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This paper comparatively discusses hydrogen production options through coal gasification, including plasma methods, and evaluate them for practical applications. In this regard, it focuses on numerous aspects of hydrogen production from coal gasification, including (i) state of the art and comparative evaluation, (ii) environmental and economic dimensions, (iii) energetic and exergetic aspects, (iv) challenges, opportunities and future directions. Furthermore, this review paper outlines what differences it brings in and what contributions it makes to the current literature about such a significant domain of potential hydrogen production which can be used as clean fuel, energy carrier and feedstock. Accordingly, this comprehensive review offers some results as follows: (i) plasma gasification system produces higher amount of hydrogen from other gasification processes, (ii) less amounts of solid wastes (slag, ash, tar, etc.) are released during plasma gasification process compared to other gasification processes, and (iii) it is overall more sustainable Thus, plasma gasification is proposed as a potential option for hydrogen fuel production from coals and for practical application in energy sector. As a case study, some plasma gasifiers in the literature are analyzed in terms of the exergetic sustainability. Furthermore, the case study results show that the exergetic sustainability index decreases from 0.642 to 0.186, and the exergetic efficiency drops from 0.342 to 0.156, while the environmental impact factor increases from 1.556 to 5.372 with an increase of waste exergy ratio from 0.839 to 0.532, respectively.

The main objective of this research paper is to perform a parametric comparison of gas flow (air and hydrogen) through a curved channel in terms of thermodynamic based environmental and sustainability analysis. For this analysis, the following sustainability indicators which are i) exergetic efficiency (ee), ii) waste exergy ratio (wer), iii) environmental effect factor (eef) and iv) exergetic sustainability index (esi) are defined and estimated in terms of the channel aspect ratio (AR), Dean Number (De) and reference temperature (T0). Consequently, it is found that ee and esi rise with the increment of De and AR of the curved channel and with the decrease of T0. However, wer and eef show the opposite behavior. As an important conclusion, air flow through the channel is found to be more exergetic than that of hydrogen under the boundary conditions assumed for the problem. The ee and esi increases with the rise of De while rising with the decrement of T0. For air, maximum ee and esi values are obtained to be 99.9% and 751.69 incase De is 207.1 and T0 is 243 K. Adding that, for hydrogen, the maximum ee and esi values have been estimated to be 99.8% and 710.5 while De is 202.3 and T0 is 243 K. The ee and esi increase with the rise of AR. For air, the maximum ee and esi values are found to be 97.9% and 45.8 while De is equal to 207.1 and AR is 5.5. Also, for hydrogen, the maximum ee and esi values have been calculated to be 97.5% and 38.6 while De is 202.3 and AR is 5.5.

The main objective of this study is to parametrically compare the exergetic performance of air and hydrogen gas flow through the curved annular duct. For this purpose, it is assumed that, i) air and hydrogen are considered to be ideal gas, ii) the flow of these gases is steady state and laminar fully developed, ii) these gases have constant physical properties, iii) the channel inner and outer walls are exposed to constant wall boundary condition. Moreover, the following important parameters are taken into consideration: i) aspect ratio (four different values which are 5.50, 3.80, 2.90 and 2.36), ii) environment temperature (ranging from −30 to 30 with 10 °C intervals), iii) Dean number (varying between 24 and 208), and iv) operating pressure (=1 atm). Considering these parameters, exergy destruction and exergy efficiencies are calculated for each aspect ratio. Consequently, exergetic efficiency rises with the increase of Dean number, inner wall temperature, aspect ratio and the decrease of dead state temperature. Also, it is noticed that the gas specie highly affects the volumetric entropy generation rate, exergy destruction rate and exergy efficiency.

In this study, a vertical ground source heat pump wall heating system belonging to the Yildiz Renewable Energy House on the Davutpasa Campus of Yildiz Technical University was experimentally and theoretically studied. The examination included energy, exergy, exergoenvironmental and exergoeconomic analyses from 1 January 2013 to 30 March 2013 (i.e., the “Winter Session”). Data were collected and uploaded to a MySQL database. “The moments when the heat pump is activated” was detected and “Monthly Average Values” were analysed. Theoretical analyses were conducted for the Winter Session and correlated with the experimental results. This study includes exergetically, exergoeconomically, and exergoenvironmental evaluate a building and its heating system from the generation stage to the envelope of the building. The findings are based on applying a low exergy, exergoenvironmental and exergoeconomic analysis to investigate the system performance. The energy and exergy efficiencies of the entire system were 67.36% and 27.40%, respectively, and the energy and exergy efficiencies of the wall heating system panels were 86.61% and 82.90%, respectively. The monthly average exergy-based environmental impact value was 0.212 mPts/s. The exergoeconomic factors changed from 74.97% to 75.77%.

