•It is shown that isenthalpic Joule-Thomson effect as refrigeration is more effective than isentropic process for quantum magnets.•Inversion temperature TJT corresponds to the maximal temperature of ...liquefaction of triplons in quantum magnets.•Calculated inversion temperature is in good agreement with experiment.
It is well known that, for a system of atomic (molecular) gases both kinds of processes, isentropic as well as isenthalpic are realizable and widely used in refrigeration technique. Particularly, magnetic refrigeration exploits always isentropic process, characterized by Grüneisen parameter ΓH=(∂T/∂H)S/T. We propose that, for quantum magnets an isenthalpic (Joule-Thomson) process, characterized by Joule-Thomson coefficient κT=(∂T/∂H)W may be also available. We considered this effect for a simple paramagnetic and dimerized spin-gapped quantum magnets at low temperatures. We have shown that for both kind of materials refrigeration by using Joule-Thomson effect is more effective than by using ordinary isentropic process, i.e. κT>TΓH at low temperatures. For dimerized spin-gapped magnets, where Bose–Einstein condensation of triplon gas may take place, the Joule-Thomson temperature corresponds to the maximal temperature of liquefaction of the triplon system, which is compared with recent experimental observations performed by Dresden group (Wang et al. (2016) 21). The inversion temperature, where reverse of cooling and heating up regimes takes place, found to be finite for triplons, but infinite for magnons in a simple paramagnetic.
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With the development of the hydrogen fuel cell automobile industry, higher requirements are put forward for the construction of hydrogen energy infrastructure, the matching of parameters and the ...control strategy of hydrogen filling rate in the hydrogenation process of hydrogenation station. Fuel for hydrogen fuel cell vehicles comes from hydrogen refueling stations. At present, the technological difficulty of hydrogenation is mainly reflected in the balanced treatment of reducing the temperature rise of hydrogen and shortening the filling time during the fast filling process. The Joule-Thomson (JT) effect occurs when high-pressure hydrogen gas passes through the valve assembly, which may lead to an increase in hydrogen temperature. The JT effect is generally reflected by the JT coefficient. According to the high pressure hydrogen in the pressure reducing valve, the corresponding JT coefficients were calculated by using the VDW equation, RK equation, SRK equation and PR equation, and the expression of JT effect temperature rise was deduced, which revealed the hydrogen temperature variation law in the process of reducing pressure. Make clear the relationship between charging parameters and temperature rise in the process of decompression; the flow and thermal characteristics of hydrogen in the process of decompression are revealed. This study provides basic support for experts to achieve throttling optimization of related pressure control system in hydrogen industry.
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•A literature review was performed for experimental data of density, speed of sound, and heat capacity of pure glycerol.•Experimental measurement of density was carried out using a vibrating tube ...densitometer at a temperature range of (298–423) K and a pressure up to 55 MPa.•Through-transmission ultrasonic measurements were conducted to determine the speed of sound in glycerol at temperatures of (298–398) K and a pressure up to 55 MPa.•Sound velocity data were used to calculate derived properties, including isobaric and isochoric heat capacity and Joule-Thomson coefficient of glycerol using the integration technique.•Obtained data were compared against various data from the literature.
A vibrating tube density meter (VTD) was used to measure density of pure glycerol at different isotherms between 298.16 and 423.12 K, and a pressure range up to 55 MPa. The VTD was calibrated based on the measurements conducted for water and nitrogen. Speed of sound in glycerol was also obtained by mean of a double path acoustic technique in a high pressure acoustic cell. Speed of sound measurements were conducted at five isotherms between 298.14 and 398.16 K with pressures limited to 55 MPa. The acoustic cell was calibrated with distilled water. Validation tests were performed by measuring the density and sound velocity in pure toluene using the VTD and acoustic cell, respectively. The maximum uncertainty (with 95 % level of confidence, k = 2) of the measured densities and sound velocities were found to be 1.27 kg.m−3 and 4.07 m.s−1, respectively.
In addition, the measured sound velocities combined with some reliable literature data for density, heat capacity and sound velocity at atmospheric pressure were utilised to determine density, isobaric, and isochoric heat capacities and the Joule-Thomson coefficient using a numerical integration method. Finally, the calculated densities were compared with measured densities from this work and literature, and a good agreement was observed.
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The Joule–Thomson effect is one of the important thermodynamic properties in the system relevant to gas switching reforming with carbon capture and storage (CCS). In this work, a set ...of apparatus was set up to determine the Joule–Thomson effect of binary mixtures (CO2 + H2). The accuracy of the apparatus was verified by comparing with the experimental data of carbon dioxide. The Joule–Thomson coefficients (μJT) for (CO2 + H2) binary mixtures with mole fractions of carbon dioxide (xCO2 = 0.1, 0.26, 0.5, 0.86, 0.94) along six isotherms at various pressures were measured. Five equations of state EOSs (PR, SRK, PR, BWR and GERG-2008 equation) were used to calculate the μJT for both pure systems and binary systems, among which the GERG-2008 predicted best with a wide range of pressure and temperature. Moreover, the Joule–Thomson inversion curves (JTIC) were calculated with five equations of state. A comparison was made between experimental data and predicted data for the inversion curve of CO2. The investigated EOSs show a similar prediction of the low-temperature branch of the JTIC for both pure and binary systems, except for the BWRS equation of state. Among all the equations, SRK has the most similar result to GERG-2008 for predicting JTIC.
