Renewable Energy Global Innovations features: Optimization of A Three-Bed Adsorption Chiller by Genetic Algorithms and Neural Networks

Significance Statement

Recovery of waste heat is one of the main techniques of improving maximum energy efficiency utilization of a variety of processes with low parameters of heat generated as by-product. The use of waste heat driven pumps is slowly overtaking the predominantly applied mechanical coolers. Increased attention is currently being paid to adsorption chillers since they can be powered with low-temperature heat sources and yet allow to be integrated into cogenerative systems. Adsorption cycles of the applied systems have a distinctive advantage over other systems in that they can use low grade waste heat of near ambient temperature. A Tri-bed twin-evaporator adsorption chiller comprise of a ground-breaking design in cooling production which allows more efficient conversion and management of low grade sources of thermal energy due to more effective way of utilization adsorptive abilities of the beds during a single work. Although it is the most effective way in chilled water production, the intricacy of the Tri-bed twin evaporator adsorption chiller operation is still not sufficiently recognized and the enhancement in cooling capacity of the cooler is still a puzzling task.

A team of researchers led by professor Jaroslaw Krzywanski at the Jan Dlugosz University in Poland optimized a three-bed adsorption chiller by applying genetic algorithms and neural networks. They introduced an artificial intelligence approach for the optimization study of the Tri-bed twin evaporator adsorption chiller using low-temperature heat from cogeneration. Their research work is now published in the peer-reviewed journal, Energy Conversion and Management.

The research team began by developing genetic algorithms and artificial neural networks. The developed algorithm and network were then tested and validated before they were used to develop the model. The researchers then used the developed model to estimate the behavior of the adsorption heat pump by assessing the effects of: the time cycle, cooling and heating inlet water temperatures and that of temperatures in low-high pressure evaporators. The team also examined the cooling capacity as one of the major energy efficiency factors in cooling production during the study for various scenarios.

The authors also observed that the highest value which could be obtained for the considered range of input operational parameters was equal to 93 kW. It was also noted that such a value was only attainable where specific: cycle time, cooling water temperature, heating water temperature, high pressure inlet temperature and low pressure inlet temperatures as specified in this paper were used.

Results of their study showed the cooling capacity evaluated using the model, is in good agreement with the experimental data. The maximum relative error between the measured and calculated results is lower than ±10%. Therefore, the developed model in Krzywanski  and colleagues is an easy to use and powerful optimization tool which allows to estimate the cooling capacity of the Tri-bed twin evaporator adsorption chiller, integrated into multi-generative systems.

The structure of the [5-2-2-1] type of neural network for optimization of a Tri-bed twin evaporator adsorption chiller

About The Author

Jaroslaw Krzywanski is an Associate Professor the head the Division of Advanced Computational Methods at the Faculty of Mathematics and Natural Science of Jan Dlugosz University in Czestochowa, Poland.

He received the M.Sc. degree from Czestochowa University of Technology, Department of Mechanical Engineering and Computer Sciences, Institute of Thermal Machinery, Poland and Ph.D. degree from Silesian University of Technology, Faculty of Energy and Environmental Engineering, Poland.

He has published more than 120 refereed works, including papers, a monograph, conference proceedings and serves as an editorial board member of several international journals. He has participated in the scientific committee of several conferences and serves as a reviewer in a wide range of international journals.

He is interested in modeling of energy devices and processes, including solid fuels combustion, waste driven adsorption chillers as well as gas emissions and hydrogen production from biomass combustion and gasification, respectively.

Reference

Krzywanski, K. Grabowska, F. Herman, P. Pyrka, M. Sosnowski, T. Prauzner, W. Nowak. Optimization of a three-bed adsorption chiller by genetic algorithms and neural networks. Energy Conversion and Management, volume 153 (2017) pages 313–322.

