Discharge Duration Research Articles

Techno-Economic Analysis of Using Reversible Turbomachinery for Pumped Thermal Energy Storage Systems

Abstract The objective of this paper is to assess the techno-economic performance of different cycle configurations for pumped thermal energy storage (PTES), including the effects of charging electricity costs. Reversible turbomachinery was employed to reduce the capital cost of the system. Brayton cycles with different working fluids and a subcritical Rankine cycle operating with ammonia were compared. Both liquid and packed bed thermal storages were investigated. A new cost correlation for turbomachines, initially established for the turbines of organic Rankine cycles, was developed for compressors and reversible machines. This correlation is based on the number of stages and physical size of the machine, which were estimated considering thermodynamic as well as mechanical limitations. The results indicate that for a plant size of 50 MW and a discharge duration of 8 h, the Brayton system with liquid storage and helium as a working fluid has the lowest levelized cost of storage at 0.138 $/kWh, mainly due to the high thermal conductivity of the fluid. Packed bed thermal energy storage systems were found to be more expensive than liquid storage systems due to the large cost of the pressure vessels, with cost parity reached at a discharge duration of 4 h. However, at this duration, lithium-ion batteries are likely to be cheaper. The results suggest that the levelized cost of storage for the Rankine cycle-based system is slightly higher at 0.151 $/kWh.

Full lifetime demonstration of a Micro-Cathode-Arc thruster evolution characteristics

Ground lifetime test is the most crucial experiment to assess the performance, reliability, and flight qualification of electric propulsion, and it can bring new insights for understanding the operation characteristics. This work demonstrates a full lifetime test of 140000 cycles on a Micro-Cathode-Arc Thruster (μCAT) with 160 μs charging time and 86 mJ charging energy. A four-probe resistivity measurement method is utilized to investigate variations in the conductive film thickness and resistivity throughout the thruster lifespan. Direct film parameters show that the lifetime of the μCAT can be divided into three stages. In the initial stage, the film thickness decreases by 1.2 μm and the resistivity increases significantly due to the high discharge intensity and intense film ablation; In the steady stage, the change of the film thickness is within 5%, and the resistivity of the film increases slowly from 0.050 Ω·mm to 0.223 Ω·mm. In the end stage, the resistivity exponentially increases from 0.223 Ω·mm to 1.176 Ω·mm, with the increase accounting for 81%, ultimately resulting in the failure of the thruster open circuit. Additionally, the evolution of discharge parameters, and the variation of plume parameters are measured throughout the lifetime. The discharge characteristics also show significant differences in the duration of voltage and current in these three stages. The results of plume shape and plasma parameters are also well consistent with the discharge parameters and film state. These results suggest that, for evaluating the steady stage lifetime of thrusters, the film thickness is the best indicator compared to the variations in resistivity and voltage-current characteristics. For the end stage, the plasma plume morphology, discharge duration, and plume parameters can conveniently and clearly characterize the thruster failures and irregularity.

Enhancing flood risk assessment in the Johor River Basin through trivariate copula

ABSTRACT Copulas are a vital statistical tool, particularly in hydrology, for understanding complex relationships among flood characteristics. This study focuses on three key flood features: peak discharge, flood volume, and flood duration, using trivariate copulas to capture their interdependencies. This is crucial because bivariate and univariate analyses fall short in considering all three factors simultaneously. To handle extreme flood values, L-moment is proposed over maximum likelihood estimation and inference function margin due to its enhanced reliability and susceptibility to outliers and extreme values. Akaike information criterion was employed to identify the best-fit marginal distribution and copula. The Lognormal distribution effectively models peak discharge, while Weibull and generalized extreme value distributions fit flood volume and duration best, respectively. Various copula families, including elliptical and Archimedean, are assessed, where Clayton copula emerge as the most suitable. This analysis demonstrates that when more flood features are considered together, the return period increases, indicating the reduced likelihood of occurrence. The trivariate case of the AND-joint return period surpasses the trivariate case of the OR-joint return period where the TP, V, DAND=5, 405.93 years, while TP, V, DOR=500.46 years. This comprehensive approach enhances hydrological modeling and decision-making for water resource management and flood mitigation projects.

