Browsing by Author "Kalinci, Yildiz"

Now showing 1 - 8 of 8

Citation - WoS: 78
Citation - Scopus: 81
Energy and exergy analyses of a hybrid hydrogen energy system: A case study for Bozcaada
(Elsevier Ltd, 2017) Yildiz Kalinci; I. Dincer; A. Hepbasli; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In the study a hybrid energy system for hydrogen and electric production is conceptually developed and applied to an island Bozcaada. A thermodynamic analysis is performed using energy and exergy approaches. The conceptual system is examined from the viewpoints of economic and energy load distributions by the Hybrid Optimization Model for Electric Renewable (HOMER) tool. In the study stand-alone island model is selected for analysis scenarios. The model consists of photo voltaic (PV) array wind turbines electrolyzer polymer electrolyte membrane fuel cell (PEMFC) hydrogen tank and converter. Energy and exergy analyses are applied to determine of the locations and magnitudes of system inefficiencies. The analyses are essentially made for the main equipment under dynamically changing operating and environmental conditions. In addition hourly distributions of changing energy and exergy rates are illustrated. As a result the daily average energy and exergy efficiencies of the PV array are 13.31% and 14.26%. Also the efficiency values are calculated for the wind turbine as 46% for energy and 50.12% for exergy and the electrolyzer equipment as 59.68% for energy and 60.26% for exergy respectively. © 2017 Elsevier B.V. All rights reserved.
Citation - Scopus: 4
Exergetic performance assessment of a binary geothermal power plant
(Springer International Publishing, 2014) Yildiz Kalinci; A. Hepbasli; I. Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
Electricity generation is achieved by means of the medium-temperature geothermal water in the range of 90–140 ºC in binary plants with the organic Rankine cycle. So we investigate a binary geothermal power plant as a case study from the energy and exergy point of view. Also exergy destruction rates throughout the plant are quantified and illustrated for comparison purposes. In the plant considered the brine injection and reinjection temperatures are 140 and 80 ºC with a mass flow rate of 64.87 kg/s respectively. The energy and exergy efficiencies are calculated as 5.34 and 30.84 % respectively based on the heat and exergy input rates to the system at the net power. Furthermore we examine the effects of some parameters on energy and exergy efficiencies and net power output (e.g. brine injection temperature brine mass flow rates turbine inlet temperature and inlet pressure). © 2017 Elsevier B.V. All rights reserved.
Citation - WoS: 26
Citation - Scopus: 32
Exergoeconomic analysis and performance assessment of hydrogen and power production using different gasification systems
(Elsevier Sci Ltd, 2012) Yildiz Kalinci; A. Hepbasli; I. Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In this paper we investigate three different gasifiers for hydrogen production namely downdraft gasifier (DG) circulating fluidized bed gasifier (CFBG) and plasma gasifier (PG) as taken from the literature under Cases 1-3 respectively. These cases are then modified for cogeneration of hydrogen and power. We use the specific exergy cost (SPECO) method to calculate exergy-related parameters and display cost flows for all streams and components. The case studies are selected from different countries. We study how flow rates of streams cost and hydrogen unit costs change if these facilities operate in Turkey. The process life time is considered 15 years and the inflation rate and energy inflation rate are taken from the Central Bank of the Republic of Turkey as 8.91% and 19.25% while unit energy water and biomass costs are taken 31.38 $/GJ 4.59 $/t and 35.42 $/t for Turkey respectively. The electric power requirements are calculated to be 0.0915 12.53 and 23.26 MW e for DG CFBG and PG respectively. In Cases 1-3 the electric power generated by the systems are 0.144 MW 1.17 MW and 3.88 MW respectively and may be sold to the national grid with cost rates of 31.8 $/h 258.39 $/h and 856.88 $/h. In the systems the hydrogen production rates and costs per unit mass are obtained to be 0.004 kg/s 0.521 kg/s and 0.155 kg/s and 1.16 $/kg 3.33 $/kg and 2.45 $/kg for the DG the CFBG and the PG respectively. © 2012 Elsevier Ltd. All rights reserved. © 2012 Elsevier B.V. All rights reserved.