In this study, exergoenvironmental, and exergoeconomic analyses of wall cooling systems fed by a vertical type of ground source heat pump integrated wall cooling system for cooling were examined experimentally and theoretically in Yildiz Renewable Energy House at Davutpasa Campus of Yildiz Technical University. The examination includes energy, exergy, exergoenvironmental and exergoeconomic analyses, between the dates of 1 July and 30 September 2013. The main aim of this objective is to minimize energy usage in Residential Sector as low as possible. Therefore, a particular system working with low temperature regime was chosen. According to the outcomes; energy and exergy efficiency of all the system have been found as 74.85% and 29.90%. Part-based environmental factor values are calculated. The compressor and underground heat exchanger have the highest values calculated as 0.040 mPts/s, 0.026 mPts/s respectively. The exergoenvironmental impact values of all system are detected as 42.60%. On the other hand; the exergoeconomic factor values of all system are calculated as 77.68%. The value of exergoeconomic factor changes depending on some particular components: accumulator tank, undersoil heat exchanger, evaporator and condenser calculated respectively as 69.43%, 62.59%, 62.53% and 29.15%. As a result; it is found that in order to determine economic and environmental impacts of irreversibilities occurring in the system and its components, economic and environmental analyses of thermal system as well as wall cooling systems, should be done based on exergy concept.

In this study, a vertical ground source heat pump wall cooling system that belongs to the Yildiz Renewable Energy House at the Davutpasa Campus of Yildiz Technical University was studied both experimentally and theoretically. The principal objective was to perform a system analysis to determine the parameters that allow the energy usage of the cooling system to be as low as possible. For this reason, a system working in a low temperature regime was chosen. The examination includes energy and exergy analyses conducted during the period between 1 July and 30 September 2012, which is described as the “Summer Session”. By using the data that were collected on a per-second basis during these processes and conveyed to a MySQL database, “The moments when the heat pump is activated” were detected, and the “Monthly Average Values” were analyzed. Thus, a theoretical analysis was conducted for the Cooling Session and its correlations. These correlations were used in the energy and exergy analyses. According to the analysis results, the energy and exergy efficiencies of the entire system were found to be 74.85% and 29.90%, respectively, and the Wall Heating Cooling System panels calculated the heat with energy and exergy efficiencies of 90.29% and 80.4%, respectively.

To explore the opinions and the level of awareness of university students on renewable energy and environment issues in the fields of engineering and economics/business in Canada, Romania, and Turkey, surveys were conducted in several universities in these three countries. The survey results that are presented and discussed here indicate that while there are differences between the three groups, they are small and can be explained by cultural and socioeconomic factors. A larger study with an expanded survey questionnaire applied to a wider spectrum of groups in a larger set of countries would be useful to identify differences and educational needs. Government of Canada -- The authors gratefully acknowledge the help of Drs. M. Cross, A. S. Fung, D. Hansen, T. Hubbard, J. Gonzalez-Cueto in Canada; Drs. S. Dascalescu, I. Mihu, A. Nita, in Romania; and E., Aytore, M. Kaya, G. Atli, O. Kapucu in Turkey in the administration of the surveys. Special thanks are due for Mr. Huseyin Bas of Zeta for processing part of the questionnaires. V. I. Ugursal is grateful to the Government of Canada for the Research Grant in Lieu of Salary. --

In this study, effect of viscous dissipation on entropy generation for fully developed incompressible laminar flow mixed convection in vertical parallel-plate channels with asymmetric and symmetric uniform heat fluxes was parametrically analysed. Analytical equations were derived by using continuum approach and perturbation method. A specific MATLAB code was created to solve the governing equations. The effects of Gr/Re, the Brinkman number, and the ratio of wall heat flux on the entropy generation are presented and discussed. It is concluded that viscous dissipation has a significant effect on the entropy generation for mixed convection in heated vertical parallel-plate channels. Entropy generation resulting from fluid friction goes up, however, entropy generation due to heat transfer decreases by increasing of viscous dissipation. Consequently, it can be said that, this study will contribute to literature in optimising the systems that operates under mixed convection conditions in the vertical parallel-plate configuration.

This paper presents a parametric study on the exergetic performance assessment of an electrolyte supported solid oxide fuel cell (SOFC) stack. Considering the operating and design parameters of yttria stabilised zirconia (YSZ) electrolyte supported SOFC stack, the variations of overpotentials, the rational overpotentials and the exergetic efficiencies are investigated for comparison purposes. Consequently, considering the selected operating conditions and design parameters, it is suggested that the YSZ electrolyte supported SOFC stack having higher exergetic efficiency than 30% is used. Moreover, in order to operate such a fuel cell in an exergetically more efficient manner, the minimum YSZ electrolyte thickness needs to be thicker than 150 μm. Otherwise, some durability and manufacture problems may occur. However, a decrease of operating temperatures from 1273 K to 1073 K and an increase of YSZ electrolyte thickness from 150 μm to 500 μm will result in a reduced exergetic efficiency.

In recent years, sustainable energy and green buildings are developed as important issues. Many helpful systems were developed to profit from advantages of different renewable energy sources. However, the research on disadvantages of sustainable energy systems is very rare and papers focus on only economic issues. In this paper, an innovative building integrated wind, solar, and rainwater harvester (WSRH) system was analyzed by nonlinear static pushover (NSP) analysis. The results are compared in terms of energy performance and its effects on the structural system.

