Legal Aspects

The experimental sample of the video-computer system has been successfully examined on the basis of psychological and medicinal tasks. Patent application for the method has been approved in Russia. Software for auto-training and auto-correction is under development at the Center of Human Ecology, IPC RAS. (For example: A man sits at a computer and observes on the video display terminal his own image, made with the help of video camera. He sees the two portraits representing both his spirit and mind. As a result of this observation of man's own internal duality, the process of restoration of personal harmony between spirit and mind occurs. It is ascertained that this process enhances the protective forces of human organism. In due course, the person begins to feel an increase of his vital force, self-confidence and optimism).

№-0128 Data Base Porous Coating Depositions on Cooling Porous Channels

Full Title:	Developing of an Experimental and Calculated Data Base on Heat Transfer Intensification and Critical Heat Fluxes at Using Innovation Technology of Porous Coating Depositions on Cooling (or Steam Generating) Channels Surfaces
Technology Field(s):	NNE-HCS: Non-Nuclear Energy / Heating and Cooling Systems MAT-SYN: Materials / Materials Synthesis and Processing PHY-PLS: Physics / Plasma Physics

Contributors

Vitaly A Divavin

Efremov Scientific Research Institute of Electrophysical Apparatus (NIIEFA Efremov) 1, Sovetskiy pr., Metellostroj, St Petersburg, 189631, Russia Phone: 7+812+4627836; 7+812+2655991 Fax: 7+812+4644623; 7+812+4639812; 7+812+3143360 divavva@niiefa.spb.su

Present Status of Research

Brief Description of Research

The value of the heat flux conducted to a cooled, smooth surface is properly restricted by heat transfer characteristics (heat removal coefficient) inside the flow of the liquid coolant, and by the critical heat flux value (CHF) defined by the flow hydrodynamic. In exceeding the CHF value, physical burnout of the channel walls led immediately to equipment breakout. In order to increase the CHF to the required value, it is necessary to increase the coolant circulation velocity, the pressure drop in the system, the subcooling of coolant, etc. Such means, however, complicated and weighted the equipment, leading to an increase in the auxiliary equipment cost and, in several cases, to a decrease in reliability.

Different methods of heat transfer intensification (surface development, longitudinal and transverse ribbing, twisted tape placement into a cooling channel, the cutting of a thread on the inner channel surface, etc.) led to a deterioration in the design manufacturability and a rise in cost, with a slight increase in the CHF value. Moreover, development of the crisis regime (burnout) remains quick, and without intensifier. This time is so short that it is not allowed to make corrections on the decrease in flux with the aim of preventing physical burnout.

The use of porous a coating (PC) on the surface in contact with the coolant permited an abrupt increase in the heat transfer level and CHF value without increasing pumping power (i.e. velocity and pressure), and without design complications. Another significant feature of PC usage is a protracting process of heat transfer crisis development over time, especially at one-side loading of elements by high heat fluxes (HHF). Given time, the length is quite sufficient for a decrease in heat flux value and the prevention of breakout.

Application of PC was developed by us on two fronts: 1. Plasma facing components subjected by HHF impact at one-side loading (in particular ITER tokamak divertor); 2. Industrial and household appliances using boiling regimes (domestic refrigerators, evaporators, boilers, condensors, desalinators with operating environments of water, ammonia, R-12, etc.).

For HHF components, PC use allowed for a comparative increase in the CHF value by approximately 1.4–1.6 times with smooth channels - without changing the cooling operating parameters and channel design. The greater reliability was provided in such a way. The values of the ultimate heat load levels reached in these experiments were 5–50 MW/m² at a velocity of 5–8 m/s. The crisis development currents were at an increased temperature rate of 5–7 °C/s.

For industrial and household appliances using a boiling regime, PC application led to a significant heat removal coefficient that increased under boiling. Some positive sequences are explained in the following examples: — In an adsorptive refrigerator at "INEY" (Moscow refrigerator plant), the temperature in the frost camera decreased from minus 6 °C to minus 18 °C while, at the same, consuming power; — In commercial ice generators of the compression type, productivity increased by 30 percent; — In industrial evaporator of the boiling type, productivity increased by 20 percent without increases in size.

PC deposition technology is realized at the following parameters:

Particle sizes 5 to 100 micro meter

Porosity 35 to 60 percent

Length of elements for PC depositing 12 m

Internal tube diameter (PC on inner surface) >3 mm

Method of PC adhesion with base material sintering

Materials metals and alloys

Legal Aspects

PC application technology is protected by Author's Certificates of the USSR:

Author's Certificate No. 95615 "Device for coating deposition from porous powders," Priority of USSR from 27.11.80.

Author's Certificate No. 1237310 "Method of porous obtaining on internal tube surface and device for it implementation," Priority of Russia from 30.06.94.

Special Facilities

At our disposal for the PC sintering process are vacuum and gas-filled (without oxygen) ovens with conveyances of renovator (H₂), or neutral gas (Ar). Experiments with one-side loading were carried out on electron beams at a power of 60 kW, and on a specially made stand with resistive one-side loading of mock-ups (at a heat power of 40 kW).

Scientific Papers

V.A.Divavin, S.A.Grigoriev, V.N.Tanchuk. “High Heat Flux Experiment on Mock-ups with Porous Coating on the Inner Surface of Circular Coolant Channels,” Proc.of the ASME Heat Transfer Division, HTD. Vol. 317-1 (ASME International Mechanical Engineering Congress and Exposition, Sun-Francisco, USA, 1995).

V.A.Divavin, S.A.Grigoriev et al. “Boiling Crisis by Heat Transfer Intensification on Divertor Surfaces in Resistive Heating Condition,” Proc. of 19th Symposium on Fusion Techology, Lisbon, Portugal (1996).

M.Y.Belenky, M.A.Gotovsky, V.A.Divavin et al. “Heat Transfer Crisis at Water Boiling in Tubes at Large Velocities and High Subcoolings (in Russian),” Proc. of 1st Russian National Conference on Heat Transfer, v.4, pp. 26-31 (1994).

N.Avgan, L.Jovic, S.Kovalev, V.Lenkov. “Prenos donlate pri kljucannju tecnosti na porcini sa poroznim clejem,” Termotechnica, N2, pp. 67-84. (Yugoslavia, 1982).

N. Avgan, L. Jovic, et al. “Boiling Heat Transfer from Porous Layer,” Int. J. Heat and Mass Transfer, v.28, N2, pp. 415-422 (1985).