Upgrading Of Energy Research Articles

Efficiency improvement and flexibility enhancement by molten salt heat storage for integrated gasification chemical-looping combustion combined cycle under partial loads

Chemical-looping combustion offers a promising carbon capture technology for coal-fired power generation. Enhancing the operational flexibility and energy efficiency of such plants is crucial for achieving primary energy savings and renewable energy accommodation. In this study, the operating characteristics of an integrated gasification chemical-looping combustion combined cycle (IGCLCCC) under various loads are studied, and the deterioration mechanism of its thermodynamic performance is revealed. Further, an IGCLCCC scheme coupled with molten salt heat storage is proposed and evaluated from thermodynamic performance and operational flexibility. Study results indicate that the net efficiency of the IGCLCCC reaches 37.7% under 30% load, which is superior to those of conventional CO2 capture power plants under full load. Adopting the heat storage system significantly improves the operational flexibility and energy efficiency of the IGCLCCC by expanding its operating range from 30.0∼100.0% to 25.7∼105.3%. The equivalent round-trip efficiency of the heat storage system reaches 134.6% due to the upgrading of the thermal energy from the exhaust gas of the air turbine from original low levels to high levels driven by the exergy saving during the oxygen carrier-air reaction because of the air preheating to a high temperature.

Energy supply chain efficiency in the digital era: Evidence from China's listed companies

With the widespread adoption of cutting-edge digital technologies, including big data, blockchain, artificial intelligence (AI), and cloud computing, the development and digitalization of the supply chain are experiencing significant integration. According to China's Fourteenth Five-Year Plan for a Modern Energy System, the country has embarked on a new phase of constructing a modern energy system. An accelerating trend in the digital upgrading of energy businesses marks a period of innovation and upgrading for the modern energy industry. Although policy documents highlight the role of digital technology in advancing the digital transformation of energy businesses, the underlying relationships and transmission mechanisms have yet to be fully explored, underscoring the necessity for targeted policy development. This study examines the link between enterprise digital transformation and energy supply chain efficiency, utilizing a bidirectional fixed-effects framework and analyzing data from 112 listed companies in the energy sector from 2011 to 2019. Employing a three-stage DEA model and text analysis to measure the primary indicators, findings suggest that digital transformation enhances energy supply chain efficiency by fostering technological innovation, leveraging government subsidies, and increasing openness levels. Moreover, the positive impact is more pronounced in large and private enterprises, especially in the eastern and northeastern regions. This study offers empirical support for the policy framework mentioned, advocating for the advancement of business digital transformation, the establishment and enhancement of digital supply chain systems, and the integration of supply chain enterprise resources upstream and downstream.

The Impact of Digital Finance on the Green Utilization Efficiency of Urban Land: Evidence from 281 Cities in China

In the era of digital economy, digital finance, as an innovative financial model, plays an important role in driving urban industrial transformation and development, technological innovation, industrial upgrading and sustainable utilization of energy, and has a significant impact on sustainable urban development. At present, in the process of building a new pattern of Chinese-style modernization in China, it is of great significance to improve the green use efficiency of urban land through digital finance and realize the sustainable use of land resources and the sustainable development of the city. The current study employed 281 Chinese cities from 2010 to 2020 as research samples to investigate the effects of technological financing on the productivity of city land green usage. Based on the ideas of responsible growth and efficient urban development, an assessment index system was developed. Comprehensive empirical tests, such as the Super-SBM model, fixed effect model, and mediation effect model, were implemented in the research. The study’s findings indicate that: (1) Throughout the research period, the benchmark model’s regression outcomes demonstrate that digital banking impacts urban land’s green development efficiency, with positive moderating effects offered by environmental legislation; the optimization of industrial structure has not yet played a positive regulating effect. (2) Urban area green usage performance is more clearly impacted by the extent of use and the degree of digitization, according to the regression results of digital financing heterogeneity. The positive effect of online financial services on a city’s green use efficiency occurs mainly in eastern cities and southern cities, given the results of urban development level difference. In light of resource endowment unpredictability, “non-resource cities” stand to gain more from global finance’s encouragement of resource-efficient urban land use than do “resource cities”. The results of the mechanism test indicate that there is a strong mediating influence from digital finance, city land environmental use productivity, and green technological breakthroughs. In consideration of these results, the following measures are suggested in this paper: (1) Persist in advocating for the transformation of traditional finance into online financing. (2) Intensify the impact of significant variables on the environmentally friendly use of urban areas. (3) Encourage technology creativity and execution through the application of technological economics.

