Methods and electrodes for the drying of damp buildings

Claim 2

AN ACTIVE ELECTRO-DEHUMIDIFICATION METHOD FOR A DAMP STRUCTURE, SAID METHOD COMPRISING EMBEDDING POSITIVE AND NEGATIVE ELECTRODES IN ALTERNATION IN A WALL OF THE STRUCTURE IN A DAMP REGION THEREOF WHICH IS TO BE DEHUMIDIFIED, FORMING THE NEGATIVE ELECTRODES AS HALLOW WATER-PERMEABLE MEMBERS WHICH CAN RECEIVE WATER EXTERNALLY THEREOF AND CONVERYY THE WATER FOR DISCHARGE OUTSIDE SAID WALL, AND APPLYING POSITIVE AND NEGATIVE CHARGES TO RESPECTIVE ELECTRODES BY CONNECTING THE ELECTRODES TO RESPECTIVE POLES OF A VOLTAGE SOURCE.

Claim 3

A method as claimed in claim 1, wherein the distance between adjacent electrodes is given by the formula d -distance between adjacent electrodes r -radius of the electrode Rho z -electrical resistivity of the wall R -electrical resistance of the wall l -length of the electrode e -base of natural logarithms; and the electrodes are fixed at a distance from ground level equal to 0.86 of the distance between adjacent electrodes, and no lower than 5 cm from ground level.

Claim 4

A method as claimed in claim 2 comprising terminating dehumidification after full removal of the moisture in the wall after a minumum period of time as given by the following formula: t ( Va in (d/r) )/( Ke pi U l) ps wherein: Va is the volume of water to be removed Ke is the electro-osmotic permeability of the wall and U is the magnitude of voltage of the source.

Claim 5

A method as claimed in claim 3 comprising limiting the current density applied to the electrodes to a value of less than 2 ma/cm2.

Claim 6

A method as claimed in claim 4, wherein the current density is between 0.1 and 1.0 A/m2.

Claim 7

A method as claimed in claim 5, wherein the magnitude of the voltage of the source is given by the formula U 32 j Rho z d wherein: j -is the current density and Rho zand dare as defined above.

Claim 8

a method as claimed in claim 1 comprising disconnecting the electrodes from said voltage supply after dehumidification and connecting the electrodes to ground to cause migration of water from the electrodes to ground to prevent subsequent increase of humidity in the structure.

Claim 9

A method as claimed in claim 1, wherein said electrodes incorporate depolarizing material to prevent corrosion of the electrodes.

Claim 10

A method as claimed in claim 8, wherein each said electrode comprises an active material of copper, graphite or steel and the depolarizing material for the copper is 50% powdered clay, 20% powdered copper sulphate and 30% Portland cement; for the graphite is 20% pyrolusite (MnO2), 20% potassium permanganate (KMnO4), 40% powdered graphite, 0.5% ammonium chlorate, and 20% Portland cement; and for steel is 60% Portland cement and 40% powdered graphite.

Claim 11

A method as claimed in claim 9. wherein the electrode inclusive of the depolarizing material contains a sufficient maount of water to form a moldable paste, and embedding the active material in dried form into the paste.

Claim 12

A method as claimed in claim 10, including the step of covering the active electrode material with the mixture inclusive of depolarizing material, said active electrode material being a winding a copper, steel, or aluminum wire or a graphite rod, the diameter of the wire being between 3 and 4 mm, the pitch of the turns of the winding being 25 mm and the length of the electrode is two thirds of the depth of the wall.

Claim 13

A method as claimed in claim 10, including the steps of forming the active material of the negative electrode in cylindrical form and covering the active material with said mixture inclusive of depolarizing material to form a tubular electrode with a hollow bore, said active material being open and water-permeable.

Claim 14

A method as claimed in claim 12, wherein said active material of the negative electrode is selected from the group consisting of a perforated zinc-coated steel tube in which the perforations cover 45 percent of the surface area; an open meshwork of copper, steel or aluminum; and a spiral winding of copper, steel or aluminium wire of 3 -4 mm in diameter, the pitch of the turns of the winding being 10 mm, the diameter of the spiral being 28 mm; a graphite stick of approximately 7 mm in diameter and 7 cm in length and the length of the electrode is two thirds of the depth of the wall, the bore of the electrode being 15 mm in diameter.

