Joule-Thomson Effect Research Articles

Joule–Thomson expansion of 5-dimensional [formula omitted]-charged black holes

In this article, we study the Joule–Thomson expansion for a given number of electric charges for 5-dimensional R-charged black holes in the extended phase space. We analyze both the isenthalpic and numerical inversion curves in the T−P plane and show the cool-heat zones associated with 5-dimensional R-charged black holes. A concrete comparison of Joule–Thomson expansion comes from the relationship between minimum inversion and critical temperatures for 5-dimensional R-charged black holes.

Study on the influence of distributed Joule-Thomson effect on the performance of microchannel cryocooler

At present, the pros and cons of distributed Joule-Thomson (J-T) effect in throttling refrigeration systems have been controversial. In this paper, a microchannel J-T cryocooler is used as the prototype. The distributed J-T effect is produced by the friction loss in the throttling channel. The refrigeration performance of the cryocooler at 6.0 MPa is analyzed. Then, according to the dependence of the J-T coefficient on pressure and temperature, a fully distributed J-T effect microchannel is designed to replace the separate counterflow heat exchanger and throttling device on the high-pressure side. The characteristics are simulated and compared with the prototype. The results show that the refrigeration ability of the fully distributed J-T cryocooler is slightly inferior to that of the prototype under the same pressure drop, and excessively increasing or reducing the cross-sectional size of the channel is not conducive to cooling. However, the fully distributed J-T effect structure can effectively delay the occurrence of choked flow due to the low velocity of the fluid. Under 6.0 MPa inlet pressure, the limited mass-flow rate of fully distributed cryocooler is 7.51 g/s, and the lowest temperature can reach 147.7 K, which is significantly lower than 163.3 K that the prototype can reach in the choked state. In addition, this paper also explores the influence of distributed J-T effect on the low-pressure side, which is beneficial to precooling the high-pressure fluid more efficiently using a little distributed J-T effect. A proper part of the friction loss in the low-pressure channel helps improve the refrigeration ability. At 6.0 MPa inlet pressure, the best cooling effect is obtained when the pressure drops in the low-pressure channel account for 15.85 % of the total pressure drop.

Computational study of compressible flow through choke valve

Failure of choke valves due to vortex shedding and flow-induced vibration (FIV) is common problem in industry. Mechanisms of head-on collision of fluid jets within a choke valve is investigated computationally in this manuscript. The benchmarked simulations are conducted at fixed flow rate and two different choke positions. The vorticity contours overlaid by velocity field are presented across various planes within the valve, shedding light on dynamics of the flow. The formation of a time-averaged four-lobed vortical structure is evident within the valve chamber. There is strong vortex shedding taking place along the tails of head-on colliding jets exhibiting unsteady flipping motion. Mach contours reveal choked flow condition upon constricted region of the valve ports. Pressure contours, accompanied by density graphs, uncover stagnation zone forming within the valve. Temperature profiles, on the other hand, detail significant gas cooling upon throttling due to Joule–Thomson effect. In order to extract dominant frequencies of vibration and corresponding Strouhal numbers, signal processing of transient pressure data at various probes inside the valve chamber has been performed through Fast-Fourier Transform (FFT), autocorrelation analysis, and continuous wavelet transform. At higher valve opening, spread-out dominant frequencies lie in the range <5000 Hz. However, at lower opening (or valve flow coefficient) two distinct peaks approximately at 5000 Hz and 10,000 Hz are visible from processed signals.