Correlation between Clinical and Audiological Factors with Ossicular Chain Continuity in Chronic Otitis Media

Introduction: Chronic otitis media (COM) with the perforation of the tympanic membrane, myringoplasty is preferred treatment, but if ossicles are involved, myringoplasty is done with ossiculoplasty which is termed as tympanoplasty. Preoperative assessment of ossicular status is important to decide the type of tympanoplasty. Ossicular chain continuity is generally seen in the patient who has short duration of disease and smaller air–bone gap. Our study was conducted to support the relationship between preoperative clinical, audiological, and other factors in relation to the ossicular chain status. Materials and Methods: This was a prospective, cross-sectional study conducted at a tertiary care center, for 2-year duration (November 2019 to November 2021), on 100 patients who presented with COM (mucosal type). Preoperative diagnosis and assessment based on the clinical examination and investigations were compared with operative findings. Results: Thirty percent of the patients had ear discharge duration <1 year, 28% had 1–5 years, and 18% patients had 6–10-year duration. Hearing loss was present in 80% of the cases. Correlation of pure-tone average (PTA) with ossicular chain status was significant with P = 0.028. The majority of patients were in the moderate category 31% and 19.36% of patients had ossicular chain defect. The second common category was mild hearing loss (24%), of which 4.17% of patients showed ossicular chain defect. Conclusion: Maximum percentages of patients with severe hearing loss had ossicular chain discontinuity followed by profound hearing loss. Most of cases had moderate to moderately severe conductive hearing loss in PTA. As the air–bone gap increases, the possibility of ossicular discontinuity increases.

Shorting at Long Duration: Impact of Extended Discharge Capacity on Battery Solid Electrolytes

Long-duration energy storage (LDES) is critical to a stable, resilient, and decarbonized electric grid. While batteries are emerging as important LDES devices, extended, high-power discharges necessary for cost-competitive LDES present new materials challenges. Focusing on a new generation of low-temperature molten sodium batteries, we explore here unique phenomena related to long-duration discharge through a well-known solid electrolyte, NaSICON. Specifically, molten sodium symmetric cells at 110 °C were cycled at 0.1 A cm−2 for 1–23 h discharges. Longer discharges led to unstable overpotentials, reduced resistances, and decreased electrolyte strength, caused by massive sodium penetration not observed in shorter duration discharges. Scanning electron microscopy informed mechanisms of sodium penetration and even “healing” during shorter-duration cycling. Importantly, these findings show that traditional, low-capacity, shorter-duration tests may not sufficiently inform fundamental materials phenomena that will impact LDES battery performance. This case highlights the importance that candidate LDES batteries be tested under pertinent long-duration conditions.

Flow rate control in a plug-flow reactor for liquid organic hydrogen carriers dehydrogenation

Liquid organic hydrogen carriers can store hydrogen for later release through dehydrogenation reactions. The kinetic rate depends on the temperature, pressure, and hydrogen concentration itself, so it varies throughout the discharge. As such, control systems are needed to meet the end-user power demand. An innovative plug flow reactor coupled with two vessels is introduced and accurately sized. Multiple strategies are implemented in a Matlab/Simulink model to test the efficacy of control methods based on pressure, temperature, and mass flow rate. The results obtained with the simulations highlight a dramatic drop in performance (utilisation factor lower than 80%) associated with relatively high power demands (higher than 70% in the case of temperature control), whereas low demands are met with satisfactory degrees of utilisation under both pressure and temperature control. Control over the mass flow rate of external fluid leads to lackluster results and should only be chosen as an auxiliary controlled variable. Lastly, Ragone diagrams for pressure and temperature control are presented and used to identify the optimal system sizing range: effective discharge duration should be in the range 10–40h with pressure control or 5–40h with temperature control to achieve a utilisation factor of at least 80%.

Flexibility options in a 100% renewable grid for Australia

Flexibility options for operating technologies available in a power system can facilitate the large-scale integration of variable renewable sources such as wind and solar whilst maintaining firm generation. In prior work, contributions of different flexibility options in future net-zero electricity networks vary widely across regions and scenario assumptions. Here we simulate a competitive-bidding process for an energy-only electricity system at 1-hour intervals to assess multiple flexibility options for supply and storage – including biomass, hydropower, concentrating solar power (CSP), electrical energy storage (EES), pumped hydro energy storage (PHES) and hydrogen (H2). We examine systemic effects of competing flexibility options and compare their grid-integrated cost-effectiveness in a future Australian 100% renewable grid. Our simulations indicate a variety of constellations with coexisting technologies, including flexibility options at various penetrations depending on storage cost and design points. We reveal the potentially significant role of long-term storage technologies (with months-deep discharge durations) in Australia's future 100% renewable grid, enabling significant reductions in the installed capacity of wind and solar PV, and thus overall system cost.