Research on environmental monitoring and governance of air contamination in the Beijing‐Tianjin‐Hebei region stemmed from spatiotemporal data collection

AbstractFrom 2013 to now, Beijing‐Tianjin‐Hebei (Hereinafter referred to as “the region”) has carried out comprehensive air pollution governance, which has promoted the sustained and rapid development of the regional economy while significantly improving regional air quality. However, the spatial and seasonal differences in atmospheric quality are obvious, and the regional and structural problems are still prominent. There is a long way to go for new challenges of cooperate governance of PM2.5 and O3. Therefore, first, we should further deepen the joint prevention and control mechanism based on regional collaborative governance. Second, we should rely on technological innovation to impetus the upgrading of energy and industrial structure. Third, we should adjust the transportation structure and create a new pattern of transportation network. Fourth, we should improve the ecological compensation mechanism and give full play to the functions of ecological conservation areas. Fifth, we should think highly of the self‐purification capacity of the ecosystem and build urban forest parks. At last, we should Strengthen publicity and mobilization, and participate in joint governance through nationwide action.

Investigations on a bubble-pump-aided diffusion absorption heat transformer using deep eutectic solvent for harvesting and upgrading thermal energy

Absorption heat transformer shows promising potential in thermal energy harvesting and upgrading, while the corrosion and crystallization risks of existing working substance restrict its promotion. A bubble-pump-aided diffusion absorption heat transformer using deep eutectic solvent is proposed in this study. The influence of operating parameters of bubble pump is analyzed, indicating that motive head should be as large as possible while diffusion gas flow rate has the optimum. Because of worse pumping ability, deep eutectic solvent has narrower normal operating range compared with LiBr, but the optimal energy performance shows little difference. Ethaline exhibits the best performance among deep eutectic solvents. With heat source of 90 ℃, COP and ηEX of 0.401 and 48.9% can be reached to output thermal energy of 120 ℃, leading to a CO2 emission reduction of 20.1 Mt per year. Parametric analysis demonstrates that single-stage diffusion absorption heat transformer using ethaline can realize temperature lift up to 50 ℃, which delivers comparative performance against existing AHT systems, except for operating range. Approaches are discussed to enlarge its operating range and further improve its performance as well. The results in this paper contribute to: 1) providing a promising absorption heat transformer configuration for large-scale and long-term use; 2) quantitatively demonstrating the prospect of deep eutectic solvent; 3) enlightening insights in the recovery of industrial waste heat, the upgrading of thermal energy and the reduction of CO2 emission.

Toxicity, Leakage, and Recycling of Lead in Perovskite Photovoltaics

AbstractPerovskite solar cells (PSCs) have developed rapidly in recent years due to their excellent photoelectric properties. Among them, lead‐based perovskite photovoltaics have shown great potential for both outdoor and indoor applications, whose power conversion efficiency and stability are much higher than that of lead‐free PSCs. However, based on results of in vivo animal studies, Kyoto Encyclopedia of Genes and Genomes annotations and pathway analysis of microbiota and metabolites influenced by lead, it has been proved that lead exposure from PSCs probably causes systematic toxicity to human body. For the purpose of reducing lead leakage, some methods mainly based on polymer resin protective layers and self‐healing encapsulation have been introduced, which can increase lead capture rate up to 95% under harsh conditions. Eventually, the devices will still face damage and obsolescence, accompanied by lead leakage into the environment. Comprehensive recycling strategies are necessary to solve this problem from the root and also shorten the energy payback time for further transformation and upgrading of green energy. The vertical and in‐depth collaborative strategy for lead leakage prevention and comprehensive recycling would provide an environmentally‐friendly guarantee for the final large‐scale market of perovskite photovoltaics.

Proposal and assessment of a solar-coal thermochemical hybrid power generation system

The thermochemical complementarity is an efficient path to improve the utilization efficiency of coal and address the intermittence of solar energy. In this paper, a solar-coal thermochemical hybrid power generation system based on supercritical water gasification is proposed, and the feature is that the low gasification temperature of 650 °C makes it feasible to use concentrated solar energy to provide reaction heat for the gasification process. The energy and exergy analysis methods are used to evaluate the thermodynamic performance of the system with a net power output of 500 MW. The results show that the net power generation efficiency and exergy efficiency of the proposed system can reach 53.06 % and 52.24 %, respectively, which are approximately 6.94 and 6.83 percentage points higher than those of the reference system. The significant role of thermochemical method is that the chemical energy of syngas produced by the proposed system is 851.57 MW, which is increased by approximately 29.70 %. Through the energy utilization diagram analysis, it is found that the key to performance improvement is that the exergy destruction of the fuel conversion process and heat exchange process are decreased by 10.36 % and 54.68 %, respectively. Finally, the proposed system has better performance and lower exergy destruction. The solar thermal energy of low energy level is converted into syngas chemical energy of high energy level, and the upgrading of solar energy is achieved. In addition, the proposed system is simpler, and eliminates the air separation unit and syngas purification unit. This work provides a promising method for the complementary utilization of solar energy and coal.

