Partial Condensation Research Articles

The origin of 4-Vesta's volatile depletion revealed by the zinc isotopic composition of diogenites.

Volatile element abundances vary substantially among terrestrial planetary bodies like Earth, Mars, Moon, and differentiated asteroids, leading to intense debate about the governing processes. howardites-eucrites-diogenites (HED) meteorites, most likely from asteroid 4-Vesta, represent highly volatile-depleted Solar System samples, offering critical insights into these processes. Zinc is a moderately volatile element and its isotopic composition reveals sources of volatiles in planetary bodies. Our study finds Zn isotopic anomalies in diogenites overlapping with noncarbonaceous reservoirs, indicating negligible contributions of outer solar system materials to 4-Vesta's volatiles. Besides, zinc isotopic composition of 4-Vesta is lighter than that of chondrites, contrary to the expected signature of evaporation-based volatile depletion. This suggests that after 4-Vesta lost all its volatiles through evaporation during the magma ocean stage, partial kinetic recondensation occurred that produced the observed isotopically light composition. These insights, combined with previous data, underscore the process of global evaporation followed by partial condensation as a key factor influencing the final volatile budget of planetary bodies.

Bio-methanol with negative CO2 emissions from residual forestry biomass gasification: Modelling and techno-economic assessment of different process configurations

The paper presents a techno-economic comparison among five alternative process configurations for bio-methanol production from the gasification of residual forestry biomass. Process design and simulations are performed in Aspen Plus for mass and energy balance calculation, followed by preliminary sizing and economic analysis. Process schemes include a gasification island (state-of-the-art low-pressure gasification compared against a high-pressure gasifier) with syngas conditioning and compression, heat recovery, syngas composition adjustment (by CO2 capture or addition of hydrogen produced by electrolysis), methanol synthesis and purification and a heat recovery cycle for power generation. CO2 capture is performed with conventional chemical absorption in the benchmark cases, while low-temperature partial condensation of CO2 is modeled in the advanced scenario. Methanol output is 14–15 kt/y in the CO2 capture cases and 36 kt/y in the H2 addition option.Configurations with a pressurized gasifier and phase-change-based CO2 separation are the most efficient ones, with a primary energy efficiency of 50 % and a Levelized Cost of Methanol (LCOM) of 700 €/tMeOH. In comparison, LCOM increases to 730 €/tMeOH in the case with conventional capture or between 792 €/tMeOH and 831 €/tMeOH (depending on the CCS technology) if the gasification pressure is conservatively reduced to 2.5 bar. In the H2 addition scenario, LCOM increases to 821 €/tMeOH due to the significant impact of the electricity consumption for H2 production, (only partly compensated by the increased methanol production). Scenarios with CO2 capture feature negative CO2 emissions, in the range −1.64 to −1.84 tCO2eq/tMeOH, as a result of the capture and storage of biogenic CO2 (BECCS approach).

Effects of production temperature on the molecular composition and seed-germination-promoting properties of sludge-based hydrochar-derived dissolved organic matter

Sludge hydrothermal carbonization demonstrates potential for converting sludge into multifunctional carbon materials for soil remediation. However, the influence of dissolved organic matter (DOM) with unclear molecular characteristics in sludge-based hydrothermal carbon on plant growth has not been sufficiently investigated. Herein, the effects of hydrothermal temperature on the molecular transformation pathways and plant-growth-promoting properties of DOM were investigated via FT-ICR MS–based molecular network analyses and seed germination experiments. Results indicated that the highest DOM yield was achieved at 220 °C. During low-temperature (180 °C) hydrothermal treatment, the hydrolysis of biopolymers, as well as the partial condensation and cyclization of small-molecule intermediates, occurred in the sludge. This process produced unsaturated CHNO compounds containing one or two N atoms, which promoted seed germination. Further, the toxicity of DOM to plants increased with rising hydrothermal temperature. This was accompanied by S doping and aromatization reactions, which mitigated the effects of plant growth hormones. This study provides theoretical support for the optimization of sludge hydrothermal treatment and production of plant growth hormones, enhancing the ecological value of sludge-based hydrochar.

