Thermo-Economic Analysis on Integrated CO 2, Organic Rankine Cycles, and NaClO Plant Using Liquefied Natural Gas

The thermal energy conversion of natural gas (NG) using appropriate configuration cycles represents one of the best nonrenewable energy resources because of its high heating value and low environmental effects. The natural gas can be converted to liquefied natural gas (LNG), via the liquefaction process, which is used as a heat source and sink in various multigeneration cycles. In this paper, a new configuration cycle is proposed using LNG as a heat source and heat sink. This new proposed cycle includes the CO2 cycle, the organic Rankine cycle (ORC), a heater, a cooler, an NaClO plant, and reverse osmosis. This cycle generates electrical power, heating and cooling energy, potable water (PW), hydrogen, and salt all at the same time. For this purpose, one computer program is provided in an engineering equation solver for energy, exergy, and thermo-economic analyses. The results for each subsystem are validated by previous researches in this field. This system produces 10.53 GWh electrical energy, 276.4 GWh cooling energy, 1783 GWh heating energy, 17,280 m3 potable water, 739.56 tons of hydrogen, and 383.78 tons of salt in a year. The proposed system energy efficiency is 54.3%, while the exergy efficiency is equal to 13.1%. The economic evaluation showed that the payback period, the simple payback period, the net present value, and internal rate of return are equal to 7.9 years, 6.9 years, 908.9 million USD, and 0.138, respectively

Compressed Air Energy Storage—An Overview of Research Trends and Gaps through a Bibliometric Analysis

Electrical energy storage systems have a fundamental role in the energy transition process supporting the penetration of renewable energy sources into the energy mix. Compressed air energy storage (CAES) is a promising energy storage technology, mainly proposed for large-scale applications, that uses compressed air as an energy vector. Although the first document in literature on CAES appeared in 1976 and the first commercial plant was installed in 1978, this technology started to gain attention only in the decade 2000–2010, with remarkable scientific production output and the realization of other pre-commercial demonstrators and commercial plants. This study applies bibliometric techniques to draw a picture of the current status of the scientific progress and analyze the trend of the research on CAES and identify research gaps that can support researchers and manufacturers involved in this entering technology. Recent trends of research include aspects related to the off-design, the development of thermal energy storage for adiabatic CAES, and the integration of CAES with combined heating and cooling systems

Numerical Design of a 3-Stage Cascaded Thermal Energy Storage System for Solar Application

The analysis of a three-stage cascaded thermal energy storage is presented in this dissertation. Cascaded thermal energy storage systems has many advantages over conventional thermal energy storages, majorly it allows for maintaining of a nigh-constant temperature between the HTF and PCM during the charging and discharging cycles leading to improved performance of the system. This dissertation investigates the performance and transient response of a packed bed operating under high-temperature conditions with phase change materials in varying encapsulations (cascaded in a three-stage format) during charging and discharging cycle by employing computational numerical techniques via commercially available ANSYS Fluent software. The analysis was performed for nine different encapsulation geometries with increased surface area and constant volume in comparison to the base geometry (sphere) to determine the effects of each new encapsulation on the performance of the thermal energy storage (TES). The computational model used in the development of this work compares well with the experimental results by Raul [1]. Additionally, the effect of packing scheme/PCM layout is also investigated in this work. Comparative data analysis was performed on the TES with the various PCM encapsulation designs and the standard spherical PCM encapsulation to determine which geometry provides better performance during charging and discharging cycles. The results of this study show that the thermal performance of the cascaded thermal energy storage improves with each new encapsulation as evidenced by the decreases in charging and discharging times in comparison to the base encapsulation. This study also highlights which capsule design is most practical when considering the bed dimension increases/ decreases with in increasing thermal performance. This study's findings can serve as a benchmark for future optimization of cascaded thermal energy storage systems