General Thermodynamic Properties of FRW Universe and Heat Engine

In this work, the Friedmann–Robertson–Walker (FRW) Universe is considered a thermodynamic system, where the cosmological constant generates the thermodynamic pressure. Using a unified first law, we have determined the amount of energy dE crossing the apparent horizon. Since heat is one of the forms of thermal energy, so the heat flows δQ through the apparent horizon = amount of energy crossing the apparent horizon. Using the first law of thermodynamics, on the apparent horizon, we found TdS=A(ρ+p)Hr˜hdt+Aρdr˜h where T,S,A,H,r˜h,ρ,p are respectively the temperature, entropy, area, Hubble parameter, horizon radius, fluid density and pressure. Since the apparent horizon is dynamical, so we have assumed that dr˜h cannot be zero in general, i.e., the second term Aρdr˜h is non-zero on the apparent horizon. Using Friedmann equations with the unified first law, we have obtained the modified entropy-area relation on the apparent horizon. In addition, from the modified entropy-area relation, we have obtained modified Friedmann equations. From the original Friedmann equations and also from modified Friedmann equations, we have obtained the same entropy. We have derived the equations for the main thermodynamical quantise, such as temperature, volume, mass, specific heat capacity, thermal expansion, isothermal compressibility, critical temperature, critical volume, critical pressure and critical entropy. To determine the cooling/heating nature of the FRW Universe, we have obtained the coefficient of Joule–Thomson expansion. Next, we have discussed the heat engine phenomena of the thermodynamical FRW Universe. We have considered the Carnot cycle and obtained its completed work. In addition, we studied the work completed and the thermal efficiency of the new heat engine. Finally, we have obtained the thermal efficiency of the Rankine cycle.

Joule–Thomson expansion of Einstein–Skyrmion black holes

The Joule–Thomson expansion of Einstein–Skyrmion black holes in four dimensions was studied in the extended phase space. We obtained the inversion curves and isenthalpic curves for different values of parameters K and λ, which represent the coupling strength between the gravity field and matter field. We found that parameters K and λ have the same effects during the entire Joule–Thomson expansion and larger parameter K or λ corresponds to smaller inversion pressure. Analogously, the phase space { T, P} consists of cooling–heating regions. In addition, the dispersion point of the Joule–Thomson coefficient μ is in correspondence with the zero point of the Hawking temperature T, and the ratio of the minimum inversion temperature [Formula: see text] and the critical temperature Tc is a constant.

A novel thermal stimulation approach for natural gas hydrate exploitation —— the application of the self-entry energy compensation device in the Shenhu sea

Thermal stimulation is a common measure used to improve the decomposition efficiency of natural gas hydrate. However, the conventional thermal stimulation methods require considerable investments in wellbore construction. According to the penetration mechanism of the torpedo anchor, the self-entry energy compensation device (ECD) is innovatively proposed to replace the existing wellbore platform. The principle and critical technologies of the ECD are described and analyzed in detail. Then, a penetration model and an exploitation model are developed using the reservoir data from the W17 station in the Shenhu sea area, and the main conclusions are: It takes about 4 s for the ECD to penetrate from the overburden layer to the reservoir, and its penetration depth is about 50.1–370.4 m, which covers the buried depth of most marine reservoirs. Nevertheless, the combined depressurization + thermal stimulation method is unsuitable for the Shenhu reservoir due to the low permeability, low thermal conductivity, and high initial temperature. Overall, the ECD can provide a new idea for developing the NGH thermal stimulation method to solve the Joule-Thomson effect and seawater freezing problems during the depressurization production.

Effects of magnetic monopole charge on Joule–Thomson expansion of regular Ayón Beato–García black hole

We investigate Joule–Thomson (J–T) expansion process of the regular Ayón Beato–García (ABG) black hole, and compare the J–T expansion process between the regular ABG black hole and the singular AdS black holes. We find that the inversion curves are unclosed and closely related to magnetic monopole charge (MMC) in the black hole solution. The results show that the temperature decreases/increases with the increase of MMC parameter at low/high pressure, in contrast to a branch of the inversion curves for singular AdS black holes. The ratio between the minimum inversion temperature and the critical temperature is also greater than that of any known ratio of singular AdS black holes. In addition, the minimum inversion mass is greater than the minimum mass, so there are some isenthalpic curves without inversion points below the inversion curves, which means that the regular black hole is always in heating process. In contrast of singular charged AdS black holes, the isenthalpic curves cannot exist below the inversion curves, because the event horizon cannot be defined here. Furthermore, we obtain that the minimum inversion mass and the minimum mass depend only on MMC parameter. By fixing the parameters of MMC and the black hole mass, we find that a repulsive core near the origin of the regular black hole may lead to different results from that of the singular AdS black holes in the J–T expansion process.

