Thermodynamic Comparison Research Articles

Thermodynamic performance comparison of calcium looping processes for post-combustion capture: influence of CO2 enrichment routes among three heat supply methods

Thermodynamic performance comparison of calcium looping processes for post-combustion capture: influence of CO2 enrichment routes among three heat supply methods

Active phase and amplitude temperature control method for cryostat: A case in the thermodynamic temperature international comparison system

Achieving highly stable temperature control is essential for cryostats. However, the cryocooler used in cryostats, such as the pulse tube cryocooler, produces regular sinusoidal temperature fluctuations due to its inherent working principles. To establish a highly stable temperature environment, an active phase and amplitude control method for suppressing temperature fluctuation is proposed in this paper, by which the optimal phase and amplitude can be predicted in theory. To validate this approach, a thermal response model was developed based on experiments conducted in the thermodynamic temperature international comparison cryostat at approximately 3.7 K. Based on this model, we conducted both single-stage and multi-stage active temperature control experiments. The results demonstrate that the temperature control effect is the best when the active temperature control current is added at the second cold head, the fluctuation of the comparison copper block from 3.3mK to 0.166mK with 94.9 % suppression rate. The multi-stage joint temperature control reduced the temperature fluctuation with an attenuation rate of 95.4 %. These findings offer significant potential for improving temperature stability in future thermodynamic temperature comparison experiments.

A Thermodynamic Comparison of Exergy Production from Sugarcane and Photovoltaic Modules in the Context of Brazilian Energy Transition

This article applies the exergy analysis to the production and use of sugarcane, considering a model published in the literature. In this way, we compute incident solar irradiation, carbohydrate production, water consumption, and the production of stalks and straws. Following the production estimate, we analyze a biorefinery production cycle, from solar irradiation to the biorefinery products on an exergy basis, from birth to production of sugar, electrical energy, and ethanol. The calculated sugarcane production values are 80.7 tons per hectare for a 52-week cycle. As a result, the average exergy efficiency of sugarcane is 4.99%, reaching peaks of 8.3%. When considering only the useful exergy generated in the production of stalks and straw, an annual yield of 17.86 kWh/m2 represents an overall exergy efficiency of 1.31%. Considering the energy conversion processes in the biorefinery, the exergy efficiency from the radiation to the products from the biorefinery was 0.38%. The photovoltaic modules already have a well-established application in the country, though they need to increase their insertion over time, whereby the panels exhibit an average exergy efficiency of 31.6%, resulting in an annual electrical energy production of 255.84 kWh/m2. The results show that photovoltaic modules are a more efficient alternative than sugarcane regarding exergy land use. In conclusion, this study briefly discusses the use of sugarcane and photovoltaic modules in the context of Brazil’s energy transition towards a reduced dependence on fossil fuels, based on the fact that sugarcane already has a low carbon footprint for transportation using ethanol, with supply from more than 40,000 stations, and a similar or lower carbon footprint than electrical vehicles used across the country.

Saline Brine Separation: Thermodynamic and Techno-Economic Comparison of Counterflow Reverse Osmosis with Electrodialysis

Saline Brine Separation: Thermodynamic and Techno-Economic Comparison of Counterflow Reverse Osmosis with Electrodialysis

Thermodynamic and economic comparisons of supercritical water oxidation and gasification of oily sludge under hydrothermal flames

Dual-shell reactors using hydrothermal flames as internal heat source were proposed for supercritical water gasification (SCWG) and oxidation (SCWO) of oily sludge to achieve fast preheating and avoid corrosion, salt plugging, and overheating. The SCWG and SCWO systems with hydrogen-rich syngas and electricity outputs, respectively, were established and simulated using Aspen Plus 11. Simulation models were validated by comparing with experimental products and temperature profiles. The maximum exergy destruction coefficients of 28.01% and 24.31% appear in the combustion reactor for both the SCWG and SCWO systems, respectively, indicating the indirect preheating method with hydrothermal flame is critical to the energy efficiency. The increase of reaction temperature promotes hydrogen but inhibits methane formation in the SCWG, and more steam but less syngas is output at higher reaction temperatures. Although more steam and electricity outputs are present at higher reaction temperatures for the SCWO, more fuel input is required. Lower exergy efficiencies are obtained at higher reaction temperatures in both the SCWG and SCWO systems for more energy is output as low grade steam. Less fuel input is required for both the SCWG and SCWO systems at higher feed concentrations, and higher exergy efficiencies can be obtained. The net treatment cost for the SCWG and SCWO systems are 119.19 and 215.47 USD/t, respectively, indicating the SCWG is more economically competitive compared with the SCWO.

