong potential to dominate the fenestration market in the near future. In this research, a comprehensive review of HISG technology is presented. Power generation, thermal insulation, energy saving, self-cleaning, acoustic and aesthetic features of HISG are evaluated in detail through the state-of-The-art literature survey. Existing research projects on the scope and future prospects are also addressed within the scope of this study.
AtıfScopus75WoS62OpenAlex84İncele - MakaleYalnız künye2016Scopus SJRQ1Energy saving potential of heat insulation solar glass: Key results from laboratory and in-situ testing
Cuce, Erdem; Cuce, Pinar Mert; Young, Chin-Huai
HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively.
AtıfScopus52WoS46OpenAlex56İncele - BildiriAçık Erişim2016Scopus SJRQ4Thermodynamic analysis of a cascade refrigeration system
Karaali, R.
There is a need for cooling by using the waste heat energy in food industry. Absorption cycles can be driven by waste thermal, geothermal, solar or industrial processes energies. In this study, cascade refrigeration system is thermodynamically modeled, and analyzed by using first law of thermodynamics, and exergy method. Thermodynamic properties such as pressure, temperature, entropy, enthalpy, exergy, mass flow rate in each stream are calculated for 50, 75, 100?C and for 0.8, 1.0, and 1.5 MPa pump pressure. A computer program is used that was prepared in FORTRAN by the author for the analyses. It is found that the compression-absorption cascade cooling cycle is appropriate for most of the kind of waste heat applications. Increase of the generator inlet heat temperature increases the generator inlet heat, the absorber outlet heat and the condenser 2 outlet heat energies and decreases the coefficient of performance of the absorption and the overall cycles. The generator heat decreases with increase of the pump pressure. Also increase of the pump pressure decreases the coefficient of performance of the absorption and the overall cycles. Increase of the pump pressure and the generator temperature decreases the exergetic coefficient of performance. Increase of the generator temperature and pump pressure increases the generator inlet exergy. It is concluded that increase of the generator temperature and the pump pressure increases the total destructed exergy of the cycle.
AtıfScopus10WoS5OpenAlex13İncele - Derleme MakaleYalnız künye2016Scopus SJRQ1Renewable and sustainable energy saving strategies for greenhouse systems: A comprehensive review
Cuce, Erdem; Harjunowibowo, Dewanto; Cuce, Pinar Mert
In this study, a comprehensive review focusing on key strategies of energy saving and climate control technologies for greenhouses is presented. Following the brief and concise assessment of existing greenhouse systems in terms of their role in total energy consumption; cost-effective, energy-efficient and environmentally friendly technologies are analyzed in detail for potential utilization in greenhouses for notable reductions in energy consumption and emission levels. The technologies considered within the scope of this research are mainly renewable and sustainable based solutions such as photovoltaic (PV) modules, solar thermal (T) collectors, hybrid PV/T collectors and systems, phase change material (PCM) and underground based heat storage techniques, energy-efficient heat pumps, alternative facade materials for better thermal insulation and power generation (heat insulation solar glass, PV glazing, aerogel and vacuum insulation panel, polycarbonate sandwich panels), innovative ventilation technologies using pre-heating and cooling (high performance windcatchers) and efficient lighting systems. The findings from the research clearly reveal that up to 80% energy saving can be achieved through appropriate retrofit of conventional greenhouses with a payback period of 4-8 years depending on climatic conditions and crop type.
