HEAT EXCHANGER FOR A MOTOR VEHICLE AIR CONDITIONING SYSTEM

摘要

The heat exchanger (1) for a motor vehicle air conditioning system has mutually parallel and vertically arranged flat tubes (2), the ends of which join each of two headers (10, 18). The opposed and mutually spaced surfaces of adjacent flat tubes (2) define air flow channels (8, 9) allowing condensed moisture to flow away easily and preventing the accumulation of dirt. The heat exchanger (1) is compact and yet has a sufficiently large surface area on the air side because of the close spacing of the flat tubes (2). The correspondingly large number of flat tubes (2) produces a large flow cross-section on the working fluid side with correspondingly little pressure loss, so that the flat tubes (2) can be traversed more than once through the action of flow deflectors in the headers of the heat exchanger (1). The close spacing is achieved by bunching the tube ends (35) together at the connection point and incorporating a bend (36). Bead-like raised portions (11) of the flat tubes (2) running parallel to each other and obliquely to the longitudinal direction of the flat tubes (2) give both the air-side flow channels (8, 9) and the internal channels for the air conditioner working fluid within the flat tubes (2) an undulating form which promotes heat transfer. The smooth surface of the flat tubes (2) on the air side with its hydrophilic coating promotes the drainage of moisture from the heat exchanger (1) and thus makes it more effective for both cooling and heating a switchable air conditioning system without generating large quantities of steam when the system is switched to heating mode.