Thermodynamic and Optimization Comparison of a Solar-Powered Compressor-Assisted Combined Absorption Refrigeration and Power Systems

Thermodynamic and Optimization Comparison of a Solar-Powered Compressor-Assisted Combined Absorption Refrigeration and Power Systems

Thermodynamic Comparison of the Steam Ejectors Integrated at Different Locations in Cogeneration Systems

Thermodynamic Comparison of the Steam Ejectors Integrated at Different Locations in Cogeneration Systems

Thermodynamic Analysis and Comparison of Power Cycles for Small Modular Reactors

Small nuclear power plants can provide a stable, carbon-free energy supply to civil infrastructure and industrial enterprises in remote regions isolated from unified energy systems. More than 70 projects of small modular reactors are currently being developed by IAEA member countries; several low-power power units are already supplying thermal and electrical energy to consumers. One of the main limitations standing in the way of widespread dissemination of this technology is the high specific capital cost of a low-power nuclear power plant; therefore, new scientific and technical solutions are needed in this industry. Increasing the thermodynamic efficiency of power cycles of small modular reactors can become a driver for reducing the cost of supplied electrical energy. This paper presents the results of a comprehensive thermodynamic analysis of existing and promising power cycles for small modular reactors. In addition to traditional steam power cycles, cycles using non-traditional working fluids, including carbon dioxide, freons, and helium cycles, are considered. Optimal sets of thermodynamic parameters were determined to ensure maximum net efficiency of electricity production. For water-cooled reactor plants, a maximum efficiency of 33.5% at an initial temperature of 300 °C could be achieved using a steam turbine cycle. It was revealed that for reactor plants with liquid metal and liquid salt coolant in the range of initial temperatures above 550–700 °C, the maximum thermal efficiency was provided by the Brayton recompression cycle with a carbon dioxide coolant: the net electrical efficiency exceeded the level of steam turbine plants, with intermediate superheating of the steam, and could reach a value of 49.4% at 600 °C. This makes the use of these cycles promising for low-power nuclear power plants with a high initial temperature. In small gas-cooled reactor plants with a helium coolant, the use of a binary cycle consisting of a helium Brayton cycle and a steam-powered Rankine cycle provided an efficiency of 44.3% at an initial helium temperature of 700 °C and 52.9% at 1000 °C. This was higher than in the Brayton cycle with a recuperator, with a minimum temperature difference in the heat exchanger of 20 °C: the efficiency was 40.2% and 52%, respectively. Also, the transition to power cycles with non-traditional working fluids will lead to a change in the operating conditions of turbomachines and heat exchangers.

Thermodynamic and economic performance comparison of biomass gasification oxy-fuel combustion power plant in different gasifying atmospheres using advanced exergy and exergoeconomic approach

Regarding the growing concern about carbon emission and environmental pollution, biomass has received extensive attention as renewable energy because of environmentally friendly and carbon-neutral. To enhance the utilization of biomass energy and reduce carbon emission, a biomass gasification oxy-fuel combustion power system is established. Advanced exergy and exergoeconomic analyses are applied to evaluate the system in different gasifying atmospheres of air, steam, and air/steam. The air, steam, and air/steam systems have exergy destruction of 155.9 MW, 163.2 MW, and 199.5 MW, and exergy efficiency of 43.47%, 49.48%, and 40.17%. The operating cost of the air, steam, and air/steam system is 305556.4 $/h, 393550.0 $/h, and 276284.8 $/h, and the annualized cost is 64.1 M$, 74.7 M$, and 63.9 M$, respectively. The thermodynamic improvement potential is 25.97% for the air system, 32.29% for the steam system, and 24.91% for the air/steam system. The avoidable cost ratios of the three systems are above 70%, suggesting a high cost-saving potential. The results reveal the effects of gasifying agents on the biomass gasification power system. Strategies are proposed for system improvement based on the advanced exergy and exergoeconomic analysis.

Generalized thermodynamic modeling of hydrogen storage tanks for truck application

Hydrogen-driven heavy-duty trucks are a promising technology for reducing CO2 emissions in the transportation sector. Thus, storing hydrogen efficiently onboard is vital. The three available or currently developed physical hydrogen storage technologies (compressed gaseous, subcooled liquid, and cryo-compressed hydrogen) are promising solutions. For a profound thermodynamic comparison of these storage systems, a universally applicable model is required. Thus, this article introduces a generalized thermodynamic model and conducts thermodynamic comparisons in terms of typical drive cycle scenarios. Therefore, a model introduced by Hamacher et al. [1] for cryo-compressed hydrogen tanks is generalized by means of an explicit model formulation using the property cv2P from REFPROP [2], which is understood as a generic specific isochoric two-phase heat capacity. Due to an implemented decision logic, minor changes to the equation system are automatically made whenever the operation mode or phase of the tank changes. The resulting model can simulate all three storage tank systems in all operating scenarios and conditions in the single- and two-phase region. Additionally, the explicit model formulation provides deeper insights into the thermodynamic processes in the tank. The model is applied to the three physical hydrogen storage technologies to compare drive cycles, heat requirement, dormancy behavior, and optimal usable density. The highest driving ranges were achieved with cryo-compressed hydrogen, however, it also comes with higher heating requirements compared to subcooled liquid hydrogen.

