Fluid-heating apparatus

A heating unit comprising:

• a ceramic burner body formed with a plurality of parallel slit-like passages at least some of which open at a side of said body;
• means for supplying a fuel to alternate ones of said passages of said burner body and for supplying a combustion-sustaining gas to the remainder of said passages whereby a combustible gas mixture is formed at said side of said body;
• means defining a combustion chamber at said side of said body and into which said some of said openings discharge whereby hot combustion gases are formed in said combustion chamber;
• a ceramic recuperator body formed with mutually parallel slit-like channels, alternate ones of said channels communicating with said combustion chamber for conducting said hot combustion gases therefrom;
• means for passing a fluid to be heated through others of said channels in a direction counter to the flow of said combustion gases for heat exchange between said fluid and said combustion gases through walls of said recuperator body between said channels, said ceramic burner body, said recuperator body and the means forming said combustion chamber being part of a unitary ceramic structure;
• and
• insulating layers of porous ceramic material lining said combustion chamber.

A heating unit comprising:

• a ceramic burner body formed with a plurality of parallel slit-like passages at least some of which open at a side of said body;
• means for supplying a fuel to alternate ones of said passages of said burner body and for supplying a combustion-sustaining gas to the remainder of said passages whereby a combustible gas mixture is formed at said side of said body;
• means defining a combustion chamber at said side of said body and into which said some of said openings discharge whereby hot combustion gases are formed in said combustion chamber;
• a ceramic recuperator body formed with mutually parallel slit-like channels, alternate ones of said channels communicating with said combustion chamber for conducting said hot combustion gases therefrom;
• means for passing a fluid to be heated through others of said channels in a direction counter to the flow of said combustion gases for heat exchange between said fluid and said combustion gases through walls of said recuperator body between said channels, said ceramic burner body, said recuperator body and the means forming said combustion chamber being part of a unitary ceramic structure;
• and
• said recuperator body is subdivided into zones and a first of said zones proximal to said combustion chamber for heating by said combustion gases and a second fluid is passed through a second of said zones downstream of said first zone for heating by said combustion gases.