High Thermodynamic Efficiency Research Articles

Application of dividing wall column in azeotropic distillation with intermediate boiling-point heteroazeotrope: Simulation and optimization

Dividing wall column (DWC), as a proven process intensification technology, has been used widely in separation of ideal multi-components, and some azeotrope systems. For heterogeneous azeotrope with the potential possibility of crossing distillation boundary by liquid-liquid splitting, it is advantageous to integrate liquid-liquid decanter with distillation column, especially with DWC to further simplify flowsheets and reduce energy consumption. In this work, existing heterogeneous azeotrope separation processes are described, and an innovative DWC-based process (MHADWC) is proposed for intermediate boiling-point heteroazeotropic systems. Then an industrial case of MIPK system, is used to evaluate mentioned configurations by rigorous simulation and optimization. These configurations are compared and analyzed in detail on energy consumption, exergy analysis and equipment invest. The results show that, from the perspective of process energy consumption, MHADWC process has the most advantages, because it saves 37% of energy consumption; if both equipment costs and exergy recovery are taken into account, HADWC2 has a higher thermodynamic efficiency (43.5%) at its TAC and can be used as a preferred target. And in this work, purification of an intermediate boiling-point heteroazeotrope is the main difference of these processes compared with the well-known heterogeneous azeotropic distillation process where the top vapor product is the lowest boiling point of the ternary system.

Numerical study of air-breathing two-phase rotating detonation engine under Ma 6 flight conditions

Air-breathing two-phase rotating detonation engines possess high thermodynamic cycle efficiency and have attracted extensive attention in domain of wide range flight aircraft. In this study, an engine configuration is proposed, and the corresponding numerical model is established using the Euler-Lagrange method. The engine type is suitable for flying at an altitude of 28 kilometers and a flying speed of Ma 6. Our data show that the engine operates primarily in chaos in this flight state. The peak pressure of the detonation wave is about 0.85 MPa, the peak temperature of the detonation wave is about 4500 K, the average thrust of the engine is 2637 N, and the average fuel-specific impulse is about 2989 s.

Influences of thermal physical property parameters on operating characteristics of simulated rotating detonation ramjet fueled by C12H23

Two-phase rotating detonation ramjets are considered to be suitable for aerospace applications due to their high thermodynamic cycle efficiency. These engines have an extremely complex internal flow field, in which the liquid fuel undergoes physical and chemical processes such as fragmentation, evaporation, mixing, and combustion; these processes also interact with detonation waves that have significant gradients. This makes it difficult to simulate a three-dimensional (3D) full-process rotating detonation combustion chamber. Here, based on the Euler–Lagrangian simulation method, a 3D numerical combustion chamber was simulated using kinetic theory and the constant thermal physical property parameter (TPPP) calculation method. The accuracy of these methods was then compared with the existing experimental results and theoretical values. Calculating the TPPPs using kinetic theory brought about a relatively high-pressure peak and detonation wave temperature; the detonation wave profile was also finer and more precise. The detonation wave propagation velocity of the two-phase detonation is estimated to be about 60% of the theoretical gas-phase CJ velocity. The calculation method of physical parameters has relatively little influence on the engine’s operating frequency and the detonation wave's propagation velocity but has a more significant influence on the peak pressure. Constant TPPPs can be used when the Kelvin–Helmholtz–Rayleigh–Taylor model with insufficient precision is used to consider the breakup of droplets and leads to the acceleration of the propagation speed of two-phase detonation waves.

Methanol production from natural gas reforming and CO2 capturing process, simulation, design, and technical-economic analysis

In this paper, a methanol production process with high thermodynamic efficiency and a low production cost is presented. The proposed process is based on steam methane reforming, in which carbon dioxide (CO2) captured from a power plant flue gas is employed to improve the stoichiometric number, methanol efficiency, and carbon efficiency and increase CO2 conversion. In addition to the sensitivity analysis, comprehensive technical, economic, and environmental analyses are performed. Furthermore, the obtained results of this paper are compared to those of previous studies. A parametric study showed that the optimum steam-to-methane ratio is 3.75, and the optimum flow rate for CO2 utilization is 140 kmol/h. From the economic point of view, it is demonstrated that the total annual cost is 11,799,484 USD, and the total production cost rate is 0.1 $/kg. The environmental analysis showed that the total net CO2 emission in this process is 6580.64 kg/h, and for producing 1 kg of methanol, 0.41 kg of CO2 is emitted.