The general class of accelerating, rotating and charged Plebanski-Demianski black holes as heat engine

We first review the general class of accelerating, rotating and charged Plebanski-Demianski (PD) black holes in the presence of cosmological constant, which includes the Kerr-Newman rotating black hole and the Taub-NUT spacetime. We assume that the thermodynamical pressure may be described by the negative cosmological constant, and so the black hole represents anti-de Sitter (AdS) PD black hole. The thermodynamic quantities like surface area, entropy, volume, temperature, Gibb's and Helmholtz's free energies of the AdS PD black hole are obtained due to the thermodynamic system. Next, we find the critical point and corresponding critical pressure, critical temperature and critical volume for the AdS PD black hole. Due to the study of specific heat capacity, we obtain the specific heat capacity (with constant volume) CV=0 and the specific heat capacity (with constant pressure) CP≥0. From this result, we conclude that the AdS PD black hole may be stable. We examine the Joule-Thomson expansion of the PD black hole, and by evaluating the sign of the Joule-Thomson coefficient μ, we determine the heating and cooling nature of the PD black hole. Putting μ=0, we find the inversion temperature. Next, we study the heat engine for the AdS PD black hole. In the Carnot cycle, we obtain the work done and its maximum efficiency. Also, we describe the work done and its efficiency for a new engine. Finally, we analyze the efficiency of the Rankine cycle in the PD black hole heat engine.

Black-Box Mathematical Modeling and Heuristic Optimizing of Hampson-Linde Cycle Based on Joule-Thomson Effect and Ohm’s Law for Thermal Circuits

Nowadays, due to recent global climate changes, replacing non-environmental friendly technology with more sustainable energy is desired. Thus, researchers are designing new, environmentally friendly products, for which some use the black box modeling method. Therefore, the presented work represents a Hampson-Linde cryogenic cooler model based on Joule-Thomson Effect and Ohm’s Law for thermal circuits, optimized using a parallel “Particle Swarm Optimization” (PSO) algorithm. An innovative feature of this model is that it uses two translations—from electrical to the thermal domain and a simplifying time domain—and is implemented to provide results using less demanding computational resources and simulation time. Furthermore, a possibility for superconductive states is presented for commonly used category II superconductors. Last, but not least, based on the predicted output temperature, models of more complex processes could be developed, such as a model for the Hyperloop concept.

A Cycle Analysis of Flow and Thermal Parameters in the Hydrogen Charging System at the Pressure of 50 MPa

In the currently developed hydrogen compression cycle system, hydrogen is compressed through a compressor and stored in a tank at high pressure. In the filling process from A (tube trailer) to B (high-pressure tank), thermal stress in the B arises due to the temperature rise of hydrogen together with the internal pressure increase in the tank. In the study, in order to achieve safe filling, it is necessary to investigate the flow and thermal parameters of the system. Based on the principles of thermodynamics, a thermodynamic prediction model for the temperature change during the hydrogen cycle was established by comprehensively considering the real state of gas, convective heat transfer between hydrogen and the inner wall, heat conduction through the tank wall, and natural convection of the outer wall. Prediction values of temperature, hydrogen charge amountm and heat transfer to the outside were calculated. Additionally, by investigating the performance of the hydrogen refueling station heat exchanger, the heat of the heat exchanger needed to keep the hydrogen temperature within a safe range was calculated. Due to the Joule–Thomson effect, the hydrogen temperature passing through the pressure reducing valve changed, and the changed value in the hydrogen charging cycle was predicted and calculated by calculating the temperature change value at this time. This study provides a theoretical research basis for high-pressure hydrogen energy storage and hydrogenation technology.

