A fuel material processing system includes a hopper assembly configured to receive a fuel material. A drying system is configured to remove moisture from the fuel material to generate a dried fuel material. A material delivery system is configured to provide the dried fuel material to a combustion system.

A fuel material processing system includes a hopper assembly configured to receive a fuel material. A drying system is configured to remove moisture from the fuel material to generate a dried fuel material. A material delivery system is configured to provide the dried fuel material to a combustion system.

A method for transferring thermal energy to a separate endothermic process includes: (a) providing a carbon dioxide (CO.sub.2) stream and a carbonaceous fuel to a heater; (b) reacting the carbonaceous fuel in the heater to produce a heated stream; (c) transferring heat from the heated stream to the separate endothermic process; (d) separating the CO.sub.2 stream from the heated stream after (c); and (e) recycling the CO.sub.2 stream to the heater after (d).

A water heater according to the present invention includes: a heating unit that includes a burner provided to cause a combustion reaction from air and fuel, and that is provided to generate heated water by using heat generated by the combustion reaction; and a humidifier unit that generates water steam by evaporating water using a combustion gas generated by the combustion reaction and discharged from the heating unit, and provides the water steam together with the air to the burner.

A water heater according to the present invention includes: a heating unit that includes a burner provided to cause a combustion reaction from air and fuel, and that is provided to generate heated water by using heat generated by the combustion reaction; and a humidifier unit that generates water steam by evaporating water using a combustion gas generated by the combustion reaction and discharged from the heating unit, and provides the water steam together with the air to the burner.

Described herein are catalytic heating systems, comprising catalytic reactors and dual-mode fuel evaporators, and methods of operating such systems. A dual-mode fuel evaporator is thermally coupled to a catalytic reactor and comprises an electric heater used for preheating the evaporator to at least a fuel-flow threshold temperature. Upon reaching this threshold, the liquid fuel, such as ethanol or methanol, is flown into the evaporator and evaporates therein, forming vaporized fuel. The vaporized fuel is mixed with oxidant, and the mixture is flown into the catalytic reactor where the vaporized fuel undergoes catalytic exothermic oxidation. At least some heat, generated in the catalytic reactor, is transferred to the evaporator and used for the evaporation of additional fuel. When the evaporator reaches or exceeds its operating threshold, the electric heater can be turned off and all heat is supplied to the evaporator from the catalytic reactor.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

A vent attachment facilitates attaching a coaxial air intake and exhaust vent of a tankless water heater to a Category I vent, such as B-vent. The vent attachment comprises a first end with a coaxial connector comprising a central exhaust pathway and a circumferential air intake pathway. The vent attachment also comprises a second end with a tubular exhaust vent connector in fluid communication with the central exhaust pathway. The vent attachment further comprises a frame that encloses the central exhaust pathway and comprises a mesh configured to provide fluid communication through the frame with the air intake pathway. Additionally, operation of the tankless water heater is modified to ensure that the exhaust generated is suitable for venting through a Category I vent. The tankless water heater maintains a high fuel consumption rate such that the temperature of hot water produced increases throughout each of a plurality of burner stages.

A vent attachment facilitates attaching a coaxial air intake and exhaust vent of a tankless water heater to a Category I vent, such as B-vent. The vent attachment comprises a first end with a coaxial connector comprising a central exhaust pathway and a circumferential air intake pathway. The vent attachment also comprises a second end with a tubular exhaust vent connector in fluid communication with the central exhaust pathway. The vent attachment further comprises a frame that encloses the central exhaust pathway and comprises a mesh configured to provide fluid communication through the frame with the air intake pathway. Additionally, operation of the tankless water heater is modified to ensure that the exhaust generated is suitable for venting through a Category I vent. The tankless water heater maintains a high fuel consumption rate such that the temperature of hot water produced increases throughout each of a plurality of burner stages.

Systems and processes provide for a thermal process to transform sludge (and a variety of other natural waste materials) into electricity. Dewatered sludge and other materials containing a high amount of latent energy are dried into a powdered biofuel using a drying gas produced in the system. The drying gas is recirculated and is heated by the biofuel produced in the system, waste heat (from turbines or internal combustion engines), gas (including natural gas or digester gas) and/or oil. The biofuel is combusted in a boiler system that utilizes a burner operable to burn biofuel and produce heat utilized in a series of heat exchangers that heat the recirculating drying air and steam that powers the turbines for electricity production.