Heat transfer systems, water handling

Also shown in Fig. 9.3 is the capillary pressure in a water-air system with the mean radius of curvature equal to the particle radius. It is clear that as the particle size spans over many orders of magnitude, the handling of the radiative heat transfer and the significance of forces such as capillarity and gravity also vary greatly. 

Further discussion of nuclear reactor control problems resulting from water leakage is beyond the scope of the present paper, and the discussion presented hereafter is on the effects of the chemical reaction between sodium and water. As a corollary of this discussion, the necessity for the use of a double-barrier heat exchanger in systems where nuclear control problems are absent has been examined. The desirability of eliminating the double-barrier design where feasible is obvious. The double-barrier results in a more complex design with associated fabrication and operational problems, requires additional heat transfer area due to the increased thermal resistance of the double barrier, and requires external equipment to handle the third-fluid system. All these factors increase the size and cost of the heat exchanger. 

Calculating pressure drop is of considerable importance in atmospheric absorbers, heat transfer services, and vacuum distillations. Although pressure drop plots are available for most commercial types and sizes of random dumped tower packings, these data usually have been collected on air/water systems. While the air flow rate can be corrected for changes in gas density, no adequate method exists for handling the effect of liquid properties. 

To potentially replace the need for large scale experiments to develop fuel btmdles in future R D work, the three-dimensional CFD code ACE-3D, developed by IAEA based on the two-fluid model for BWR conditions, was modified to handle supercritical pressure fluid in the fuel bundle geometries. The heat transfer experiments by Kyushu University with HCFC22 and by JAEA with water were analyzed for its validation [31-36]. Also the three-dimensional model of this code for the fuel btmdles was combined with the one-dimensional model for future applications to plant system analyses. 

Sheet Drying. At a water content of ca 1.2—1.9 parts of water per part of fiber, additional water removal by mechanical means is not feasible and evaporative drying must be employed. This is at best an efficient but cosdy process and often is the production botdeneck of papermaking. The dryer section most commonly consists of a series of steam-heated cylinders. Alternate sides of the wet paper are exposed to the hot surface as the sheet passes from cylinder to cylinder. In most cases, except for heavy board, the sheet is held closely against the surface of the dryers by fabrics of carefuUy controUed permeabiHty to steam and air. Heat is transferred from the hot cylinder to the wet sheet, and water evaporates. The water vapor is removed by way of elaborate air systems. Most dryer sections are covered with hoods for coUection and handling of the air, and heat recovery is practiced in cold climates. The final moisture content of the dry sheet usually is 4—10 wt %. 

The major components of the mass spectrometer are a gas-handling manifold that enables the gas to be transferred from the ovens to the ion source, the ion source that consists of an electron impact source, magnetic mass analyzer with gap field of 6500 G, four different EM detectors, and an ion pump to ensure low pressure for the EMs. The gas handling system also included a controlled leak valve that could obtain Martian gas and feed the gas directly into the mass spectrometer for analysis. All the tubes in the gas handling system were heated to 35 C to ensure that there is no condensation of water and other volatile vapors on the hardware. 

Sodium is a chemical that has been used extensively and has an established record of safe handling on a large scale. The PRISM reactor has been designed with the potential for sodium-water reaction in mind. The primary sodium system is entirely encompassed within the reactor vessel and surroxmded by the containment vessel, to eliminate the potential for loss of primary coolant and to reduce the potential for sodium-water reaction. The IHTS transports heat from the primary system to the SG where the heat is transferred to the cooling water. The sodium-water interaction is mitigated in the SG with the pressure cap inert gas and the SGIS as described in Section 6.4.5.I. 

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