Claim 15

A method as claimed in claim 1 wherein said electrodes are disposed in a single horizontal row.

Claim 16

A passive electro-dehumidification method for a damp structure, said method comprising embedding hollow, tubular, water-permeable electrodes into the lower portion of a wall of a structure which is to be dehumidified, connecting the electrodes to a grounding electrode whereby water migrates to said grounding electrodes by electro-dehumidification, discharging the water in the course of said migration externally of the structure, and spacing the electrodes at intervals given by the formula: d (J Ke N Rho z)/(981 K g l) wherein: d spacing of the electrodes j intensity of generated current flow Ke electro-osmotic permeability coefficient of the wall n viscosity of the migrating water Rho electrical resistivity of the wall g specific gravity of the migrating water, and l length of the electrode, K hydraulic filtration coefficient and the maximum number of electrodes connected to the grounding electrode is given by the formula: Ne (2 pi r h Rho z)/(d Rp Sp) wherein: Ne number of electrodes for a grounding electrode Rp electrical resistance of the grounding electrode Sp lateral surface area of the grounding electrode r radius of the tubular electrodes h height of the moisture in the wall from ground level, and d, and Rho z are as defined hereinabove.

Claim 17

A passive electro-dehumidification method for a damp structure, said method comprising embedding hollow, tubular, water-permeable electrodes into the lower portion of a wall of a structure which is to be dehumidified, connecting the electrodes to a grounding electrode whereby water migrates to said grounding electrodes by electro-dehumidification, discharging the water in the course of said migration externally of the structure, and spacing the electrodes at intervals given by the formula: d (J Ke N Rho z)/(981 K g l) wherein: d spacing of the electrodes j intensity of generated current flow Ke electro-osmotic permeability coefficient of the wall n viscosity of the migrating water Rho electrical resistivity of the wall g specific gravity of the migrating water, and l length of the electrode, K hydraulic filtration coefficient and the maximum number of electrodes connected to the grounding electrode is given by the formula: Ne (2 pi r h Rho z)/(d Rp Sp) wherein: Ne number of electrodes for a grounding electrode Rp electrical resistance of the grounding electrode Sp lateral surface area of the grounding electrode r radius of the tubular electrodes h height of the moisture in the wall from ground level, and d, and Rho z are as defined hereinabove.

Claim 18

A method as claimed in claim 15, wherein said tubular electrodes are formed with mixtures of depolarizing material to prevent corrosion of the tubular electrodes.

Claim 19

A method as claimed in claim 16, wherein/each said tubular electrode comprises an active material of copper, graphite or steel and the depolarizing material for the copper is 50% powdered clay, 20% powdered copper sulphate and 30% Portland cement; for the graphite is 20% pyrolusite (MnO2), 20% potassium permanganate (KMnO4), 40% powdered graphite, 0.5% ammonium chlorate, and 20% Portland cement; and for steel is 60% Portland cement and 40% powdered graphite.

Claim 20

A method as claimed in claim 16, wherein the depolarizing material contains a sufficient amount of water to form a moldable past which may embed the dried active material.

Claim 21

A method as claimed in claim 16, including steps of forming the active material of the tubular electrodes in cylindrical form and covering the active material with said mixture of depolarizing material to form a tublar electroDe with a hollow bore, said active material being open and water-permeable.

Claim 22

A method as claimed in claim 19, wherein said active material of the tubular electrode is selected from the group consisting of a perforated zinc-coated steel tube in which the perforations cover 45percent of the surface area; an open meshwork of copper, steel or aluminum; and a spiral winding of copper, steel or aluminum wire of 3-4 mm in diameter, the pitch of the turns of the winding being 10 mm, the diameter of the spiral being 28 mm; a graphite stick of approximately 7 mm in diameter and 7 cm in length and the length of the electrode is two-thirds of the depth of the wall, the bore of the electrode being 15 mm in diameter.

Claim 25

A method as claimed in claim 21, wherein said negative electrical charge is established by connecting the electrodes to the negative pole of a D.C. voltage source.

Claim 26

A method as claimed in claim 21, wherein said electrodes are mounted in the structure such that their hollow interiors are open to the atmosphere whereby the collected moisture is directly evaporated into the atmosphere.