Patent Publication Number: US-2013248142-A1

Title: Geo-Thermal Air Coil

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a non-provisional application of provisional patent application No. 61/634,581, filed on Mar. 2, 2012, and priority is claimed thereto. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     The interest in acquiring geothermal energy from the earth is great due to the tremendous potential benefit it offers. Failure to master the technology, however, results in limitations which are found in current geothermal systems. Balance with natural forces which this patent refers to as “seasonal soil variation” is a fundamental part in overcoming these limitations. This patent will address current shortcomings, by offering a specific design which offers a revolutionary new improvement, constant air temperature production. 
     The first law of thermodynamics teaches that energy can neither be created nor destroyed. Many conditions energy is something that cannot be observed by the human eye, therefore understanding the laws which govern it become very critical in identifying how it will behave in a given system. Today&#39;s geothermal systems lack a complete accounting of the influences that interact within a system, and therefore come short in their abilities to correctly harness this great energy source. Geothermal systems have the potential to be some of the cheapest energy produced, yet they account for one of the smallest producers of energy in today&#39;s market. Until now, this has been due to the limitations that our found in these systems. 
     Since the first law of thermodynamics teaches that the total energy in a system will remain constant in that system, it became essential that in the designing of a heat exchange system that all energy is accounted for and balanced, otherwise the energy being transferred will end up in an undesired location, and cause system the system to become unbalanced. 
     The first major limitation that geothermal systems face is the medium for the exchange. Most geo-thermal systems use water or a “liquid” as the medium of exchange for the heat transfer. Liquids have a major limitation in geothermal applications which is their natural capacity to hold and transfer energy. In a system where energy transfer is very slow like the earth&#39;s soil, a median which carries large amount of energy will quickly saturate of the surrounding area. 
     To compensate for this, the liquid geothermal system adds additional length to the overall tube loop. This increases in length allows additional room for energy transfer to accomplish a specific system requirement, but does not correct the original obstacle of using a medium which transfers energy at a rate faster than the rate soil can absorb. 
     To compensate for this, the liquid geothermal system adds additional length to the overall tube loop. This increases in length allows additional room for energy transfer to accomplish a specific system requirement, but does not correct the original obstacle of using a medium which transfers energy at a rate faster than the rate soil can absorb. 
     This brings up a secondary limitation in a liquid geo-thermal system which is tube size. The size of the tube directly effects the surface area of soil around the tube for the energy transfer. Liquid geo-thermal systems us a small diameter pipe of approximately one inch. ( FIG. 4   b ) The amount of soil area participating in the exchange is limited. The greater area of soil you have interacting in the energy transfer the more energy it will hold. 
     An example of this relationship is shown in  FIG. 4 . These drawing use a measurement of 3 inches of soil immediately around the tube to show the example. If the majority of energy transfer in soil is accomplished in 3 inches of soil surrounding the surface of a pipe, that would be a total diameter of 7 inch circle (3 inches on one side, 1 inch pipe, 3 inches on the opposite side), minus the 1 inch in the center for the pipe which the liquid medium passes. The total surface area of the soil in the heat exchange would be 38.48 square inches minus the 0.76 square inches for the center pipe, for a total of 37.72 square inches around the tube. ( FIG. 4   b ) However, if that tube had a 12 inch diameter, and you take that same distance of soil, 3 inches, around the pipe the total amount of soil becomes 141.3 square inches. ( FIG. 4   a ) Most liquid geothermal system do not use a 12 inch tube or larger tubes in general because of the fundamental problem that liquids can hold large amounts of energy and will transfer more energy than the soil can hold. 
     One way to help with this obstacle would be to increase the amount of soil for the transfer, without increasing the amount of liquid a pipe will carry. This could be done by placing a 9 inch pipe inside of a 10 inch pipe, and run the water between the in inch diameter gap between the two. ( FIG. 4   c ) While the area for the liquid to move thru may not be exactly equal to the one in pipe in  FIG. 4   b , the point is still made, you can increase square inches of soil the energy has to transfer to while keeping the volume of the medium lower. 
     As more energy is transferred, the temperature of the soil and the temperature of the liquid medium will become closer and closer to each other until they no longer are able to exchange energy, which will occur once they become the same temperature. When this happens the energy will travel farther down the tube till there is a difference in temperature and an energy transfer can happen. 
     When air or a gas is used as the medium in a geo-thermal system, you do not have these limitations. Air lacks the ability to carry large amounts of energy compared to solids or liquids. The soil is no longer the weakest link in the system, the air inside the tube is. This fundamentally changes certain characteristics in the system. 
     The most important change is transfer rate of the energy relationship. Shape of the tube now becomes a critical factor in deterring what rate the energy is transferred. A strait tube will follow the principles of laminar flow. Air in the center moves with less resistance than air touching the edges of the tube. This produces a lower rate of energy transfer. This means the energy in air must travel farther down the tube before it will transfer to the soil. 