NiCo2O4 Nanowires Immobilized on Nitrogen-Doped Ti3C2Tx for High-Performance Wearable Magnesium-Air Batteries.

Flexible magnesium (Mg)-air batteries provide an ideal platform for developing efficient energy-storage devices toward wearable electronics and bio-integrated power sources. However, high-capacity bio-adaptable Mg-air batteries still face the challenges in low discharge potential and inefficient oxygen electrodes, with poor kinetics property toward oxygen reduction reaction (ORR). Herein, spinel nickel cobalt oxides (NiCo2O4) nanowires immobilized on nitrogen-doped Ti3C2Tx (NiCo2O4/N-Ti3C2Tx) are reported via surface chemical-bonded effect as oxygen electrodes, wherein surface-doped pyridinic-N-C and Co-pyridinic-N moieties accounted for efficient ORR owing to increased interlayer spacing and changed surrounding environment around Co metals in NiCo2O4. Importantly, in polyethylene glycol (PVA)-NaCl neutral gel electrolytes, the NiCo2O4/N-Ti3C2Tx-assembled quasi-solid wearable Mg-air batteries delivered high open-circuit potential of 1.5V, good flexibility under various bent angles, high power density of 9.8mW cm-2, and stable discharge duration to 12h without obvious voltage drop at 5mA cm-2, which can power a blue flexible light-emitting diode (LED) array and red smart rollable wearable device. The present study stimulates studies to investigate Mg-air batteries involving human-body adaptable neutral electrolytes, which will facilitate the application of Mg-air batteries in portable, flexible, and wearable power sources for electronic devices.

THE COMPARISON OF OXIDATION EFFICIENCY OF REACTIVE OXYGEN SPECIES (ROS): PILOT SCALE OF MICROBUBBLE TECHNOLOGIES WITH OXYGEN CONCENTRATION

The objective of this study is to assess and compare the effectiveness of an oxidizing agent. Within the field of advanced oxidation processes (AOPs), ozone, a highly reactive gas, generates reactive oxygen species (ROS) as byproducts through chemical reactions. The study employed a dielectric barrier discharge (DBD) plasma generator to produce ozone gas. This study was carried out under different gas source conditions, including both air and oxygen. Additionally, the ROS produced as byproducts from the interaction between ozone gas and water were measured using oxidation-reduction potential (ORP) values. The ORP values exhibit strong foundational attributes for both ozone dissolution and ROS oxidation efficiency. To extend the interaction duration between ozone gas and water, a stone diffuser was utilized to introduce ozone gas into the water. This mechanism resulted in the creation of ozone microbubbles through a process known as cavitation. The results illustrate a positive relationship between the flow rate and ozone yield. This trend reached its highpoint with the highest observed ozone concentrations approximately 14.11 mg/L for oxygen and 4.55 mg/L for air both achieved at a flow rate of 11 L/min. Furthermore, the highest ozone concentrations were recorded at 15.17 mg/L for oxygen and 12.59 mg/L for air after a 10 min discharge period. Interestingly, ozone generated from oxygen feed gas exhibited a higher concentration yield than that from air feed gas. Moreover, the ORP value displayed a continuous increase with longer treatment times, eventually stabilizing at around the 15 min. This pattern corresponded to the water reaching its highest the ORP values approximately 821 mV for oxygen and 569 mV for air. In summary, this study emphasizes the potential benefits of utilizing ozone as an effective oxidant in both gaseous (ozone gas) and liquid (ROS) phases. It especially emphasizes the essential role played by the generation of ozone and ROS from an oxygen-fed gas source. Moreover, it highlights the significance of maintaining an optimal flow rate of 11 L/min and a discharge duration of 10 min for achieving the highest ozone concentration. Similarly, a treatment time of 15 min for the liquid phase is recommended to maximize ORP values. Both of these values indicate the highest potential advantages for producing an effective oxidant.