Nitrogen-enriched, Highly Pressurized Nebular Clouds Surrounding a Super Star Cluster at Cosmic Noon

Strong lensing offers a precious opportunity for studying the formation and early evolution of super star clusters that are rare in our cosmic backyard. The Sunburst Arc, a lensed Cosmic Noon galaxy, hosts a young super star cluster with escaping Lyman continuum radiation. Analyzing archival Hubble Space Telescope images and emission line data from Very Large Telescope/MUSE and X-shooter, we construct a physical model for the cluster and its surrounding photoionized nebula. We confirm that the cluster is ≲4 Myr old, is extremely massive M ⋆ ∼ 107 M ⊙, and yet has a central component as compact as several parsecs, and we find a gas-phase metallicity Z = (0.22 ± 0.03)Z ⊙. The cluster is surrounded by ≳105 M ⊙ of dense clouds that have been pressurized to P ∼ 109 K cm−3 by perhaps stellar radiation at within 10 pc. These should have large neutral columns N HI > 1022.8 cm−2 to survive rapid ejection by radiation pressure. The clouds are likely dusty as they show gas-phase depletion of silicon, and may be conducive to secondary star formation if N HI > 1024 cm−2 or if they sink farther toward the cluster center. Detecting strong [N iii]λ λ 1750,1752, we infer heavy nitrogen enrichment . This requires efficiently retaining ≳500 M ⊙ of nitrogen in the high-pressure clouds from massive stars heavier than 60 M ⊙ up to 4 Myr. We suggest a physical origin of the high-pressure clouds from partial or complete condensation of slow massive star ejecta, which may have an important implication for the puzzle of multiple stellar populations in globular clusters.

High D2/H2 selectivity performance in MOF-303 under ambient pressure for potential industrial applications

The commercial demand for D2 is poised to increase significantly; however, the low natural abundance and the energy- and capital-intensive industrial separation (i.e., 24 K cryogenic distillation) will hamper future scientific and industrial growth in isotopologue separation. Alternatively, kinetic quantum sieving (KQS)-based adsorptive D2 separation has been proposed recently, but the separation performance is reported mostly at near zero pressure or in the sub-few ten mbar range. Herein, an Al-based Metal-Organic Framework, MOF-303, with 1-D narrow-micro pores is studied for D2/H2 adsorptive separation at ambient pressure. Cryogenic thermal desorption spectroscopic analysis of MOF-303 confirmed that the synergetic effect of binding affinity & enhanced KQS (owing to molecular rearrangement of D2 adsorbed phase at high pressure induced by strong D2 confinement), along with D2 partial condensation, leads to a significant increase in the D2 uptake with increasing exposure pressure up to 1,000 mbar. Consequently, a remarkable selectivity of 21.6 at 25 K has been achieved even at an operating pressure of 1000 mbar, which is an industry-friendly condition. The observed D2/H2 separation selectivity is about ten times higher than that of the industrial cryogenic method (best selectivity of below 2.5 at 24 K), and comparable to the performance of the adsorbent materials already reported with low operating pressure, making adsorptive D2/H2 separation through MOF-303 an alternative for cryogenic industrial isotopologue separation.

Topological Manipulation of Fully Biobased Poly(epoxy imine): From Thermoplastic Elastomers to Covalent Adaptable Networks and Permanently Cross-Linked Networks

Tunable properties arising from variable topologies make polymers versatile and irreplaceable in modern society. However, manipulating the topology of a specific polymer with a determined composition remains a big challenge. This study aimed to propose a facile approach to manipulate the topology of fully biobased poly(epoxy imine)s (PEIs), which were synthesized from the reaction between epoxy-derived trialdehyde precursors (ETPs) and decamethylene diamine (DDA). PEIs with topologies varying from branched structures to covalent adaptable networks (CANs) and permanently cross-linked networks (PCNs) were easily obtained by simply adjusting the reaction temperature. At a low temperature (T = 120 °C), partial aldehyde-amine condensation between ETP and DDA gave rise to a branched thermoplastic; at medium temperature (120 °C < T ≤ 160 °C), enhanced extent of aldehyde-amine condensation led to a CAN cross-linked by imine bonds; at a high temperature (T > 160 °C), self-cross-linking of imine bonds occurred to result in a PCN. With different topologies, fully biobased PEIs showed different mechanical, physical, and chemical properties and thus great potential as alternatives to fossil-derived polymers in various applications.