A thermodynamic comparison of membrane-assisted processes for hydrogen production with integrated CO2 capture

The energy efficiency of two novel process designs for the production of ultra-pure hydrogen with simultaneous capture of CO2 using CH4 as the feedstock, namely membrane-assisted chemical looping reforming (MA-CLR) and membrane-assisted sorption-enhanced reforming (MA-SER) has been compared. The modelling of the integrated network for mass and heat balances has been carried out using the ASPEN® Plus V10 process simulation tool to quantify the benefits and disadvantages of integrating hydrogen perm-selective membranes with either chemical looping or sorption-enhanced reforming. The evaluation of the MA-CLR process is carried out for a range of the following operating conditions: 10 < pR < 60 bar, 500 < TR < 900°C, and 1.5 < H2O/CH4 < 3.0. On the other hand, for the MA-SER process the operation ranges of 1.0 < pR < 10 bar, 400 < TR < 900°C, and 2.5 < H2O/CH4 < 4.0 were considered. Within the operation window of the MA-SER process, no carbon formation is observed, as any carbon present in the system reacts with CaO in the form of CO2. However, in the case of the MA-CLR process, carbon formation can occur during the pre-reforming stage, particularly at low H2O/CH4 ratios. In terms of hydrogen yield, energy utilization and carbon capture, the MA-CLR outperforms the MA-SER plant. However, the MA-SER plant offers certain advantages over the MA-CLR system, such as a pure CO2 product stream and lower reactor design temperatures. In the MA-CLR system, a carbon capture rate of 99.8% and a hydrogen product yield of 74.4% are achieved, whereas the MA-SER plant achieves a carbon capture rate of 98.5% and a hydrogen product yield of 69.7%.

Assessing Efficient Waste Heat Recovery System for Marine Engine – A Thermodynamic Comparison of Organic Rankine Cycle and Kalina Cycle

Assessing Efficient Waste Heat Recovery System for Marine Engine – A Thermodynamic Comparison of Organic Rankine Cycle and Kalina Cycle

Research on two novel hydrogen-electricity-heat polygeneration systems using very-high-temperature gas-cooled reactor and hybrid-sulfur cycle

The combination of the hybrid-sulfur (HyS) cycle with a very-high-temperature gas-cooled reactor (VHTR) presents a promising nuclear hydrogen production technology. This study proposes two novel hydrogen-electricity-heat polygeneration systems using VHTR and HyS cycle. A thermodynamic model is developed via energy and exergy analyses. Thermodynamic performance analysis and comparison are conducted on the two systems. For the two systems under design basis condition, the recommended variation range of the split ratio is 0–0.6395 and the hydrogen production rate is 0–55.7 mol/s. For systems 1 and 2, the energy utilization efficiencies are 65.91 % and 64.53 %, and the exergy efficiencies are 68.55 % and 67.36 %, at a hydrogen production rate of 55.7 mol/s. The process heat supply unit, steam generator (SG) and HyS cycle exhibit the top three largest exergy loss coefficients of 6.32 %, 6.26 % and 4.21 % at the split ratio of 0.5; therefore, they are key units for improving system performance. The intermediate heat exchanger's primary-side helium outlet temperature and SG's secondary-side main steam temperature both affect the variation range of split ratio. A slightly lower main steam temperature can increase the maximum hydrogen production rate and maximum energy utilization efficiency.

