About State Key Laboratory of Multiphase Flow in Power Engineering

State Key Laboratory of Multiphase Flow in Power Engineering

Overview at Xi'an Jiaotong University

The State Key Laboratory of Multiphase Flow in Power Engineering is at the School of Energy and Power Engineering of Xi'an Jiaotong University in Xi'an, Shaanxi. Multiphase flow is the simultaneous movement of matter in more than one phase: gas with liquid, liquid with solid particles, steam with water, or several of those together. Such flows govern boilers, reactors, fuel cells, pipelines and energy-conversion equipment, so a laboratory dedicated to them sits at the foundation of power engineering rather than at its margins.

The laboratory researches two-phase and multiphase flow, heat and mass transfer, and energy conversion, including supercritical water gasification and hydrogen production, according to the candidate record for this profile. Research groups documented in that record include those of Hui Jin and Dengwei Jing, while the laboratory's best-known figure in the sources consulted is Liejin Guo, listed as laboratory head and head of department in his research profile, whose publication record spans multiphase flow, fuel cells and solar and supercritical-water hydrogen production.

Xi'an Jiaotong University lists the laboratory as one of its two state key laboratories, alongside the State Key Laboratory for Mechanical Behavior of Materials. Together they represent the university's national platforms in energy and materials, the two engineering pillars on which the university's Xi'an campus, to which it relocated from Shanghai in 1956, built its reputation. This profile covers the energy laboratory.

Why multiphase flow matters in power systems

Almost every practical energy device is multiphase. In a steam generator, water boils into steam while both phases move through heated tubes. In a coal or biomass gasifier, solid particles react with gases and liquids at high temperature. In a proton-exchange-membrane fuel cell, gases, liquid water and a solid membrane interact in channels thinner than a millimetre. In a nuclear reactor, coolant may boil around fuel rods, and predicting that boiling is a safety question, not only an efficiency question.

Because the phases move at different speeds, exchange heat and mass across interfaces, and change phase as conditions vary, multiphase flow cannot be predicted from single-phase fluid mechanics alone. Laboratories in this field combine experiments on dedicated test platforms with mathematical models and numerical simulation, then validate the models against measured temperatures, pressures, void fractions and flow patterns. A flow-calorimeter study from this laboratory, measuring the heat capacity of a kerosene-type hydrocarbon fuel from 330 to 900 kelvin at pressures up to about 6 megapascals using a multiphase flow test platform, is a typical example of the measurement work involved.

That combination of measurement and modelling explains the laboratory's name. It is not a power station and does not generate electricity commercially. It produces the flow, heat-transfer and reaction knowledge, and the trained engineers, that allow power equipment designed elsewhere to operate efficiently and safely at conditions that cannot be explored by theory alone.

Heat and mass transfer research

Heat transfer in multiphase systems includes boiling, condensation, evaporation and the behaviour of fluids near and above their critical points, where properties change rapidly with temperature and pressure. Mass transfer covers how species move between phases: oxygen dissolving, steam reforming gases, or reaction products leaving a particle surface. The laboratory's publications address both, from hydrocarbon fuel properties at near-critical and supercritical conditions to the specific heat capacity of water confined in graphene nanochannels below five nanometres in height, studied by molecular dynamics simulation by Chengzhen Sun, Bofeng Bai and colleagues.

At the nanoscale, the laboratory's work extends to molecular sieving: a 2021 Frontiers in Energy Research study by Sun and colleagues used molecular dynamics to show that a graphene and hexagonal boron nitride bilayer nanopore achieves quasi-unidirectional molecular transport and carbon dioxide and methane selectivity 3.7 times higher than a single-layer graphene pore. Such work connects classical power engineering to membrane separations for gas processing, a reminder that multiphase and interfacial transport operate from boiler tubes down to single pores.

Nuclear energy is a further documented setting. Researchers including Wenxi Tian, Suizheng Qiu and G. H. Su at the laboratory and the Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology published computational-fluid-dynamics meshing methods for wire-wrapped fuel assemblies used in Generation IV liquid-metal reactors. Predicting coolant flow through such assemblies is a multiphase and thermal-hydraulics problem on which reactor design depends, and the laboratory's combination of flow modelling with nuclear applications is well represented in its journal output.

Supercritical water gasification and hydrogen

Supercritical water gasification is the laboratory's most distinctive energy-conversion programme in the sources consulted. Above water's critical point, water behaves as a dense fluid that can dissolve organic material and support rapid gasification reactions, converting wet feedstocks such as coal, biomass and organic waste directly into a hydrogen-rich gas without first drying them. Liejin Guo's group proposed a system described in the literature as boiling coal in water: hydrogen production and power generation based on coal and supercritical water gasification with zero net carbon dioxide emission as the design concept.

Experimental and kinetic studies from the laboratory include lignite gasification in a continuous tubular reactor at 560 degrees Celsius and 25 megapascals, with lignite slurry concentration of five percent and residence times between about 4.7 and 12.4 seconds, from which a seven-reaction kinetic model predicted hydrogen and carbon dioxide fractions of about 65.6 and 34.3 percent. Shuzhong Wang, a professor in the university's energy and power engineering department associated with this research area, specialises in waste treatment by supercritical water oxidation and hydrogen production by supercritical water gasification, with more than forty Chinese invention patents and two United States patents recorded in his publisher biography.