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Renewable Energy Global Innovations features: Feasibility of a clean CAES system coupled with wind and solar energy in China

Significance Statement

Energies are the important driving force for global social, economic and technological developments. Renewable energy sources, such as wind and solar power, have been discussed as renewable, sustainable and environmentally friendly forms of energies. However, it is a big challenge to utilize them stably. Compressed air energy storage (CAES) is a method of energy storage which can convert the surplus power to the internal energy of compressed air, and regenerates electricity whenever power is needed. This paper proposes a clean CAES system hybrid with wind and solar energy, which uses heat storage/heat exchange devices instead of combustion chamber of traditional CAES, uses the surplus energy of the wind power plant to provide power for compressed air storage, and uses solar energy to provide heat source for heat storage/heat exchange devices, so as to solve the dependence on fossil fuels of traditional CAES systems. The operating variables of the hybrid system include heat exchanger effectiveness, ambient temperature, mass flow rate, total pressure ratio and compressor/turbine stages. The effects of those on the system performances are evaluated, including output power, overall efficiency, energy ratio (ER) and heat ratio (HR). Additionally, the parameters, delineating criteria of the potential development localities for the hybrid CAES system sites, such as solar and wind energy resources, abandoned cavities of mines resources used as compressed air containers and the distribution of cross-transmission lines in China are investigated. We find that more than 13 major zones are of the capability to support the hybrid system in China. Finally, comparing to the conventional thermal power plants, the environmental and economic benefits of this CAES system are calculated.

This paper primarily presented a clean CAES system coupled with wind and solar energy in China and analyzed the technical feasibility, potentially suitable areas, environmental and economic benefits of the system.

About The Author

Jie Chen, associate professor at Chongqing University, Chongqing, PR China. In 2012, he received his Ph.D. degree in College of Resource and Environmental Science from Chongqing University, Chongqing, China. In 2013, he stated Postdoctoral researsh at State Key Laboratory of Rock and Soil Mechanics and Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China.

He has accomplished several significant projects from National Science Foundation (NSF) and China Postdoctoral Science Foundation. His research areas include rock mechanics, damage and self-healing of rock materials, and underground energy storage. He has published more than 60 papers and served as a reviewer for many prestigious journals. (jiechen023@cqu.edu.cn)

About The Author

Deyi Jiang, professor at Chongqing University, Chongqing, PR China. He was born on June 13, 1962, in Sichuan, PR China. He finished his studies at Chongqing University in 1985 and obtained his Ph.D. degree in 2001, in China. He is now the Dean of College of Resources and Environmental Science, Chongqing University. Also, He is the Executive Deputy Director of State Key Laboratory of Coal Mine Disaster and Control from 2011 to present.

His research areas include rock mechanics, solution mining disasters control and salt cavern comprehensive utilization. He has published more than 100 articles in international periodicals, many of which in high-ranking journals, and held more than 30 lectures worldwide. Under his guidance, more than 60 master theses and the same number of Ph.D. dissertations have been done.

About The Author

Wei Liu, lecturer and researcher at Chongqing University, Chongqing, PR China. In 2015, he had received his Ph.D. degree in University of Chinese Academy of Sciences, Wuhan, China. Thereafter, he stated Postdoctoral researsh at College of Resource and Environmental Science in Chongqing University, Chongqing, China. He is now taking charge of several funds supported by the National Science Foundation (NSF) and China Postdoctoral Science Foundation.

His research areas include rock mechanics, permeability and damage of low permeable rock materials and energy storage technologies. He has published more than 40 papers and served as a reviewer for many international journals, such as Energy, Applied Thermal Engineering, and Environmental Earth Sciences.

Journal Reference

Jie Chen ^{a, b}, Wei Liu ^{a, b, *}, Deyi Jiang ^{a, b}, Junwei Zhang ^{a, b}, Song Ren ^{a, b}, Lin Li ^{a, b}, Xiaokang Li ^{a, b}, Xilin Shi ^c. Preliminary investigation on the feasibility of a clean CAES system coupled with wind and solar energy in China. Energy, Volume 127, 15 May 2017, Pages 462-478.

Show Affiliations

^a State Key Laboratory of Coal Mine Disaster and Control, Chongqing University, Chongqing 400044, China.

^b College of Resources and Environmental Sciences, Chongqing University, Chongqing 400044, China

^c State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, The Chinese Academy of Science, Wuhan, Hubei, 430071, China.

 

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Renewable Energy Global Innovations features: Steam Reforming of n-dodecane over K2Ti2O5-added Ni-Alumina and Ni-Zirconia (YSZ) catalysts

Significance Statement

Diesel is known to contain high presence of hydrogen, which makes them a favorite source for catalytic conversion process of fuel. Hydrogen, which provides clean energy to the environment, is often produced through the catalytic conversion form of steam reforming process due to its high optimality and selectivity towards hydrogen.

