Heat exchanger for e.g. gas condensing boiler, has flow channel systems, whose flow cross sections are varied over axial length to receive value relying on temperature of fluid flowing via respective sections, so that flow rate is constant

摘要

The exchanger has a flow channel system (11) formed between an external wall (10) of a base (1) and an inner wall (30) of a casing (2). Another flow channel system (21) is limited by an inner wall (20) of the base, where the systems are designed such that heat transmission between fluids (3, 4) e.g. water and exhaust gas, is via the base. Flow cross section of the system (11) and/or the system (21) is varied over an axial length of the base to receive a value depending on temperature of the fluid that flows via the respective section, such that the flow rate is constant over the axial length.