Rapid Decompression Research Articles

Sulfur diffusion in dacitic melt at various oxidation states: Implications for volcanic degassing

The diffusivity of S in a hydrous dacitic melt (4.5–6.0 wt.% H2O) has been investigated in the temperature (T) and pressure (P) range of 950 °C to 1100 °C and 200 to 250 MPa, respectively. Three series of experiments were conducted at relatively low oxygen fugacity (fO2) conditions [0.8 log units below fayalite-magnetite-quartz equilibrium (FMQ −0.8); referred to as “low fO2”] and high fO2 conditions (FMQ +2.5; referred to as “high fO2”) to determine if the diffusivity of S is affected by its oxidation state and speciation. Sulfur concentration profiles were measured by electron microprobe and the diffusion coefficient (D) was calculated by fitting these profiles. Sulfur diffusion is approximately one order of magnitude faster when S is dominantly present as sulfide species (low fO2) in comparison to the sulfate dominated experiments (high fO2). The following Arrhenian equations were obtained for high and low fO2 conditions at 200 MPa:highfO2:D=10-5.92±0.86∗exp-137.3±21.5kJ/molRTlowfO2:D=10-5.18±1.39∗exp-125.7±34.4kJ/molRTwhere D is the average diffusion coefficient in m2 s−1, R is the gas constant in 8.3144 J mol−1 K−1 and T is the temperature in K. Our results demonstrate for the first time in natural melts that S diffusion is strongly sensitive to fO2. Our S diffusivities under low fO2 conditions are only slightly slower of those found for H2O, suggesting that S can be rather efficiently purged from reduced dacitic melts during volcanic eruptions. However, for more oxidized systems (e.g. subduction zones), S diffusion will be much slower and will hinder equilibrium syn-eruptive degassing during rapid decompression. Therefore, we conclude that the “excess S” measured during many explosive volcanic eruptions in arcs is dominantly derived from S-rich bubble accumulation in the eruptible portion of the magma reservoir.

Determining barotrauma in the Pictus catfish, Pimelodus pictus, experimentally exposed to simulated hydropower turbine passage

Hydropower development poses severe threats to the aquatic diversity and ecosystem services. One such threat is the exposure of fish to extreme conditions within hydropower facilities. Fish may suffer rapid decompression when passing through turbines or when entering the draft tubes, which can lead to barotrauma and mortality. We aimed to evaluate the effects of rapid decompression on the Amazonian benthic species Pimelodus pictus (Pictus catfish), by simulating in hypo–hyperbaric chambers. The most frequent injuries in Pictus catfish exposed to simulated rapid decompression were swim-bladder rupture, intestine rupture, internal haemorrhage and embolism. The occurrence and magnitude of internal haemorrhaging and emboli were related to the ratio of pressure change and the decompression timespan, whereas swim-bladder rupture occurred even at relatively low ratios. Emboli was present almost entirely among fish with a ruptured swim bladder. Importantly, all fish were negatively buoyant before exposure to decompression, posing challenges to data analysis. Therefore, barotrauma studies with benthic fish species are deemed to be challenging and are likely to require the use of complementary approaches. Research is needed to understand the state of buoyancy of benthic fish in the wild and to develop methods to accurately replicate these in a controlled testing environment.

Predicting hydraulic structure-induced barotrauma in Australian fish species

When fish pass downstream through river infrastructure, such as dams and weirs, barotrauma may occur as a result of rapid decompression. In severe cases, barotrauma may lead to mortality. Different species are likely to respond differently to these decompressions. Therefore, to predict barotrauma for a specific species, surrogate species may not be a valid approach, and it may be necessary to examine each species individually. For the present study, Australian bass and carp gudgeon were exposed to a range of rapid decompressions using hyper- and hypobaric hydro-chambers and examined for injuries and mortality. Rapid decompression data from these two fish species, in addition to previously examined Murray cod and silver perch, were evaluated to determine which injuries were highly associated with and likely to predict mortality. Dose–response logistic regression models were developed for each species to predict injury and mortality over a range of rapid decompressions. These models are valuable for estimating injury and mortality rates for fish passing though river infrastructure and can be applied to specific sites where pressure profiles have been developed. Applying these models to current and future infrastructure can provide important insight into what measures or design alterations may be necessary to reduce negative effects of infrastructure on fish populations.