Citation - WoS: 21
Citation - Scopus: 27
Exergoeconomic analysis of hydrogen production from biomass gasification
(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Yildiz Kalinci; Arif Hepbasli; Ibrahim Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In this study we investigate biomass-based hydrogen production through exergy and exergoeconomic analyses and evaluate all components and associated streams using an exergy cost energy and mass (EXCEM) method. Then we define the hydrogen unit cost and examine how key system parameters affect the unit hydrogen cost. Also we present a case study of the gasification process with a circulating fluidized bed gasifier (CFBG) for hydrogen production using the actual data taken from the literature. We first calculate energy and exergy values of all streams associated with the system exergy efficiencies of all equipment and determine the costs of equipment along with their thermodynamic loss rates and ratio of thermodynamic loss rate to capital cost. Furthermore we evaluate the main system components consisting of gasifier and PSA from the exergoeconomic point of view. Moreover we investigate the effects of various parameters on unit hydrogen cost such as unit biomass and unit power costs and hydrogen content of the syngas before PSA equipment and PSA hydrogen recovery. The results show that the CFBG system which has energy and exergy efficiencies of 55.11% and 35.74% respectively generates unit hydrogen costs between 5.37 $/kg and 1.59 $/kg according to the internal and external parameters considered. Copyright (C) 2012 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Citation - WoS: 107
Citation - Scopus: 125
Life cycle assessment of hydrogen production from biomass gasification systems
(Pergamon-Elsevier Science Ltd, 2012) Yildiz Kalinci; A. Hepbasli; I. Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In this study a Life Cycle Assessment (LCA) of biomass-based hydrogen production is performed for a period from biomass production to the use of the produced hydrogen in Proton Exchange Membrane (PEM) fuel cell vehicles. The system considered is divided into three subsections as pre-treatment of biomass hydrogen production plant and usage of hydrogen produced. Two different gasification systems a Downdraft Gasifier (DG) and a Circulating Fluidized Bed Gasifier (CFBG) are considered and analyzed for hydrogen production using actual data taken from the literature. Fossil energy consumption rate and Green House Gas Emissions (GHG) are defined and indicated first. Next the LCA results of DG and CFBG systems are compared for 1 MJ/s hydrogen production to compare with each other as well as with other hydrogen production systems. While the fossil energy consumption rate and emissions are calculated as 0.088 MJ/s and 6.27 CO2 eqv. g/s in the DG system they are 0.175 MJ/s and 17.13 CO2 eqv. g/s in the CFBG system respectively. The Coefficient of Hydrogen Production Performance (CHPP) (newly defined as a ratio of energy content of hydrogen produced from the system to the total energy content of fossil fuels used) of the CFBG and DG systems are then determined to be 5.71 and 11.36 respectively. Thus the effects of some parameters such as energy efficiency ratio of cost of hydrogen on natural gas and capital investments efficiency are investigated. Finally the costs of GHG emissions reduction are calculated to be 0.0172 and 0.24 $/g for the DG and CFBG systems respectively. © 2012 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. © 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 24
Citation - Scopus: 28
Performance assessment of hydrogen production from a solar-assisted biomass gasification system
(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Yildiz Kalinci; Arif Hepbasli; Ibrahim Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In this study we investigate a solar-assisted biomass gasification system for hydrogen production and assess its performance thermodynamically using actual literature data. We also analyze the entire system both energetically and exergetically and evaluate its performance through both energy and exergy efficiencies. Three feedstocks namely beech charcoal sewage sludge and fluff are considered as samples in the same reactor. While energy efficiencies vary from 14.14% to 27.29% exergy efficiencies change from 10.43% to 23.92%. We use a sustainability index (SI) as a function of exergy efficiency to calculate the impacts on sustainable development and environment. This index changes from 1.12 to 1.31 due to intensive utilization of solar energy. Also environmental impact of these systems is evaluated through calculating the specific greenhouse gas (GHG) emissions. They are determined to be 17.97 17.51 and 26.74 g CO2/MJ H-2 for beech charcoal sewage sludge and fluff respectively. Copyright (C) 2013 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
PERFORMANCE INVESTIGATION OF GEOTHERMAL DISTRICT HEATING SYSTEMS
(BEGELL HOUSE INC, 2012) Yildiz Kalinci; Ismail Tavman; Arif Hepbasli; Hepbasli, Arif; Kalinci, Yildiz; Tavman, Ismail
In this study we investigate the Dikili geothermal district heating system (GDHS) in Izmir Turkey. The system mainly consists of three cycles namely (i) the transportation network (ii) the Danistay region and (iii) the Bariskent region. While the Bariskent region contains 1100 residences equivalence the Danistay region is 2900 residences equivalence. The system is simulated using the PipeLab software to define problematic points first while some problems have been found out according to velocity and pressure drops in the Bariskent and Danistay regions. Next the problems have been solved by revising diameters of the lines. The system is then investigated from the view point of sustainability. Finally sustainability index (SI) values are considered as an environmental indicator and examined for main components of the system. The value is calculated to be 2.057 for the Dikili GDHS with an exegy efficiency value of 51.4%.
Citation - WoS: 296
Citation - Scopus: 321
Techno-economic analysis of a stand-alone hybrid renewable energy system with hydrogen production and storage options
(PERGAMON-ELSEVIER SCIENCE LTD, 2015) Yildiz Kalinci; Arif Hepbasli; Ibrahim Dincer; Hepbasli, Arif; Kalinci, Yildiz; Dincer, Ibrahim
In the present study a hybrid renewable energy system using hydrogen energy as energy storage option is conceptually modeled for the Bozcaada Island in Turkey. The system is investigated from the techno-economic point of view. The Hybrid Optimization Model for Electric Renewable (HOMER) tool is used to define the optimum size of the equipment based on the geographical and meteorological data of the island. The HOMER uses the net present cost (NPC) method while ranking the system suitability. Also the cost of energy (COE) is calculated with the total annual cost (ACT). The study considers two scenarios which are only wind turbine and wind turbine/PV hybrid systems. Using the wind turbine/PV array system instead of wind turbine only decreases the NPC from $14624343 to $11960698. Also it decreases the hydrogen tank capacity to 400 kg and hence affects other equipment size and NPC. So the COE varies between $1.016/kWh and $0.83/kWh. According to this the optimum system components are defined as PV array-300 kW wind turbine (E33x2) fuel cell-100 kW converter-150 kW electrolyzer-200 kW and hydrogen tank-400 kg to supply a 1875 kWh/d primary load. Furthermore the effects of some parameters and the equipment on NPC are examined. Increasing potential of the renewable energy sources such as annual average wind speed or solar radiation decreases both COE and NPC. While the annual average solar radiation increases to 5 kWh/m(2)/d the NPC and CUE decrease to $11673704 and $0.81/kWh. Likewise an increase in the annual average wind speed will decrease the costs to $11452712 and $0.795/kWh respectively. Also increasing the real interest i to 5% increases the COE to $1.043/kWh as expected. Copyright (c) 2014 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.