As a natural working fluid, Carbon dioxide (CO2, R744) has been widely applied in various energy systems by the academic and industrial communities. In the field of refrigeration, CO2 has a great potential to replace the traditional refrigerants, due to the zero ODP, one GWP, non-toxicity, and non-flammability. Furthermore, the favorable thermophysical properties make the CO2 system have a small footprint and capability to achieve low temperatures. Recently, with the diversification of application scenarios, further research is required for the development of new knowledge and tools to advance the efficiency benefits and reduce the costs of CO2 refrigeration systems. For the CO2 heat pump, depending on the application and the heat source, academia and industry have paid much effort to develop several technological innovations that span from an internal heat exchanger to parallel and cascade systems. Even so, the application of a CO2 heat pump still faces many challenges, such as high-temperature CO2 compressor, gas cooler design. Furthermore, how to effectively combine heat pumps with other renewable energy is still an open question to be answered. As for the power generation, there exist transcritical and supercritical configurations, depending on whether the cycle minimum temperature is below the critical temperature or not. Because CO2 has good stability and inertness, the maximum temperature of the power cycle can be up to more than 1000? theoretically. Thus, the CO2 power cycle has been widely applied to nuclear reactors, solar energy, fossil fuel, waste heat recovery, fuel cell, and geothermal energy. Facing so many heat sources, various cycle layouts have been proposed. However, considering different characteristics, seeking the best cycle configurations still has many issues to be solved. Furthermore, demonstrating a CO2 power system at full scale is still hindered by the lack of system knowledge and the ability to manufacture key system components. Researchers and engineers have to further enhance the maturity and strengthen the competitive position of this technology. Aiming at the above CO2 systems for cooling, heating, and power, developing various cogeneration systems is an inevitable choice to achieve high-efficient energy conversion and utilization, according to the user’s demanding. Besides the above applications, CO2 can be also directly used as heat transfer media of district heating/cooling, or the fluid in energy storage. Therefore, with the expanding scope of the CO2 energy systems, more efforts have to be paid to develop and enrich CO2-based energy systems.
This Research Topic aims to address the issues existing in the development of CO2-based energy systems. Our attention will be paid to the refrigeration, heat pump, power cycle, and energy storage, including system construction, numerical modeling, and experimental research. To enhance the system performance, investigations on system components are welcome. Furthermore, because impurity gases will inevitably penetrate the CO2 system and CO2 can also be actively mixed with other fluids to adjust the critical properties, another aim of this topic is to present recent research on CO2-based mixtures in energy systems.
The research topic welcomes submissions of original research articles, review articles, and other papers. Suggested topics are as follows, but are not limited to:
• CO2 refrigeration system
• CO2 heat pump
• Transcritical CO2 power cycle
• Supercritical CO2 power cycle
• CO2 energy storage
• Cogeneration system based on CO2
• Energy system with CO2-based mixtures
• Thermodynamic analysis and optimization of CO2 system
• Dynamic modeling of CO2 system
• Experimental tests of CO2 system
• Key component investigations of CO2 system
• CO2 and CO2-based mixtures heat and mass transfer
As a natural working fluid, Carbon dioxide (CO2, R744) has been widely applied in various energy systems by the academic and industrial communities. In the field of refrigeration, CO2 has a great potential to replace the traditional refrigerants, due to the zero ODP, one GWP, non-toxicity, and non-flammability. Furthermore, the favorable thermophysical properties make the CO2 system have a small footprint and capability to achieve low temperatures. Recently, with the diversification of application scenarios, further research is required for the development of new knowledge and tools to advance the efficiency benefits and reduce the costs of CO2 refrigeration systems. For the CO2 heat pump, depending on the application and the heat source, academia and industry have paid much effort to develop several technological innovations that span from an internal heat exchanger to parallel and cascade systems. Even so, the application of a CO2 heat pump still faces many challenges, such as high-temperature CO2 compressor, gas cooler design. Furthermore, how to effectively combine heat pumps with other renewable energy is still an open question to be answered. As for the power generation, there exist transcritical and supercritical configurations, depending on whether the cycle minimum temperature is below the critical temperature or not. Because CO2 has good stability and inertness, the maximum temperature of the power cycle can be up to more than 1000? theoretically. Thus, the CO2 power cycle has been widely applied to nuclear reactors, solar energy, fossil fuel, waste heat recovery, fuel cell, and geothermal energy. Facing so many heat sources, various cycle layouts have been proposed. However, considering different characteristics, seeking the best cycle configurations still has many issues to be solved. Furthermore, demonstrating a CO2 power system at full scale is still hindered by the lack of system knowledge and the ability to manufacture key system components. Researchers and engineers have to further enhance the maturity and strengthen the competitive position of this technology. Aiming at the above CO2 systems for cooling, heating, and power, developing various cogeneration systems is an inevitable choice to achieve high-efficient energy conversion and utilization, according to the user’s demanding. Besides the above applications, CO2 can be also directly used as heat transfer media of district heating/cooling, or the fluid in energy storage. Therefore, with the expanding scope of the CO2 energy systems, more efforts have to be paid to develop and enrich CO2-based energy systems.
This Research Topic aims to address the issues existing in the development of CO2-based energy systems. Our attention will be paid to the refrigeration, heat pump, power cycle, and energy storage, including system construction, numerical modeling, and experimental research. To enhance the system performance, investigations on system components are welcome. Furthermore, because impurity gases will inevitably penetrate the CO2 system and CO2 can also be actively mixed with other fluids to adjust the critical properties, another aim of this topic is to present recent research on CO2-based mixtures in energy systems.
The research topic welcomes submissions of original research articles, review articles, and other papers. Suggested topics are as follows, but are not limited to:
• CO2 refrigeration system
• CO2 heat pump
• Transcritical CO2 power cycle
• Supercritical CO2 power cycle
• CO2 energy storage
• Cogeneration system based on CO2
• Energy system with CO2-based mixtures
• Thermodynamic analysis and optimization of CO2 system
• Dynamic modeling of CO2 system
• Experimental tests of CO2 system
• Key component investigations of CO2 system
• CO2 and CO2-based mixtures heat and mass transfer