Injury and mortality of two Mekong River species exposed to turbulent shear forces

Global hydropower development is one solution proposed to address the increase in energy needs. However, hydropower-related impacts on riverine ecological systems are not well understood. The Mekong River Basin (MRB) is one of the world’s largest waterways and is presently experiencing significant hydropower expansion. It is also one of the most biodiverse rivers; serving as home to many species that are blocked or hindered by the development of dams. One source of injury and mortality for downstream moving fishes is passage through the turbine environment where fishes may be exposed to several physical stressors (e.g. shear forces, rapid decompression, blade strike and turbulence). The current study sought to understand the susceptibility of blue gourami (Trichopodus trichopterus) and iridescent shark (Pangasianodon hypophthalmus) to shear forces. Fishes were exposed to an underwater jet with velocities up to 21.3ms–1 (equating to strain rates of up to 1185s–1) and were assessed for behavioural effects, injuries and mortality. Overall, it was determined that both species were susceptible to the shear forces applied in this study and the effects were more pronounced at higher strain rates. Gouramis were more susceptible than sharks. To minimise impacts on these species, shear forces within turbines should not exceed critical limits.

The role of radiosurgery in the acute management of fourth ventricle compression due to brain metastases.

Background:Approximately 20–30% of all intracranial metastases are located in the posterior fossa. The clinical evolution hinges on factors such as tumor growth dynamics, local topographic conditions, performance status, and prompt intervention. Fourth ventricle (V4) compression with secondary life-threatening obstructive hydrocephalus remains a major concern, often requiring acute surgical intervention. We have previously reported on the application of adaptive hypofractionated Gamma Knife Radiosurgery in the acute management of critically located metastases, a technique known to us as rapid rescue radiosurgery (3R). We report the results of 3R in the management of posterior fossa lesions and ensuing V4 decompression.Case Descriptions:Four patients with V4 compression due to posterior fossa metastases were treated with 3R by three separate gamma knife radiosurgical sessions (GKRS) over a period of seven days. Mean V4 volume was 1.02 cm3 at GKRS 1, 1.13 cm3 at GKRS 2, and 1.12 cm3 at GKRS 3. Mean tumor volume during the week of treatment was 10 cm3 at both GKRS 1 and 2 and 9 cm3 at GKRS 3. On average, we achieved a tumor volume reduction of 52% and a V4 size increase of 64% at the first follow-up (4 weeks after GKRS 3). Long-term follow-up showed continued local tumor control, stable V4 volume, and absence of hydrocephalus.Conclusion:For this series, 3R was effective in terms of rapid tumor ablation, V4 decompression, and limited radiation-induced toxicity. This surgical procedure may become an additional tool in the management of intractable posterior fossa metastasis with V4 compression.

It's a catfish! Novel approaches are needed to study the effects of rapid decompression on benthic species

Barotrauma as a result of rapid decompression has been recorded as the most common injury among fish captured in the tailrace of hydropower dams in Brazil, with catfishes representing the majority of them. Nevertheless, studies investigating barotrauma on catfish are scarce, with the majority determining dose–response curves and thresholds of pressure changes for nektonic species, such as salmonids. Experiments conducted with Pimelodus pictus showed that the current hypo-hyperbaric chambers used to study barotrauma in nektonic species can have limitations when applied to benthic groups. The negative buoyancy showed by the catfish prevented the definition of the acclimation pressure of the fish before exposure to decompression and, therefore, the method had to be adapted to allow the calculation of the ratio of pressure change (RPC). The adaptation involved anaesthetising the fish, which added a potential bias to the experiments. Therefore, new approaches deemed to be needed to complement barotrauma studies with benthic fish. We aimed to discuss the limitations observed for studies with benthic species and present potential methods to overcome them. The diversification of approaches for barotrauma studies with benthic species is critical to provide information for the development of mitigation and new turbine designs that would improve protection of this group.

Numerical study of the effect of heat transfer on solid phase formation during decompression of CO2 in pipelines

CO2 solid phase formation accompanying rapid decompression of high-pressure CO2 pipelines may lead to blockage of the flow and safety valves, presenting significant hazard for safe operation of the high-pressure CO2 storage and transportation facilities. In this study, a homogeneous equilibrium flow model, accounting for conjugate heat transfer between the flow and the pipe wall, is applied to study the CO2 solid formation in a 50 mm internal diameter and 37 m long pipe for various initial thermodynamic states of CO2 fluid and wide range of discharge orifice diameters. The results show that the rate of CO2 solid formation in the pipe is limited by heat transfer at the pipe wall. The predicted amounts of solid CO2 are discussed in the context of venting of CO2 pipelines.