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•Joule-Thomson Coefficient is predicted for several mixtures with the CPA EoS.•Results compared with other EoS.•Results shows that this approach is suitable for working with ...associative systems.
Several approaches involving some particular cubic equation of state (EoS) have been tested over the last 50 years as attempts to assess the Joule-Thomson coefficient (JTC) and inversion curves, though most of the cubic EoS are limited with regard to delivering good results for associating substances. The present work applies the Cubic Plus Association (CPA) EoS to predict the JTC for several pure substances (methane, ethane, propane, ethylene, benzene, toluene, nitrogen, carbon dioxide, sulfur hexafluoride, water, hydrogen sulfide and ethanol) and mixtures, focusing on systems with at least one associating substance. The results were compared with experimental and correlated data from the literature, as well as with the SRK EoS and molecular simulation. CPA EoS was capable of predicting the general trend for the Joule-Thomson coefficient and inversion curves even at extreme conditions, with reduced pressure values up to 20 and reduced temperatures up to 5.
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The Joule-Thomson characteristics of hydrogen-blended natural gas (HBNG) differ from those of natural gas for the differences in properties, deserving a profound study. We foremost analyzed the ...effects of hydrogen on the properties of HBNG using the Soave-Benedict-Webb-Rubin (BWRS) equation of state (EOS) owing to its lowest deviation among the concerned EOSs. Based on BWRS EOS, the fundamental differential equation, and the isenthalpic equation, we developed a thermodynamic model to evaluate the effects of hydrogen on the isenthalpic curve, Joule-Thomson coefficient (JTC), and Joule-Thomson inversion curve (JTIC) of HBNG within the hydrogen mole fraction (x-H2) range of 30%. The average absolute relative deviation (AARD) for the isenthalpic curve of the N2-H2 mixture and the JTC of natural gas is 0.02% and 1.62%. We mainly discussed how hydrogen affects the isenthalpic curve, JTC, and JTIC of HBNG. The isenthalpic curve of the CH4-H2 mixture and HBNG rise in a descending gradient with increasing x-H2. Compared to natural gas, the JTC of HBNG decreases (about 48% when x-H2 is 30%) and negatively correlates to x-H2, pressure, and temperature in a nonlinear function. The JTC is more sensitive to the x-H2 at higher temperatures and lower pressures. The blended hydrogen narrows the positive effect region of HBNG but does not turn the positive effect into a negative one within the x-H2 range of 30%. When x-H2 increases from 0% to 30%, the maximum inversion pressure and corresponding temperature drop at a rate of 0.227 MPa/x-H2% (roughly linear) and 4.9385 K/x-H2% (linear), respectively.
•The effects of hydrogen on the isenthalpic curve weaken with increasing x-H2.•Compared to natural gas, the JTC of HBNG decreases and negatively correlates to x-H2, pressure, and temperature in a nonlinear function.•The JTC of HBNG is more sensitive to the x-H2 at higher temperatures and lower pressures.•Hydrogen narrows the positive effect region of HBNG but does not turn the positive effect to negative within x-H2 of 30%.
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In the present work, two different intermolecular potentials are considered for the three real gases such as Ar, Kr and Xe. The effect of attraction term of the potential models on internal energy, ...enthalpy, entropy and Joule-Thomson (JT) coefficient of aforementioned gases has been investigated. To This end, the second virial coefficient of each potential was analytically derived. The suggested potential models have different attraction terms and the same repulsive terms. Our theoretical results in this work have been compared with experimental data. Our results reveal that the attraction term of the interaction potential has an important and main role to the thermodynamic properties of the selected gases. According to the results, it is found that the calculated thermodynamic function of the aforementioned gases obtained using both potential models are in acceptable agreement with available data. The degree of agreement depends strongly on the type of the used potential model and the range of pressures and temperatures. For instance, the JT coefficient of the Kr gas calculated by potential model (1) at high pressures and temperatures are in good agreement with experimental results. This property for the Ar gas has better agreement when we employ the potential model (2). This work allows us to select the suitable potential model and desired rages of pressure and temperature to give better results in comparison with experimental data.
•Two different intermolecular potentials are considered for the three real gases.•The effect of attraction term of the potential models on thermophysical function is studied.•We can select the suitable potential model to give better results in comparison with experimental data.