Study on Mechanism of Preparing Spherical Aluminum Powder by Evaporative Condensation

The nucleation of aluminum vapor in phase transition and its condensation were studied at 15 pa. The impacts of the condensing conditions, including the aluminum partial pressure, temperature, and condensation zone temperature gradient, on aluminum vapor nucleation and condensation, were discussed from the point of view of atom collision. Aluminum powder and beads were produced under different conditions and characterized by scanning electron microscopy (SEM) and the proportion of fine powder. The rate of evaporation increases with increasing temperature and evaporation surface area. The condensation position at which the aluminum vapor becomes solid is further away from the evaporation surface area, with the temperature of the heating source increasing. It can benefit to the condensation and crystallization of aluminum vapor by appropriately increasing the condensing zone’s crucible diameter and temperature gradient.

Exposure to bisphenol A induces neurotoxicity associated with synaptic and cytoskeletal dysfunction in neuro-2a cells.

Bisphenol A (BPA) has been reported to injure the developing and adult brain. However, the underlying mechanism still remains elusive. This study used neuro-2a cells as a cellular model to investigate the neurotoxic effects of BPA. Microtubule-associated protein 2 (MAP2) and tau protein maintain microtubule normal function and promote the normal development of the nervous system. Synaptophysin (SYP) and drebrin (Dbn) proteins are involved in regulating synaptic plasticity. Cells were exposed to the minimum essential medium (MEM), 0.01% (v/v) DMSO, and 150μM BPA for 12, 24, or 36h. Morphological analysis revealed that the cells in the BPA-treated groups shrank and collapsed compared with those in the control groups. CCK-8 and lactate dehydrogenase assay (LDH) assays showed that the mortality of neuro-2a cells increased as the BPA treatment time was prolonged. Ultrastructural analysis further revealed that cells demonstrated nucleolar swelling, dissolution of nuclear and mitochondrial membranes, and partial mitochondrial condensation following exposure to BPA. BPA also decreased the relative protein expression levels of MAP2, tau, and Dbn. Interestingly, the relative protein expression levels of SYP increased. These results indicated that BPA inhibited the proliferation and disrupted cytoskeleton and synaptic integrity of neuro-2a cells.

In situ preparation of compounds using silanized mPEG inspired by talc-like structures.

Composite materials show improved properties compared to pristine materials, in particular when the filler is dispersed homogeneously in the matrix. For polymer-clay composites, different strategies exist to improve clay mineral dispersion in the polymer matrix. In this study, an innovative approach is suggested which consists of forming a talc-like structure directly in a polymer matrix using a silanized polymer as the silicon source. Poly(ethylene glycol) methyl ether of different average molar masses (Mn = 350, 500, 750, 1900 g mol-1) were functionalized with (3-isocyanatopropyl)triethoxysilane and added to the ethanolic solutions of magnesium nitrate. 1H-29Si CPMAS solid state NMR experiments revealed partial condensation of silane compounds, and FTIR analysis confirmed the presence of both Si-O and Mg-O bonds, but an additional proof of the Si-O-Mg bond is needed to prove the formation of such a structure.

Heat Integration for Phenols and Ammonia Recovery Process of Coal Gasification Wastewater Considering Optimization of Process Parameters

A heat integration optimization method that considers the changes in process parameters is proposed to find the global optimal process scheme for a coal chemical company’s phenols and ammonia recovery process. The phenols and ammonia recovery process is simulated by Aspen Plus, and a programming method for heat exchanger networks synthesis that can simultaneously optimize process parameters and heat integration is constructed by Matlab. Taking the total annual cost as the objective function, the following process parameters are optimized: the hot feed temperature and cold/hot feed ratio of sour water stripper, the temperature of three-step partial condensation system, the feed temperature and column pressure of both solvent distillation column and solvent stripper. The result shows that, compared with the heat integration process under original process parameters, the new heat integration process saves 14.3% energy consumption and reduces the total annual cost by about 15.1%. The new heat integration process provides guidance for the optimization of the phenols and ammonia recovery process. The proposed heat integration optimization method based on changing process parameters is an effective and practical tool that offers good application prospects.