Comparison between Ventriculosubgaleal Shunt and Extraventricular Drainage to Treat Acute Hydrocephalus in Adults.

Context:Hydrocephalus, due to subarachnoid or intraventricular hemorrhage (IVH), meningitis, or tumor compression, is usually transient and may resolve after treatment. There are several temporary methods of cerebrospinal fluid (CSF) diversion, none of it is superior to the other, and the decision is based on its various etiologies and factors. Ventriculosubgaleal shunt (VSGS) is one of those temporary measures, which is a simple and rapid CSF decompression method without causing electrolyte and nutritional losses.Aims:The aim is to study the efficacy of VSGS for temporary CSF diversion, compared to extraventricular drainage (EVD) in adult hydrocephalus patients; to evaluate the outcome in terms of avoiding a permanent shunt, and to look for incidences of their complications.Settings and Design:This was a retrospective observational study.Subjects and Methods:The data were acquired from case notes of fifty patients with acute hydrocephalus: 26 secondary to IVH, 10 from aneurysm rupture, 8 posttrauma, and 6 from infection. All these patients had undergone CSF diversion in Hospital Queen Elizabeth II, Sabah, Malaysia, between 2013 and 2015. The patients were followed up from the date of treatment until the resolution of hydrocephalus, where parameters such as shunt dependency and complications were documented.Statistical Analysis Used:All analyses were carried out using Statistical Packages for the Social Sciences Version 22.0. Chi-squared test or Fisher's exact test is used for univariate analysis of categorical variables.Results:A total of 21 (42%) patients underwent EVD insertion and 29 (58%) underwent VSGS insertion. Thirty-seven (74%) patients did not require a permanent shunt; 24 (64.8%) of them were from the VSGS group (P = 0.097). EVD had more intracranial complications (44.1%) compared with VSGS (23.5%), with a statistically significant P = 0.026.Conclusions:VSGS is a safe and viable option for adult hydrocephalus patients, with the possibility of continuation of the treatment for such patients in nonneurosurgical centers, as opposed to patients with EVDs. Furthermore, even though this method had no statistical difference in avoiding a permanent ventriculoperitoneal shunt, VSGS has statistically significant less intracranial complications compared with EVD.

Early radiological intervention and haematology screening is associated with excellent outcomes in Budd-Chiari syndrome.

Budd-Chiari syndrome (BCS) is a rare and life-threatening disorder, resulting from thrombosis of the hepatic veins. Various treatments, including pharmacological, radiological and surgical interventions, have been used. To describe retrospectively our institution's experience with management of patients with BCS. A retrospective study of all cases of primary Budd-Chiari syndrome presenting to our institution between January 2000 and August 2012 was performed. Patients with secondary Budd-Chiari syndrome due to malignancy or local mass compression were excluded. Between 2000 and 2012, 27 patients with primary BCS presented with a median Rotterdam score of 1.16 (range: 0.07-2.11). A total of 24 patients (89%) had at least one risk factor, with the commonest being myeloproliferative neoplasm (MPN), detected in 17 of 24 (71%) of the tested patients, including four patients with normal blood counts at diagnosis. All patients were anticoagulated with warfarin or low-molecular-weight heparin (LMWH). A total of 25 (92.6%) patients also had primary radiological interventions, consisting of transjugular intrahepatic portosystemic shunt (TIPS) in 18 (67%) patients and/or angioplasty/stenting in 11 (40%). A total of 14 patients developed TIPS stenoses, requiring a median of 1.5 (range: 1-14) revisions. No patient developed TIPS failure requiring alternative therapy. Two patients were lost to follow-up. At a median follow up of 59 months (range: 2-248 months), the overall survival was 96% at 1 year and 81% at 5 years, much greater than predicted by the Rotterdam score. No patients required liver transplantation. There is a high incidence of MPN in patients with primary BCS, including patients with normal peripheral blood counts at the time of diagnosis. Our approach of anticoagulation, aggressive and early radiological intervention aimed at rapid decompression of the congested liver resulted in excellent medium-term outcomes.