Two-phase flow, pressure drop, and Joule-Thomson effect in a micro-orifice with trans critical carbon dioxide flow

Two-phase flow, pressure drop, and Joule-Thomson coefficient (JTh) of sub- and super- critical carbon dioxide expanding through a 81 µm orifice embedded inside a 300 µm microchannel was experimentally studied. It was demonstrated and validated that a flow of CO2 in a micro-orifice can support the thermodynamic conditions that are ripe for the JTh effect to be significant. The inlet pressure, temperature, and mass flux were independently varied between 5.6 MPa and 10.2 MPa, 293 K and 314 K, and 47,277 kg/m2s and 162,101 kg/m2s, respectively. The measured pressure drop and Joule-Thomson coefficient ranged from 0.1 MPa to 5 MPa and from 0 K/MPa to 10 K/MPa, respectively. Pressure drop results were compared with the homogenous two-phase flow model, the separated two-phase flow model, the capillary tube model, and an empirical fit equation that resulted in mean average errors of 0.84 MPa, 1.4 MPa, 0.7 MPa, and 0.75 MPa, respectively.

A closed-cycle miniature Joule–Thomson cooler for cooling cold electronics

There is growing interest in operating electronics at low temperatures; however, the complexity of the cryogenic burden imposed by large coolers impedes the widespread usage of low-temperature electronics. In this study, we present a Hampson-type miniature Joule–Thomson (JT) cold stage driven by a linear compressor, and the performance of the cooler operating with a ternary mixture of methane, ethane and neopentane is investigated experimentally and numerically. Gas chromatography analysis shows that the composition of the circulated mixture is different from the charged mixture due to the liquid hold-up of neopentane. The cooler has a cold-end temperature of 143 K in steady state when operated between 0.15 MPa and 1.92 MPa, and a net cooling power of 198 mW at 145 K, 212 mW at 150 K, and 173 mW at 155 K. A dynamic numerical model is developed to predict cooler performance, and the feasibility of the numerical model is validated through the comparison between measured and calculated net cooling powers. The model can be used to estimate cooler performance at different operating conditions. This study is conducive to promote the widespread use of cryogenic electronics in the fields of military, space science, and biomedicine among others. • A miniature Joule–Thomson cooler driven by a linear compressor is built. • A ternary mixture of methane, ethane and neopentane for 145 K cooling is proposed. • The Joule–Thomson cooler achieves 143 K and has a cooling power of 198 mW at 145 K. • A model of Hampson-type Joule–Thomson cooler operating with mixture is developed.

Maximum Liquefaction of Gases Revisited

Joule-Thomson liquefiers are the commonest machines to liquefy gases. Over the years, countless number of articles have been published on the subject. Dozens of 1st and 2nd law analyses were carried out on Joule-Thomson liquefaction cycles. And yet an aspect of purely theoretical interest seems to have passed unnoticed, namely: for a given volume of gas, what conditions should be fulfilled to achieve maximum liquefaction without considering engineering details of design equipment and the highly irreversible character of work-consuming devices, heat exchangers, heat leaks and the throttling process. This work addressed this issue by applying the 1st law analysis and elementary calculus prescriptions to a simple Linde-Hampson liquefying process. The same approach could be applied to other liquefying cycles. As is well-known, for a given mass flow rate of a gas, maximum fraction liquefied occurs when the pre-cooling temperature, Ti , and initial pressure, Pi , lie on the inversion curve. It has been proved that this is only true if an additional condition is fulfilled. Expressions for it were derived for the van der Waals, RKS and PR equations of state.

