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Thermoacoustic technology emerges as a sustainable and low-carbon method for energy conversion, leveraging environmentally friendly working mediums and independence from electricity. This study presents the development of a multimode heat-driven thermoacoustic system designed to utilize medium/low-grade heat sources for room-temperature cooling and heating. We constructed both a simulation model and an experimental prototype for a single-unit direct-coupled thermoacoustic system, exploring its performance in heating-only, cooling-only, and hybrid heating and cooling modes. Internal characteristic analysis including an examination of internal exergy loss and a distribution analysis of key parameters was first conducted in the hybrid cooling and heating mode. The results indicated a positive-focused traveling-wave-dominant acoustic field within the thermoacoustic core unit, enhancing energy conversion efficiency. The output system performance was subsequently tested under different working conditions in the heating-only and cooling-only modes. A maximum output heating power of 2.3 kW and a maximum COPh of 1.41 were observed in the heating-only mode. Meanwhile, a cooling power of 748 W and a COPc of 0.4 were obtained in the typical cooling condition at 7 °C when operating in cooling-only mode. These findings underscore the promising potential of thermoacoustic systems for efficiently utilizing medium/low-grade heat sources for cooling and/or heating applications in the future.

Thermoacoustic technology emerges as a sustainable and low-carbon method for energy conversion, leveraging environmentally friendly working mediums and independence from electricity. This study presents the development of a multimode heat-driven thermoacoustic system designed to utilize medium/low-grade heat sources for room-temperature cooling and heating. We constructed both a simulation model and an experimental prototype for a single-unit direct-coupled thermoacoustic system, exploring its performance in heating-only, cooling-only, and hybrid heating and cooling modes. Internal characteristic analysis including an examination of internal exergy loss and a distribution analysis of key parameters was first conducted in the hybrid cooling and heating mode. The results indicated a positive-focused traveling-wave-dominant acoustic field within the thermoacoustic core unit, enhancing energy conversion efficiency. The output system performance was subsequently tested under different working conditions in the heating-only and cooling-only modes. A maximum output heating power of 2.3 kW and a maximum COPh of 1.41 were observed in the heating-only mode. Meanwhile, a cooling power of 748 W and a COPc of 0.4 were obtained in the typical cooling condition at 7 °C when operating in cooling-only mode. These findings underscore the promising potential of thermoacoustic systems for efficiently utilizing medium/low-grade heat sources for cooling and/or heating applications in the future.

The lifetime and reliability of power transformers are primarily dependent on the hot-spot temperature in the windings, as temperature is the most important factor determining the insulation degradation rate. Key to removing the heat from the transformer is the radiator which must be carefully designed to keep the temperatures within limits under all operating conditions whilst minimizing the transformer size, weight and cost. This paper compares the analytical method used to predict the radiator performance with computational fluid dynamics (CFD) models in terms of heat dissipation. It is found that the analytical method and CFD models give similar results in the air natural (AN) cooling modes, whereas the analytical method overestimates the heat dissipation in the air forced (AF) cooling modes. Moreover, the thermal conduction effect in the radiator wall is investigated under different operating conditions and for different radiator sizes using the CFD models. The simulation results indicate that the radiator wall contributes to 6%-10% of the total heat dissipation under some circumstances and therefore should not be simply ignored in radiator models.

The lifetime and reliability of power transformers are primarily dependent on the hot-spot temperature in the windings, as temperature is the most important factor determining the insulation degradation rate. Key to removing the heat from the transformer is the radiator which must be carefully designed to keep the temperatures within limits under all operating conditions whilst minimizing the transformer size, weight and cost. This paper compares the analytical method used to predict the radiator performance with computational fluid dynamics (CFD) models in terms of heat dissipation. It is found that the analytical method and CFD models give similar results in the air natural (AN) cooling modes, whereas the analytical method overestimates the heat dissipation in the air forced (AF) cooling modes. Moreover, the thermal conduction effect in the radiator wall is investigated under different operating conditions and for different radiator sizes using the CFD models. The simulation results indicate that the radiator wall contributes to 6%-10% of the total heat dissipation under some circumstances and therefore should not be simply ignored in radiator models.