Two-phase expansion processes in heat pump – ORC systems (Carnot batteries) with volumetric machines for enhanced off-design efficiency

Carnot batteries enable novel perspectives for decarbonizing the energy sector as an emerging technology for electrical energy storage. A power-to-heat process stores excess electrical energy as thermal energy which is transferred back to electrical energy on demand by a power cycle. This paper focuses on Carnot batteries by means of heat pumps and organic Rankine cycles (HP-ORC systems) as these systems combine the advantages of technically mature components, effective integration of heat sources and low-cost scalable storage. In combination with low-enthalpy geothermal heat, Carnot batteries offer an efficient synthesis of electrical energy storage and upgrading of low-enthalpy geothermal energy. Previous works highlighted that two-phase expansion can enhance the efficiency of heat recovery cycles. The present paper discusses partial evaporation and flash evaporation in Carnot batteries based on organic Rankine cycles and organic flash cycles (OFC) with volumetric machines as they enable two-phase expansion processes. The three investigated cycles ORC, OFC and OFC with two-phase expander are systematically analyzed in three steps. First, the potential cycle performances are identified without restrictions of volumetric machines. Afterwards, the effects of under- and over-expansion due to fixed built-in volume ratios are taken into account. Finally, a validated screw expander model is utilized to determine the performance of the three cycles in off-design conditions. The results show that the vapor quality of the partially evaporated ORC as well as the flash pressure ratio of the OFC both indicate a specific optimum depending on the storage temperature. The fixed built-in volume ratio of volumetric machines limits the efficiency of partial evaporation in the ORC due to strong under-expansion. Notably, the built-in volume ratio does not affect the optimal flash pressure ratio in the OFC. Partial evaporation increases the power output at the cost of efficiency which can be utilized during temporary peak loads. The ORC yields higher efficiencies than the basic OFC in all operating conditions due to the throttling losses of the OFC. Contrarily, the OFC with two-phase expander increasingly outperforms the ORC with rising storage temperature spread. This advantage increases in part load conditions as the OFC becomes less sensitive to the flash pressure ratio. Hence, this facilitates the control of flash pressure ratio and enables advantageous efficiencies. Thus, partial evaporation and flash evaporation can enhance the performance of Carnot batteries throughout a wide operational range.

Multi-dimensional evaluation method for new power system

New power system that takes strong smart grid as the platform is supported by source-grid-load-storage interaction and multi-energy complementarity, because the system is green, efficient, flexible and digital. This paper focused on the research of multi-dimensional evaluation method of the new power system. Firstly, the internal and external elements of the new power system were sorted out, and KPI indicators were obtained through the analysis of the logical relationship of indicators. Secondly, this paper innovatively proposed to use “Generation Side Grid and Load” (GSGL) as the internal element and “Reliable Efficient Green and Intelligent” (REGI) as the evaluation effect. Meanwhile, this paper innovatively put forward a new multi-dimensional evaluation system of power system, with 4 secondary indicators and 16 tertiary indicators. Finally, the AAHM-weighted grey relational TOPSIS comprehensive evaluation model was constructed, and the validity and applicability of the proposed evaluation index system and model method were verified by numerical examples. Through the example analysis, under the new multi-dimensional evaluation system of power system, the comprehensive evaluation results and ranking of different provincial power enterprises were obtained. This paper provides theoretical support to further promote the transformation and upgrading of energy and electric power industry and power grid enterprises to speed up the construction of safe, reliable, green, efficient and intelligent modern power grid.

Research on Smart Energy System Technology Based on Cloud Computing Platform

Based on the social and economic development, environmental protection needs, industrial policies and other smart energy systems have brought a new round of great changes compared with the traditional energy structure. Now the development of information technology provides a strong technical support for the transformation and upgrading of traditional energy to smart energy. This paper combines cloud computing, big data, artificial intelligence, blockchain and other emerging technologies to enable the traditional energy system, a smart energy system architecture based on cloud computing platform is proposed, which connects the bottom layer to the top layer of the energy system, and realizes the comprehensive integration of physical energy flow, information flow and value flow of smart energy.

