Heat transfer pipe with spiral internal ribs

A pipe having several internal ribs with a spiral twist running with rotational symmetry with the longitudinal axis of symmetry of the pipe, characterized by following features:

• a) the free ends of the internal ribs are a distance from the longitudinal axis of symmetry of the pipe, which is in the range of 1:12 to 1:3 in relation to the inside diameter of the pipe;
• b) all the internal ribs run in the same direction and with the same spiral length with a spiral twist to the longitudinal axis of symmetry;
• and
• c) the cross-sectional shape of each internal rib forms an acute equilateral triangle with straight legs whose triangular tip develops into the two legs with a rounded tip because of radius, with two adjacent internal ribs forming an interspace having a trapezoidal cross section.

A pipe having several internal ribs with a spiral twist running with rotational symmetry with the longitudinal axis of symmetry of the pipe, characterized by following features:

• a) the free ends of the internal ribs are a distance from the longitudinal axis of symmetry of the pipe, which is in the range of 1:12 to 1:3 in relation to the inside diameter of the pipe;
• b) all the internal ribs run in the same direction and with the same spiral length with a spiral twist to the longitudinal axis of symmetry;
• and
• c) the cross-sectional shape of each internal rib of the pipe has the shape of the tooth of gear wheels with side flanks with a convex outward curvature and with a rounded tip of the tooth, and two adjacent ribs extend around an interspace having a U-shaped cross section with side faces having a concave curvature.

A pipe having several internal ribs with a spiral twist running with rotational symmetry with the longitudinal axis of symmetry of the pipe, characterized by following features:

• a) the free ends of the internal ribs are a distance from the longitudinal axis of symmetry of the pipe, which is in the range of 1:12 to 1:3 in relation to the inside diameter of the pipe;
• b) all the internal ribs run in the same direction and with the same spiral length with a spiral twist to the longitudinal axis of symmetry;
• and
• c) the cross-sectional shape of each internal rib has an acute equilateral triangle with legs having a concave inward curvature and a semicircular shape at the tip, with two adjacent internal ribs extending in a U-shape around an interspace having a trapezoidal cross section, the trapezoidal legs having an outward convex curvature.

A pipe having several internal ribs with a spiral twist running with rotational symmetry with the longitudinal axis of symmetry of the pipe, characterized by following features:

• a) the free ends of the internal ribs are a distance from the longitudinal axis of symmetry of the pipe, which is in the range of 1:12 to 1:3 in relation to the inside diameter of the pipe;
• b) all the internal ribs run in the same direction and with the same spiral length with a spiral twist to the longitudinal axis of symmetry;
• and
• c) the number of ribs, the length of the twist, the thickness and the shape of the ribs are selected as a function of the type of fluid and its flow rate as well as the pressure drop.

A pipe having several internal ribs with a spiral twist running with rotational symmetry with the longitudinal axis of symmetry of the pipe, characterized by following features:

• a) the free ends of the internal ribs are a distance from the longitudinal axis of symmetry of the pipe, which is in the range of 1:12 to 1:3 in relation to the inside diameter of the pipe;
• b) all the internal ribs run in the same direction and with the same spiral length with a spiral twist to the longitudinal axis of symmetry;
• and
• c) the distance of the free ends of the internal ribs from the longitudinal axis of symmetry of the pipe is selected to be larger in the case of high-viscosity fluids such as oils than in the case of low-viscosity fluids such as water and gases.