     SUMMARY OF PRESENT INVENTION 
     The goal of a geo-thermal system is harness the energy in the earth. Energy in the earth is a combination of energy between the sun and the earth&#39;s core. 
     Using air or gas as a medium to transfer energy, the location of energy transfer can be manipulated. By increasing or decreasing form drag, the system will transfer energy at different rates. A straight tube will have the lowest rate of energy transfer, and while coiling the tube will increase the transfer rate. A straight 90 degree turn would have the highest. 
     Increasing the rate of energy transfer in geothermal system that uses air or gas will decrease the amount of tube length necessary to transfer the energy. 
     With knowing how to control where energy will be transferred inside the system, the system can be designed to transfer the greatest amounts of energy closer to the top of the soil, where it will gain the most benefit from season soil variation. 
     Once the majority of energy transfer has been accomplished in the higher soil, air can continue deeper into the soil to gain addition temperature change without running the risk of having energy transferred in a location where seasonal soil temperatures cannot reach. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  displays the general shape of a geo-thermal air coil in relation to depth in the spoil and seasonal soil variation. 
         FIG. 2  displays the use of a system being used to control the ambient temperature of air moving thru the condensing coils on a heat pump/AC unit. 
         FIG. 3  displays the use of a system being blown across a road to keep the surface of the road above freezing. 
         FIG. 4   a  displays a 3 inch area of soil surrounding the outside edge of a 10 inch pipe,  FIG. 4   b  displays a 3 inch area of soil surrounding the outside edge of a 1 inch pipe,  FIG. 4   c  displays a 3 inch area of soil surrounding the outside edge of a 10 inch pipe where the 10 inch pipe contains an internal 9 inch pipe, where liquid passes in the space between the 9 and 10 inch pipe. 
         FIG. 5  displays a graph showing the transfer of energy inside of a geo-thermal air coil at different ambient air temperatures. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is a system for created air at a constant temperature regardless of season or ambient air temperature. To escape the temperature difference of seasonal soil variation, a system must reach a sufficient depth where energy from the sun in no longer influencing the energy produced by the earth&#39;s core. However this area is problematic for transferring large amounts of energy over time. Energy can become trapped and soils can become saturated at this deeper level. To balance this, as much energy as possible should be transferred as close to the surface as possible to benefit from the net gain or loss of season soil variation. Every 6 months this works as a reset button to help restore any imbalance by the energy transfer in the soil. 
     Air enters the system [ 03 ] and moves down under the soil [ 02 ] where the energy exchange begins. This is usually where the greatest difference between the temperatures of air and soil are. The greater the temperature difference the more energy can be transferred. The soils at this level have the greatest variation as shown by the graph chart which is superimposed over the system [ 3 ]. The temperature variation [ 10 ] and the corresponding lines for soil depth [ 06 ] and [ 7 ] are help illustrate how seasonal soil variation will become diminished each foot as is travel farther below the surface of the soil [ 1 ]. As shown on the graph in  FIG. 5 , both share a common parabolic shape for the rate of energy transfer. Because both shapes are similar, the conclusion is simple; to gain the most benefit from season soil variation you want the greatest amount of energy transferred highest in the soil, before moving lower in the soil to gain the addition degrees of constant core temperatures [ 9 ] which are only obtained in lower depths. 
     By understanding this behavior of the system, you can control the location of energy in the soil, and thus its output. A system that does not produce a constant temperature year round, runs the risk of having energy built up in undesired locations, which is likely due to energy saturation in the soil. 
     Once air has reached the lowest point in the system, a plenum is installed [ 8 ] to act as a drain for any moisture buildup or debris in the system. This allows for a sump pump or one way drain to be installed if required by the system. The air at this point in the system will be at its most optimal temperature, and begin its journey back to the surface in the most direct path possible. The use of insulated tubing could be used at this level but the benefits of laminar flow will help to reduce the energy exchange as the difference in temperature of the soil and temperature of the air begins to grow. The air leaving the system [ 4 ] can be used for the application of the system. 
     In  FIG. 2  a system for a heat pump or AC unit is demonstrated. Outside ambient air temperature is pulled into an air circulating fan [ 20 ], and pushed down thru the unit [ 21 ]. The air once conditioned [ 22 ], can be configured around [ 23 ] the condensation coils of heat pump or AC unit [ 24 ]. Blowing thru a drain cover [ 26 ] towards the compressor, the air is pulled thru the condensation coil by the compressor fan [ 25 ] and out the exhaust of the unit. While the method of delivery using underground vents is not essential, the basic understanding of using the moderate air of the system [ 22 ] to pass thru the condensing coils of the unit [ 24 ] will help the efficiency of that unit. 
     In  FIG. 3  a system for road is demonstrated. To show a different application of the fan, the fan is place in the ground below grade [ 32 ] with a ventilation cover [ 31 ] at ground level. The fan [ 33 ] operates the same as other applications, and the air exists a vent within a curb [ 34 ]. The air is blown across the road [ 35 ] to prevent ice from forming during freezing temperatures, keeping the road safe for vehicles [ 36 ].