Heat transfer equipment and method

A method for heating a fluid by means of a bundle of generally horizontal tubes with external fins lying in generally upright planes, comprising effecting flow of said fluid through the inside of said tubes, effecting forced flow of hot products of combustion of gaseous fuel and air in a downward direction generally paralleling the planes of the fins substantially throughout the length of the tubes and in external contact with the finned tubes, and establishing conditions of temperature and rates of flow of said fluid and of said products of combustion providing for cooling of the products of combustion to a temperature below the dew point before delivery of the products of combustion from said tube bundle.

Heat transfer equipment comprising a combustion chamber, means for introducing a mixture of gaseous fuel and air into an upper region of the combustion chamber, a group of spaced externally finned tubes in a lower region of the combustion chamber, the tubes being arranged in a plurality of spaced superimposed planes, header means providing for flow of a fluid to be heated serially first through tubes in a lower plane and then through tubes in an upper plane, an exhaust manifold below the tubes for receiving gaseous products of combustion and having a discharge opening for delivery of gaseous products of combustion, and means establishing a flow of the mixture of fuel and air in a path extended downwardly through the combustion chamber and providing for delivery of products of combustion downwardly between the tubes substantially throughout the length thereof and into the manifold, the tubes being extended transversely of the path of flow of the products of combustion with the tube fins lying in planes generally paralleling said path of flow substantially throughout the length of the tubes.