Direct High Voltage Water Heater System

Abstract

A direct high voltage flow-through water heater system transmits high voltage power to a remote ice penetrating robot, converts the power to heat in a very small space, and then uses the heat to melt the ice, providing a path ahead of the robot allowing penetration deeper into a remote ice-covered location, such ice of substantial (e.g., kilometers) thickness, such as, for example, glacial ice caps. High voltage, low current, AC power is passed through a moving conducting fluid, inducing resistive heating in the fluid with 100% efficiency. The exiting fluid is stripped of common mode voltage before exiting. Energy transfer from the electrical source to the fluid is instantaneous and occurs at 100% efficiency. In an alternative embodiment, the fluid heater system operates at standard residential/industrial mains voltages and runs from 220 VAC as other applications of the present invention include the traditional water heater industry as well.

Claims

1. A direct high voltage fluid heater system comprising: a first housing having a first end and a second end; an end plate removably attached to said first end of said housing, said end plate and said first housing defining a first volume; a plurality of electrode plates within said first housing and having a plurality of apertures therethrough, each plate spaced a predetermined distance from each other, there being no contact between electrode plates, said plurality of apertures of one electrode plate in longitudinal alignment with said plurality of apertures of an adjacent electrode plate; an intake port traversing said end plate; an exhaust port at said second end of said first housing; an insulator covering the inside surface of said first housing; a second housing removably attached to said first housing and forming a second volume therebetween, said second volume filled with an oil; a plurality of feedthrough fittings in electrical communication with said plurality of electrode plates, said plurality of feedthrough fittings within said second volume of said second housing; a high voltage tether in electrical communication with said plurality of feedthrough fittings; and a conductive fluid having an ionic content sufficient to facilitate resistive heating, said conductive fluid_flowing through said first volume of said first housing, said conductive fluid in electrical communication with said plurality of electrode plates, and wherein said direct high voltage fluid heater system is feedback controllable to produce a constant output temperature regardless of flow rate of said conductive fluid; wherein said direct high voltage fluid heater system is powered exclusively by alternating current; and wherein the energy transfer from said alternating current to said conductive fluid is instantaneous and occurs at 100% efficiency without inducing electrolysis; and wherein the amount of said energy transfer may be varied electronically.

2. The direct high voltage fluid heater system of claim 1 wherein said insulator is comprised of a polyether ether ketone (PEEK) material.

3. The direct high voltage fluid heater system of claim 2 further comprising a transformer in electrical communication with said plurality of electrode plates, said transformer capable of producing 10 kV phase-to-phase and 5 kV phase-to-ground.

4. The direct high voltage fluid heater system of claim 3 further comprising a ground fault interrupter circuit located between an exhaust fluid and protective earth ground, said ground fault interrupter circuit monitoring and detecting current flow between said first housing and said earth ground, and if said current flow is detected exceeding a pre-determined threshold, disconnecting said direct high voltage fluid heater system from mains power via a mechanical relay.

5. The direct high voltage fluid heater system of claim 4 wherein said conductive fluid is water.

6. The direct high voltage fluid heater system of claim 5 wherein said exhaust fluid is stripped of common mode voltage before exiting said first housing.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0026] FIG. 1 shows a schematic detailing the present invention.

[0027] FIG. 2 shows a plot of the temperature (° F.) and current (A.U.) versus time (sec) of the present invention.

[0028] FIG. 3 is a cross sectional perspective view of an embodiment of the present invention.

[0029] FIG. 4 shows a partial perspective environmental view of an embodiment of the present invention integrated into an ice penetrating vehicle.

[0030] FIG. 5 is a flow chart of an embodiment of the present invention in the context of an ice penetrating vehicle.

[0031] FIG. 6 is a flow chart of an embodiment of the present invention in the context of a household residence.

DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 depicts a schematic 10 of a 10 kV high-voltage flow through heater. A 10 kV center tapped transformer 12 produces 10 kV phase-to-phase and 5 kV phase-to-ground. Pump 14 circulates conductive fluid 16 (in this case tap water) through non-conducting loop 18. This loop 18 is broken in four locations by conductive sections of tube 20, 22, 24 and 26 that act as electrical contacts to conductive fluid 16. It is critical to note the outer contacts 20 and 26 are held at neutral/ground potential. Therefore, the input water and the output water are stripped of all common mode voltage.

[0033] The inner two contacts 22, 24 are connected to the phase outputs of transformer 12. Because the phase-to-neutral voltage is half (.sup.1/.sub.2) of the phase-to-phase voltage, the physical length between the phase-to-neutral is half (.sup.1/.sub.2) of the length of the phase-to-phase voltage. This maintains the resistance (and current) in each of the three flow-through resistors roughly constant. In reality, the resistance varies somewhat because the output water is hotter and of lower resistivity than the input water. Pump 14 circulated conductive fluid 16 in loop 18. The temperature rise is measured using thermocouples (not shown) in the input and exhaust water streams.

[0034] Still referring to FIG. 1, the exhaust water is completely stripped of all common mode voltage before returning to process fluid reservoir 28. This makes the system of the present invention inherently safe—the addition of a ground fault interrupter (GFI) circuit (not shown) between the exhaust fluid and protective earth ground provides active safety for the system.

[0035] Referring now to FIG. 2, a graphical representation 30 illustrates the relationship between the temperature and current of conductive fluid being heated using the present invention. Left axis 32 represents the temperature (° F.). Right axis 34 represents the current (A.U.). Bottom axis 36 represents time (sec).

[0036] As shown in FIG. 2, an almost linear and proportional relationship between the current and temperature exists as a function of time. As more current is applied to the conductive fluid passing through the water heater of the present invention, the higher the temperature becomes over time. For example, curve 38 shows a temperature of approximately 70° F. for conductive fluid entering the direct voltage water heater. Curve 40 shows the current initially applied to the conductive fluid which is approximately 0.06 A.U. After almost approximately 290 secs (4.83 min) of continued application of current to the conductive fluid entering the direct voltage water heater, the temperature of the conductive fluid exiting the direct voltage water heater had increased to approximately 220° F.

[0037] Referring now to FIG. 3, the direct high voltage water heater 42 of the present invention is shown. Fluid flow (as indicated by the direction of the arrows) is assumed to be from right to left. However, this convention could be reversed and achieve the same heating function while remaining within the contemplation of the present invention. Direct high voltage water heater 42 has housing 44 having end plate 46 at one end. Fasteners 47 removably secure end plate 46 to housing 44. Spacer or insulator 45 lines the inside surface of housing 44, except for the areas in which heater electrodes element plates 58, 60, 62 and 64 traverse and separate insulator 45. Insulator 45 may be comprised of a polyether ether ketone (PEEK) material, though other comparable material may be used and still remain within the contemplation of the present invention. Housing 44 and end plate 46 define a volume 68. End plate 46 contains intake port 48 through which conductive fluid, e.g., melt water, may enter and pass through volume 68. The conductive fluid exits volume 68 at an elevated temperature (hot) via exhaust port 54 at the other end 52 of housing 44. Insulator 56 lines the interior surface (volume side) of end 52. The present invention uses an ethylene propylene diene monomer (EPDM) molded insulator, though other comparable material may be used.

[0038] Heater electrodes element plates 58, 60, 62 and 64 are secured within volume 68 of housing 44 at a predetermined distance relative to each other. Each plate contains a plurality of apertures 66 through which conductive fluid may pass. Heater electrode element plates 58, 60, 62 and 64 are arranged from left to right. The first (leftmost) plate 58 is held at neutral potential, corresponding to the center tap of the high-voltage transformer (not shown). The spacing from first plate 58 to the next (second) plate 60 is distance L.