Multi-aspect comparative analyses of two innovative methanol and power cogeneration systems from two different sources

This study aims to develop two economically viable processes with high thermodynamic efficiency for the cogeneration of methanol and electricity from coke oven gas and blast furnace gas. In process A, syngas is obtained from coke oven gas reforming, and blast furnace gas, after providing the required heat for the reformer, is injected into the methanol synthesis reactor as a rich carbon source. In process B, in addition to coke oven gas and blast furnace gas, additional hydrogen produced by the proton exchange membrane electrolyzer is injected into the methanol reactor to enhance CO2 conversion. The performance of the proposed systems is evaluated using parameters like energy efficiency, exergy efficiency, net CO2 emission, and total production cost. Results show that energy efficiencies for processes A and B are 53.53% and 67.4%, and their exergy efficiencies are 23% and 25.12%, respectively. Moreover, environmental analysis demonstrates that process B has a net CO2 emission of −1.818 kgCO2/kgmethanol, while for process A, this parameter is relatively higher, and it is positive. From the economic viewpoint, it is concluded that process B is more feasible, and the total production cost of methanol decreases by 55.51% compared to process A.

What If Electrochemical Energy Systems Were Made 40% More Efficient?

Electrochemical systems related to energy storage and generation have inherent thermodynamic advantages over thermal energy systems because electrochemical systems have do not require moving parts. Thermodynamic Carnot limitations restrict internal combustion engines (ICEs) to about 40% theoretical energy conversion efficiencies. Thermodynamically, electrochemical energy systems can be 100 % efficient. The high thermodynamic efficiency is however challenged by dynamics of kinetics and transport. Because electrochemical energy systems generally operate at lower temperatures and pressures than ICEs, greater finesse in design of catalysis is needed.Electrochemical energy systems made 40% more efficient would substantially advance the economic and environmental advantages of electrochemical electrochemical energy. Consider mechanisms of physical catalysis where a physical gradient rather than a chemical composition drives chemical change. Magnetoelectrocatalysis is an example of physical catalysis that may provide means to enhance the efficiency of electrochemical energy systems.Magnetoelectrocatalysis exploits magnetic gradients imposed at electrode surfaces to facilitate electron transfer and so electrocatalysis.Here, magnetoelectrocatalysis is shown to increase energy, power, and conversion efficiency of several electrochemical energy systems by 40%. Examples include: Proton exchange membrane (PEM) fuel cellsAlkaline batteries (MnO2|Zn)Hydrogen evolution reaction (HER) at glassy carbonMnO2 supercapacitors Magnetic gradient effects on electrochemical efficiency are also observed for several environmentally relevant electrode reactions. CO oxidation on PtHER on various metal electrodes and photocathodesC1 reactions at rare earth electrocatalysts From these outcomes, it is suggested that magnetoelectrochemical catalysis may provide a path to substantially more efficient electrochemical energy systems, perhaps approaching 40%.Work is undertaken at the University of Iowa. The National Science Foundation (NSF CHE-1309366 and NSF CHE-0809745) and the Army Research Office (W911NF-19-1-0208 (74912-CH-II)) supported these projects.

Numerical modelling of a single stage adiabatic demagnetization refrigerator (ADR)

Adiabatic demagnetization refrigerators (ADR) are gaining traction for space applications due to their numerous advantages such as gravity independence, very high thermodynamic efficiency and absence of moving parts. A typical ADR consists of multitude of components such as salt pill, refrigerant, superconducting magnets, heat switches, etc. Its system design involves selection and optimization of multiple design parameters. To establish a holistic system design methodology, development of a numerical model is necessary to study the effect of various parameters on ADR system performance and to reduce developmental cost. In this work, a numerical model has been developed for performance prediction to optimize the various design parameters and the results are reported.

