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Patents with Abstracts

Phase Change Materials





1. “In chemistry, paraffin is a term that can be used synonymously with "alkane", indicating hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to a mixture of alkanes that falls within the 20 ≤ n ≤ 40 range; they are found in the solid state at room temperature and begin to enter the liquid phase past approximately 37 °C (99 °F).

The simplest paraffin molecule is that of methane, CH4, a gas at room temperature. Heavier members of the series, such as octane, C8H18, and mineral oil appear as liquids at room temperature. The solid forms of paraffin, called paraffin wax, are from the heaviest molecules from C20H42 to C40H82. Paraffin wax was identified by Carl Reichenbach in 1830.

Paraffin, or paraffin hydrocarbon, is also the technical name for an alkane in general, but in most cases it refers specifically to a linear, or normal alkane — whereas branched, or isoalkanes are also called isoparaffins. It is distinct from the fuel known in the United Kingdom, Ireland and South Africa as paraffin oil or just paraffin, which is called kerosene in most of the U.S., Canada, Australia and New Zealand.

The name is derived from Latin parum ("barely") + affinis, meaning "lacking affinity" or "lacking reactivity" indicating paraffin's unreactive nature.”

(Wikipedia, Paraffins, 8/7/2012)

2. “Paraffins in the C12-C24 range have useful applications as phase change material (PCM). The paraffins undergo solid-liquid phase transition in the about C. ( F.) to about C. ( F.). Heat is absorbed as the PCM paraffin melts and heat is released later when the PCM freezes. Fabricated systems that use PCM's as such are referred to as passive thermal storage devices. Due to relatively high latent heats of solid-liquid phase transition (referred to simply as latent heats hereafter), as well as compatibility with common material of construction and high stability, paraffins are considered particularly well-suited for PCM applications. Wall boards of a house impregnated with a PCM are an example of a passive thermal storage device. During a hot day, the PCM will absorb heat as it melts. Since there is no temperature change during phase transition, the surface in contact, with the thermal storage device stays at constant temperature until all. PCM therein has melted. The heat that would have made the house hot has thus been stored in the molten PCM. At night, as the temperatures get cooler, the molten PCM freezes and releases the heat thus preventing the home from getting cold. The melting-freezing cycles moderate the temperature of the space enclosed within the passive thermal storage device despite extreme night-day temperature swings outside. In general PCMs are an effective way of storing thermal energy (e.g. solar, off-peak electricity, industrial waste heat), and reducing energy demand (e.g. for heating and air-conditioning).” [Abhari US Patent 8,231,804 (7/31/2012)]


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(RDC 6/5/2012)


Roger D. Corneliussen

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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen

* Date of latest addition; date of first entry is 8/7/2012.