The catalyst majorly used in a catalytic conversion of fuels to hydrogen in the steam reforming process, is nickel-based with other supporting materials such as alumina and yttrium-stabilized zirconia. However, deposition of carbon on catalyst during the steam reforming process limits the efficiency of the nickel supported catalyst. This as a result led to the introduction of second catalytic material such as K₂Ti₂O₅ which has high thermal stability and ability to oxidize the carbon deposits at the same time.

Researchers led by Professor Jong Shik Chung from Pohang University of Science and Technology in Republic of Korea investigated the addition of  K₂Ti₂O₅ particles on nickel supported on alumina Ni-Al₂O₃ and yttrium-stabilized zirconia Ni-YSZ catalyst in the steam reforming reaction of n-dodecane. The research work is now published in peer-reviewed journal, International Journal of Hydrogen Energy.

The authors investigated the performance of the added K₂Ti₂O₅ on nickel-based supported catalyst with the use of Brunauer-Emmett-Teller analysis, x-ray diffraction, thermogravimetric analysis, transmission electron microscopy and electron energy loss spectrometer coupled with their total selectivity towards hydrogen, carbon monoxide, carbon dioxide and methane.

At gas hourly space velocity of 15000h^-1, the yttrium-stabilized zirconia supports on the nickel catalyst possessed more selectivity towards hydrogen and other gases compared to other alumina supported catalyst. However, the addition of K₂Ti₂O₅ particles on the nickel supports on yttrium-stabilized zirconia catalyst maintained the conversion process without a decrease in its activities compared to others.

The decreased activity of K₂Ti₂O₅ particles on the nickel supported on alumina catalyst was due to the low contact between the nickel particles and K₂Ti₂O₅ phase as a result of the hindered presence of nickel particles in the alumina pores. This was a different case for that of yttrium-stabilized zirconia catalyst as nickel particles were found in the zirconia supports, aiding good contact.

At high gas hourly space velocity below 20000h^-1, the addition of K₂Ti₂O₅ particles on the nickel-supported yttrium-stabilized zirconia catalyst maintained good stability due to the oxidation of deposited carbon on the surface of the catalyst.  The addition of K₂Ti₂O₅ particles on the nickel-supported yttrium-stabilized zirconia catalyst also aided the non-existence of hard carbons except at gas hourly space velocity of 30000h^-1.

Results from transmission electron microscopy and electron energy loss spectroscopy the authors indicated that both the present and absent K₂Ti₂O₅ particles on the nickel-based yttrium-stabilized zirconia catalyst were effective in selectivity of hydrogen at a gas hourly space velocity of 5000h^-1. The absence and presence of K₂Ti₂O₅ particles on the nickel-based yttrium-stabilized zirconia catalyst deactivates at gas hourly space velocity of 5000h^-1 and 20000h^-1 respectively.

This study was able to provide an absolute range of effectiveness of the added K₂Ti₂O₅ on yttrium-stabilized zirconia catalyst for the steam reforming process of n-dodecane.    

About The Author

Dr. Taewook Kim is a postdoctoral and assistant researcher in the Department of Chemical Engineering at Pohang University of Science and Technology (POSTECH), Korea. He received Ph.D. degree at the same university (POSTECH) in 2017. His research areas are Reforming Catalysts of Hydrocarbon and Solid Oxide Fuel Cells.

About The Author

Dr. Jong-Shik Chung is a professor in the Department of Chemical Engineering and a head of Institute of New and Renewable Energy at Pohang University of Science and Technology (POSTECH), Korea. His research areas are Solid Oxide Fuel Cells (Materials, Stacks, and System), Reforming Catalysts and Reformers, Desulfurization, and Waste water treatments.

Journal Reference

Kim, T., Song, K.H., Yoon, H., Chung, J.S. Steam Reforming of n-dodecane over K₂Ti₂O₅-added Ni-alumina and Ni-zirconia (YSZ) Catalysts, International Journal of Hydrogen Energy 41 (2016) 17922-17932.

Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 37673, Republic of Korea.

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