Cooling applications

Slime masses or any biofilm may substantially reduce heat transfer and increase flow resistance. The thermal conductivity of a biofilm and water are identical (Table 6.1). For a 0.004-in. (lOO-pm)-thick biofilm, the thermal conductivity is only about one-fourth as great as for calcium carbonate and only about half that of analcite. In critical cooling applications such as continuous caster molds and blast furnace tuyeres, decreased thermal conductivity may lead to large transient thermal stresses. Such stresses can produce corrosion-fatigue cracking. Increased scaling and disastrous process failures may also occur if heat transfer is materially reduced. 

The overall economics of an air-cooled application depends upon the following ... 

Lee J, Mudawar I (2005b) Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications. Part II heat transfer characteristics. Int J Heat Mass Transfer 48 941-... 

Of these systems, heat pump supported combined heating and cooling applications (system B) are dominating. However, in recent years, there is a growing interest for storage of natural cold (system D), which is used for district cooling applications or for industrial process cooling. 

One good example are ice-water slurry storages, which are widespread in cooling applications. Water is cheap and easy to handle. Today, it is state of the art to produce ice-water slurries that can be stored and pumped to a demand when needed. 

Modular systems mostly use flat plate bags for air has heat transfer medium and spheres (balls) for liquids as heat transfer medium. In cooling applications the system used by Cristopia (France) using PCM filled balls is the state of the art. Systems with bags for cooling air in air-conditioning systems are currently developed. 

There are a number of suggested and implemented techniques of snow and ice storage for cooling applications. In Japan about 100 projects have been realized during the last 30 years, and in China there is about 50-100 snow and ice storage systems (Kobiyama, 2000). Also Canada, USA and Sweden have made efforts in the field. Below both realised and suggested techniques are presented. 

The family Hamamelidaceae consists of 26 genera and about 100 species of shrubs or tress known to contain tannins and iridoids. The leaves are alternate, simple, and often palmately lobed. The flowers are small and appear in spikes. The fruits are woody, capsular, and scepticidal. In Western medicine, the dried leaves of Hamamelis virginiana (hamamelis, British Pharmaceutical Codex, 1963), yielding not less that 20% of alcohol (45%)-soluble extractive, have been used as astringents for the treatment of hemorrhoids. Hamamelis water (British Pharmaceutical Codex, 1969) made from the stems has been used as a cooling application to sprains and bruises and as a styptic remedy. It is also used in cosmetics and as active ingredient of eye lotions. 

In thermoelectric cooling applications, extensive use has been made of cascaded systems to attain very low temperatures, but because the final stage is so small compared to the others, the thermal flux is limited (Fig. 3). The relative sizes of the stages are adjusted to obtain the maximum AT. Thus, for higher cooling capacity, the size of each stage is increased while the area ratios are maintained. 

A study of the ecology of many cooling systems shows that, despite the diverse nature of cooling applications, system materials of construction, makeup water sources, and geographical location, the characteristics of their particular ecosystems remain very similar. As a consequence, the major... 

Gas-Controlled The gas side dominates in gas cooling applications. An example is the quenching of a furnace effluent with a vaporizing liquid. In this application the liquid is nearly uniform in temperature. Restated, the reduction in driving force across the liquid side of the interface is unimportant. 

Inventor Seuer, R.C. andM.B. Cool Applicant Beech Nut Nutrition Corp (U.S.)... 

U-tube heat exchangers are commonly used in steam heating applications, or heating and cooling applications that handle chemical fluids as opposed to water. 

Still another method of evaluating fin performance is discussed in Prob. 2-68. Kern and Kraus [8] give a very complete discussion of extended-surface heat transfer. Some photographs of different fin shapes used in electronic cooling applications are shown in Fig. 2-13. 

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