Reform of Replacing Business Tax with VAT, Industrial Interconnection and Manufacturing Upgrading: Based on the Mechanism Test of Tax Reduction and Producer Service Industry Agglomeration

Recently, the reform of “replacing business tax with VAT” has been an important means for the Chinese government to promote economic growth. It has had a profound impact on the service industry’s tax burden, social welfare and local fiscal revenue. However, the ultimate goal of this reform is not simply to reduce taxes, but to promote China’s transformation and upgrading by promoting the division of labor among industries. The research on the impact of replacing business tax with VAT has been concentrated on the service industry, while fewer studies have analyzed its impact on manufacturing enterprises. Theoretically, “replacing business tax with VAT” can promote the development of the service industry by encouraging specialization and innovation, thereby providing new information and knowledge flow to the manufacturing industry, and promoting the manufacturing industry to increase R&D, procurement, marketing and other links to help it achieve a higher value chain. On the other hand, the manufacturing industry is also a net beneficiary of this reform. After the reform, the VAT input tax amount of its outsourcing services has changed from non-deductible to deductible, and the tax burden has been reduced, which will also stimulate the transformation and upgrading of manufacturing enterprises. Which path matters more? This paper takes the A-share manufacturing enterprises in Shanghai and Shenzhen stock markets from 2009 to 2015 as the object, and tests the influence and mechanism of the replacing business tax with VAT on the transformation and upgrading of manufacturing enterprises. It finds that the reform promotes manufacturing enterprises’ transformation and upgrading, and its effect can last at least two years. The concentration of regional producer service industry plays a significant intermediary effect in promoting manufacturing upgrading, while the influence of turnover tax burden reduction is limited. The reform obviously promotes the upgrading of private manufacturing enterprises and districts of higher institutional pressure, instead of state-owned enterprises and districts of lower institutional pressure. The research in this paper shows that the reform’s influence is not limited to the service industry. What is more significant is that it will promote the transformation and upgrading of traditional kinetic energy（manufacturing industry）by cultivating new kinetic energy in the service industry. The latter will then provide a more solid market demand for the service industry, and eventually achieve the conversion of old and original kinetic energy. This paper reveals the impact and mechanism of the reform of replacing business tax with VAT on manufacturing upgrading. Its conclusions have important policy implications for current tax reduction and industrial upgrading policies.

Photochemical Phase Transitions Enable Coharvesting of Photon Energy and Ambient Heat for Energetic Molecular Solar Thermal Batteries That Upgrade Thermal Energy.

Discovering physicochemical principles for simultaneous harvesting of multiform energy from the environment will advance current sustainable energy technologies. Here we explore photochemical phase transitions-a photochemistry-thermophysics coupled regime-for coharvesting of solar and thermal energy. In particular, we show that photon energy and ambient heat can be stored together and released on demand as high-temperature heat, enabled by room-temperature photochemical crystal↔liquid transitions of engineered molecular photoswitches. Integrating the two forms of energy in single-component molecular materials is capable of providing energy capacity beyond that of traditional solar or thermal energy storage systems based solely on molecular photoisomerization or phase change, respectively. Significantly, the ambient heat that is harvested during photochemical melting into liquid of the low-melting-point, metastable isomer can be released as high-temperature heat by recrystallization of the high-melting-point, parent isomer. This reveals that photon energy drives the upgrading of thermal energy in such a hybrid energy system. Rationally designed small-molecule azo switches achieve high gravimetric energy densities of 0.3-0.4 MJ/kg with long-term storage stability. Rechargeable solar thermal battery devices are fabricated, which upon light triggering provide gravimetric power density of about 2.7 kW/kg and temperature increases of >20 °C in ambient environment. We further show their use as deicing coatings. Our work demonstrates a new concept of energy utilization-combining solar energy and low-grade heat into higher-grade heat-which unlocks the possibility of developing sustainable energy systems powered by a combination of natural sunlight and ambient heat.