Complete characterization of non-Abelian topological phase transitions and detection of anyon splitting with projected entangled pair states

It is well-known that many topological phase transitions of intrinsic Abelian topological phases are accompanied by condensation and confinement of anyons. However, for non-Abelian topological phases, more intricate phenomena can occur at their phase transitions, because the multiple degenerate degrees of freedom of a non-Abelian anyon can change in different ways after phase transitions. In this paper, we study these new phenomena, including partial condensation, partial deconfinement and especially anyon splitting (a non-Abelian anyon splits into different kinds of the new anyon species) using projected entangled pair states (PEPS). First, we show that anyon splitting can be observed from the topologically degenerate ground states. Next, we construct a set of PEPS describing all possible degrees of freedom of the same non-Abelian anyon. From the overlaps of this set of PEPS of a given non-Abelian anyon with the ground state, we can extract the information of partial condensation. Then, we construct a central object, a matrix defined by the norms and overlaps among the PEPS in that set. The information of partial deconfinement can be extracted from this matrix. In particular, we use it to construct an order parameter which can directly detect anyon splitting. We demonstrate the power of our approach by applying it to a range of non-Abelian topological phase transitions: From $D(S_3)$ quantum double to toric code, from $D(S_3)$ quantum double to $D(Z_3)$ quantum double, from Rep($S_3$) string-net to toric code, and finally from double Ising string-net to toric code.

The case for the angrite parent body as the archetypal first-generation planetesimal: Large, reduced and Mg-enriched

Angrites are silica-undersaturated achondrites formed very early in the history of the Solar System, and the most volatile-depleted known meteorites. As such, the study of angrites can provide critical insights into the early stages of planetary formation, melting and differentiation. Yet, understanding the origins of angrites and the nature of their parent body has long been hindered by the initially small number of specimens available. Here, we leverage (i) the rapidly growing number of known angrites, and (ii) equilibrium crystallization experiments at various pressure, temperature and oxygen fugacity conditions (P-T-fO2), to revisit the petrogenesis of angrites and constrain key features of the angrite parent body (APB), such as its composition and size.We observe that quenched (i.e., volcanic) angrites define two compositional groups, which we show are readily related by fractional crystallization. This crystallization trend converges on an olivine-clinopyroxene-plagioclase (Ol + Cpx + Plag) multiple saturation boundary, whose composition is sampled by D’Orbigny, Sahara 99555 and NWA 1296. Using the observation that some quenched specimens represent primitive angritic melts, we derive a self-consistent bulk composition for the APB. We find that this composition matches the proposed Mg/Si ratio of 1.3 derived from the angrite δ30Si values, and yields a core size (18 ± 6 wt%) in agreement with the siderophile elements depletion in the APB mantle. Our results support a primary control of nebular fractionation (i.e., partial condensation) on the composition of the APB. To establish the liquid phase equilibria of angrites, a series of 1 atmosphere and high-pressure crystallization experiments (piston cylinder and internally heated pressure vessel) were performed on a synthetic powder of D’Orbigny. The results suggest that the APB was a large (possibly Moon-sized) body, formed from materials condensed at relatively high-temperature (∼1300–1400 K), and whose fO2 changed from mildly reducing (∼IW-1.5) to relatively oxidizing (∼IW+1 ± 1) in the ∼ 3 Myr between its core formation and the crystallization of D’Orbigny-like (Group 2) angrites. Based on its timing of accretion and differentiation, its composition, redox, and size, we argue that the APB represents the archetype of the first-generation of refractory-enriched planetesimals and embryos formed in the innermost part of the inner Solar System (<1 AU), and which accreted in the telluric planets.

Energy saving in distillation by combining vortex contact device and thermal effects

• Energy efficiency assessment of the thermal distillation in the column apparatuses is presented. • Heat extra removed from the upper tray of the column leads to a decrease in heat flows by 9–12%. • Vortex contact devices provide an increase in the mole fraction of the light-volatile component in the liquid by 5.61%. Thermal effects are proposed to improve the efficiency of heat and mass transfer phenomena in distillation columns. The new design of the vortex contact device is developed. The paper investigates a combined use of the vortex devices that act as the contact stages of the distillation column and heat removal from the upper contact stage. Theoretical results on the distribution of vapor and liquid flows on each tray of the vortex device are obtained. The mass flow rate of the liquid phase as a result of the partial condensation of vapors is determined based on the amount of heat removed and the location of the tray with additional heat removal. A reduction in the mass flow rate of reflux during thermal distillation is experimentally established. The dependence of the average Murphree tray efficiency of the vortex contact stage is obtained depending on the reflux ratio at thermal distillation, which is confirmed experimentally. Experimental study shows an increase in the average efficiency of the stage by 10.6% compared to the adiabatic column without heat removal. A distillate mass fraction of 0.884 in the liquid phase is achieved at the outlet of the column when using 10 vortex contact stages and the working reflux ratio of 1.83. The comparative analysis of the use of the developed vortex contact devices in the thermal distillation process is performed in terms of the separation quality of the ethanol–water mixture, energy costs for the supply, and removal of heat.