The Optimization of Combined Power-Power Generation Cycles

An investigation into the performance of several combined gas-steam power generating plants’ cycles was undertaken at the School of Engineering and Technology at the University of Hertfordshire and it is predominantly analytical in nature. The investigation covered in principle the aspect of the fundamentals and the performance parameters of the following cycles: gas turbine, steam turbine, ammonia-water, partial oxidation and the absorption chiller. Complete thermal analysis of the individual cycles was undertaken initially. Subsequently, these were linked to generate a comprehensive computer model which was employed to predict the performance and characteristics of the optimized combination. The developed model was run using various input parameters to test the performance of the cycle’s combination with respect to the combined cycle’s efficiency, power output, specific fuel consumption and the temperature of the stack gases. In addition, the impact of the optimized cycles on the generation of CO2 and NOX was also investigated. This research goes over the thermal power stations of which most of the world electrical energy is currently generated by. Through which, to meet the increase in the electricity consumption and the environmental pollution associated with its production as well as the limitation of the natural hydrocarbon resources necessitated. By making use of the progressive increase of high temperature gases in recent decades, the advent of high temperature material and the use of large compression ratios and generating electricity from high temperature of gas turbine discharge, which is otherwise lost to the environment, a better electrical power is generated by such plant, which depends on a variety of influencing factors. This thesis deals with an investigation undertaken to optimize the performance of the combined Brayton-Rankine power cycles' performance. This work includes a comprehensive review of the previous work reported in the literature on the combined cycles is presented. An evaluation of the performance of combined cycle power plant and its enhancements is detailed to provide: A full understanding of the operational behaviour of the combined power plants, and demonstration of the relevance between power generations and environmental impact. A basic analytical model was constructed for the combined gas (Brayton) and the steam (Rankine) and used in a parametric study to reveal the optimization parameters, and its results were discussed. The role of the parameters of each cycle on the overall performance of the combined power cycle is revealed by assessing the effect of the operating parameters in each individual cycle on the performance of the CCPP. P impacts on the environment were assessed through changes in the fuel consumption and the temperature of stack gases. A comprehensive and detailed analytical model was created for the operation of hypothetical combined cycle power and power plant. Details of the operation of each component in the cycle was modelled and integrated in the overall all combined cycle/plant operation. The cycle/plant simulation and matching as well as the modelling results and their analysis were presented. Two advanced configurations of gas turbine cycle for the combined cycle power plants are selected, investigated, modelled and optimized as a part of combined cycle power plant. Both configurations work on fuel rich combustion, therefore, the combustor model for rich fuel atmosphere was established. Additionally, models were created for the other components of the turbine which work on the same gases. Another model was created for the components of two configurations of ammonia water mixture (kalina) cycle. As integrated to the combined cycle power plant, the optimization strategy considered for these configurations is for them to be powered by the exhaust gases from either the gas turbine or the gases leaving the Rankine boiler (HRSG). This included ChGT regarding its performance and its environmental characteristics. The previously considered combined configuration is integrated by as single and double effect configurations of an ammonia water absorption cooling system (AWACS) for compressor inlet air cooling. Both were investigated and designed for optimizing the triple combination power cycle described above. During this research, tens of functions were constructed using VBA to look up tables linked to either estimating fluids' thermodynamic properties, or to determine a number of parameters regarding the performance of several components. New and very interesting results were obtained, which show the impact of the input parameters of the individual cycles on the performance parameters of a certain combined plant’s cycle. The optimized parameters are of a great practical influence on the application and running condition of the real combined plants. Such influence manifested itself in higher rate of heat recovery, higher combined plant thermal efficiency from those of the individual plants, less harmful emission, better fuel economy and higher power output. Lastly, it could be claimed that various concluding remarks drawn from the current study could help to improve the understanding of the behaviour of the combined cycle and help power plant designers to reduce the time, effort and cost of prototyping

Thermodynamic Cycles for Low- and High-Temperature Waste Heat Recovery from Heavy-Duty Engines