Width undulation drives flow convergence routing in five flashy ephemeral river types across a dry summer subtropical region

AbstractDuring the last decade, meter‐resolution topo‐bathymetric digital elevation models (DEMs) have become increasingly utilized within fluvial geomorphology, but most meter‐scale geomorphic analyses are done on just one to a few rivers. While such analyses have contributed greatly to our collective understanding of river discharge‐topography interactions, which is applicable in both river restoration design and environmental flow regulation contexts, their generalizability across a range of river types remains largely unevaluated. This study assessed the dominance of a single hydro‐morphodynamic mechanism, flow convergence routing, in 35 ephemeral rivers divided among five river types in California's South Coast region by answering five questions. Geomorphic covariance structure (GCS) analysis was performed on longitudinal standardized width and standardized, detrended bed elevation spatial series from meter‐resolution DEMs. All river types had coherent, multi‐scalar structures of longitudinal fluvial topography, implicating a process‐morphology link. GCS metrics revealed that landform patterning was consistent with the requirements of the morphodynamic mechanism of flow convergence routing. Thus, that process was found to be a broadly relevant channel altering mechanism among sites, but its relationship with water stage differed between river types. Specifically, river types in unconfined valleys exhibited a strong bankfull width control over base flow bed undulations, with no obvious flood‐stage control over bankfull landform patterning. River types in partially confined valleys also exhibited strong bankfull width control over base flow bed undulations, but their bankfull landform patterns appear to have coalesced with coherent width and bed elevation undulations during flood flows. Finally, metrics for confined river types showed that it takes higher magnitude, less frequent floods to set their coherent width and bed elevation undulations, but even these channels do exhibit flow convergence routing when given enough discharge for sufficient duration.

The Influence of Voltage on Gliding Arc Discharge Characteristics, the Composition of Air Plasma, and the Properties of BG-11 Medium

A gliding arc discharge (GAD) plasma device has been developed and tested. Possible applications areas for GAD plasma could be microalgae suspension treatments and the creation of plasma-activated water. To understand its behavior, the influence of the input power on the electrical characteristics of the generated GAD plasma was investigated using an oscilloscope. The waveforms of the voltage and current of GAD plasma are presented. The duration of the discharge time and the evolution of the arc during discharge were determined and investigated. It was revealed that the increase in the output voltage prolonged the duration of the arc discharge. The composition of the air plasma was investigated using a flame-emission spectrometer and acousto-optic emission spectrometer. It was revealed that the main species in the emission spectra of the GAD air plasma were N2, N2+, N+, NO, and O species. Furthermore, the increase in the input power enhanced the ionization degree of the air plasma and increased the intensities of the emission lines associated with N2+, NO, and O species. An increase in the conductivity of the BG-11 medium was observed. Physicochemical analyses of the plasma-activated BG-11 medium indicated an increase in the concentration of nitrite and nitrate ions and hydrogen peroxide with an enhancement of the voltage.

Neuropathic pain after orthopaedic surgery with continuous peripheral nerve block.

Continuous peripheral nerve blocks (cPNBs) have shown favourable post-operative pain control results but may be associated with a risk for long-term neurological complications. This study sought to examine factors associated with persistent post-operative pain and potential neuropathy after orthopaedic lower-limb surgery with the use of post-operative cPNB. Patients who underwent lower limb orthopaedic procedures with cPNBs between November 2021 to May 2022 were included. Patient demographics and perioperative data were noted. At discharge, patients completed the PainDetect (PD) questionnaire and were followed up six months after discharge. Seventy-seven patients with a total of 171 catheters completed the follow up. The median time to follow-up was 214 days after catheter removal, and 18 patients (23%) had a PD score ≥ 13. Univariate analysis showed that multiple variables were associated with a PD score ≥ 13 at the six-month follow-up. Multiple logistic regression showed that a high PD score at discharge, high BMI and longer duration of cPNBs were associated with higher risk of having a PD score ≥ 13 at the six-month follow-up. Several factors were associated with a higher risk of having possible neuropathy after six months. BMI, duration of catheter and PD score at discharge were correlated with risk of possible neuropathic pain. None. The study was a quality control project and therefore did not require registration under Danish law.

Analysis of Surface Water Availability and Projection of Domestic Water Demand in The Logawa Sub-Watershed 2030

Water is a vital element that is used to meet human needs such as domestic and non-domestic activities (agriculture, fisheries, tourism, and industry). The more human activities carried out, the greater the amount of water needed. Therefore, it is necessary to analyze the availability and demand for water to determine the conditions of shortage and excess water to meet future water needs. The method used in this research was the quantitative descriptive method with the study area unit covering all parts of the Logawa Sub-Watershed. The research sample was taken using the purposive sampling method with data collection techniques including secondary data in the form of literature studies and related institutions and primary data in the form of direct observations in the field. Data analysis was determined by the discharge duration curve formula to obtain a reliable discharge and calculate the water demand in each sector. The results of the study show that the availability of water in the Logawa Sub-Watershed can suffice the water needs of the domestic and non-domestic sectors (agriculture and livestock) in 2023 and domestic water needs in 2030.