Assessment of methanol and electricity co-production plants based on coke oven gas and blast furnace gas utilization

This study aims to develop an economically viable novel process with high thermodynamic efficiency for the co-generation of methanol and electricity from coke oven gas (COG) and blast furnace gas (BFG). For this purpose, two processes are proposed to utilize COG and BFG. In process A, syngas is obtained from COG reforming, and BFG, after providing the required heat for the reformer, is injected into the methanol synthesis reactor as a rich carbon source. In process B, in addition to the above-mentioned, additional hydrogen is injected into the methanol reactor to enhance carbon dioxide conversion. The performance of the proposed systems is evaluated using energy efficiency, exergy efficiency, net CO2 emission, and total production cost. Results show that energy efficiencies for processes A and B are 53.53% and 72.8%, and their exergy efficiencies are 23% and 26%, respectively. Moreover, environmental analysis demonstrates that process B has a net CO2 emission of −1.82 kgCO2/kgmethanol, while for process A, this parameter is relatively higher, and it is positive. From the economic viewpoint, it is concluded that process B is more feasible, and the total production cost of methanol decreases by 87.62% compared to process A. Also, it can be deduced that in the case of utilizing additional hydrogen electricity and methanol production from COG and BFG is interesting from the thermodynamic and economic point of view, and due to negative net CO2 emission, it is environmentally desirable, too.

Direct Comparison of Schlieren and Soot Foil Measurements of Detonation Cell Sizes

Detonation-based combustion cycles have the potential to have higher thermodynamic efficiencies than the more common deflagration-based combustion cycles because the pressure of the products is higher than that of the reactants. The geometry to which a detonation is confined can have a strong influence on the detonation’s behavior, or even prevent a detonation from occurring. A key measurement that can be used to design detonation-based engines is the cell size of the mixture. The cell size is a characteristic length scale of a chemical mixture. For the first time, this study compares two methods of collecting cell size measurements within a single tube. This approach controls for the effects of tube geometry and surface roughness, which may confound studies whose schlieren and soot foil measurements have been collected from different tubes. This study indicates that measurements taken using the two measurement techniques agree to within experimental uncertainty (a difference of 1.3 mm, or 7%). Soot foil methods are generally preferable for detonation cell size measurements because soot foils provide larger triple point sample sizes per detonation and lower instrumentation costs relative to schlieren methods. Various sources of uncertainty are extensively analyzed and reported for the two techniques.

Study of increasing thermodynamic efficiency and hydrogen amount in the process of solid fuels and biomass gasification

The effect of fuel composition such as hard coal and biomass in fluidized bed on the thermodynamic efficiency of three gasifier types, low heating value (LHV) and syngas composition was studied by simulation in CFD program. The paper presents various small gasification systems with fluidized bed of water-coal mixture and water-biomass mixture both with oxygen (air) and without oxygen. The work presents the extended mathematical model of gasification process taking into account also 13 kinetic chemical reactions enabled to apply them in CFD program. The chemical model is based on surface reactions given in the model of Equivalent Reactor Network (ERN) in Ansys Energetico. Simulation of gasification of different reactor designs enabled to obtain the mass concentration of chemical compounds in the syngas which influenced on thermodynamic efficiency and LHV. Additionally, heating of the gasifier walls by electrical system without air gives higher mass ratio of hydrogen (15%) and carbon monoxide (75%) in the syngas than in the oxidized gasification system. The simulation tests showed high thermodynamic efficiency, taking into account the exergy above 80%, both for the oxygen gasification of hard coal-slurry and biomass as well as for the externally heated gasifier without the supply of oxygen. The highest thermodynamic efficiency 90.5% was obtained during gasification of energy willow in the oxidation reactor due to the large difference in LHV of syngas and fuel. Obtaining the maximum possible mass ratio of H2 in syngas and a high thermal efficiency for the OXGR system from the gasification of subbituminous coal dust occurs at a ratio C/O2 = 0.314 and at almost stoichiometric ratio of C/H2O = 0.63. In the case of gasification of biomass in the form of finely ground energy willow in the OXGR system, these ratios were respectively: O2/C = 1.82 and C/H2O = 0.47. While maintaining the almost stoichiometric ratio C/H2O = 0.75, resulting from the water-gas shift reaction, low heating value of the syngas for the analysed gasification systems was over 25 MJ/kg. The paper shows comparison of mass fractions of CO, H2, H2O, H2S, CO2, O2, CH4, tar and other chemical compounds in the syngas. Application of the gasification reactor with external heated walls and without oxygen inflow produces the syngas without tar and volatile species in comparison to the systems with additional oxygen supply. In oxidized reactors the syngas contains a large amount of CO2 about 25–30% of total mass.

