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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.