Development of a solar farm powered quadric system with thermal energy storage option

Due to the increase in energy and fresh water demands and the expected hydrogen economy, it is important to find solutions that can meet these various energy demands. In this study, an investigation of a PV/T powered integrated system for a quadric generation of electricity, hydrogen, fresh water and space heating with a novel thermal energy storage unit is considered. This study introduces for the first time the upgrading of thermal energy using a high-temperature heat pump for thermal energy storage by using a combination of excess electric power and waste heat from a PV/T solar farm. After establishing and validating a thermodynamic model to analyze this integrated system, the results show that the energy and exergy coefficients of performance of this heat pump are 1.18 and 0.336, respectively at the base case. Also, the temperature lift is 132.6 K up from 333 K at the PV/T solar farm. The overall energy and exergy efficiencies of the integrated system are found to be 11.6% and 6.49%, respectively. In addition, parametric studies are conducted to investigate how the system performance is affected by changing the operating conditions and state properties, and their results show that, in general, improving the isentropic efficiencies of compressors of the heat pump, enhances the overall performance energetically and exergetically. In regards to the hydrogen production rate, increasing this rate reduces the overall energy and exergy efficiencies of the integrated system respectively from 12.9% and 6.83% at a mass flow rate of 0.01 kg s−1 down to 8.17% and 5.71% at a mass flow rate of 0.035 kg s−1, respectively.

Experimental investigations on the temperature lift performance of a novel diffusion absorption heat transformer

A novel diffusion absorption heat transformer was proposed and built. The temperature lift performance of the novel system was experimentally tested with the diffusion gas supplied by an electric gas pump or a thermally driven pump, and the gross temperature lift was realized as high as 17.6 °C and 11.8 °C, respectively. Higher mass fraction of HCOOK in aqueous HCOOK solution, lower flow rate of aqueous HCOOK solution, and larger flow rate of refrigerant, were all beneficial to higher temperature lift. It is of remarkable significance for the utilization and upgrading of low grade thermal energy that a temperature lift can be realized by the diffusion absorption heat transformer with heat input but no need of electricity.

Use of Low/Mid-Temperature Solar Heat for Thermochemical Upgrading of Energy, Part I: Application to a Novel Chemically-Recuperated Gas-Turbine Power Generation (SOLRGT) System

This paper is the first part of a study presenting the concept of indirect thermochemical upgrading of low/mid temperature solar heat, and demonstration of its integration into a high efficiency novel hybrid power generation system. The proposed system consists of an intercooled chemically recuperated gas turbine (SOLRGT) cycle, in which the solar thermal energy collected at about 220 °C is first transformed into the latent heat of vapor supplied to a reformer and then via the reforming reactions to the produced syngas chemical exergy. The produced syngas is burned to provide high temperature working fluid to a gas turbine. The solar-driven steam production helps to improve both the chemical and thermal recuperation in the system. Using well established technologies including steam reforming and low/mid temperature solar heat collection, the hybrid system exhibits promising performance: the net solar-to-electricity efficiency, based on the gross solar thermal energy incident on the collector, was predicted to be 25–30%, and up to 38% when the solar share is reduced. In comparison to a conventional CRGT system, 20% of fossil fuel saving is feasible with the solar thermal share of 22%, and the system overall efficiency reaches 51.2% to 53.6% when the solar thermal share is increased from 11 to 28.8%. The overall efficiency is about 5.6%-points higher than that of a comparable intercooled CRGT system without solar assist. Production of NOx is near zero, and the reduction of fossil fuel use results in a commensurate ∼20% reduction of CO2 emissions. Comparison of the fuel-based efficiencies of the SOLRGT and a conventional commercial Combined Cycle (CC) shows that the efficiency of SOLRGT becomes higher than that of CC when the solar thermal fraction Xsol is above ∼14%, and since the SOLRGT system thus uses up to 12% less fossil fuel than the CC (within the parameter range of this study), it commensurately reduces CO2 emissions and saves depletable fossil fuel. An economic analysis of SOLRGT shows that the generated electricity cost by the system is about 0.06 $/kWh, and the payback period about 10.7 years (including 2 years of construction). The second part of the study is a separate paper (Part II) describing an advancement of this system guided by the exergy analysis of SOLRGT.

Use of Low/Mid-Temperature Solar Heat for Thermochemical Upgrading of Energy, Part II: A Novel Zero-Emissions Design (ZE-SOLRGT) of the Solar Chemically-Recuperated Gas-Turbine Power Generation System (SOLRGT) guided by its Exergy Analysis