Thrust Chamber Dynamic and Propulsive Performance of Biofuels Under Detonation Combustion

Detonation is a shock wave obtained from the energy that releases after the combustion. Chapman-Jouguet(CJ) theory can be used to identify the behaviour of the detonation in gasses. Pulse Detonation Engines (PDEs) is one of the engines that implement the detonation in its combustion system. The Humphrey cycle is the thermodynamic cycle which is similar to the Pulse Detonation Engines (PDEs). It is the modification of the Brayton cycle where the constant-pressure heat addition process of the Brayton cycle is replaced by a constant-volume heat addition process. The Humphrey cycle can provide the pressure rise combustion by utilizing the shock inside the combustion chamber. Compared to the Brayton cycle, the Humphrey cycle has higher thermodynamic efficiency. However, the detonation process has unsteady combustion which makes it more difficult to handle. The purpose of the study is to calculate the performance of the aircraft by using alternative fuel in the ZND model. An analytical model is started by having the molecular structure of each biofuel and it has been used to determine detonation velocity, Mach number at C-J point, temperature ratio, pressure ratio, density ratio, Brayton and Humphrey efficiency, specific impulse, and specific thrust. In addition, the physical properties of the flow are investigated by changing the initial temperature, initial pressure, and mass flux. The pressure ratio, temperature ratio, and density ratio will all decrease as the initial pressure varies. The variation of mass flux and initial temperature, on the other hand, generates the opposite outcome as the change of pressure. The feasibility of the fuels in the detonation combustion can be known as they show high propulsive performance after the initial condition is changing.

An advanced optimization strategy for enhancing the performance of a hybrid pressure-swing distillation process in effective binary-azeotrope separation

The separation of binary azeotropes with low cost and energy consumption is important and challenging for the production of chemicals. A hybrid heat-integrated pressure-swing distillation process (HHIPSD) with heat pump was proposed for the separation of both maximum- and minimum-boiling azeotropes in this work. Compared to the conventional fully heat-integrated pressure-swing distillation process (FHIPSD), the HHIPSD process showed lower total annual cost and higher thermodynamic efficiency in the separation of seven minimum-boiling azeotropes of benzene-ethanol, methanol-acetone, methanol-ethyl acetate (EA), ethanol-EA, acetonitrile-ethanol, isobutanol (IBA)/isobutyl acetate (IBAc) and diisopropyl ether (DIPE)-isopropyl alcohol (IPA), and two maximum-boiling azeotropes of water-ethylenediamine (EDA) and acetone-chloroform. For the best performance of HHIPSD process, robustness and algorithm optimization were studied in this paper. Scenario analysis method was proven to greatly enhance the convergence of HHIPSD models. The improved genetic algorithm (GA) was modified by particle-swarm optimization and pattern search method and validated by 13 benchmark functions. Meanwhile, different constraint handling methods were studied to ensure the better performance of the improve GA method. With the improvement of model robustness and optimization algorithm, the HHIPSD process achieved 21.6 % and 4.2 % decrease of TAC for water-EDA and methanol-acetone separation, respectively, compared to FHIPSD process. The proposed HHIPSD process together with the optimization strategy suggests the pressure-swing distillation technology can be highly effective in azeotrope separation.