Comparison of CO2 and water as working fluids for an enhanced geothermal system in the Gonghe Basin, northwest China

Because of the additional benefit of geological storage and the self-sustaining thermosiphon effect, CO2 instead of water as a working fluid for geothermal energy production has attracted much interest. In this study, based on the geological and geothermal conditions in the Gonghe Basin of China, a more realistic physical model is built by coupling the wellbore and the thermal reservoir. In our model, a novel dual-vertical well pattern and the heterogeneous fractured reservoir are considered. Based on the novel dual-vertical well pattern, the CO2– based enhanced geothermal system (EGS) can avoid premature thermal breakthrough. The results demonstrate that the CO2-EGS is more efficient than the water-EGS. The heat extraction rate of the CO2-EGS increased by 58% when compared to the water-EGS. However, the CO2-EGS results in drastic drops of production temperature in the wellbore (approximately 62 ℃) due to the strong Joule-Thomson effect. In addition, the sensitivity results suggest that the CO2-EGS is more suitable for developing in low permeability geothermal reservoirs. This work provides important references for the working fluid selection and well placement to develop the clean power generation in the Gonghe Basin geothermal field.

Exergoeconomic assessment of air separation units for pressurized O2 production incorporating two-phase expanders

Cryogenic air separation units (ASU) are the predominant method for delivering high-purity pressurized O2 at large capacities to relevant industrial processes. This study presents an exergoeconomic assessment of the integration of two-phase expanders (TPE) in two ASU configurations with (1) intermediate liquid oxygen pumping followed by gaseous O2 compression and (2) total liquid oxygen pumping to the delivery pressure. A comprehensive exergy analysis showed that TPE integration in the latter resulted in exergy efficiency increase of 1.1%-points and specific power consumption (SPC) reduction 15.5 kWh/ton (−4.4%), while for the former, the exergy efficiency increase amounted to 1.8%-points with 17.9 kWh/ton (−5.2%) lower SPC. A complete thermodynamic mapping for the different cases was presented. From an economic perspective, total liquid pumping reached levelized cost of oxygen reductions of 1.68 €/ton (−4.7%), while in the configuration with gas compressors it was limited to only 0.45 €/ton (−1.2%), relative to analogous ASU configurations with Joule-Thomson valve expansion. The total liquid pumping scheme with TPE presented a cost reduction of 4.3 €/ton (−11.2%) relative to the gaseous O2 compression counterpart. N2 by-product monetization can further improve the plant economic performance. Based on this assessment, integration of reliable TPE technology for incremental efficiency gains of pressurized O2 production in ASUs presents a promising opportunity to profitably contribute to energy efficiency and decarbonization goals.

In-flow measurement of the composition of a binary gas mixture

The performance of many cryocoolers that utilize the Joule-Thomson effect can be improved by using a gas-mixture as the working fluid. This paper presents a measurement setup to characterize a sorption compressor operating with a binary mixture. The composition of the binary mixture delivered by the sorption compressor is determined in-flow by correlating the outputs of a Coriolis flow meter and a thermal mass-flow meter. Based on this method, the composition of a binary mixture was measured continuously with an error of ±0.02. Multiple sorption cycles with three different mixtures of ethane and nitrogen using the same compressor were measured, allowing for the observation of the dynamic desorption behavior of a mixture.

Nonlinearly charged AdS black holes, extended phase space thermodynamics and Joule–Thomson expansion

We study thermodynamics and phase transitions of magnetically charged by nonlinear electrodynamics (NED) Anti-de Sitter (AdS) black holes in an extended phase space. The cosmological constant is treated as a thermodynamic pressure whereas the black hole mass is considered such as the chemical enthalpy. The horizon thermodynamics of black holes shows an analogy with the Van der Walls liquid–gas system. We define a quantities which are conjugated to the parameter of NED and a magnetic charge. It is shown that the first law of thermodynamics and the generalized Smarr relation hold. The critical exponents are the same as in the Van der Waals system. The Joule–Thomson adiabatic expansion of NED-AdS black holes is investigated because of thermodynamic behavior of black holes. The Joule–Thomson coefficient, the inversion and isenthalpic curves are discussed. The minimum of inversion temperature and the corresponding event horizon radius are obtained.