Advancement of magma fragmentation by inhomogeneous bubble distribution

Decompression times reported in previous studies suggest that thoroughly brittle fragmentation is unlikely in actual explosive volcanic eruptions. What occurs in practice is brittle-like fragmentation, which is defined as the solid-like fracture of a material whose bulk rheological properties are close to those of a fluid. Through laboratory experiments and numerical simulation, the link between the inhomogeneous structure of bubbles and the development of cracks that may lead to brittle-like fragmentation was clearly demonstrated here. A rapid decompression test was conducted to simulate the fragmentation of a specimen whose pore morphology was revealed by X-ray microtomography. The dynamic response during decompression was observed by high-speed photography. Large variation was observed in the responses of the specimens even among specimens with equal bulk rheological properties. The stress fields of the specimens under decompression computed by finite element analysis shows that the presence of satellite bubbles beneath a large bubble induced the stress concentration. On the basis of the obtained results, a new mechanism for brittle-like fragmentation is proposed. In the proposed scenario, the second nucleation of bubbles near the fragmentation surface is an essential process for the advancement of fragmentation in an upward magma flow in a volcanic conduit.

Phreatic activity and hydrothermal alteration in the Valley of Desolation, Dominica, Lesser Antilles

Phreatic eruptions are possibly the most dramatic surface expressions of hydrothermal activity, and they remain poorly understood. The near absence of precursory signals makes phreatic eruptions unpredictable with respect to both time and magnitude. The Valley of Desolation (VoD), Dominica, located close to the Boiling Lake, the second largest high-temperature volcanic crater lake in the world, hosts vigorous hydrothermal activity with hot springs, mud pools, fumaroles, and steaming ground. A phreatic or phreatomagmatic eruption from this site is considered to be the most likely scenario for future volcanic activity on Dominica. Yet there is little information regarding the trigger mechanisms and eruption processes of explosive events at this active hydrothermal center, and only a very small number of studies have investigated hydrothermal activity in the VoD. We therefore conducted two field campaigns in the VoD to map hydrothermal activity and its surficial phenomena. We also investigated alteration processes and their effects on degassing and phreatic eruption processes. We collected in situ petrophysical properties of clay-rich unconsolidated samples, and together with consolidated rock samples, we investigated the range of supergene and hydrothermal alteration in the laboratory. In addition, we performed rapid decompression experiments on unconsolidated soil samples. Our results show that alteration leads to an increasing abundance of clay minerals and a decrease in both strength and permeability of the rocks. In the immediate vicinity of degassing acid-sulfate fluids, advanced argillic alteration yields a mineral zoning which is influenced by meteoric water. The water-saturated basal zone is dominated by kaolinite run 0whereas alunite formation is favored at and above the groundwater table where atmospheric oxidation of H2S to H2SO4 occurs (e.g., steam-heated alteration). Alteration effects may in turn inhibit degassing at the surface, increasing the potential for pressurization in the subsurface and thus lead to phreatic eruptions. Rapid decompression experiments, together with ballistic trajectory calculations, constrain estimates of the conditions prior to the 1997 small-scale phreatic event in the VoD. The results presented here may serve as a contribution to the understanding of the hazard potential of ongoing hydrothermal activity within the VoD. On a broader perspective, our results will help evaluate hydrothermal activity in similar areas worldwide which might also have the potential for phreatic eruptions, for instance Poas (Costa Rica) or Tongariro and Waimangu (New Zealand).

A convenient dynamic loading device for studying kinetics of phase transitions and metastable phases using symmetric diamond anvil cells

ABSTRACTWe have designed and implemented a novel DLD for controlling pressure and compression/decompression rate. Combined with the use of the symmetric diamond anvil cells (DACs), the DLD adopts three piezo-electric (PE) actuators and three static load screws to remotely control pressure in accurate and consistent manner at room temperature. This device allows us to create different loading mechanisms and frames for a variety of existing and commonly used diamond cells rather than designing specialized or dedicated diamond cells with various drives. The sample pressure compression/decompression rate that we have achieved is up to 58.6/43.3 TPa/s, respectively. The minimum of load time is less than 1 ms. The DLD is a powerful tool for exploring the effects of rapid (de)compression on the structure of materials and the properties of materials.

