Heat-pump buried tubing providing enhanced heat transfer - has axially directed ribbing inside metal tube and outside plastic sheath to increase transfer rate

摘要

The tubing (1), preferably of spun or drawn aluminium, has internal ribs (3) of triangular cross-section. These may be formed by longitudinal or helical grooves in the inner tube surface. An extruded plastic sheath (2) likewise has externally directed longitudinal or helical ribs (4). The tube, forming part of a heat-pump evaporator or condenser, contains (5) a refrigerant fluid, and may be buried in the soil or immersed in a tank or reservoir near the premises to be served. The sheath may be left smooth, and suitably shaped plates clipped over it to support it in the soil and assist in heat dissipation. ADVANTAGE - Ribbing, by increasing the surface area and fluid turbulence, increases the rate of heat transfer.