AtıfScopus354WoS302OpenAlex382İncele - MakaleYalnız künye2015Scopus SJRQ1Thermoeconomic optimization of gas turbine cogeneration plants
Karaali, Rabi; Öztürk, Ilhan Tekin
In this study, a novel thermoeconomic optimization method that is simple and efficient, for real complex cycles is introduced. First, a thermoeconomic analysis method that is called non-linear simplex direct search method is improved for the purposes of this study. The objective of this paper is to apply this method to four cogeneration cycles that are simple cycle, inlet air cooling cycle, air preheated and air-fuel preheated cycles for analyzing and optimizing. The four cycles are thermoeconomically optimized for constant power and steam mass (30 MW and 14 kg/s saturated steam flow rate at 2000 kPa), for constant power (30 MW) and for variable steam mass, and for variable power and steam mass by using the cost equation method and the effect of size on equipment method. The results obtained by the effect of size on equipment and by the cost equations methods are very different from each other. For the case of global optimization, the optimum electricity costs which also correspond to minimum are obtained as 0,0432 $/kWh for simple cycle, 0,0514 $/kWh for inlet air cooling cycle 0,0577 $/kWh for air preheated cycle and 0,058 $/kWh for air-fuel preheated cycle by using cost equations method. (C) 2014 Elsevier Ltd. All rights reserved.
AtıfWoS32OpenAlex39İncele - MakaleAçık Erişim2015Scopus SJRQ3Experimental and numerical investigation of a novel energy-efficient vacuum glazing technology for low-carbon buildings
Cuce, Erdem
In this study, a recently developed innovative window technology called vacuum tube window is introduced, and its performance assessment is presented through an experimental and numerical research. The novel design of vacuum tube window consists of evacuated tubes surrounded by Argon as inert gas to eliminate conductive and convective effects inside the window and thus to produce a building element with remarkably low overall heat transfer coefficient (U-value). Heat transfer inside the window was modelled via a reliable commercial computational fluid dynamics software ANSYS FLUENT. The accuracy of simulations was verified by environmental chamber tests. For the vacuum tube diameter of 28 mm, an excellent agreement between experimental and numerical data was achieved. For different values of design parameters such as pane thickness, tube thickness, tube diameter and Argon gap, total heat loss and U-value of the vacuum tube window and optimum data were evaluated. Optimum tube diameter was found to be 60 mm in terms of thermal performance characteristics, cost, lightness and aesthetic issues. It is concluded that the vacuum tube window is able to provide a U-value lower than 0.40 W/m2K, which is very promising for both retrofitting of existing buildings and new-build applications.
AtıfScopus16WoS11OpenAlex18İncele - BildiriAçık Erişim2015Scopus SJRQ3Investigation of an alternative fuel for diesel engines
Keven, A.; Karaali, R.
Internal combustion engines use generally fossil fuel products. World resources of it is limited. Renewable alternative energy sources are getting important solution for energy demand. Hazelnut oil ethyl ester is obtained from raw hazelnut and mixed with diesel oil in certain proportions to use in a four-stroke direct injected single cylinder diesel engine. In this study the effects of the mixture of diesel oil with hazelnut oil ethyl ester on the engine performance and exhaust gas emissions are investigated for the first time in literature. The fuel injection system is regulated to use the mixture in the engine for the investigation. The results show that, the mixture with 25% ethyl ester extracted from hazelnut oil can be used as an alternative fuel without any change or regulation of the diesel engine.
AtıfScopus7WoS3OpenAlex7İncele - BildiriAçık Erişim2015Scopus SJRQ3Thermoeconomic analyses of steam injected gas turbine cogeneration cycles
Karaali, R.; Öztürk, I.T.
In this study, three different gas turbine cogeneration systems that are preheating air, preheating air-fuel and simple cycles where steam injected in to combustion chamber are analyzed. The effects of steam injection on thermoeconomic performance are calculated and obtained. By using the first law of thermodynamics, the exergy analysis and economic methods, simulation programs written by the authors in FORTRAN code are obtained to use for the analyses. Thermoeconomic performance of these three different cycles for different stage and variable mass of injected steam are obtained and compared with literature. The effects of injection steam in to combustion chambers of those three cycles for variable compressing ratios, on power, efficiencies, product price and performances are obtained. Consequently, the advantages and the disadvantages of injection steam are evaluated. The results obtained in this study are compared with the results available in the literature. Injection steam into combustion chamber increases the electricity efficiency and electricity power but decreases the heat power of the cycles. Also the produced electricity price for per kWh is increasing.
AtıfScopus15WoS12OpenAlex18İncele