Study on Forming Mechanism of the Recast Layer on the Workpiece Surface during Micro EDM.

In comparison to conventional EDM, micro EDM distinguishes itself through its brief discharge duration, narrow discharge channel radius, and concentrated energy density. However, there remains a paucity of comprehensive research on the surface formation characteristics in this domain. This paper delves into the formation mechanism of the recast layer in micro EDM workpieces, scrutinizing the primary factors that influence the formation process and the morphological attributes of the recast layer. We conducted a series of single-pulse experiments and micro EDM trials. Utilizing surface fitting tools, our experimental findings facilitated the derivation of a relational expression between the recast layer thickness of high-speed steel and the discharge parameters in micro EDM. Notably, when the energy is below 100 μJ, the recast layer thickness remains under 10 μm. Specifically, at an energy level of 16 μJ, opting for a smaller capacitance of 2200 pf and a higher voltage of 120 V in micro EDM results in a thinner recast layer. This study serves as a cornerstone for future efforts aimed at controlling and assessing the surface morphology of micro EDM.

Numerical study on dust particle charging and dynamics in continuous and pulsed radio frequency argon discharges

AbstractCharging and dynamics of a spherical dust grain injected into a continuous and pulsed radio frequency (RF) discharge have been studied using a one‐dimensional fluid model. First, the plasma characteristics of the two types of discharges are computed and compared. In the pulsed discharge, it is found that the central electron density exhibits a periodic variation while the averaged electron density is lower compared to that in the continuous discharge due to the decrease in the total ionization rate. Further, the dust charge is computed using the plasma characteristics. It is found that the dust charge negatively increases as the duty cycle ratio increases. Also, the charge in the pulsed discharge is lower in comparison to the continuous discharge due to the shorter duration of the pulsed RF discharge limiting the amount of energy transferred to electrons. On the other hand, the dust particle remains in the powered sheath region exhibiting a damped oscillation in the two discharges with higher oscillation frequency in the continuous discharge.

Remote sensing assessment of anthropogenic and climate variation effects on river channel morphology and vegetation: Impact of dry periods on a European piedmont river

AbstractRivers are subject to increasing human pressure, resulting in a loss of their natural characteristics, further enhanced by climate change. The present study focuses on a piedmont reach of the Italian Po River and combines Landsat satellite information with hydrological records to investigate changes in sandbars exposure and riparian vegetation coverage, considering the summer period of 1984–2022. Satellite data were handled via Google Earth Engine, looking at common indexes such as the Modified Normalized Difference Water Index, which was used to identify temporal variations in wetted channel area, and the Normalized Difference Vegetation Index, considered as a proxy of vegetation coverage variations. Changes in the river hydrology were analysed by looking at the annual minimum water levels, the discharge duration curve, the stage–discharge relationship and the yearly annual water volume. Results suggest that a process of oversimplification is affecting this reach of the Po River, showing how climate change can affect piedmont European watercourses. Indeed, after an initial period where bars tended to be barer and somehow stable over time, in the most recent decade a different trend appeared, with vegetation able to colonize the exposed sandbars more. Using the Po River as an exemplary case study, this work suggests that prolonged dry periods, which are more common in recent decades, might impact large and medium rivers located in temperate climates, favouring the development of vegetation on exposed sandbars, eventually resulting in a less dynamic active channel.

Gene and Allele-Specific Expression Underlying the Electric Signal Divergence in African Weakly Electric Fish.

In the African weakly electric fish genus Campylomormyrus, electric organ discharge signals are strikingly different in shape and duration among closely related species, contribute to prezygotic isolation, and may have triggered an adaptive radiation. We performed mRNA sequencing on electric organs and skeletal muscles (from which the electric organs derive) from 3 species with short (0.4 ms), medium (5 ms), and long (40 ms) electric organ discharges and 2 different cross-species hybrids. We identified 1,444 upregulated genes in electric organ shared by all 5 species/hybrid cohorts, rendering them candidate genes for electric organ-specific properties in Campylomormyrus. We further identified several candidate genes, including KCNJ2 and KLF5, and their upregulation may contribute to increased electric organ discharge duration. Hybrids between a short (Campylomormyrus compressirostris) and a long (Campylomormyrus rhynchophorus) discharging species exhibit electric organ discharges of intermediate duration and showed imbalanced expression of KCNJ2 alleles, pointing toward a cis-regulatory difference at this locus, relative to electric organ discharge duration. KLF5 is a transcription factor potentially balancing potassium channel gene expression, a crucial process for the formation of an electric organ discharge. Unraveling the genetic basis of the species-specific modulation of the electric organ discharge in Campylomormyrus is crucial for understanding the adaptive radiation of this emerging model taxon of ecological (perhaps even sympatric) speciation.

