ABSTRACT
The enrichment of conventional fuels by hydrogen is quite popular owing to positive environmental aspects compared to the main fuel. In most of the studies, the entropy analysis was not examined in detail. In this research, exergy (second law) analysis of hydrogen-enriched methane, natural gas, propane, LPG, and biogas were analyzed using the numerical model in a premixed burner due to their wide usage in the industry as well as in the household appliances. In the numerical model, the discrete ordinates radiation and Realizable k- ε turbulence models were coupled with the premixed combustion model. The rate of increase for hydrogen of each fuel is considered as 10%. The premixed burner exhibited better performance in terms of energy and exergy with the rise of hydrogen enrichment. The most improvement was observed at biogas tests. The results showed that the chemical composition of the base fuel is a significant parameter that affects the exergy and energy capability of the burner due to chain reactions of radicals in the base fuel with hydrogen. It can be concluded that the hydrogen enrichment of biogas in premixed burners is promising in comparison with other tested fuels from both energy and exergy perspective.
Disclosure statement
The authors declare no competing conflicts of interest.
Nomenclature
Ċc | = | = cost per exergy product ($/kW.h) |
Ċf | = | = unit cost of input fuel ($/kW.h) |
Cinv | = | = investment cost ($/h) |
Ėd | = | = exergy destruction rate (kW) |
Ėxch | = | = chemical exergy (kW) |
HHV | = | = higher heating value (MJ/kg) |
LHV | = | = lower heating value (MJ/kg) |
LBV | = | = laminar burning velocity (m/s) |
= | = heat transfer (kW) | |
Ru | = | = universal gas constant (J/(mol.K)) |
T | = | = temperature (K) |
a | = | = molar amount (mole) |
= | = specific flow exergy rate (kJ/kmol) | |
= | = specific enthalpy (kJ/kmol) | |
= | = mass flow rate (kg/s) | |
= | = molar flow rate (kmol/s) | |
= | = specific entropy (kW/(K.kg)) | |
Greek | = | |
ηI | = | = energy efficiency (-) |
ηII | = | = exergy efficiency (-) |
Subscripts | = | |
ch | = | = chemical |
exh | = | = exhaust |
ht | = | = heat transfer |
i | = | = inlet, ith component |
j | = | = jth component |
loss | = | = loss |
net | = | = net |
o | = | = outlet, reference state |
pot | = | = pot |
tm | = | = thermo-mechanical |
Additional information
Notes on contributors
Mehmed Rafet Özdemir
Mehmed Rafet Ozdemir graduated from the Mechanical Engineering Department, Faculty of Engineering, Marmara University, Turkey. He was employed as a research assistant in the same department since 2009. He obtained his master’s degree from Sabancı University in the field of two-phase heat transfer and fluid flow in microtubes in 2010. He got his PhD in 2016 in single-phase flow and flow boiling of water in rectangular metallic microchannels. Currently, he is an assistant professor in the Mechanical Engineering Department, Faculty of Engineering, Marmara University, Turkey. His research interests include micro/nanoscale heat transfer, boiling heat transfer, microfluidic systems, phase change materials, heat transfer improvements and exergetic analysis of various systems.
Murat Umut Yangaz
Murat Umut Yangaz graduated in 2012 from Mechanical Engineering Department, Faculty of Engineering, Uludag University. After working as an engineer in the automotive industry for a brief period, he started his graduate education at Marmara University for his Master’s Degree in Mechanical Engineering in 2013 and graduated in 2014. During this period, he was employed at Sakarya University as a research assistant. After graduation, he began to work at Marmara University, where he is currently doing his PhD in Mechanical Engineering. He also holds a Master’s Degree in Chemical Engineering.
Ilker Turgut Yilmaz
Ilker Turgut Yilmaz was graduated from the Automotive Teacher Education Department, Faculty of Technical Education, Pamukkale University, in 2006. He got his Master's degree in the field of Mechanical Education in 2008. He worked as a lecturer in the Automotive Technologies Programme, Luleburgaz Vocational School of Higher Education, Kirklareli University between the years of 2009-2011. He received his PhD from Marmara University in 2015 and has been working as an assistant professor since 2018 in the Department of Mechanical Engineering, Faculty of Technology, Marmara University. His main research areas include dual-fuel engines, alternative gaseous fuels, emission control, combustion analysis.