[0039] During heating, the conductive fluid between plates 58 and 60 is exposed to a voltage gradient equal to the line-to-neutral voltage of the transformer (not shown). For the present invention, this line-to-neutral voltage is 5kVAC. The second and third plates 60 and 62 are separated by distance 2L. Third plate 62 is connected to line voltage L2 which exposes the conductive fluid between second plate 60 and third plate 62 to the line-to-line voltage, which, in the present invention is 10 kV.

[0040] Spacing between the third and fourth plates 62 and 64 is again distance L. Fourth plate 64 is connected to neutral exposing the conductive fluid between third plate 62 and fourth plate 64 to the line-to-neutral gradient which is 5 kV. As the fluid passes through first plate 58, all common mode voltage is stripped from the fluid rendering the exhaust fluid completely safe for personnel and for any electronic equipment which may come in contact with the exhaust fluid.

[0041] Attached to and part of housing 44 is housing 70 having a top end 72. Fasteners 74 removably attach top end 72 to housing 70 to form volume 76. Oil (not shown) fills volume 76 of housing 70. Housing 70 houses several feedthrough fittings 78, 80, 82 and 84. Feedthrough fitting 86 traverses housing 70 and connects to high voltage tether 88. Feedthrough fitting 86 also traverses housing 44 so as to be in electrical communication with heater electrodes element plates 58, 60, 62 and 64. Insulated conductors 90, 92, 94 and 96 connect feedthrough fittings 78, 80, 82 and 84 to high voltage tether 88 via feedthrough fitting 86. The present invention uses CONAX® feedthrough fittings and KAPTON® insulated conductors commercially available, though other comparable fittings and conductors may be used and still remain within the contemplation of the present invention.

[0042] Should a fault occur, ground fault interruption circuitry (not shown) detects any current flow between housing 44 and safety ground. If current flow is detected, the fault is reported to mission control and the mission is suspended until further troubleshooting measures can be completed.

[0043] Now referring to FIG. 4, the present invention is shown integrated with an ice penetrator vehicle 98 (only a portion of which is shown). The present invention utilizes a closed loop heater system that is in thermal communication through heat exchanger 100 with an open loop hot water drill. The primary heater loop utilizes a process fluid pumped by process fluid pump 108 with a depressed freezing point so the vehicle 98 can restart even after being frozen in the ice for a long period of time.

[0044] Primary loop circulation is accomplished by a high volume, low pressure centrifugal pump 108. Process fluid transits through the high-voltage heater core 42 and into the primary side of heat exchanger 100. Meltwater enters inlet ports via melt water intake 104 aft of nose cone 102 and is pumped through the secondary side of the heat exchanger 100 by a series of high pressure, high volume diaphragm pumps. After the water travels through heat exchanger 100, the water is ejected from vehicle 98 via hot water to jet intake 114 in a series of jets 110 that can be turned on or off via a series of solenoid valves 112.

[0045] In an alternative embodiment, the present invention may be modified to operate at standard (low-voltage) residential/industrial mains voltages. This is accomplished by changing the spacing between the plates. Referring back to FIG. 3, in the residential/industrial case, the heater runs from 220 VAC. The two outer plates 58, 64 are connected to neutral while the inner plates 60, 62 are connected to line voltage L1 and L2, respectively. This places a 110 VAC gradient across the outer plates 58, 64 and places an 220 VAC gradient across the inner plates 60, 62. Again, the exhaust fluid must pass through the neutral plate 58 before exiting the heater 42, stripping any common-mode voltage from the exhaust fluid.

[0046] Flow-rate independent temperature control is achieved by a thermocouple (not shown) in the exhaust port that closes a feedback loop to a controller (not shown). The controller pulse-width-modulates a silicon controlled rectifier (not shown), or zero switch crossing relay (not shown) on the mains voltage. Housing 44 is bonded to earth-ground and ground-fault interruption circuitry monitors current flow from housing 44 to earth ground. Should the current flow exceed a preset threshold the circuitry disconnects direct high voltage water heater 42 from mains power via a mechanical relay. This supplements ground fault interruption circuitry on the 220 VAC mains.

