Special Features of Organization of Heat Exchange Process under Conditions of Possible Ice Formation on Working Surface
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SPECIAL FEATURES OF ORGANIZATION OF HEAT EXCHANGE PROCESS UNDER CONDITIONS OF POSSIBLE ICE FORMATION ON WORKING SURFACE A. I. Smorodin, A. L. Shuyakov, and T. I. Murashkina
UDC 536.24
The article deals with processes of heat exchange between two media in conditions where the triple point temperature of one medium is below the boiling point of the other. It is shown that ice formation can be avoided by organizing the heat exchange process rationally by selecting the ratios of the parameters of the media involved in the heat exchange. Examples of practical implementation of the proposed approach are given. Keywords: triple point, boiling point, heat exchange, ice formation.
Some technological processes of refrigeration and cryogenic engineering take place in conditions of formation or possible formation of a solid phase on the heat-exchange surface [1-4]. These are processes of extraction of valuable components from gas mixtures, functioning of ice generators, ice accumulators, freezers of air-drying systems, gasifiers of cryogenic liquids, etc. The purpose of this work was to study a specific case of implementation of such processes, especially to study the conditions of cooling of a medium whose temperature is much below the triple point temperature of the medium being cooled. For ensuring stability of this process it is essential to prevent formation of solid phase on the heat-exchange surfaces. Similar conditions of cooling of media are achieved in refrigeration engineering, for example, for getting what is called “solid water” in cryogenic engineering for cooling cryogenic fuel and oxidant. Cooling of cryogenic products is used to increase the duration of drainless storage of liquid, to ensure single-phase flow of cryogenic products through pipelines, and to increase density and cold content of cryogenic components of fuels in tanks of various aviation items. Three major studied technical methods of implementation of cooling process used in practice in various extents are known, namely, evacuation of the vapor space of the products storing vessel, sparging of the liquid volume by cooled gas, and use of external cold sources. Thus, filling of spaceship carrier rockets with liquid methane cooled by 12 K below its boiling point increases the fuel mass in the tank by 4%. Solution of this technical problem by the method of evacuation of the vapor space involves use of complicated machinery and is characterized by high energy consumption and substantial losses of cryogenic products. Furthermore, when the evacuation method is used, the liquefied natural gas is enriched with high-boiling fractions whose content in the rocket fuel is stringently regulated. Cooling of liquid cryogenic product by the method of sparging with a cooled gas takes place primarily due to partial evaporation of the cryogenic liquid inside the gaseous sparging medium. Use of this method for multicomponent fuels also causes enrichment of the fuel with high-boiling fractions. Bauman Moscow State Technical University (Moskovskii Gosudarstvennyi Tekh
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