New Mechanisms for Cryogenic Solid-Gas Sublimation Refrigeration: Basic Principles and System Designs

New Mechanisms for Cryogenic Solid-Gas Sublimation Refrigeration: Basic Principles and System Designs

Lin Chen (Tohoku University, Japan)
DOI: 10.4018/978-1-4666-8398-3.ch004
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Abstract

Sublimation is one phase change mechanism which usually happens under low-to-moderate temperatures and at the same time large amounts of latent heat is absorbed or released. Low temperature sublimation has been proposed in a lot of applications as one useful fast cooling/refrigeration mechanisms, such as medical cooling, food engineering, chemical synthesis, domestic cooling and many industrial sectors. In this brief chapter, the basic mechanisms of static sublimation process and sublimation two-phase flows are clarified and analyzed first, which covers the theoretical and physical problems of sublimation phase-change. Then the previous studies are classified into numerical modeling and experimental verifications. Representative refrigeration systems are also introduced and compared in this chapter, which may give useful indications for future innovations in this field. Future research focuses are also summarized and proposed in this chapter.
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Introduction

In recent years, sublimation flow and heat transfer has been proposed and utilized in real applications. Compared with traditional vapor-compression thermodynamic refrigeration cycles, using solid-gas sublimation flow can achieve more stable operation and probably higher heat recovery capacity, due to the relative high latent heat of sublimation process. Therefore, recently the investigation of solid-gas sublimation flows and its related application system designs has attracted a lot of research groups and engineer from both scientific world and industrial sectors (Robertson, 1932; Nelson, 1942; Lester & Somorjai, 1968; Eisenbraun et al., 1995; Michaelides & Lasek, 1987).

Indeed, sublimation is one of the phase change mechanisms happening everyday in the world. As shown in Figure 1 (Aoki et al., 2002), dry ice sublimation is shown specifically for two different states when immersed in liquid tank. Early studies around 1930s have begun to investigate the basic thermo-physical nature (Robertson, 1932; Nelson, 1942). At that stage, the main topics were set around the sublimation rate from the viewpoint of chemical reaction/engineering or chemical physics. Later, more groups have studied the thermal equilibrium and near-equilibrium sublimation process, which may assume the ideal condition of vacuum sublimation in order to obtain reasonable results with experiments. As the sublimation substances such as Iodine, Naphthalene and Camphor were more and more used in domestic and engineering field, more studies came out since 1970s (Somorjai, 1968; Davy & Branton, 1970). However, the sublimation mechanism and physics behind what is seen is still unknown. At the same time, more studies has focused on the different factors that affect the sublimation rate of a crystal or particle, where the structural and chemical arrangements are analyzed from surface vaporizing to sublimation. Many groups have reported theoretical and experimental results measured for atomic crystal, molecular crystal, ionic crystal and others, under congruent or non-congruent sublimation process (Lester and Somorjai, 1968). Until recent years, there are still studies based on this general understanding of sublimation physics and the main focus on theoretical analysis and methods of numerical developments can be found (Schinzer & Kinzel, 1998; Smilauer & Vvedensk, 1995; Zhu et al., 2007; Krishnamurthy et al., 1990; Latyshev et al., 1996). The current review study will focus on the basic historic development of sublimation field and related cryogenic/refrigeration oriented applications in recent years.

Figure 1.

Sublimation patterns of dry ice in liquid. (a) film-state sublimation (water of 25 ºC); (b) nucleate-state sublimation (ethanol of 17 ºC)

(Aoki et al., 2002)

However, the majority of those theories and experiments are based on strict assumptions of crystal structure and surface vaporization/sublimation laws (Somorjai & Lester, 1967). Large deviations are found between experiments and theoretical predictions, or from experiment to experiment. Since 1980s, with the development of social technology, sublimation flow related scientific and application studies became activated again (Gershanik & Zeiri, 2010; Goldstein & Cho, 1995; Mendes, 1991). New application demand from industry sectors, such as process cooling, refrigeration, domestic cooling, food engineering, medical cooling, drying and engineering chilling/cleaning, has triggered a lot of new developments in this field. With the aid of recently developed precise experimental methods and advanced computational method and capacity, a lot of new results have been reported (Eisenbraun et al., 1995).

Key Terms in this Chapter

Evaporation: Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance. Evaporation that occurs directly from the solid phase below the melting point, as commonly observed with ice at or below freezing or moth crystals (napthalene or paradichlorobenzine), is called sublimation.

Sublimation Dynamics: Sublimation Dynamics is the study of basic process, mass, momentum and Energy transportation topics that involved in the sublimation process. The dynamic behaviors of sublimation surface, the movement of molecules and the basic dynamic testing of the sublimation system parameters are also the main branches of the center topic.

Solid-Gas Two-Phase Flow: Solid-Gas Two-Phase Flow is one type of multi-phase flows that includes only solid phase and gas phase. Usually the situation is particle dispersed in a gaseous phase and moves inside some kind of geometry.

Multi-Scale Analysis: Multi-Scale Analysis means the solution or the investigation of a specific problem that coves several time, spatial or other scales. Usually in physics study, the time scaling and spatial scaling are the major challenges of a problem, such as the sublimation problem, the particles may changes from micro to nano scale during the process.

Carbon Capture and Sequestration (CCS): Carbon capture and storage (CCS) (or carbon capture and sequestration) is the process of capturing waste carbon dioxide (CO 2 ) from large point sources, such as fossil fuel power plants, transporting it to a storage site, and depositing it where it will not enter the atmosphere, normally an underground geological formation.

Cold Energy: Cold Energy comes from the materials or environment that contains ‘cold’, or low temperature. Many valuable industrial byproducts can be produced using cold energy of LNG. Also, the ice remains frozen by way of its own cold energy, and it can be used to chill guests’ food throughout the summer.

Thermal Equilibrium: Thermal equilibrium is an axiomatic concept of classical thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by permeable walls. In thermodynamic equilibrium there are no net macroscopic flows of matter or of energy, either within a system or between systems.

Cryogenics: Cryogenics is the study of the production and behaviour of materials at very low temperatures (below -150 °C, -238 °F or 123 K).

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