Desalination Fuel Cells with High Thermodynamic Energy Efficiency.

Sustainably-produced hydrogen is currently intensively investigated as an energy carrier to replace fossil fuels. We here characterize an emerging electrochemical cell termed a desalination fuel cell (DFC) that can continuously generate electricity and desalinate water while using hydrogen and oxygen gases as inputs. We investigated two operational modes, a near-neutral pH operation with H2, O2, and feedwater inputs (H2|O2), and a pH-gradient mode with H2, O2, feedwater, acid, and base inputs (H2 + B|O2 + A). We show that our cell can desalinate water with 30 g/L of salt content to near-zero salt concentration, while generating an enormous amount of electricity of up to 8.6 kW h per m3 of treated water when operated in the pH-gradient mode and up to about 1 kW h per m3 for the near-neutral mode. We quantify the thermodynamic energy efficiency of our device in both operational modes, showing that significantly higher efficiency is achievable in the pH-gradient mode, with up to 95.6%. Further, we present results elucidating the key bottlenecks in the DFC process, showing that the cell current and voltage are limited in the near-neutral pH operation due to a lack of H+ to serve as a reactant, and further reinforce the deleterious effect of halide poisoning on the cathode Pt catalyst and cell open circuit voltage. Such findings demonstrate that new fuel cell catalyst materials, tailored for environments associated with water treatment, can unlock yet-improved performance.

Theoretical Thermodynamic Efficiency Limit of Isothermal Solar Fuel Generation from H2O/CO2 Splitting in Membrane Reactors

Solar fuel generation from thermochemical H2O or CO2 splitting is a promising and attractive approach for harvesting fuel without CO2 emissions. Yet, low conversion and high reaction temperature restrict its application. One method of increasing conversion at a lower temperature is to implement oxygen permeable membranes (OPM) into a membrane reactor configuration. This allows for the selective separation of generated oxygen and causes a forward shift in the equilibrium of H2O or CO2 splitting reactions. In this research, solar-driven fuel production via H2O or CO2 splitting with an OPM reactor is modeled in isothermal operation, with an emphasis on the calculation of the theoretical thermodynamic efficiency of the system. In addition to the energy required for the high temperature of the reaction, the energy required for maintaining low oxygen permeate pressure for oxygen removal has a large influence on the overall thermodynamic efficiency. The theoretical first-law thermodynamic efficiency is calculated using separation exergy, an electrochemical O2 pump, and a vacuum pump, which shows a maximum efficiency of 63.8%, 61.7%, and 8.00% for H2O splitting, respectively, and 63.6%, 61.5%, and 16.7% for CO2 splitting, respectively, in a temperature range of 800 °C to 2000 °C. The theoretical second-law thermodynamic efficiency is 55.7% and 65.7% for both H2O splitting and CO2 splitting at 2000 °C. An efficient O2 separation method is extremely crucial to achieve high thermodynamic efficiency, especially in the separation efficiency range of 0–20% and in relatively low reaction temperatures. This research is also applicable in other isothermal H2O or CO2 splitting systems (e.g., chemical cycling) due to similar thermodynamics.