Modeling of CO2 Decompression across the Triple Point

The formation of significant quantities of solid CO2 as a result of surpassing its triple point during rapid decompression of CO2 pipelines employed as part of the carbon capture and sequestration (CCS) chain can present serious operational and safety challenges. In this paper, the development, testing and validation of a rigorous computational fluid dynamics (CFD) flow model for predicting solid CO2 formation during decompression is presented. Multiphase flow is modeled by assuming homogeneous equilibrium, and the pertinent thermodynamic data are computed using real-fluid equations of state. The flow model is validated against pressure and temperature data recorded during the decompression of an extensively instrumented 144 m long, 150 mm i.d. CO2 pipe initially at 5.25 °C and 153.3 bar. For the conditions tested, the simulated results indicate CO2 solid mass fractions as high as 35% at the rupture plane, whose magnitude gradually decreases with distance toward the pipe’s intact end.

CO2 SOLUBILITY AND DIFFUSIVITY AND RAPID GAS DECOMPRESSION RESISTANCE OF ELASTOMERS CONTAINING CNT

ABSTRACTUnderstanding the structure–property relationship of elastomers is of critical importance in developing next-generation elastomers for high-pressure, high-temperature (HPHT) applications and in extending the application temperature and pressure range of existing oilfield products. Gas dissolution and diffusion in elastomers are essential to understanding the relationship among elastomer structures, rapid gas decompression (RGD) resistance, and sealing performance. Solubility and diffusivity (or diffusion efficiency) of carbon dioxide (CO2) in hydrogenated nitrile butadiene rubber (HNBR) and fluoroelastomers (FKM) comprising carbon nanotubes (CNT) were measured using a gravimetric method. The Rubotherm method was also used to estimate the solubility and swelling of HNBR in both subcritical liquid and supercritical CO2. It was demonstrated that CNT had a direct impact on CO2 solubility, diffusion, and mechanical properties of elastomers, hence improving the RGD resistance of the elastomers.

Systems Theoretic Accident Model and Process (STAMP) safety modelling applied to an aircraft rapid decompression event

Understanding a crew’s response to a rapid decompression, and factors which can influence the decisions crew members make, can facilitate a safe resolution of a potentially life threatening hazard. Anticipating the Human Factors issues is an appropriate way to assess potential risk factors before such an event happens. The Systems Theoretic Accident Model and Process (STAMP) and its predictive risk assessment method, System-Theoretic Process Analysis (STPA), is a systemic approach to safety analysis. This approach is ideal when considering complex systems, such as aviation. The scenario of an aircraft experiencing a decompression event was analysed using STAMP-STPA across a series of workshops during which key safety elements were identified and reflected upon. It was found that the use of the STAMP-STPA methodology successfully identified factors central to the Helios 522 accident. Based on the outputs of this research, it is suggested that, due to its inherent utility, the STAMP-STPA method can be used to elicit a variety of safety critical insights, and does so in a way that considers individuals, organisations and technology at the same level of granularity, in a way that does not attribute blame to any single agent.

Порівняльна оцінка динаміки холестатичних та цитолітичних показників і темпу декомпресії жовчних проток після одноетапних лапароскопічних та відкритих операційних втручань у хворих на холедохолітіаз, ускладнений обтураційною жовтяницею (повідомлення 2)

Мета роботи: визначити темп декомпресії жовчних проток та оцінку показників синдромів цитолізу й холестазу після одноетапних лапароскопічних і відкритих операційних втручань у пацієнтів із холедохолітіазом, ускладненим обтураційною жовтяницею.Матеріали і методи. Проведено порівняння динаміки біохімічних показників холестазу й цитолізу та темпу біліарної декомпресії у 81 хворого з холедохолітіазом, ускладненим обтураційною жовтяницею, із різним рівнем білірубіну, на 3-тю, 5-ту та 7-му добу після одноетапних лапароскопічних і відкритих операційних втручань. Темп відповіді жовтяниці на декомпресію визначали за формулою T. Shmizu і K. Yoshida в модифікації Э. И. Гальперина.Результати досліджень та їх обговорення. Встановлено, що лапароскопічна холедохолітотомія у пацієнтів із рівнем гіпербілірубінемії до 100 мкмоль/л і від 100 до 200 мкмоль/л супроводжується затяжним і помірним темпом декомпресії, що є оптимальним у післядекомпресійному періоді. У хворих із рівнем гіпербілірубінемії від 100 до 200 мкмоль/л, яким виконаний холедоходуоденоанастомоз, відмічається швидкий темп декомпресії в післяопераційному періоді, що потребує профілактичної медикаментної корекції можливого синдрому “швидкої декомпресії”.

Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Incidental capture, or ‘bycatch’ in fishing gear is a major global threat to sea turtle populations. A recent study showed that underwater entrapment in fishing gear followed by rapid decompression may cause gas bubble formation within the blood stream (embolism) and tissues leading to organ injury, impairment, and even mortality in some bycaught individuals. We analyzed data from 128 capture events using logistic and ordinal regression to examine risk factors associated with gas embolism in sea turtles captured in trawls and gillnets. Likelihood of fatal decompression increases with increasing depth of gear deployment. A direct relationship was found between depth, risk and severity of embolism, which has not been previously demonstrated in any breath-hold diving species. For the trawl fishery in this study, an average trawl depth of 65 m was estimated to result in 50% mortality in by-caught turtles throughout the year. This finding is critical for a more accurate estimation of sea turtle mortality rates resulting from different fisheries and for devising efforts to avoid or minimize the harmful effects of capture.

A Case of Bilateral Pneumoparotid Improved with Conservative Treatment

이하선 기종은 이하선 종대의 원인 중 매우 드문 질환으로, 이하선의 종창과 통증 등의 증상을 나타낸다. 이하선 기종은 유리 부는 직공이나 관악기 연주자 등 여러 구강 내 압력이 증가하는 상황에서 이하선 내로 공기가 들어가 발생할 수 있다. 저자들은 최근 습관적인 볼 부풀리기로 유발된 양측 이하선 기종 환자를 경험하고, 이에 대해 습관 교정을 통한 보존적 치료로 호전되었기에 문헌 고찰과 함께 보고하고자 한다.Pneumoparotid is defined as the presence of air within the parotid gland or duct. Pneumoparotid is an extremely rare cause of parotid gland swelling. Pneumoparotid can be induced by air insufflation from oral cavity into the intraparotid salivary ducts, in condition like nose blowing, blowing up balloons, during extubation after general anesthesia while receiving positive pressure, rapid decompression while scuba diving, chronic attempts to suppress cough, and glassblowers. It can also be self-induced, and the literature contains an increasing number of reports involving pediatric and adolescent patients who induce parotid insufflation to avoid school or gain attention. Here, we report a case of pneumoparotid caused by habitual cheek inflating and improved with conservative treatment.

Superposed and refolded metamorphic isograds and superposed directions of shear during late orogenic extension in the Alborán Domain, southern Spain

AbstractThe timing, kinematics, and mode of exhumation within the Alpujárride Complex, the largest tectonic unit of the Alborán Domain, are controversial. Alternative tectonic models include synorogenic exhumation during pre‐Miocene crustal thickening, intraorogenic exhumation during repeated phases of contraction and extension, and late orogenic exhumation during early Miocene crustal thinning. New structural and petrographic relationships documented in this study support the latter model: subhorizontal foliations, stretching lineations, and recumbent folds are associated with early Miocene high‐temperature decompressional metamorphism and vertical condensation of the metamorphic sequence. Relict isograds associated with high‐pressure metamorphism and burial are systematically overprinted by isograds associated with high‐temperature metamorphism and rapid decompression. During the early stages of extensional exhumation and growth of sillimanite, ENE directed shear (D2) overprinted thrusts and foliations associated with crustal thickening (D1). During the later stages of extensional exhumation and growth of andalusite, from ductile to semibrittle conditions, north directed shear (D3) produced kilometer‐scale recumbent folds that refold isograds. Stretching lineations characterize superposed directions of orogen‐parallel (L2) and later orogen‐perpendicular (L3) shear associated with a rapid temporal transition in the kinematics of extensional exhumation. During the final stages of crustal thinning and cooling, ductile structures (D2/D3) were cut by brittle low‐angle normal faults (D4).

Modeling of Depressurization-Induced Superheating for Compressed Liquefied Gases

During the rapid depressurization of a liquefied gas, its superheating can lead to a boiling liquid expanding vapor explosion (BLEVE). Such an event is of enormous concern during carbon capture and storage (CCS) given the significant amounts of pressurized CO2 involved during its transportation and storage. This article presents, for the first time, the development and validation of a rigorous split-fluid blowdown model for predicting the degree of superheating following the rapid decompression of liquefied gases or two-phase mixtures with particular reference to CO2. The model was successfully validated through a comparison of the predicted vapor- and liquid-phase pressures and temperatures against the recorded data from a number of depressurization tests conducted for pure dense-phase CO2 and its mixtures representing those associated with different capture technologies. The effects of changes in the pressure-relief-valve diameter and CO2 purity on the degree of superheating and, hence, the spontaneity ...