This paper adds an exergy analysis of the novel SOLRGT solar-assisted power generation system proposed and described in detail in Part I of this study (Zhang and Lior, 2012, “Use of Low/Mid-Temperature Solar Heat for Thermochemical Upgrading of Energy, Part I: Application to a Novel Chemically-Recuperated Gas-Turbine Power Generation (SOLRGT) System,” ASME J. Eng. Gas Turbines Power, Accepted. SOLRGT is an intercooled chemically recuperated gas turbine cycle, in which solar thermal energy collected at about 220 °C is first transformed into the latent heat of water vapor supplied to a reformer, and then via the reforming reactions to the produced syngas chemical exergy. This integration of this concept of indirect thermochemical upgrading of low/mid temperature solar heat has resulted in a high efficiency novel hybrid power generation system. In Part I it was shown that the solar-driven steam production helps improve both the chemical and thermal recuperation in the system, with both processes contributing to the overall efficiency improvement of about 5.6%-points above that of a comparable intercooled CRGT system without solar assist, and nearly 20% reduction of CO2 emissions. An economic analysis of SOLRGT predicted that the generated electricity cost by the system is about 0.06 $/kWh, and the payback period about 10.7 years (including two years of construction). The exergy analysis of SOLRGT in this (Part II) paper identified that the main potentials for efficiency improvement is in the combustion, the turbine and compressors, and in the flue gas due to its large water vapor content. Guided by this, an improved solar-assisted zero-emissions power generation system configuration with oxy-fuel combustion and CO2 capture, ZE-SOLRGT, is hereby proposed, in which the exergy losses associated with combustion and heat dumping to the environment are reduced significantly. The analysis predicts that this novel system with an 18% solar heat input share has a thermal efficiency of 50.7% and exergy efficiency of 53%, with ∼100% CO2 capture.

Thermodynamic analysis of the main devices for thermal energy upgrading

The problem of using low-level energies is a general one, in the light of the amount of thermal waste in numerous sectors. It is important both in the utilization of new energy sources available in thermal form (e.g., low-enthalpy geothermal and solar energies) and in the industrial field. The upgrading of low-level energy can be achieved either by means of absorption and resorption cycles or by heat transformers or by their combinations. Steam recompression is a particular case, but by no means a negligible one. Indeed, vent steam, for example, is probably one of the largest untapped sources of industrial waste energy. On the basis of a general definition of efficiency examined in a previous paper, in this note, the relative entropy production and the exergy efficiency of the various upgrading techniques are considered. Besides, the possibilities and the convenience of recompressing vent steam are examined.

Study of Carbonation Reactions of Ca-Mg Oxides for High Temperature Energy Storage and Heat Transformation.

Storing and temperature upgrading of heat energy at 773 K by means of a CaO-CO2 reaction seems very attractive. One way of storing the reaction product CO2 gas is in the form of an other carbonate by letting it react with a metal oxide, such as MgO or ZnO. Two metal oxides, MgO and (CaMg)O2 were selected for CO2 storage, with the CaO-CO2 energy storage system as CaO-CO2-MgO and CaO-CO2-CaMgO2 systems, and studies on CaO-CO2, MgO-CO2 and CaMgO2-CO2 reactions over the temperature range 773–1073 K were carried out. As the CaO-CO2 system is used not only for storing the heat energy but is also expected to perform as a heat transformer, verification of the temperature upgrading ability is made by means of a lab-scale adiabatic reactor. Pseudo-steady state temperature and pressure existed during the experiments, which correspond quite well with Haul’s equilibrium dissociation values of CaCO3, illustrating that upgraded temperatures of above 1273 K can be achieved by adjusting the carbonating CO2 gas pressure to around 500 kPa.

Resolving membrane and shear locking phenomena in curved shear‐deformable axisymmetric shell elements

AbstractA simple two‐node axisymmetric shell element with shallowly curved meridian assumptions and the inclusion of shear deformation and rotary inertia is presented. The principal developments include: (a) consistent resolution of the membrane and shear related excessive stiffening (locking) via anisoparametric interpolations of the displacement variables; (b) further upgrading of strain energy by means of a shear relaxation (correction) parameter. The resulting element possesses an improved condition of the stiffness matrix, increased efficiency in explicit time integration and enhanced accuracy in coarse discretizations. Comprehensive vibration examples are carried out to assess the element performance. The numerical results demonstrate a wide applicability range with respect to element slenderness and curvature properties.

On the chemical heat pump system and its second-law efficiency

This paper is concerned with the description of a chemical heat pump for the recovery or upgrading of low-level thermal energy. A four-tank configuration of a chemical heat pump is presented that has potential applications for heating and cooling of thermal energy storage. An analysis of the second-law efficiency of the chemical heat pump system, operated in the heating or cooling mode, is made. Effects of the temperatures of the heat source, sorrounding and desired task on the second-law efficiency are also discussed.