The present study deals with an exergetic analysis and assessment of a Vertical Ground-Source Heat Pump System (VGSHP) combined with a Wall Heating System (WHCS) in a building. This study is an experimental investigation of a real building’s heating system. The system is located at Yildiz Renewable Energy House (YREH) in Yildiz Technical University and fulfills the heating demand of YREH and a living room of the neighboring dormitory. In order to validate an exergetic model, the system is divided into three subsystems: (1) the ground coupling circuit, (2) the refrigerant circuit, and (3) the WHS circuit. The schematic diagram of the constructed experimental system is given in Fig. 26.1. Exergetic model is obtained by applying mass, energy, and exergy equations for each system component. YREH has four rooms, each has 8 m2 floor area, and the neighboring dormitory has a 50 m2 living room. In this study three rooms of YREH and the living room have been heated during heating season. The heating season was assumed to be between 1 January and 31 March. As average results on the heating season, 6.509 kW heat energy was extracted from ground and 5.799 kW was used in the WHS. In this process electrical energy consumption of system components are as follows: compressor 1.711 kW, ground heat exchanger pump 0.092 kW, accumulator tank circulation pump 0.114 kW, and WHS circulation pump 0.108 kW. For heating season, calculated overall system efficiency was 67.36 % while GSHP unit’s efficiency was 85 %. In addition, overall system COP was 2.76, while GSHP unit’s COP was 4.13. Total exergy destruction was found 1.759 kW and largest exergy destruction has occurred in the compressor as 0.714 kW. The exergy efficiency values for the individual components of the system have been found ranging from 58.3 to 98.4 % according to P/F concept. It is expected that the model would be beneficial for evaluating low exergy heating systems which use ground source as a renewable energy.

The main objective of this study is to numerically investigate the entropy generation of both hydrodynamically and thermally fully developed laminar flow of hydrogen gas under various operating pressures and temperatures in the concentric curved annular ducts with rectangular cross section. In this regard, the solutions of discretized continuity, momentum and energy equations have been obtained using elliptic Fortran Program based on the SIMPLE algorithm. The solutions have been achieved for (1) Dean numbers ranging from 2.3 to 202.9, (2) Annulus dimension ratios of 5.5, (3) Operating pressures of 0.101325, 1, 10, 40, 70 and 100 MPa, (4) Core wall temperature of 50 and 80 °C, (5) Duct wall temperature of 25 °C. In this regard, overall entropy generation in the whole flow field has been analyzed in detail. Moreover, the effects of Dean number, operating pressure and core wall temperature on entropy generation arising from the flow and heat transfer have been investigated. Accordingly, it is concluded that the effect of volumetric entropy generation that is a result of fluid flow can be neglected as compared with volumetric entropy generation due to heat transfer. When Dean number, operating pressure and core wall temperature increase the total volumetric entropy generation goes up. Thus, it is expected that this study will contribute to develop the energy efficient-hydrogen gas heaters for practical applications including hydrogen exchangers, PEMFC applications, hydrogen gas turbines, chemical mixing processes and hydrogen gas dryers in hydrogen industry.

Extensive studies on ground-source heat pump systems' performance have been published in the literature. Coefficient of performance (COP) on heating and cooling modes significantly influences thermal energy economics for these systems. This study is an experimental investigation of a real building's heating and cooling system. Heating and cooling season analysis of a vertical ground-source heat pump (VGSHP) system with wall heating and cooling (WHC) is investigated. WHC systems are equipped with heating coils mounted on the walls, through which water is circulated. The system used is located in Yildiz Renewable Energy House (YREH) at Yildiz Technical University and fulfills the heating and cooling demands of both YREH and a living room in a neighboring dormitory. System parameters were recorded every second during the year 2010. For heating season, calculated overall system efficiency was 67.36%, while the GSHP unit's efficiency was 85%. In addition, overall system COP was 2.76, while the ground-source heat pump (GSHP) unit's COP was 4.13. As for the cooling season, calculated system efficiency was 74.90%, while the GSHP unit's efficiency was 80.76%. Furthermore, overall system COP was 4.38 while the GSHP unit's COP was 4.78. The heat extraction rate was 50 and the heat rejection rate 54 W/m of bore depth for the heating and cooling periods, respectively, which corresponds to the range already reported in the literature

In this study, technical and economic performance analyses are conducted in order to determine the optimum collector surface area for indoor swimming pools. Required heat and economical conditions are taken into consideration while performing these evaluations. A brief summary of solar energy source and heat transfer equations for the Olympic pools are given. An Olympic swimming pool is assumed to be in different cities, and energy losses are calculated. For our sample Olympic pool, convective heat loss obtained is −3.86 kW and evaporative heat loss obtained is 265 kW. Total heat loss always maximum in January from 384 kW to 455.1 kW. Solar energy gain (assumption 1000 m2 collector area) and energy gain from boiler for different cities are calculated as maximum solar energy gain in July between 160 and 175 kW and minimum in January between 54.9 and 82 kW. High investment costs for solar power systems are responsible for low value of the reduction rate. Also, according to the energy demand and economical conditions, technical evaluations are performed in order to obtain optimum surface collector area, and economical analyses are conducted using unified cost method.