Combustion – Candle – e.g. – taper – etc. – Having structure additional to wax and wick
Reexamination Certificate
2001-08-09
2002-05-07
Price, Carl D (Department: 3743)
Combustion
Candle, e.g., taper, etc.
Having structure additional to wax and wick
C431S289000, C362S163000, C362S180000
Reexamination Certificate
active
06382962
ABSTRACT:
BACKGROUND OF THE INVENTION
Containerized candles have been well known for hundreds of years. Candles were first placed in containers as an improvement over conventional candle sticks. When a candle burns, the heat generated by the flame melts a layer of the wax around the flame, which is drawn up by the wick to feed the flame. Much of the candle wax, which fuels the candle flame, melts and runs down the body of conventional candle sticks, which not only reduces the longevity of the candle, but also detracts from the appearance of the candle. Containerized candle have the tallow or wax and wick contained in a transparent or translucent vessel, such as a glass apothecaryjar. Containerized candles enclose the wax within the vessel, which prevents the loss of wax from run off and allows for a more decorative presentation. Containerized candles in glass apothecary jars have become increasingly popular, and are general referred to as apothecary jar candles.
One drawback of containerized candles is the efficiency of their combustion. It is well known that the flame in a candle is a diffusion combustion flame. The flame is a reaction front (or wave) in a gaseous medium into which the reactants flow and out of which the products flow. Diffusion flames occur when fuel and oxidizer mix and burn simultaneously. In a candle, the candle wax is consumed as a fuel and the oxidizer is oxygen from the atmosphere drawn in a convection stream toward the base of the flame. The candle wax is melted and vaporized by the heat of the flame and emerges as a steady stream of vapor from the wick. The candle wax is rich in hydrocarbons, which are consumed in the exothermic reaction of the flame. Hot incandescent carbon particles in the flame make it appear yellow. If sufficient ambient air is not drawn to the base of the flame to oxidize the carbon particles in later stages of combustion, the flame will be smoky, and the exhaust will contain dark carbon residue, smoke. Consequently, providing a sufficient air flow is critical for a clean or smokeless combustion.
Heretofore, providing sufficient air flow to the base of the flame in a containerized candle has been a problem. While the vessel prevents the run off of melted wax and contains the thermal energy to melt more wax near the wick, the container limits and obstructs the air flow to the flame, which is needed for the combustion process. Ambient air must simultaneously be drawn downward into the containerwhile hot exhaust vents out of the container. Hot exhaust from the flame rises upward in a convection flow, which creates a negative pressure to draw cool ambient air into the interior toward the base of the flame. Passing through the mouth of the container, the proximity of the opposing exhaust and intake airflows create turbulence within the container interior. The turbulence within the container increases proportionately to proximity between the exhaust and intake air flows, as well as, the temperature and velocity differentials of the air flows. The turbulent air flow within the container restricts and retards flow of the ambient air to the base of the flame. Consequently, the combustion in containerized candles often produces smoke. Turbulence within the container also destabilizes the flame, and can even extinguish it. The instability of the flame is evidenced by the flicker of the flame, which is common in containerized candles.
In addition, “tunneling” has been a problem for large diameter candles whether containerized or not. The thermal energy released in the combustion of conventional candle waxes can only melt a thin layer of wax with a limited cross-sectional area. Consequently, “tunneling” occurs when the cross-sectional area of the solid candle wax is much greater than the cross-sectional area of the melted candle wax around the flame. As the melted candle wax is consumed by the flame, the flame descends down into a cylindrical cavity or “tunnel” within the solid candle wax. Eventually the flame becomes encircled within this “tunnel” of candle wax. The quantity of solid candle wax which forms the tunnel walls is lost to the candle as a fuel source, simply due to the inability of the flame to melt the remote solid wax.
Since the candle wax and flame are enclosed, containerized candles can have slightly greater diameters than conventional stick candles. The glass enclosure partially insulates the thermal energy from the combustion so that more solid wax can be melted. Nevertheless, the thermal energy released in the combustion of conventional candle waxes still limits the maximum diameter of single wick containerized candles to approximately three inches. As the diameter of containerized candles begins to exceed three inches tunneling begins to become a problem. With air flow within the container already inherently restricted, tunneling can prematurely limit the life of a containerized candle. Furthermore, the in flow of ambient air to the base of the flame can become so constricted by the tunneling effect within a containerized candle that the flame extinguishes for lack of oxidation.
SUMMARY OF THE INVENTION
The containerized candle venting cover of this invention stabilizes the combustion flame and improves the efficiency of the combustion of conventional containerized candles. The venting cover reduces turbulence in containerized candles by facilitating separated concentric laminar air flow within the candle container. The concentric laminar air flow inside the candle container enables sufficient ambient air flow directly to the base of the flame so that the flame burns more efficiently, i.e., brighter, hotter and with reduced smoke.
The venting cover of this invention can be used with any conventional containerized candle, but is ideally suited for use with conventional three inch apothecary jar candles. The venting cover of this invention is a flat disc, which is seated over the mouth of the container or jar. The venting cover has an annular flange around its periphery, a central exhaust vent and six oblong inlet vents spaced radially from the exhaust vent around the periphery of the venting cover. The venting cover creates a concentric laminar air flow within the interior of the jar, which stabilizes the flame and improves the efficiency of the combustion. The upward convection flow of the hot exhaust air from the flame exits the jar directly through the exhaust vent in the venting cover. The negative pressure inside the jar created by the convection flow of the exhaust air draws cool ambient air into the jar through the six inlet vents. This intake air flow circulates concentrically downward along the inside of the jar wall and converges toward the wick at the base of the flame.
The venting cover restricts the volume and velocity of the airflow that exits and enters the interior of the jar. The orientation of the exhaust vent and the surrounding six inlet vents provides concentric laminar air flow within the jar, which stabilizes the flame and permits sufficient air flow directly to the base of the flame. The exhaust vent is positioned directly above the candle flame, which focuses the convection draft of exhaust air directly upwards, thereby reducing the diffusion of the exhaust flow inside the jar. The six intake vents are spaced radially from the exhaust vent to separate the exhaust and intake air flows. The separation of the opposing air flows reduces turbulence within the interior of the jar, which leads to cleaner, more efficient combustion.
Accordingly, an advantage of this invention is that the venting cover stabilizes the combustion flame and improves the efficiency of the combustion of conventional containerized candles.
Another advantage is that the venting cover reduces the smoke produced in the combustion process of containerized candles.
Another advantage is that the venting cover reduces turbulence in containerized candles by facilitating separated concentric laminar air flow within the candle container, which enables sufficient ambient air flow directly to the base of the flame.
Another advantage is that the appar
Crump R. Tracy
Price Carl D
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