Joule–Thomson expansion of Born–Infeld AdS black holes in consistent 4D Einstein–Gauss–Bonnet gravity

In this paper, the Joule–Thomson expansion of Born–Infeld AdS black holes in the consistent Aoki–Gorji–Mukohyama theory of 4D Einstein–Gauss–Bonnet gravity is studied in the extended phase space. We further analyze the effect of parameters [Formula: see text] and [Formula: see text] on the inversion curves and plot the inversion and isenthalpic curves in the [Formula: see text]–[Formula: see text] plane, which can determine the cooling–heating regions.

Experimental analysis of flow instability detection in a centrifugal compressor using variational mode decomposition

AbstractIn centrifugal compressors, the identification of flow instability signals from experiments is a difficult problem owing to the nonlinear and non-stationary characteristics. Otherwise, the complicated asymmetric structure of the volute brings a huge challenge to the evolution and circumferential nonuniformity characteristics of the flow instabilities. This paper presents experimental and numerical investigations on internal flow field to understand the flow instability characteristics in a centrifugal compressor. Considering nonlinear and non-stationary signals, a method based on Fourier-transform and variational mode decomposition was introduced to analyse the flow instability characteristics. The Fourier spectrum results show that at 0.21kg/s of 80krpm, the pressure signal has a noticeable high-frequency fluctuation, which indicates that the compressor enters the flow instability state. The variational mode decomposition results show that before a surge, the compressor experiences different flow instability stages: the RI stage, the coexistence stage of RI and stall, and the stall stage. Moreover, obvious circumferential nonuniformity characteristics of flow instabilities were observed during the throttling process. RI first occurred at the 180° circumferential position and then the stall first appeared in the circumferential range of 60° to 240°. The simulation results that it is because that the asymmetric volute causes the adverse pressure gradient inside the impeller passage and a high-pressure region (120°–240°) at the upstream of the impeller inlet. Under this combined action of the two, the effect region of tip leakage vortex expands the upstream of the impeller inlet. Meanwhile, the tip leakage vortex core migrates to a lower span of blades. This study demonstrates the ability to analyse nonlinear and non-stationary signals from a centrifugal compressor via variational mode decomposition, and provides a useful guidance for the identification of flow instability signals.

Comparative study of the electrical characteristics of hydrate reservoirs before and after gas hydrate trial production in the Muli permafrost area of the Qilian Mountains, NW China

Natural gas hydrate (NGH) is considered one of the most promising alternative energy sources in the 21st century. The exploitation and decomposition of NGHs could cause geological disasters and eco-environmental problems related to climate warming, seawater blue tides, submarine landslides, drilling platform collapses, slope instability, etc. Thus, an investigation of the eco-environmental effects of NGH exploitation and decomposition has scientific and practical significance. In this paper, the electrical characteristics of NGH reservoirs before and after NGH trial production in the Muli permafrost area of the Qilian Mountains are comparatively examined for the first time. The electrical structure models before and after NGH trial production are obtained through two-dimensional and three-dimensional inversion of the NE audio-magnetotelluric (AMT) sounding profile around production test well SK2. Notably, the electrical structure of the NGH reservoir changes greatly. The research indicates that (1) after NGH trial production, the formation resistivity increases remarkably within 200 m and burial depths in the range of 120– 340 m around the production test well; (2) the main reason for the increasing resistivity after trial production is the Joule-Thomson effect caused by depressurization production and the endothermic effect of NGH decomposition, which lead to the formation of ice-bearing strata; afterwards, we explain the formation process of ice-bearing strata after NGH trial production; and (3) we speculate that the formation stability is not adversely affected after NGH trial production. These findings and research results can provide guidance for subsequent geoenvironmental safety risk assessments of NGH development in permafrost areas.