[0047] The present invention may be used as a stand-alone unit or incorporated into a high power cryobot or ice penetrating vehicle, in either scenario within a tightly enclosed and small space.

[0048] The ice penetrating vehicle that may be used with the direct high voltage fluid heater system of the present invention requires both a closed cycle heating system (which includes the heating element shown in FIG. 3) and an open loop system that draws fluid, such as water, in from the surrounding environment. This was because of the need to maintain a fluid in the heating loop that will not freeze and that had a specified electrolyte content to ensure the electrical power was dumped into the water—because if the vehicle stopped and power was turned off, the ambient water would freeze in the pipes and there would be no flow and it was uncertain whether the vehicle could start back up.

[0049] As such, the present invention functions equally proficient in both the case of heating fluids in an ice penetrating vehicle environment as it does in the residential household water heater environment regardless of external temperature or ambient water electrolyte or dissolved mineral content because a clean anti-freeze electrolyte is used in the closed (heating) part of the loop. So, in the instance where the fluid in the loop in FIG. 1 freezes (e.g., someone turns off the power temporarily and the water freezes in Alaska) then the power is turned back on, the system will work. In a similar context, if the ambient water (e.g., groundwater) has no electrolytes or is highly variable or contains too much in the way of dissolved minerals, e.g., limestone as may be found in Texas, the system will still work.

[0050] This can be demonstrated by reference to the following FIG. 5 which depicts flow chart 200 of the present invention having application in an ice penetrating vehicle. The vehicle contains a closed cycle heating system 202 and an open loop system 204. In open loop system 204, meltwater return 206 enters heat exchanger melt water loop 208.

[0051] Heat transfer 218 occurs between heat exchanger melt water loop 208 and heat exchanger process fluid loop 220, with the direction of heat going from heat exchanger process fluid loop 220 to heat exchanger melt water loop 208. Fluid in heat exchanger process fluid loop 220 passes to process fluid reservoir 222 and then to process fluid pump—HVLP 224, ultimately reaching and entering into direct high voltage fluid heater 42 where the fluid is heated. Once the fluid, now heated, flows through and exits direct high voltage fluid heater 42, the fluid continues to heat exchanger process fluid loop 220. At this point, the heat is transferred via heat transfer 218 to heat exchanger melt water loop 208, where the fluid, now heated, passes to high pressure jet pumps 210 and into routing valves and manifold 212, finally directed to both forward and aft melting HWD jets 214 and 216.

[0052] Referring now to FIG. 6, flow chart 226 depicts an alternative embodiment of the present invention having application for a house hot water heater. The house system similarly contains a closed cycle heating system 228 and an open loop system 230. In open loop system 230, water from the utility enters the system at water utility in 232 and enters heat exchanger house hot water tank 234.

[0053] Heat transfer 238 occurs between heat exchanger house hot water tank 234 and heat exchanger process fluid loop 220, with the direction of heat going from heat exchanger process fluid loop 220 to house hot water tank 234. Fluid in heat exchanger process fluid loop 220 passes to process fluid reservoir 222 and then to process fluid pump—HVLP 224, ultimately reaching and entering into direct high voltage fluid heater 42 where the fluid is heated. Once the fluid, now heated, flows through and exits direct high voltage fluid heater 42, the fluid continues to heat exchanger process fluid loop 220. At this point, the heat is transferred via heat transfer 238 to heat exchanger house hot water tank 234, where the fluid, now heated, passes to house utilities 236 and is ready to be used by the consumer. Any heat exchanger that efficiently transfers the heat energy from the heat exchanger process fluid loop 220 (heated by the direct high voltage fluid heater 42) to the house hot water tank 234 will work.

[0054] The various embodiments described herein may be used singularly or in conjunction with other similar devices. The present disclosure includes preferred or illustrative embodiments in which a system and method for a direct high voltage water heater are described. Alternative embodiments of such a system and method can be used in carrying out the invention as claimed and such alternative embodiments are limited only by the claims themselves. Other aspects and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.