Patent Application
20070221200
The invention as disclosed here consists of a self powered latent heat capturing device. In particular, this device could be used to produce heat for maintaining indoor living space temperatures. The device is installed in-line and integral or directly attached to a hot gas vent pipe connected to an apparatus such as a furnace, a wood stove or pellet stove.
Combustion efficiencies of typical bio-mass and fossil fuel furnace systems approach 85 percent at best with excess heat rising with hot exhaust gases through a vent pipe typically open to the atmosphere. At least fifteen percent of the heat is lost to the atmosphere.
In another typical configuration, machinery operates in many factory facilities producing hot gases with latent heat. Once again, the gases, sometimes scrubbed for pollution controls, are vented to the atmosphere. In certain circumstances, facilities piping is used to heat areas of a workplace in manufacturing buildings, thereby reducing the cost of a dedicated heating systems to that area. There may be instances where piping is configured purposefully to capture and direct latent heat to a certain living area or working area by routing extra piping through the general area before venting it up through a roof pipe or chimney to the atmosphere.
In the typical wood stove installation, the exiting vent pipe rises vertically, directly above the wood stove and extends up through an insulated roof venting area. Code requirements are very stringent concerning the area where the hot exhaust pipe from the wood stove travels through and close to the roof area. Typically, the temperature of a single wall pipe installation on a wood stove can reach temperatures is hot as 1,000° F., hottest just above the wood stove On a typical pellet stove, the inside gas vent temperatures approach 500° F. In the typical installation, the single wall pipe rises above the wood stove and proceeds to the roof flange area into a special double walled insulated pipe to protect nearby flammable materials. The single wall pipe directly above the installed wood stove, or pellet stove, in another case, provides extra heat to the living room by means of straight convection.
Convection thermal gradients are small from the top to the bottom of the pipe as the gas rises swiftly, providing the room with little net heat gain.
An objective of the invention is to capture latent heat from the vent pipe, essentially raising the efficiency of the attached heating device. Today, existing incentives provide for tax credits when homeowners remove old inefficient wood stoves and replace them with more efficient modern wood stoves certified by new EPA standards. And objective of the invention is to provide a quick and inexpensive way to increase the efficiency of such older wood stoves without replacing them.
In order to produce more efficient heat, another objective of the device is to be self powered. A typical thermal electric generator converts heat directly to electricity to run a blower sufficient to circulate cool room air through the invention. By attaching to or inserting in-line to the vent pipe, the invention efficiently captures latent heat by moving cool room air across a typical heat dissipation fin assembly as shown below.
An additional objective of the invention is to redirect the warm air back into a living or workspace.
In a further objective of the invention, latent heat is captured to operate the invention so it can be located in a convenient area without external power requirements. An embodiment of the invention is to not interfere with the flow of vent gases in order to capture latent heat. The machinery or heating apparatus need not be adjusted or modified in any way to accommodate the installation of the invention.
An additional embodiment of the present invention, configures placement and size of the invention to maintain proper and acceptable hot gas venting temperatures to minimize creosote buildup.
In yet another embodiment of the invention, it is easily attached to an existing vent pipe, using the vent pipe only to capture heat and does not interfere with present gas flow.
The invention as shown will deliver an economical solution in a time of rising cost of fossil and bio-mass fuels.
Turning to
The body is also comprised of a cool air inlet (3) and a hot air outlet (4).
In the spirit of the invention, the cool air inlet faces towards the back of a typically installed wood stove and the hot air outlet faces forwards the front in the same installation.
With reference to the illustration, large airflow arrows note that the cool air inlet faces perpendicular to the in-line stovepipe installation while the hot air outlet directs hot air downwards. In the spirit of the invention, the respective configurations of the inlet and outlet benefit by drawing cooler air from the back of the stove while forcing hot air down and into the living space, as further described below.
Connecting the cool air inlet to the hot air outlet is an air channel (5). The air channel is sized and configured to optimize heat transfer to a heat dissipation fin assembly (6) sandwiched between an inside wall (5A) and an outside wall (5B). The heat dissipation fin assembly optimizes heat transfer by convection and conduction from the inside wall to the air channel as is well known in the art. In the spirit of the invention, the heat dissipation fin assembly is configured to allow maximum air flow across the greatest surface area as possible. Also known in the art, the fin assembly touches or attaches to the inside wall, conducting heat directly, and not touching the outside wall allowing the airflow to absorb maximum amounts of latent heat from the appliance while minimizing the conduction of heat to the outside wall.
Continuing with the illustration, a blower fan (7) draws cool air through the cool air inlet (3) across a thermal electric generator (8). Well known in the art, the thermal electric generator is based on the seebeck principles using typically a P-N nodal solid-state array. The thermal electric generator is positioned on a on a heat-sink/insulator, optimizing heat flow to the hot side of the thermal electric generator. A power wire (9) feeds the electrical current from the back of thermal electric generator to the blower fan. The blower fan and power wire are sufficiently positioned away from the inside wall (5A) further down the throat of the cool air inlet to meet maximum heat allowances as is well known in the art. Also well known in the art, the blower fan (7) may be installed on insulated struts further protecting it from conductive heat.
In the preferred embodiment of the invention, once the hot gas venting apparatus starts, the thermal electric generator senses a heat-gradient between the inside wall and the air channel ambient air temperature. The initial gradient starts the blower fan, thus increasing the gradient more by delivering cool air across the cool side of the thermal electric generator.
In another preferred embodiment of the invention, the cool air passes over the thermal electric generator, thus producing a greater and greater heat-gradient, producing a greater and greater current flow to the blower fan thus producing a faster fan speed. As the gas venting appliance continues to reach a sustained operational temperature, the invention reaches a steady state of continuous operation, moving cool inside room air across the thermal electric generator and further across the heat dissipation fin assembly pushing freshly warmed air out the hot air outlet to the room.
Turning to the illustration of
Holding the invention to the existing stovepipe are two straps (2A) positioned sufficiently apart to secure the invention. In this embodiment, a buckle (2B) on each strap cinches it tightly round the existing stovepipe. Dual air inlets (3) are positioned on either side of the invention sufficiently open at the ends and away from the existing stovepipe to draw in cool room air. The air inlets are further configured to slip past either side of the existing stovepipe for easy installation. In this configuration, the body (2) has two inlets and one hot air outlet (4). It is the intention of this inventor to configure the invention in a symmetric fashion, but those in the art may prefer a single payer inlet on one side because a single configuration suffices and saves expense.
As described above, the body contains an air channel (5), an inside wall (5A), an outside wall (5B), a heat dissipation fin assembly (6), blower fans (7) each with aligned thermal electric generator (8) and connecting power wires (9).
This alternate embodiment of the invention provides a convenient way to slip on the invention to an existing installed hot gas vent pipe such as on a wood or pellet stove pipe. As described above, this embodiment functions the same, though the air flow is redirected through the reconfigured air channel.
In another embodiment of the invention, the self- powered blower fan is incorporated into a heating device or machinery, venting hot air to better circulate air flow within the heating device or machinery and to optimize energy use and conductive heat transfer to a living area.
Although the invention has been described in conjunction with specific embodiments, it is evident that many alternatives and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims.