THEORICAL STUDY ON PROPULSIVE PERFORMANCE OF OBLIQUE DETONATION ENGINE

Detonation combustion is characterized by the high thermodynamic efficiency and fast heat release. Benefitting from these potential advantages, an oblique detonation wave (ODW) is introduced into the combustion chamber and oblique detonation engine (ODE) plays an important role in hypersonic air-breathing propulsion systems. Previous studies mainly focused on the initiation structures, standing features and wave systems of oblique detonation, but the global analysis of ODE propulsive performance is still absent at the macro-level. In this paper, the flow and combustion processes of an ODE are decomposed into four basic modules, named as inlet model, mixing model, combustion mode and nozzle model, respectively. We solve these four basic flow processes using theoretical methods and propose a systematically theoretical approach that can be used to predict the ODE propulsion performance. On the basis of previous ODW initiation structures and waves systems, four different combustion modes, i.e., over-driven ODW, Chapman-Jouguet ODW, over-driven normal detonation wave and oblique shock-induced constant-volume combustion, are chosen to describe the heat release processes of combustible mixture in the ODE combustor. The effects of different combustion modes on fuel specific impulse of the ODE are also analyzed. In addition, the influence mechanisms of inflow parameters, combustor parameters and intake-exhaust parameters on the thrust performance of ODE are also obtained, and the results show that the major factor of fuel specific impulse of an ODE consists mainly of the inflow Mach number and the expansion ratio of engine nozzle. Finally, combined with precious detonation research results, such as the standing features and initiation structures of oblique detonation in a confined space, the preliminary design direction of oblique detonation engine are proposed, which mainly involve some constrained conditions, such as geometrical constraints, inflow velocity limitations and stability ranges of a detonation wave in ODE combustor.

Thermo-economic-environmental analysis of an innovative combined cooling and power system integrating Solid Oxide Fuel Cell, Supercritical CO2 cycle, and ejector refrigeration cycle

A novel combined cooling and power system integrating Solid Oxide Fuel Cell (SOFC), Supercritical CO2 (SCO2) partial heating cycle, and ejector refrigeration cycle is proposed, and the energy, exergy, exergoeconomic, and environmental analysis is performed to evaluate the system performance comprehensively. The parametric analysis is conducted to investigate the effects of six thermodynamic variables (i.e. fuel flow rate, excess air ratio, fuel utilization factor, turbine inlet temperature, SCO2 cycle pressure ratio, and SCO2 cycle split ratio) on the system performance. The results indicate that the lower total product unit cost conflicts with the higher thermodynamic efficiencies and lower CO2 specific emission. Therefore, multi-objective optimization is carried out to obtain a trade-off among thermodynamic, exergoeconomic, and environmental performances. Under the optimal condition, the exergy efficiency, total product unit cost, and CO2 specific emission of the system are 63.77%, 36.37 $/GJ, and 298.77 g/kWh respectively, and the system can achieve the power output of 168.95 kW and cooling output of 12.48 kW. The SOFC accounts for the largest part (15.72%) of the total exergy destruction and achieves the highest cost rate (6.90 $/h) with a high exergoeconomic factor of 90.90%, indicating its capital investment can be reduced for improving system cost-effectiveness.

Modeling and Techno-Economic Analysis of High Temperature Electrolysis Systems Using Protonic Ceramics

High temperature water splitting (HTWS) via electrochemical processes are of growing interest due to their potential for achieving high thermodynamic efficiency. In particular, protonic ceramic electrolysis cells (PCECs) operating between 500°-600°C have the attractive feature that, in theory, pure dry hydrogen is produced at the hydrogen electrode (see Figure 1) and, unlike more conventional solid oxide electrochemical cells (SOECs) operating at 800°C, no further gas separation is needed. These features allow much simpler and elegant hydrogen production system concepts that have the potential to be significantly less costly and more efficient. For example, the dry H2 gas production at the fuel electrode allows for a much simpler balance-of-plant. The lower operating temperature also has numerous benefits, including lower plant heat losses, the ability to find more options for integrating various process heat sources by virtue of the lower grade heat requirements, and reduced capital cost due to a reduction in both gas process heat exchanger temperature and surface area requirements. A simple thermodynamic evaluation indicates that balance-of-plant steam generation specific energy (kJ/kg) requirements are some 17% lower when operating at 500°C versus 800°C.The present work focuses on scale-up of advancing PCEC material sets developed by collaborating faculty at the Colorado School of Mines and an industrial partner, and their design/integration into MW-scale hydrogen production systems. Realizing high efficiency HTWS systems based on novel protonic ceramics requires understanding of numerous system-level considerations. One of our efforts is largely concerned with developing viable system designs that enable >75% system efficiency at centralized hydrogen production costs of < $2/kg (without compression, dispensing, and storage). This requires evaluation of plant operating conditions, especially in the PCEC stack periphery, where operating temperature, pressure, reactant utilization, sweep gas (if any) on the fuel electrode, thermal management, gas compression, and balance-of-plant integration all play critical roles in establishing cost effective, high performance HTWS systems. In this presentation, validated PCEC models using the latest large platform experimental cell data are used to explore optimal stack design parameter selection, such as cell voltage, reactant utilization, and reactant supply composition. System design implications from parameter sensitivity studies is summarized, and a comparative techno-economic analysis of PCEC-based hydrogen production systems with SOEC and PEMEC technologies is given. Figure 1

