A combustion system with surface-less heat energy exchange for efficient heat energy capture and lower pollutant emission, comprising: a first line feeding an oxygen-rich reactive; a second line feeding a hydro-carbon fuel; a vessel containing feed-water; a combustion enclosure without a bottom wall submersed into the feed water contained in a vessel, the combustion enclosure configured to receive the feed from each of the first and second line and combust a mixture of the two feeds in a pocket formed between an inner top and side walls of the combustion enclosure and a top surface of the feed-water contained in the vessel; and the combustion within the pocket yielding a high temperature and high pressure combustion product and by-product directly into the feed-water of the vessel.

A combustion system with surface-less heat energy exchange for efficient heat energy capture and lower pollutant emission, comprising: a first line feeding an oxygen-rich reactive; a second line feeding a hydro-carbon fuel; a vessel containing feed-water;

a combustion enclosure without a bottom wall submersed into the feed water contained in a vessel, the combustion enclosure configured to receive the feed from each of the first and second line and combust a mixture of the two feeds in a pocket formed between an inner top and side walls of the combustion enclosure and a top surface of the feed-water contained in the vessel; and the combustion within the pocket yielding a high temperature and pressure combustion product and by-product directly into the feed-water of the vessel.

A reactor system includes a pressure vessel having a vessel wall, a feed port at a superior end of the pressure vessel, a permeable liner disposed within the pressure vessel and at least one hydrothermal jet mounted to the pressure vessel. The feed port is configured for feeding a liquid target reactant stream into the pressure vessel. The permeable liner separates the pressure vessel into an internal reaction zone and an outer annular chamber. The hydrothermal jet is mounted external to the reaction zone and is configured to add heated mixture of carrier and oxidizer to the internal reaction zone. A dividing wall portions the outer annular chamber into a cooling zone and an exhaust zone through which by-products of the reaction exit from the reaction zone.