Thermodynamic performance comparison of a SOFC system integrated with steam reforming and dry reforming by utilizing different fuels

This work investigates the thermodynamic analysis of syngas production from several fuels by steam reforming or dry reforming for SOFC-integrated systems. Four commonly used fuels are considered: methanol and glycerol (alcohols), methane, and diesel (hydrocarbons). The integrated system is modeled on Aspen Plus using the Gibbs free energy minimization method and a generic electrochemical model to assess the effect of critical parameters on system performance. The results indicate a carbon-free zone within the reformer, and alcohols provide better resistance to carbon deposition than hydrocarbon fuels. Elevating the reforming temperature and STCR/CTCR increases the hydrogen concentration of syngas while also avoiding carbon deposits in the external reformer. Increasing the temperature and fuel utilization factor of SOFCs has been found to enhance electrical efficiency but at the expense of diminished thermal and total efficiency. For given operating conditions, the electrical efficiencies of methanol, glycerol, methane, and diesel are observed to be 47%, 46%, 51%, and 49% for the SR-SOFC system, and 45%, 42%, 42%, and 33% for the DR-SOFC system, respectively. The methane-SR-SOFC and methanol-DR-SOFC systems have the highest electrical efficiency, while diesel is unsuitable for the DR-SOFC system. This work can advise engineers to select the appropriate fuel types and reform technologies for SOFC-integrated systems.

Modeling of the adsorption of acidic dyes by chitosan using both kinetic and thermodynamic comparisons

Two chitosans from two different sources crab shell chitosan (CC) and deep-pink shrimp chitosan (CP) were used in a batch system to test the adsorption of two acidic dyes, Acid Red 183 (AR183) and Acid Red 114 (AR114), and the results were compared with those of acid-washed powdered activated carbon (PAC). The effects of temperature, contact time, and starting dye concentration on the removal of AR114 and AR183 dye were investigated in a series of batch adsorption studies. The two chitosans had the highest dye absorption capacity for each AR dye-adsorbent system at 45 °C. The capacity of each adsorbent to adsorb increased when the initial dye concentration was increased up to 500 mg L−1. Chitosan CP was the most efficient of the three adsorbents, with maximum AR114 and AR183 absorption of 440 and 447 mg g−1, respectively, at 45 °C. At all concentrations and temperatures examined, the pseudo-second-order kinetic model accurately represented the adsorption kinetics, and the rate constants of second-order adsorption (k2) at these temperatures were calculated, respectively. The thermodynamic study revealed that the adsorption of dyes on chitosans was feasible, spontaneous, and endothermic process, and the adsorption of the dyes on each adsorbent may be chemical in nature. Results indicated that the synthesized chitosans were shown to be a promising adsorbent for the removal of dyes from aqueous solutions.

Thermodynamic comparison of the operation of the HDH system with water heating or air heating in closed water circulation and semi-open-air circulation

The present study focuses on doing a thermodynamic analysis of a desalination system that utilizes the humidification–dehumidification (HDH) process with semi-open-air (SOA) circulation. The HDH desalination system is a notable example of a developed system utilized for freshwater production. This system has the advantage of being able to derive its energy from solar sources. The categorization of desalination units is determined by the configuration of their components, the direction of water and air movement, and the kind of heating employed for each stream. The present study noted that the utilization of this particular air circulation strategy, while maintaining a constant maximum system temperature, leads to enhanced system efficiency when combined with water heating. However, no substantial impact was detected when this method was employed in conjunction with air heating (AH). Each type of HDH desalination system has a different ratio of mass flow rates (MFRs) for the streams. This means that the efficiency of the system stays the same, no matter how the air moves through the system. The examination of temperature and relative humidity characteristics in the environment has indicated that this particular desalination unit is applicable in places characterized by both arid and humid conditions. Furthermore, in both air and water heating modes, it has been observed that the system employing SOA circulation has superior efficiency when the environment temperature is elevated. In the context of water and/or air heating, when a specific value is assigned to the MFR ratio of the two streams, modifying the mode of air circulation does not have an impact on the overall efficiency of the system. It is shown in this article for HDH with air heater the highest GOR is attained at either FCR = 1 or FCR = 0, depending on the operational temperature of the system. Also The system clearly works at its most efficient (GOR = 3.4) when it's in a Semi-open-air mode (FRC = 0.77) and the temperature is 50 °C. On the other hand, the system efficiency is 2.94 when the air exchange system is closed (FRC = 1). In the same way, the overall efficiency is 2.88 if the air flow is open (FRC = 0).

Hydrogen production via steam reforming of different fuels: thermodynamic comparison

Hydrogen, a sustainable energy source, has potential to address climate change. However, traditional steam reforming processes produce CO2. Alternative fuels like bio-alcohols, biogas, and LPG are being adopted for steam reforming processes. This study presents a thermodynamic comparative examination of steam reforming processes employing different fuels, including methane, methanol, ethanol, propane, glycerol, and biogas. The analysis focuses on the hydrogen yield, environmental impact, and energy requirements of these processes and a comparison with experimental results. The analyses were conducted using AspenPlus® software, minimizing the Gibbs free energy under specified conditions (T = 25–1000 °C, n = 1–10, P = 1–40 bar). Among the fuels examined, methanol, biogas, and methane exhibited the highest hydrogen yields, reaching maximum values of 96.10 %, 95.86 %, and 95.26 % respectively at 600 °C, 1 bar, and a water-to-fuel ratio of 10. Ethanol, glycerol, and propane achieved yields of 89.66 %, 86.55 %, and 84.03 % respectively at 700 °C and the same pressure and water-to-fuel ratio.

