Fei Duan

Bio: Fei Duan is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Heat transfer & Boiling. The author has an hindex of 31, co-authored 168 publications receiving 3080 citations. Previous affiliations of Fei Duan include University of Cambridge & University of Toronto.

Cold utilization systems of LNG: A review

Abstract: Natural gas is one of the cleanest forms of fossil fuels and its usage is rising since the importance of environment-friendly conversion systems has been seen Liquefied natural gas (LNG) and pipeline technologies are two present methods for the natural gas transportation between the exporter and importer This review presents the LNG cold utilization systems which are discussed on the applications such as separation processes, cold food storage, cryogenic carbon dioxide (CO 2 ) capture, power generation, etc The minimum power consumption and flow rate are detected as 045 kWh/kg and 8 ton/hour, respectively for the air separation processes Exergetic and energetic efficiencies are increased by nearly 40% of those of the conventional separation processes In the desalination system, it is inferred that the LNG cold utilization has provided nearly 50% energy saving while 2 kg ice melt water is produced by 1 kg equivalent LNG cold energy in the freeze seawater desalination For the cold storage systems, payback periods are found less than 5 years by using the LNG cold energy Energetic and exergetic efficiency are increased significantly by using the LNG cryogenic exergy Moreover, it is used in the cryogenic CO 2 capture systems, and there is no dramatic decrement in the overall efficiency values while the other CO 2 methods decrease the overall efficiency The LNG cold utilized power generation systems are discussed in detail with different alternatives including the gas, steam, combined and Stirling systems The minimum thermal efficiencies are found nearly 40% and 20% for the gas and steam cycles The selection of working fluids in the cycles is also discussed Lastly, the importance of economic and environmental aspects of LNG cold utilization systems is discussed Basic modeling equations are presented for the designed LNG cold utilization cycle with respect to the thermoeconomic and exergoenvironmental methods

Stirling cycle engines for recovering low and moderate temperature heat: A review

Abstract: A review is presented for the research development of Stirling cycle engines for recovering low and moderate temperature heat. The Stirling cycle engines are categorized into four types, including kinetic, thermoacoustic, free-piston, and liquid piston types. The working characteristics, features, technological details, and performances of the related Stirling cycle engines are summarized. Upon comparing the available experimental results and the technology potentials, the research directions and the possible applications of different Stirling cycle engines are further discussed and identified. It is concluded that kinetic Stirling engines and thermoacoustic engines have the greatest application prospect in low and moderate temperature heat recoveries in terms of output power scale, conversion efficiency, and costs. In particular, kinetic Stirling engines should be oriented toward two directions for practical applications, including providing low-cost solutions for low temperatures, and moderate efficient solutions with moderate costs for medium temperatures. Thermoacoustic engines for low temperature applications are especially attractive due to their low costs, high efficiencies, superior reliabilities, and simplicities over the other mechanical Stirling engines. This work indicates that a cost effective Stirling cycle engine is practical for recovering small-scale distributed low-grade thermal energy from various sources.

Viscosity affected by nanoparticle aggregation in Al2O3-water nanofluids

Abstract: An investigation on viscosity was conducted 2 weeks after the Al2O3-water nanofluids having dispersants were prepared at the volume concentration of 1-5%. The shear stress was observed with a non-Newtonian behavior. On further ultrasonic agitation treatment, the nanofluids resumed as a Newtonian fluids. The relative viscosity increases as the volume concentrations increases. At 5% volume concentration, an increment was about 60% in the re-ultrasonication nanofluids in comparison with the base fluid. The microstructure analysis indicates that a higher nanoparticle aggregation had been observed in the nanofluids before re-ultrasonication.

Turbulent transition of thermocapillary flow induced by water evaporation

Abstract: Water has been examined for thermocapillary convection while maintained just outside the mouth of a stainless-steel, conical funnel where it evaporated at different but steady rates. Evaporation at a series of controlled rates was produced by reducing the pressure in the vapor-phase to different but constant values while maintaining the temperature of the water a few millimeters below the interface at $3.56\ifmmode\pm\else\textpm\fi{}0.03\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ in each case. Since water has its maximum density at $4\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, these conditions ensured there would be no buoyancy-driven convection. The measured temperature profile along the liquid-vapor interface was found to be approximately axisymmetric and parabolic with its minimum on the center line and maximum at the periphery. The thermocapillary flow rate was determined in two ways: (1) It was calculated from the interfacial temperature gradient measured along the interface. (2) The deflection of a $12.7\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$-diameter, cantilevered probe inserted into the flow was measured and the liquid velocity required to give that deflection determined. The values determined by the two methods agree reasonably. As the vapor-phase pressure was reduced, the thermocapillary flow rate increased until a limiting value was reached. When the pressure was reduced further, certain of the variable relations underwent a bifurcation and the power spectrum of the probe displacement indicated it was a periodic function with frequency locking. These results suggest that thermocapillary flow plays an important role in the energy transport near the interface of evaporating water. In particular, it appears that the subinterface, uniform-temperature layer, reported in earlier studies, results from the mixing produced by the thermocapillary flow. The Stefan boundary condition is often applied to determine the energy flux to an interface where phase change is occurring; however, when there is strong convective flow parallel to the interface, the normal Stefan condition does not give an adequate description of the energy transport.

Water-evaporation-induced electricity with nanostructured carbon materials

Abstract: Water evaporation from the surface of cheap carbon-black materials can be used to generate sustained voltages of up to 1 V under ambient conditions.

A review on thermophysical properties of nanofluids and heat transfer applications

Abstract: This paper summarizes the important results regarding the improvement in the thermophysical properties of nanofluids. The influence of important parameters like particle's (loading, material, size, and shape), base fluid type, temperature, additives and pH value has been considered. There are many conflicting reports on the influence of parameters on thermophysical properties and the literature in this field is widespread, so this article would be beneficial for investigators to have a precise screening of a broad range of studies in this field. Further literature review of the applications of nanofluids with a particular focus on the advantages of using nanofluids in solar collectors and as coolants in automotive heat exchangers. The authors hope that this review can help in the translation of nanofluid technology from the lab scale research to industrial applications in solar collectors and automotive sector. At last, the paper identifies the opportunities for future research.