Process intensification in ternary distillation via comparative grassroots and retrofit designs: A case study of distilling an industrial multicomponent C6 alkane mixture in caprolactam processing

A systematic process intensification method via comparative grassroots and retrofit designs for distillation is proposed. Restricting to the ternary system, a case study of multicomponent C6 alkane separation in caprolactam processing is considered. The existing benchmark flowsheet of direct sequence (DS) features high economic cost but low thermodynamic efficiency. Through the investigation of the composition profile, two middle component remixing peaks and a large feed mismatch are diagnosed as the reasons of inefficiency. To achieve process intensification, potential candidates like side stream column (SSC) and dividing wall column (DWC) are enumerated and evaluated in the grassroots design step. Although DWC performs the best in thermodynamic efficiency, SSC is more preferred for retrofit as its structure is simple but has similar performance. To maximally reuse the existing equipment, two retrofit proposals of either indirect sequence (IS) or SSC are provided based on the grassroots design results. Among them, retrofitted SSC is recommended for long expected lifespan situation, while IS is more suitable for a short one. It is recommended that the proposed process intensification procedure can be extended to other similar processes or systems with more components, through enumerating and comparing the several best but similar grassroots designs with benchmark process.

Energy-saving investigation and techno-economic analysis of separation of ibuprofen sodium mother liquor using thermally coupled distillation

To further reduce the energy consumption, investment and operation cost of the distillation process, DWC-B and FTCDC are used to strengthen the separation process of ibuprofen sodium mother liquor. Based on the process simulation results, thermodynamic efficiency, economic and environmental impact assessment were carried out and compared with the benchmarked CTCD process. DWC-B and FTCDC have obvious advantages in economy, energy saving and environmental impact. Compared with the benchmarked CTCD process, the FTCDC process is more attractive economically, and its total annual cost is reduced by about 7.83%. The thermodynamic efficiency of DWC-B is 17.62%, and the CO2 emission is reduced by 11.39%. Compared with the benchmarked CTCD process, DWC-B and FTCDC have the advantages of high thermodynamic efficiency, low economic cost and low CO2 emission with a great industrial application prospect.

Dispatchable solar power using molten salt directly irradiated from above

Concentrating solar power (CSP) with thermal energy storage (TES) presents the major advantage over solar photovoltaics of dispatchability. High thermodynamic efficiencies achieved by collecting and storing heat at higher temperatures, and recent maturing of the technology, are making molten-salt central receiver plants the preferred option for CSP. To explore potential further improvements in CSP efficiency and cost the world’s first direct absorption molten salt volumetric receiver/storage system was built at pilot scale, commissioned and monitored. In this demonstration a 100 kWth beam-down tower directs solar radiation through a final concentrator into the open aperture of a 1.94 m high and 1.25 m internal diameter tank receiver situated near the ground. The receiver tank is filled with 3,800 kg of 60–40 wt% NaNO3-KNO3 and serves as a stratified or mixed single tank thermal store that can satisfy evening peak loads or provide baseload power through the night. Compared to the parasitic loads of a conventional tower-receiver plant, the energy needed for salt transport from receiver to TES and morning preheat is negligible for this new system. The hot-spot problem of tubular receivers is eliminated and. the combined receiver/storage tank reduces component costs. In-situ initial melting was accomplished using solar energy as the primary input. Thermal stratification was maintained by daily cycling of a divider plate and occasional mixing plate actions and hot spots were never observed during several months’ operation between 250 and 500 °C. Three cycles of complete salt freezing and in-situ on-sun re-melting were tested with no operational difficulty and no discernible damage.