Milk Protein Hydrolysis by Actinidin-Kinetic and Thermodynamic Characterisation and Comparison to Bromelain and Papain.

Plant proteases, including actinidin, papain and bromelain, have been widely used in the food industry but with limited application in dairy systems. This research aimed to establish and compare operational parameters (kinetics, temperature, enzyme type, time and thermodynamics) relevant to the applications of these enzymes in the hydrolysis of whey protein isolates (WPI), whey protein concentrates (WPC) or milk protein concentrates (MPC). The degree of hydrolysis (DH) increased with the rise in temperature, and the maximum DH was achieved at 60 °C for all three dairy systems. The addition of papain resulted in a greater %DH of whey proteins in comparison to bromelain. The cleavage of proteins was clearly time-dependent (p < 0.05), while the pH did not change significantly (p > 0.05) during this time. PAGE analysis revealed that all three enzymes mainly acted on α-lactalbumin and αs-casein in WPI and MPC, respectively. Kinetic parameters from the Lineweaver-Burk plot at 60 °C using WPC and MPC as a substrate varied widely, establishing that WPC hydrolysis was characterised by a lower KM, higher kcat, kcat/KM and Vmax compared to MPC in the case of all three enzymes. The difference in kcat/KM values amongst all enzymes (actinidin > papain > bromelain) indicated the difference in the strength of substrate binding sites. The thermodynamic parameters of these enzymes with MPC and WPC were also determined at a temperature range of 15-60 °C, and the results indicate the potential application of papain and actinidin in the dairy industry.

Energy, exergy, economic and environmental (4E) analysis of two-stage cascade, Linder-Hampson and reverse Brayton systems in the temperature range from −120 °C to −60 °C

Cryopreservation in the temperature range from −120 °C to −60 °C is an important way to achieve high-quality food storage. In this paper, an in-depth quantitative thermodynamic comparison of two-stage cascade cycle, Linde-Hampson cycle and reverse Brayton cycle was carried out in the temperature range from −120 °C to −60 °C. Aspen HYSYS was used to invoke advanced genetic algorithm in MATLAB to optimize the system parameters. The two-stage cascade system performs best at the evaporation temperatures above −80 °C, achieving a COP of 0.97 at −60 °C. The Linder-Hampson system performs best when the evaporation temperature is below −90 °C, achieving a COP of 0.35 at −120 °C. In order to further explore the impact of environmental change on the system performance, five typical cities in China were selected to analyze the seasonal performances of the three systems. The seasonal analysis demonstrated that Harbin has the highest latitude and its seasonal energy efficiency ratio is significantly higher than other cities, the performance of the two-stage cascade system fluctuates more obvious within 24-h. What's more, the Linder-Hampson system has the lowest annual investment cost and annual operating cost at the evaporation temperature lower than −90 °C, as well as the lowest emissions of CO2 and SO2.

Thermodynamic comparison of magnetocaloric and vapor compression wine coolers

This paper presents a comparison of the thermodynamic performances of magnetocaloric and vapor compression cooling technologies when operating the same wine cooler cabinet. The vapor compression system used is a commercially available 31-bottle domestic wine cooler, while the magnetocaloric cooling device is a state-of-the-art (TRL-5) prototype connected to the retrofitted wine cooler cabinet. The test procedures involved characterizing the unsteady and steady-state behavior of both technologies. Detailed instrumentation of both systems allowed for a unique low-level performance comparison, considering first- and second-law-based parameters, which has not been explored in the literature. Overall, the wine cooler was found to be more efficient when operated by the vapor compression system. For an ambient temperature of 25 °C and a cabinet temperature of approximately 12 °C, the coefficient of performance (COP) and second-law efficiency of the wine cooler were 0.7 and 3.6% respectively when using the vapor compression system, whereas they were 0.49 and 2.0% respectively when using the magnetocaloric refrigerator system. However, despite the contrast between the internally ideal coefficient of performance of the magnetocaloric wine cooler and the vapor compression wine cooler, significant but realistic design improvements were suggested. These suggestions were evaluated and quantified using a system-level magnetocaloric refrigerator model. The numerical results indicate that with changes in the current pumping system and magnetocaloric materials, an improved version of the magnetocaloric wine cooler could surpass the COP of its original version by 88% and the vapor compression system by 31%.