Heat exchangers with integrated electrical heating elements and with multiple fluid flow passages

A heat exchanger having an inlet and an outlet, comprising:

• (a) a first channel structure defining a first fluid flow passage, wherein said first channel structure comprises a first outer plate, an intermediate plate, and a first fluid flow passage;
• wherein the first fluid flow passage is defined by a space between the first outer plate and the intermediate plate;
• wherein the first outer plate and the intermediate plate are comprised of aluminum;
• and
• wherein each of the first outer plate and the intermediate plate has an inner surface facing inwardly toward the first fluid flow passage, and an opposed outer surface facing outwardly away from the first fluid flow passage;
• (b) a first electrical heating element located outside the first fluid flow passage and adjacent to the outer surface of the first outer plate of the first channel structure, such that heat produced by the first electrical heating element is transferred through the first outer plate to the fluid in the first fluid flow passage during use of the heat exchanger;
• (c) a second channel structure defining a second fluid flow passage, wherein said second channel structure comprises the intermediate plate, a second outer plate, and the second fluid flow passage;
• and
• (d) a second electrical heating element located outside the second fluid flow passage and adjacent to the outer surface of the second outer plate of the second channel structure, such that heat produced by the second electrical heating element is transferred through the second outer plate to the fluid in the second fluid flow passage during use of the heat exchanger;
• wherein the intermediate plate is substantially flat, wherein the first outer plate comprises a first planar flange, wherein a sealing surface of the first planar flange is sealed to a first side of the intermediate plate, wherein the second outer plate comprises a second planar flange, and wherein a second sealing surface of the second planar flange is sealed to a second side of the intermediate plate;
• wherein the first electrical heating element has a thickness from about 1 μm to about 1000 μm;
• wherein the first electrical heating element comprises an electrically insulating dielectric base layer which is closest to the outer surface of the first outer plate, and an electrically resistive heater layer on the dielectric layer;
• wherein a side of the dielectric base layer farthest from the outer surface of the first outer plate is directly in contact with a side of the electrically resistive heater layer that is closest to the outer surface of the first outer plate;
• wherein the dielectric base layer comprises a thermally conductive, electrically insulating composite layer comprising a polymer mixed with a particulate filler material;
• and
• wherein the dielectric base layer in direct contact with and thermally bonded directly to the outer surface of the first outer plate.

A heat exchanger having an inlet and an outlet, comprising:

• (a) a first channel structure defining a first fluid flow passage, wherein said first channel structure comprises a first plate, a second plate and a first fluid flow passage;
• wherein the first fluid flow passage is defined by a space between the inner surfaces of the first and second plates;
• wherein the first and second plates are comprised of aluminum;
• and
• wherein each of the first and second plates has an inner surface facing inwardly toward the first fluid flow passage, and an opposed exterior surface facing outwardly away from the first fluid flow passage;
• (b) a first electrical heating element comprising:
• an electrically insulating dielectric base layer applied directly to the exterior surface of the first plate and bonded to the exterior surface via application of heat, such that heat produced by the first electrical heating element is transferred through the first plate to the fluid in the first fluid flow passage during use of the heat exchanger, and
• an electrically resistive heater layer positioned in direct face sharing contact with a side of the dielectric layer opposite the first plate;
• wherein the first electrical heating element has a thickness from 1 μm to 1000 μm;
• and
• wherein the dielectric base layer comprises a thermally conductive, electrically insulating composite layer comprising a polymer mixed with a particulate filler material;
• (c) a second channel structure defining a second fluid flow passage;
• wherein said second channel structure comprises a first plate, a second plate and a second fluid flow passage;
• wherein the second fluid flow passage is defined by a space between the inner surfaces of the first and second plates of the second channel structure;
• wherein the first and second plates of the second channel structure are comprised of aluminum;
• and
• wherein each of the first and second plates of the second channel structure has an inner surface facing inwardly toward the second fluid flow passage, and an opposed outer surface facing outwardly away from the second fluid flow passage;
• and
• (d) a second electrical heating element located outside the second fluid flow passage and adjacent to the outer surface of the first plate of the second channel structure, such that heat produced by the second electrical heating element is transferred through the first plate of the second channel structure to the fluid in the second fluid flow passage during use of the heat exchanger;
• wherein the second electrical heating element has a thickness from 1 μm to 1000 μm;
• wherein the second electrical heating element comprises an electrically insulating dielectric base layer which is closest to the outer surface of the second plate, and an electrically resistive heater layer on the dielectric layer;
• wherein the dielectric base layer comprises a thermally conductive, electrically insulating composite layer comprising a polymer mixed with a particulate filler material;
• wherein the inlet of the heat exchanger is in flow communication with the first fluid flow passage, and the outlet of the heat exchanger is in flow communication with the second fluid flow passage;
• wherein the first plate of the first channel structure is in opposed, facing relation to the first plate of the second channel structure, and spaced apart therefrom by a gap;
• wherein the first and second electrical heating elements are spaced apart and in opposed, facing relation to one another inside said gap;
• and
• wherein the heat exchanger further comprises:
• a first spacer which is received between the first plate of the first channel structure and the first plate of the second channel structure, the first spacer having at least one fluid transfer opening providing flow communication between the first and second fluid flow passages through fluid openings in the first plates of the first and second channel structures which are aligned with the at least one fluid transfer opening of the first spacer;
• the first spacer having first and second surfaces which are sealingly engaged with the first plates of the first and second channel structures;
• and
• a mechanical sealing element providing a mechanical seal between the first spacer and the first plates of the first and second channel structures.