Nucleation effects on cloud cavitation about a hydrofoil

The dynamics of cloud cavitation about a three-dimensional hydrofoil are investigated experimentally in a cavitation tunnel with depleted, sparse and abundant free-stream nuclei populations. A rectangular planform, NACA 0015 hydrofoil was tested at a Reynolds number of $1.4\times 10^{6}$ , an incidence of $6^{\circ }$ and a range of cavitation numbers from single-phase flow to supercavitation. High-speed photographs of cavitation shedding phenomena were acquired simultaneously with unsteady force measurement to enable identification of cavity shedding modes corresponding to force spectral peaks. The shedding modes were analysed through spectral decomposition of the high-speed movies, revealing different shedding instabilities according to the nuclei content. With no active nuclei, the fundamental shedding mode occurs at a Strouhal number of 0.28 and is defined by large-scale re-entrant jet formation during the growth phase, but shockwave propagation for the collapse phase of the cycle. Harmonic and subharmonic modes also occur due to local tip shedding. For the abundant case, the fundamental shedding is again large-scale but with a much slower growth phase resulting in a frequency of $St=0.15$ . A harmonic mode forms in this case due to the propagation of two shockwaves; an initial slow propagating wave followed by a second faster wave. The passage of the first wave causes partial condensation leading to lower void fraction and consequent increase in the speed of the second wave along with larger-scale condensation. For a sparsely seeded flow, coherent fluctuations are reduced due to intermittent, disperse nuclei activation and cavity breakup resulting in an optimal condition with maximum reduction in unsteady lift.

How do zeolite-templated carbons grow?

Major insights into the formation mechanism of zeolite-templated carbons (ZTCs) were achieved via a thorough ex situ kinetic study of the hybrid (carbon/zeolite) and carbon materials. In depth characterization of the chemical, electrical, textural, and morphological properties of the materials allowed us to draw a precise picture of the key steps of the ZTC formation. An in situ time resolved GC study enabled us to achieve complementary insights into the ethylene consumption and hydrogen production during ZTC synthesis. Three stages could be disclosed: nucleation, growth and condensation. During nucleation, individual polyaromatic hydrocarbons (PAHs) develop through the aromatization of ethylene. These PAHs present high spin concentration and react upon zeolite dissolution, leading to unstructured carbon particles of undefined morphology. These carbons feature persistent radicals. During growth, the PAHs evolve to form more complex rylene-type molecules. Typical structural, textural, and morphological features of ZTCs start to emerge during this second stage. The evolution of electrical conductivity of hybrid materials indicates partial condensation of PAHs throughout the zeolite crystals leading to their connection. The carbon materials achieved during the second stage can be described as composites of ZTCs and randomly reacted PAHs. Condensation, which is importantly induced by heat treatment, triggers full connection of the ZTC network. Textural, morphological, structural, and electrical features develop, which result directly from zeolite templating. Final ZTCs feature carbonyl functionalization, which is inherent to the zeolite dissolution step and probably results from radical quenching with water.

Biogas upgrading by 2-steps methanation of its CO2 – Thermodynamics analysis

A thermodynamic analysis of the methanation of CO2 within biogas sets the limits to the achievable performances, directing process and catalyst development. Practical indications of thermodynamics are elaborated. The large presence of CH4 in the biogas does not hinder the achievement of an almost complete CO2 methanation, even with CH4/CO2 = 3. The smaller the temperature, the higher the CH4 concentration in the dry biomethane, and the lower the residual H2. Results comply with some grid specification even operating at 1 bar, below 400 °C, where active commercial catalysts are available. CO in the product is never a concern, in this temperature range. There is no advantage in operating above approx. 400 °C. The H2 slip can be further reduced increasing the pressure, but the improvement is most effective with a few bars; 15 bar is already quite good. H2 in excess of the stoichiometric is not useful. The process can be completely autothermal, but adiabatic operation must be avoided. Significant improvements in biomethane purity can be achieved with two methanation steps, with steam condensation in between. Residual H2 can be reduced from 7% (single stage, 1 bar, 300 °C), to 1.8% (two stages, at 300 °C, and 1 and 15bars, respectively). Partial steam condensation allows to limit coking in the second step, without a remarkable increase of residual H2. The second step cannot be autothermal above 150 °C, but the first step provides heat in excess, at 300 °C, to support also the second step.