Scale-up is the recognised obstacle, and the laboratory's recent work addresses it directly: studies of particle clustering in supercritical water, of horizontal particle jets in supercritical water reactors, and of the thermal and mechanical behaviour of reactor structures under high temperature and high pressure all respond to the difficulty of moving supercritical water gasification from laboratory reactors toward secure, larger application. Hui Jin's group, named in the candidate record, is among those working on these reactor and hydrogen questions.

Solar hydrogen and renewable energy conversion

The laboratory also hosts the International Research Centre for Renewable Energy at Xi'an Jiaotong University, as shown in author affiliations on its energy-materials papers. Liejin Guo's earlier influential work includes a review of solar hydrogen production and its development in China, and the laboratory designed, installed and tested an outdoor pilot demonstration of compound parabolic concentrator photoreactors for photocatalytic hydrogen production, reported in the International Journal of Hydrogen Energy. A novel thermochemical method for solar hydrogen production was likewise proposed by the laboratory.

Photocatalytic and photo-biological approaches appear in its recent output, including photo-biological hybrid systems that combine microbial whole-cell catalysis with functional catalytic materials for hydrogen production, and studies of biomass photo-fermentation in a 70-litre semi-continuous tubular photoreactor. Those systems are multiphase by construction: light, gas, liquid culture and solid catalyst or cells must all reach one another, so reactor design is as much a flow and transport problem as a chemistry problem.

Energy storage and conversion materials form a supporting strand. A laboratory study synthesised carbon and hematite composite thin films for supercapacitors, reporting a specific capacitance of 85.3 farads per gram for the optimal carbon-hematite sample, rising to 144.4 farads per gram at 5 amperes per gram with cobalt oxide addition. Such work, published from the laboratory and the renewable energy centre jointly, shows the breadth covered under energy conversion, from large thermal systems to electrochemical devices.

Fuel cells and two-phase transport modelling

Proton-exchange-membrane fuel cells are a classic two-phase problem: hydrogen and oxygen gases flow through porous electrodes while liquid water is produced, and the cell fails if water floods the cathode or the membrane dries. Guo's laboratory developed two modelling approaches documented in a keynote abstract: a single-domain, two-dimensional, two-phase flow model based on the multiphase mixture approach, which revealed two-phase phenomena in both cathode and anode, and a mixed-domain, non-isothermal model fully coupling momentum, species, heat and charge transfer with electrochemical reactions, treating water in gas, liquid and membrane phases.

A related laboratory model of a fuel-cell cathode with an interdigitated gas distributor, by Xun-Liang Liu, Ya-Ling He, Wen-Quan Tao and colleagues and published in the International Journal of Hydrogen Energy in 2006, used continuity equations and Darcy's law to study flow fields and liquid-water saturation, showing that product water behaves as vapour at small current density and as two phases at larger loads. Ya-Ling He and Wen-Quan Tao are among the university's best-known heat-transfer researchers, and their presence in this literature reflects the laboratory's depth in numerical heat and mass transfer.

Thermal management is the practical stake. The keynote abstract states plainly that a fuel cell must operate in a narrow suitable temperature range and that removing generated heat is difficult, which is why in-situ diagnosis and numerical modelling were pursued together. That pairing of diagnosis with simulation is characteristic of the laboratory across all its topics, from fuel cells to supercritical reactors.

People, publications and training

Liejin Guo's research profile lists him as laboratory head and head of department, with more than one thousand publications and tens of thousands of citations recorded on that platform; platform counts of that kind are indicative rather than official, but they correctly convey the scale of the group's output in multiphase flow, hydrogen energy and fuel cells. Named groups in the candidate record, those of Hui Jin on supercritical water and energy conversion and Dengwei Jing on solar and photocatalytic energy, add further distinct programmes within the same laboratory.

The laboratory trains graduate engineers through the School of Energy and Power Engineering, one of Xi'an Jiaotong University's founding engineering schools in Xi'an. Its test platforms, including the multiphase flow test platform cited in measurement papers, are training instruments as well as research instruments: doctoral researchers learn to run high-pressure, high-temperature flow experiments safely, to instrument them, and to reconcile measurements with models, skills that transfer directly to power-equipment manufacturers, utilities and research institutes.

Collaboration runs through its publication record, with co-authors across Xi'an Jiaotong's nuclear, materials and renewable-energy units and with international partners in solar and hydrogen research. The laboratory's symposium and conference presence in multiphase flow and hydrogen energy, including keynote work on fuel-cell thermal management presented to the International Centre for Heat and Mass Transfer community, places it in the international conversation of its field rather than only in domestic programmes.

Significance for China's energy transition

The laboratory's topics map directly onto China's energy problems: using high-moisture, low-grade coal and wet wastes more cleanly through supercritical water gasification; producing hydrogen from solar energy and biomass; operating advanced nuclear reactors safely; and making fuel cells and electrochemical devices reliable through water and heat management. Each is a multiphase problem before it is anything else, which is why a single laboratory can credibly work across all of them.

Its significance should be stated in research terms. It has not built a commercial supercritical water power station, and its solar photoreactors are pilot demonstrations. What it has built, over decades at Xi'an Jiaotong University, is measurement capability, validated models, kinetic schemes and reactor concepts that other engineers can design against, together with the specialist graduates who carry that knowledge into industry and other institutes.

For directory readers, the essential record is this: the State Key Laboratory of Multiphase Flow in Power Engineering is Xi'an Jiaotong University's national laboratory for two-phase and multiphase flow, heat and mass transfer and energy conversion in Shaanxi, documented in an extensive journal literature on boiling and supercritical fluids, fuel cells, nuclear thermal-hydraulics, solar hydrogen and supercritical water gasification for hydrogen production.