Microwave water heating method and apparatus

A fluid heating and distribution system for heating and delivering a fluid to a plurality of locations comprising:

• a single fluid line for supplying ambient temperature fluid from a source to a plurality of locations;
• a plurality of microwave fluid heating means, each being located in a respective one of said locations and utilizing microwave energy for heating the fluid delivered to each of said locations from said single fluid line, each of said fluid heating means having a fluid outlet, each of said heating means comprising means for generating microwave energy, means defining a microwave chamber for containing the microwave energy generated by said generating means, and means in said microwave chamber means for conducting the fluid to be heated through the microwave energy, said fluid conducting means comprising a solid unitary block formed of a substantially microwave-transparent material, said block having a plurality of fluid passages extending therethrough, said fluid flowing through said passages directly contacting the microwave-transparent material of the solid unitary block, said block further comprising a pair of end covers formed of a substantially microwave-transparent material and sealingly mounted to respective ends of said unitary block, each end cover having a cavity enclosing the ends of said fluid passages and a conduit extending into said cavity, the total cross-sectional flow area of said fluid passages being at least twice the cross-sectional flow area of each of said conduits whereby the flow velocity through said fluid passages is substantially less than the flow velocity through said conduits;
• and
• means associated with each of said microwave fluid heating means and operable for variably setting the temperature of the fluid delivered from said fluid outlet to a temperature between ambient fluid temperature and a predetermined maximum temperature.

A method for heating fluid, especially water utilizing microwave energy comprising:

• flowing a fluid to be heated into a microwave chamber;
• dividing the fluid into a plurality of parallel fluid flows, such that the cross-sectional flow area of the fluid flowing in said plurality of flows is at least twice the cross-sectional flow area of the fluid flow into the microwave chamber;
• whereby the water velocity in said plurality of flows is substantially less than the velocity of water flowing into the microwave chamber, thus increasing the residence time of the water in the microwave chamber;
• passing the plurality of flows in one flow direction in the microwave chamber through a substantially microwave-transparent heat conductive solid body having a plurality of fluid passages extending therethrough, said fluid directly contacting the heat conductive solid body;
• heating the parallel fluid flows by irradiating the fluid with microwave energy;
• and
• conducting heat from the heated fluid through said body in a direction countercurrent to said one flow direction.