Revealing the effects of the ball milling pretreatment on the ethanosolv fractionation of lignin from walnut and pistachio shells

ABSTRACT In this work, a detailed study on the ethanosolv lignin fractionation from endocarps, aiming at understanding the role played by the ball milling (BM) pretreatment, is presented. Walnut and pistachio shells were chosen as a case study, since they exhibit excellent mechanical properties and their tissues have been extensively studied in terms of structure, composition, and lignin distribution. Here, it was demonstrated that the BM pretreatment is not particularly suited for these biomasses, since it is not able to promote the lignin fractionation from the whole tissue, and additionally, it triggers the oxidation of the substrate. Although in the case of walnut shell this oxidation can be prevented thanks to the remarkable radical scavenger activity (RSA) of its extractives, in the case of pistachio shell the BM is responsible for a partial lignin condensation. Pistachio shells resulted a particularly attractive feedstock since they can be easily delignified using mild ethanosolv processes, leading to highly regular lignin fractions, rich in S units (86%) and β-O-4 linking motif (>60% C9 units), so particularly suited for the chemical upgrading to added-value aromatics.

Condensation heat transfer of R1234ze(E) and R134a inside a brazed plate heat exchanger: Experimental data and model assessment

Condensation from superheated vapour is an essential process widely encountered in energy applications, mostly for refrigeration and heat pump technologies and for power production systems. This paper presents and analyses the experimental results obtained during partial condensation inside a brazed plate heat exchanger (BPHE) of the HydroFluoroCarbon R134a and of one of its replacements, the HydroFluoroOlefin R1234ze(E). Tests have been conducted considering different values of the outlet vapour quality, mass flux, and a saturation temperature that ranges between 34.6 °C and 42.3 °C. Partial condensation tests revealed that the heat transfer coefficients collected with R134a are 4–8% higher than those with R1234ze(E). Experimental tests of complete condensation of R1234ze(E) with different degrees of superheating and subcooling have also been performed to investigate how these parameters affect the thermal performance in real operating conditions. The experimental results, in terms of condensation heat transfer coefficient, have been compared with the predictions of some existing correlations, highlighting those that provide the best accuracy when designing brazed plate condensers.

A rigorous approach for characterising the limiting optimal efficiency of working fluids in organic Rankine cycles

Organic Rankine cycles (ORCs) are a standard and simple layout to convert thermal energy to mechanical energy and, subsequently, electrical energy. On the one hand, it is essential to select the proper working fluids. On the other hand, criteria to choose optimal operation conditions are also necessary. This contribution presents a rigorous and general approach based on the Helmholtz energy function to analyse the optimal performance of an organic Rankine cycle irrespective of the working fluid. The new approach is applied for the n-alkane series and a set of refrigerants using the perturbed-chain statistical association fluid theory (PC-SAFT) equation of state as a calculation tool. The study reveals that a dry global optimum cannot be achieved without partial condensation, and guidelines to avoid this fact are shown. Also, it is parametrically demonstrated that the optimum behaviour of an organic Rankine cycle is not directly connected to the isentropic behaviour of the fluids. However, it is proved that a slightly dry fluid is more suitable for a good performance than a very dry fluid, because the optimum range of expansion lies in a feasible range of temperature, avoiding problems with the limit of the solid phase.

Thermodynamic analysis and evaluation of a novel trans-critical CO2 power system incorporating partial condensation, sub-cooling, and recompression

Trans-critical CO2 Rankine cycle (TRC) is a promising technology that converts heat into power generation with its safe and environment-friendly characteristics. However, the low critical temperature of CO2 restricts the practical application of TRC, which requires a relatively low temperature heat sink to ensure the CO2 condensation. In addition, the heat capacity mismatch between hot and cold CO2 streams in the recuperator restricts the performance improvement of traditional recuperative trans-critical CO2 Rankine cycle (RTRC). In this study, a novel partial condensation trans-critical CO2 recompression cycle (PCRC) is proposed to simultaneously address the issues of condensing difficulty and low performance. Thermodynamic analysis and optimization models for both PCRC and RTRC are formulated and a solution algorithm is developed. Case studies are explored to validate the superiority of PCRC over traditional RTRC in thermal efficiency and operation flexibility. Influence of key parameters on the PCRC performance is also investigated to reveal the improvement mechanism over RTRC. Furthermore, sensitivity analysis is carried out on the upper operation pressure, heat source parameter, and heat sink parameter of the PCRC to determine its operational flexibility.