To reduce the environmental impact of heavy-duty vehicles, it is critical to reduce their CO2 emissions by improving the engine efficiency. A promising way to do this is by extracting waste heat from the engine during operation and converting it into useful work. This thesis presents a comprehensive evaluation of the performance of thermodynamic cycles for waste heat recovery from heavy-duty engines. First, by identifying the combination(s) of heat source, working fluid, and thermodynamic cycle that maximizes the performance. Then, by evaluating the performance of the most promising solutions using experimental investigations and detailed simulations. The potential for waste heat recovery was investigated with steady-state simulations considering two low-temperature and two high-temperature heat sources, a wide variety of working fluids, and four thermodynamic cycles: the organic Rankine cycle (ORC), the transcritical Rankine cycle, the trilateral flash cycle, and the organic flash cycle. The best overall performance was obtained with the ORC using acetone, benzene, cyclopentane, ethanol, or methanol as the working fluid, or with R1233zd(E), MM, or Novec649 if a non-flammable and non-toxic fluid was preferred. The engine coolant was the best performing low-temperature heat source, recovering 1.5 % of the engine power, and the exhaust gas was the best performing high-temperature heat source, recovering up to 5 %. By combining multiple heat sources in series, almost 8 % was recovered. Using a dual-loop system with the engine coolant and exhaust gas as the heat source, fuel consumption was reduced by over 5 %, rising to 9 % if the engine coolant temperature was increased to 140 C. Two test setups were constructed to experimentally investigate the performance of the simulated systems. The high-temperature setup consisted of a Rankine cycle with water using the exhaust gases as the heat source while the low-temperature setup recovered heat from the engine coolant using an ORC with R1233zd(E) as the working fluid. Based on the experimental findings, models of both setups were developed to predict their performance over a driving cycle. The low-temperature system was able to recover 0.73 % of the total energy required by the engine, while the high-temperature system could recover 3.37 %

Small-Scale CCHP Systems for Waste Heat Recovery from Cement Plants: Thermodynamic, Sustainability and Economic Implications

In this paper, different combined cooling, heating and power (CCHP) systems are introduced and studied for waste heat recovery from a cement plant located in Şanliurfa, Turkey considering domestic applications. One of the systems is based on the steam Rankine cycle and the next is based on recuperative organic Rankine cycle (ORC), while both of them are equipped with a LiBr–H2O absorption chiller to produce cooling. Different working fluids are considered in the ORC simulation. Energy, exergy and exergoeconomic principles are applied to compare the examined systems from thermodynamic, sustainability and economic aspects. It is observed that utilizing siloxanes as the working fluid leads to efficient performance of the ORC. Besides, employed heat recovery steam generator in the Rankine cycle and evaporator in the ORC found to be the most exergy destructive components. Results revealed that the CCHP system operating with ORC (MM as working fluid) has a better performance thermodynamically with energy utilization factor, exergy efficiency and sustainability index of 98.07, 63.6% and 2.747, respectively. This is while, Rankine-based CCHP is economically preferable with a payback period of 4.738 year compared to the system operating with ORC and a payback period of 5.074 year

Power Generation with Renewable Energy and Advanced Supercritical CO2 Thermodynamic Power Cycles: A Review

Supercritical CO2 (S-CO2) thermodynamic power cycles have been considerably investigated in the applications of fossil fuel and nuclear power generation systems, considering their superior characteristics such as compactness, sustainability, cost-effectiveness, environmentally friendly working fluid, and high thermal efficiency. They can be potentially integrated and applied with various renewable energy systems for low-carbon power generation such that extensive studies in these areas have also been conducted substantially. However, there is a shortage of reviews that specifically concentrate on the integrations of S-CO2 with renewable energy encompassing biomass, solar, geothermal, and waste heat. It is thus necessary to provide an update and overview of the development of S-CO2 renewable energy systems and identify technology and integration opportunities for different types of renewable resources. Correspondingly, this paper not only summarizes the advantages of CO2 working fluid, design layouts of S-CO2 cycles, and classifications of renewable energies to be integrated but also reviews the recent research activities and studies carried out worldwide on advanced S-CO2 power cycles with renewable energy. Moreover, the performance and development of various systems are well grouped and discussed