Retropharyngeal manifestation of T-cell-rich B-cell lymphoma in a 7-year-old Icelandic gelding

A 7-year-old Icelandic gelding was presented with acute severe dyspnea of one day duration and purulent nasal discharge that had been present for 6 weeks. Clinically, the initial examination focused on severe enlargement of the mandibular and retropharyngeal lymph nodes as well as a mixed dyspnea.The diagnosis of a malignant lymphoma was evident following laboratory diagnostics, endoscopy, and cytological examination of a fine needle aspiration of a mandibular lymph node. The gelding was euthanized due to the poor prognosis and a significantly disturbed general condition. Pathohistological examination revealed a multicentric T-cell-rich B-cell lymphoma.

Application of cold argon plasma on germination, root length, and decontamination of soybean cultivars

Applying cold discharge plasma can potentially alter plants' germination characteristics by triggering their physiological activities. As a main crop in many countries, soybean was examined in the present study using cultivars such as Arian, Katoul, Saba, Sari, and Williams in a cold argon plasma. This study has been motivated by the importance of plant production worldwide, considering climate change and the increasing needs of human populations for food. This study was performed to inspect the effect of cold plasma treatment on seed germination and the impact of argon plasma on microbial decontamination was investigated on soybeans. Also, the employed cultivars have not been studied until now the radicals generated from argon were detected by optical emission spectrometry (OES), and a collisional radiative model was used to describe electron density. The germination properties, including final germination percentage (FGP), mean germination time (MGT), root length, and electrical conductivity of biomolecules released from the seeds, were investigated after the plasma treatments for 30, 60, 180, 300, and 420 s. The decontamination effect of the plasma on Aspergillus flavus (A.flavus) and Fusarium solani (F.solani) was also examined. The plasma for 60 s induced a maximum FGP change of 23.12 ± 0.34% and a lowest MGT value of 1.40 ± 0.007 days. Moreover, the ultimate root length was 56.12 ± 2.89%, in the seeds treated for 60 s. The plasma exposure, however, failed to yield a significant enhancement in electrical conductivity, even when the discharge duration was extended to 180 s or longer. Therefore, the plasma duration of 180 s was selected for the blotter technique. Both fungi showed successful sterilization; their infectivity inhibition was 67 ± 4 and 65 ± 3.1%, respectively. In general, the cold plasma used for soybeans in the present study preserved their healthy qualities and reduced the degree of fungal contamination.

Multivariate multi-objective collaborative optimization of pumped thermal-liquid air energy storage

Pumped thermal-liquid air energy storage (PTLAES) is a novel energy storage system with high efficiency and energy density that eliminates large volumes of cold storage. In this study, three different configurations of PTLAES systems with direct and indirect thermal energy storage were proposed. The “adaptive segmentation-based temperature transfer matrix” method was developed to capture the heat transfer characteristics of multi-stream plate-fin heat exchangers (MPFHEs), which is the key component of the system. To determine the upper limit of the techno-economic performance of the system, single/multi-objective optimization was performed with up to 35 decision variables. Additionally, the “Pareto efficiency” concept was defined to quantify the goodness of a point compared to the Pareto front. The results showed that the irreversible heat transfer and pressure drop in MPFHEs contribute 20.6 %–44.3 % of the total exergy destruction. Therefore, the design of MPFHEs significantly impacts the system performance. Multivariate multi-objective collaborative optimization can significantly improve the optimization results. PTLAES with closed loop indirect thermal energy storage was determined to have the best overall performance, achieving round-trip efficiency of 63.3–70.1 %, levelized cost of storage (LCOS) of 0.162–0.181 $/kWh, and energy density of 122–161 kWh/m3. The optimized PTLAES system can achieve lower LCOS than lithium-ion batteries when the discharge duration exceeds 3.5 h. Furthermore, it was shown that key criteria including round-trip efficiency, LCOS, and energy density can be traded off over a broad design space of different system configurations, parameter combinations, and material choices. This research demonstrated that PTLAES is a promising choice for long-duration energy storage and provided guidance for the design and techno-economic optimization of PTLAES systems.