Heat transfer system, fluid, and method

This application is a continuation-in-part of application Ser. No. 11/222,024, filed Sep. 8, 2005, which claims the benefit of U.S. provisional application No. 60/607,898, filed Sep. 8, 2004, both of which are incorporated by reference herein in their entirety. This application also claims the benefit of U.S. provisional application No. 61/080,033 filed on Jul. 11, 2008, which is incorporated by reference herein in its entirety.

This disclosure generally relates to a heat transfer system, heat transfer fluid, and heat transfer method.

The operation of a power source generates heat. A heat transfer system, in communication with the power source, regulates the generated heat, and ensure that the power source operates at an optimum temperature. The heat transfer system generally comprises a heat transfer fluid that facilitates absorbing and dissipating the heat from the power source. Heat transfer fluids, which generally comprise water and a glycol, are in intimate contact with one or several metallic parts that are prone to corrosion. Thus, several corrosion inhibitors are added to the heat transfer fluid in order to protect the metallic parts from corrosion. Traditional heat transfer fluids can exhibit extremely high conductivities, often in the range of 3000 microsiemens per centimeter (PS/cm) or more. This high conductivity produces adverse effects on the heat transfer system by promoting corrosion of metal parts, and also in the case of power sources where the heat transfer system is exposed to an electrical current, such as in fuels cells or the like, the high conductivity can lead to short circuiting of the electrical current and to electrical shock.

Aluminum, magnesium, and their alloys, are increasingly used in the manufacture of several components of a heat transfer system. They are advantageous due to their light weight, high strength, and relative ease of manufacture, among others. Aluminum, magnesium, and their alloys can be used in heat transfer systems of internal combustion engines and alternative power sources. However, magnesium, aluminum, and their alloys are highly susceptible to corrosion when in contact with traditional heat transfer fluids with high conductivity. In addition, the foaming of traditional heat transfer fluids further contributes to the corrosion of aluminum, magnesium, and their alloys.

Therefore, a need exists for heat transfer systems and fluids intended for use therein, wherein the heat transfer systems comprise aluminum, magnesium, or their alloys, in intimate contact with the heat transfer fluid. The heat transfer fluids advantageously have low conductivity and good foaming properties.

The above-described and other drawbacks are alleviated by a heat transfer system, comprising a circulation loop defining a flow path for a heat transfer fluid, and a heat transfer fluid comprising a liquid coolant, a siloxane corrosion inhibitor of formula R3-Si—[O—Si(R)2]x-OSiR3, wherein R is independently an alkyl group or a polyalkylene oxide copolymer of 1 to 200 carbons, x is from 0 to 100, and further wherein at least one alkyl group and at least one polyalkylene oxide copolymer are present, and a non-conductive polydiorganosiloxane antifoam agent, wherein the conductivity of the heat transfer fluid is less than about 100 μS/cm, and wherein the heat transfer system comprises aluminum, magnesium, or a combination thereof, in intimate contact with the heat transfer fluid.

In one embodiment, a heat transfer fluid comprises a liquid coolant, a siloxane corrosion inhibitor of formula R3-Si—[O—Si(R)2]x-OSiR3, wherein R is independently an alkyl group or a polyalkylene oxide copolymer of 1 to 200 carbons, x is from 0 to 100, and further wherein at least one alkyl group and at least one polyalkylene oxide copolymer are present, and a non-conductive polydiorganosiloxane antifoam agent, wherein the conductivity of the heat transfer fluid is less than about 100 μS/cm.

In another embodiment, a heat transfer method comprises contacting a heat transfer system with a heat transfer fluid, wherein the heat transfer system comprises a circulation loop defining a flow path for the heat transfer fluid, and aluminum, magnesium, or a combination thereof, wherein the heat transfer fluid comprises a liquid coolant, a siloxane corrosion inhibitor of formula R3-Si—[O—Si(R)2]x-OSiR3, wherein R is independently an alkyl group or a polyalkylene oxide copolymer of 1 to 200 carbons, x is from 0 to 100, and further wherein at least one alkyl group and at least one polyalkylene oxide copolymer are present, and a non-conductive polydiorganosiloxane antifoam agent, wherein the conductivity of the heat transfer fluid is less than about 100 μS/cm, and wherein the aluminum, magnesium, or combination thereof is in intimate contact with the heat transfer fluid.