Supercritical heat transfer

All these conditions can affect supercritical heat transfer. 

Zahlan, H., Groeneveld, D.C., Tavoularis, S., Mokry, S., Pioro, I., 2011. Assessment of supercritical heat transfer prediction methods. In Proc. 5th Int. Symp. on SCWR (ISSCWR-5), Vancouver, BC, Canada, March 13—16, Paper P08, p. 20. 

SCWR research in Korea has been mainly promoted by the Korea Atomic Energy Research Institute (KAERl) and Korea Electric Power Research Institute (KEPRI). The work has consisted of a feasibility study, a core conceptual study, experiments for supercritical heat transfer, and an investigation of the corrosion and radiation effects on candidate materials [80-84]. 

D. C. Groeneveld, S. Tavoularis, et al., Analytical and Experimental Program of Supercritical Heat Transfer Research at the University of Ottawa, Nuclear Engineering and Technology, Vol. 40(2), 107-116 (2008)... 

The solvent elimination appro2K h is quite straightforward for supercritical fluids lAich are often gases at atmospheric pressure. Each chromatographic peedc is deposited fron the end of a restrictor, connected to the end of the column by a heated transfer line, onto a small area of infrared-transparent support [110,128,129,134]. The support can be moved manually to collect each peak at a n osition or stetq>ed continuously to record the... 

Ionic liquids (ILs) are, together with water and supercritical fluids, one of the few alternative media for environmentally friendly processes, which seem to have more possibility of industrial application in the next 10 years. The range of demonstrated or proposed applications of ILs is extraordinary, going from their use as nonvolatile, non-flammable solvents in organic synthesis to catalysts, materials for aiding separations and gas capture, advanced heat transfer fluids, lubricants, antistatics, and so on [2 ]. Surpassing in magnitude the number of potential uses is the number of possible IL compositions, estimated to be in the billions [5]. The term ionic liquids includes all compounds composed exclusively by ions that are liquid... 

Heat Transfer fiom Supercritical Carbon Dioxide in Tube Flow—a Critical Review (Pitla et al., 1998)... 

The interest in heat-transfer for high-pressure systems is related to the extraction of a valuable solute with a compressed gas. The compressed fluid is usually a high-pressure gas-often a supercritical fluid, that is, a gas above its critical state. In this scenario, the prevalent heat-transfer mechanism is convection. 

In extraction processes using supercritical fluids it is of interest to predict the heat-transfer processes that take place in heat exchangers in forced flow. 

Kriksunov, L.B. and MacDonald, D.D., Understanding chemical conditions in supercritical water oxidation systems, ASME Heat Transfer Div., 317(2), 271-279, 1995a. 

Process intensification can be considered to be the use of measures to increase the volume-specific rates of reaction, heat transfer, and mass transfer and thus to enable the chemical system or catalyst to realize its full potential (2). Catalysis itself is an example of process intensification in its broadest sense. The use of special reaction media, such as ionic liquids or supercritical fluids, high-density energy sources, such as microwaves or ultrasonics, the exploitation of centrifugal fields, the use of microstructured reactors with very high specific surface areas, and the periodic reactor operation all fall under this definition of process intensification, and the list given is by no means exhaustive. 

Holgate HR, Webley PA, Tester JW. Carbon monoxide oxidation in supercritical water the effects of heat transfer and the water-gas shift reaction on observed kinetics. Energy Fuels 1992 6 586-597. 

Holgate, H.R. Webley, P.A. Tester, J.W. CO in Supercritical Water The Effects of Heat Transfer and the Water-Gas Shift Reaction on Observed Kinetics Energy Fuels, 6 (1992) 586-597. 

A power plant operating on heat recovered from the exhaust gases of internal-combustion < uses isobutane as the working medium in a modified Rankine cycle in which the upper pressure I is above the critical pressure of isobutane. Thus the isobutane does not undergo a change of p" as it absorbs heat prior to its entry into the turbine. Isobutane vapor is heated at 4,800 kPa to 2 and enters the turbine as a supercritical fluid at these conditions. Isentropic expansion in the turh produces superheated vapor at 450 kPa, which is cooled and condensed at constant pressure, resulting saturated liquid enters the pump for return to the heater. If the power output of the modi Rankine cycle is 1,000 kW, what is the isobutane flow rate, the heat-transfer rates in the heater condenser, and the thermal efficiency of the cycle ... 

Solution polymerization offers improved heat transfer over bulk polymerizations. Proper selection of the solvent is critical to avoid chain transfer reactions. Coupled with environmental concerns over organic solvents, the complete removal of solvents from the polymer also poses a potential problem. Recent work has been performed on the use of supercritical carbon dioxide as a solvent, which is easy to remove and poses less environmental concerns.30... 

The Heat Transfer to Supercritical Carbon Dioxide in Tubes with Mixed... 

The heat transfer to supercritical carbon dioxide was measured in horizontal, vertical and inclined tubes at constant wall temperature for turbulent flow at Re-numbers between 2300 and lxl 05. The influence of the variation of physical properties due to the vicinity of the critical point was examined, as well as the influence of the direction of flow. Therefore most of the measurements were conducted at pseudocritical points. At those supercritical points the behaviour of the physical properties is similar to the behaviour at the critical point, but to a lesser degree. At such points the heat capacity shows a maximum density, viscosity and heat conductivity are changing very fast. [1]... 

Perfluoropolyether fluids (ex., Krytox ) are commonly used as lubricants, dielectric fluids or heat transfer fluids in a number of space and military products. These fluids and other perfluorolubricants are almost impossible to dissolve in solvents other than halocarbons. Additionally, other halogenated damping fluids have compatibility problems with some of the common solvents which can dissolve the fluid. Early experiments with supercritical carbon dioxide indicated that it would dissolve both halogenated damping fluids and perfluoropolyether lubricants and thus was a candidate as a replacement solvent cleaning process. 

Corrosion Screening Tests with Ni-Base Alloys in Supercritical Water Containing Hydrochloric Acid and Oxygen. HTD-Vol. 335 Proceedings of the ASME Heat Transfer Division (International Mechanical Engineering Congress and Exposition, USA) Volume 4, 159-167. 

Since 1929, polychlorinated biphenyls (PCBs) have been produced and used as heat-transfer, hydraulic, and dielectric fluids. Because of their chemical and physical stability, PCBs have been found in many environmental samples. Generally, PCBs have been analyzed by GC with electron-capture detection. There are many reports on subcritical and supercritical fluid extraction of PCBs, but only a few on supercritical fluid separation of PCBs. 

Experimental measurements of heat transfer coefficients are reported for three binary mixtures near their lower consolute points. Two of these, respectively n-pentane and n-decane in solution with supercritical CO2, involve vapor--liquid equilibrium whereas the third, triethylamine--water, involves liquid--liquid equilibrium. Anomalously high heat transfer coefficients were found for the supercritical mixtures at compositions which condense on heating (retrograde condensation). 

Previously, Durst and Stephan Q) observed some enhancement in heat transfer coefficients in natural convection in mixtures of n-heptane -- methane as the two-phase region was entered. We reported heat transfer results earlier ( ) for free convection and cross flow about a heated horizontal cylinder in a supercritical n-decane--C02 mixture. These also showed enhancement in the two-phase region relative to single phase. At that time, analysis was hindered by the unavailability of estimates or measurements of some crucial mixture properties. Happily, this situation has been remedied somewhat and we can now draw some conclusions. 

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