Electrochemical CO2 reduction (CO2RR) is one of the most promising methods for decreasing the concentration of CO2, meanwhile, converting them into the high value-added chemicals, which has been more and more investigated and developed recently. Imidazolium ionic liquids (ILs) have been widely used as electrolytes in CO2RR and shown satisfactory performance. While the function of ILs is still unclear. Besides, the economic feasibility and potential of CO2RR with ILs-based electrolytes as well as the environmental effects are also unclear. Therefore, this work focuses on the technology evaluation and exploration for CO2RR-to-CO with ILs-based electrolyte. Firstly, a literature review about CO2RR to CO, CH4, CH3OH, and syngas (H2/CO=1:1 and 1:2) in ILs-based electrolytes was conducted. Then the processes to obtain these C1-products were analyzed from both economic and environmental aspects based on the state-of-the-art technology and the rationally hypothetical future cases. The results show that CO is the most valuable product considering both the economic benefits and environmental impact, which will be more lucrative in the future with the improvement of CO2RR performance. Then, based on 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), a series of imidazolium ILs with various proton in the group (-CH3, -CH3OH and -SH, noted as [BMMIM][PF6], [BMOHIM][PF6] and [BMSHIM][PF6], respectively) at C2 site of the imidazole ring were synthesized and used as electrolyte to perform CO2RR over a commercial Ag foil. As a result, the more inert the active proton, the more favorable for the production of CO. Notably, nearly 100% CO was obtained when [BMMIM][PF6] with the most inert proton. This confirms that the C2-H of the imidazole ring has an important influence on CO2RR performance and may be involved in the reaction. Finally, [BMMIM][PF6] and [BMIM][PF6] were selected as the electrolytes to conduct CO2RR over a bimetallic catalyst. As a result, the product from 99.69% HCOOH switched into 98.85% CO only via changing the electrolyte from [BMIM][PF6] into [BMMIM][PF6]. Mechanistic studies reveal that the CO2 adsorption configuration on the surface of the catalyst was altered when switching to another IL with a different CO2 active site, resulting in two distinct pathways for the generation of HCOOH and CO, respectively. 

Electrochemical CO2 reduction (CO2RR) is one of the most promising methods for decreasing the concentration of CO2, meanwhile, converting them into the high value-added chemicals, which has been more and more investigated and developed recently. Imidazolium ionic liquids (ILs) have been widely used as electrolytes in CO2RR and shown satisfactory performance. While the function of ILs is still unclear. Besides, the economic feasibility and potential of CO2RR with ILs-based electrolytes as well as the environmental effects are also unclear. Therefore, this work focuses on the technology evaluation and exploration for CO2RR-to-CO with ILs-based electrolyte. Firstly, a literature review about CO2RR to CO, CH4, CH3OH, and syngas (H2/CO=1:1 and 1:2) in ILs-based electrolytes was conducted. Then the processes to obtain these C1-products were analyzed from both economic and environmental aspects based on the state-of-the-art technology and the rationally hypothetical future cases. The results show that CO is the most valuable product considering both the economic benefits and environmental impact, which will be more lucrative in the future with the improvement of CO2RR performance. Then, based on 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), a series of imidazolium ILs with various proton in the group (-CH3, -CH3OH and -SH, noted as [BMMIM][PF6], [BMOHIM][PF6] and [BMSHIM][PF6], respectively) at C2 site of the imidazole ring were synthesized and used as electrolyte to perform CO2RR over a commercial Ag foil. As a result, the more inert the active proton, the more favorable for the production of CO. Notably, nearly 100% CO was obtained when [BMMIM][PF6] with the most inert proton. This confirms that the C2-H of the imidazole ring has an important influence on CO2RR performance and may be involved in the reaction. Finally, [BMMIM][PF6] and [BMIM][PF6] were selected as the electrolytes to conduct CO2RR over a bimetallic catalyst. As a result, the product from 99.69% HCOOH switched into 98.85% CO only via changing the electrolyte from [BMIM][PF6] into [BMMIM][PF6]. Mechanistic studies reveal that the CO2 adsorption configuration on the surface of the catalyst was altered when switching to another IL with a different CO2 active site, resulting in two distinct pathways for the generation of HCOOH and CO, respectively. 

Modelling the economics of climate change is daunting. Many existing methodologies from social and physical sciences need to be deployed, and new modelling techniques and ideas still need to be developed. Existing bread-and-butter micro- and macroeconomic tools, such as the expected utility framework, market equilibrium concepts and representative agent assumptions, are far from adequate. Four key issues—along with several others—remain inadequately addressed by economic models of climate change, namely: (1) uncertainty, (2) aggregation, heterogeneity and distributional implications (3) technological change, and most of all, (4) realistic damage functions for the economic impact of the physical consequences of climate change. This paper assesses the main shortcomings of two generations of climate-energy-economic models and proposes that a new wave of models need to be developed to tackle these four challenges. This paper then examines two potential candidate approaches—dynamic stochastic general equilibrium (DSGE) models and agent-based models (ABM). The successful use of agent-based models in other areas, such as in modelling the financial system, housing markets and technological progress suggests its potential applicability to better modelling the economics of climate change.

Modelling the economics of climate change is daunting. Many existing methodologies from social and physical sciences need to be deployed, and new modelling techniques and ideas still need to be developed. Existing bread-and-butter micro- and macroeconomic tools, such as the expected utility framework, market equilibrium concepts and representative agent assumptions, are far from adequate. Four key issues—along with several others—remain inadequately addressed by economic models of climate change, namely: (1) uncertainty, (2) aggregation, heterogeneity and distributional implications (3) technological change, and most of all, (4) realistic damage functions for the economic impact of the physical consequences of climate change. This paper assesses the main shortcomings of two generations of climate-energy-economic models and proposes that a new wave of models need to be developed to tackle these four challenges. This paper then examines two potential candidate approaches—dynamic stochastic general equilibrium (DSGE) models and agent-based models (ABM). The successful use of agent-based models in other areas, such as in modelling the financial system, housing markets and technological progress suggests its potential applicability to better modelling the economics of climate change.