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•Experimental data about CO2 Joule–Thomson coefficient is obtained.•Computational accuracy of 8 types of CO2 Joule–Thomson coefficient is analyzed.•An improved 25-parameter equation is proposed for ...predicting CO2 Joule–Thomson coefficient in the temperature range 283–423K and the pressure range 2–40MPa.
The Joule–Thomson coefficient is a key parameter in the calculation of temperature and pressure and the prediction of the phase state and physical parameters. However, owing to different temperature and pressure conditions, CO2 presents different states: vapor, liquid, supercritical, etc. A set of experimental apparatus for the measurement of the CO2 Joule–Thomson coefficient measurement of was designed, which accurately measures the Joule Thomson coefficient of CO2 in the ranges 283–423K, 2–40MPa. Based on the experimental results, the absolute average errors of the CO2 Joule–Thomson coefficient predicted by the state equations are relatively low in vapor and supercritical states, but larger errors appear near the CO2 critical point and liquid state. According to the study findings, the CO2 Joule–Thomson coefficient is affected by the phase and varies dramatically at vapor, liquid, and supercritical states. However, the commonly used CO2 Joule–Thomson coefficient prediction methods do not exhibit good accuracy at all phase states. In order to accurately predict the CO2 Joule–Thomson coefficient at different phase states, a 25-parameter CO2 Joule-Thomson coefficient prediction equation is proposed in a temperature range of 283–423K and a pressure range of 2–40MPa, which can accurately describe the drastic change near the critical point. The error analysis of the CO2 Joule–Thomson coefficient experimental data determined that the absolute average errors at the vapor, liquid, and supercritical states are 1.52%, 4.59% and 3.08%, respectively. This work is expected to facilitate the engineering applications of CO2.
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•Based on the industrial-scale pipeline experimental apparatus a CO2 venting pipe was built.•The venting experiment of supercritical CO2 was carried out.•The evolutions of pressure, temperature and ...joule-thomson coefficient and process of phase transition inside venting pipe were obtained during the supercritical CO2 vented.•The nusselt number was selected as a parameter to discuss the heat transfer between the CO2 and the pipeline wall.
Carbon capture utilization and storage (CCUS) is the technology with the greatest potential to decrease the content of CO2 in the atmosphere, which is the main contributor to global warming and can result in a significant number of environmental problems. The transportation of CO2 is the most important node in the CCUS chain and a pipeline is an economical and efficient means of transportation. In the process of CO2 pipeline building, a certain amount of venting devices should be installed to prevent overpressure of the main pipeline and allow for overhaul of the main pipeline. Hence it is necessary to obtain the characteristics of CO2 inside the venting pipe during the venting process in order to maintain the safety of both the venting pipe and the main pipeline during release. In this study, two 2 m long venting pipes were connected by valves and installed on an industrial-scale pipeline. Two group venting experiments were carried out with two different openings of the valve. Industrial-scale experiment apparatus was used to obtain crucial data and get results closer to an actual industrial setting. During the experiments the evolution of the temperature and the pressure of the CO2 were measured. Based on the pressure and temperature data, the differences of the phase transition of the CO2 in the two experiments were compared. No dry ice was generated inside the pipe during the experiments. A throttling effect was generated in one group experiment but not in the other. In addition, the evolution trend of the Joule–Thomson coefficient was discussed. During the whole venting process, the wall temperature was obtained and the Nusselt number was selected as a parameter to discuss the process of heat transfer between the CO2 and the pipeline wall.
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•Derivation of new relations for estimating of SHC, JTC, integral JTC and JTIC.•Introducing the most appropriate EoS for calculating of thermo-physical properties.•Evaluating the behavior of gases in ...a wide range of temperature and pressure.
In this study, six cubic equations of state (CEoSs) were used to predict the Joule-Thomson coefficient (JTC), specific heat capacity (SHC), inversion curve (IC) and outlet temperature of the Joule-Thomson (JT) valve parameters. The accuracy of each CEoS was evaluated from the comparison of experimental data with obtained results. Of the six CEoSs, three-paramter CEoSs— Esmaeilzadeh and Roshanfekr (ER), Harmen and Knapp (HK), and Patel and Teja (PT)— were more accurate than two-paramter equations— Nasrifar and Moshfeghian (NM), Peng-Robinson (PR), and Soave-Redlich-Kwong (SRK). Ironically, original SRK showed the optimum accuracy in estimation of JTC. In addition, the Joule-Thomson inversion curves (JTIC) were plotted for pure gases. Most of the CEoSs showed reasonable prediction on low-temperature branch of JTIC, but only original SRK and PT CEoSs estimated well at high-temperature branch. For two-parameter CEoSs, the effect of employing different α-functions and adding volume translation factor were also examined. The error analysis showed that the accuracy of original PR CEoS was significantly improved when volume translation factor was included as a third parameter. In addition, the SRK-Twu88 and PR-Twu91 CEoSs showed higher accuracy in prediction of SHC as compared to original SRK and original PR.
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