Hitachi Cable, Inc.

Other

Hitachi, Ltd.

Tadao Otani

Masaaki Itoh

Mari Uchida

Noboru Hagiwara

Mitsuo Kudoh

Yoshio Suzuki

Toshihiko Fukushima

Kenji Yokomizo

Hajime Abe

Kenichi Inui

Kazuo Ishida

Manabu Kagawa

Masakazu Tobe

Makoto Ohba

Osamu Kawamata

To provide a high heat transfer performance with a heat transfer pipe used to a condenser and an evaporator in a refrigerating cycle using a refrigerant mixture, the heat transfer pipe includes main grooves and auxiliary grooves each formed on the inner surface of the heat transfer pipe with the main grooves intersecting the auxiliary grooves, wherein the main grooves are separate by ridges, and the ridges are divided into ribs by the auxiliary grooves, and wherein a length of the ribs formed along the direction of the main grooves is made longer than the length of the ridges, a width of the auxiliary grooves is made smaller than the length of the ribs and further the auxiliary grooves are formed in a direction where a pressure gradient in the heat transfer pipe is reduced.

Heat transfer pipe for refrigerant mixture

In a heat transfer tube for a zeotropic refrigerant mixture, the inner surface of the tube in which the zeotropic refrigerant mixture flows is formed with grooves having cross portions where the grooves intersect with each other, or the inner surface of the tube is formed with a plurality of independent projections. Thus, concentration boundary layers generated in the zeotropic refrigerant mixture are stirred to reduce the thickness of the concentration boundary layers, thereby decreasing the diffusion resistance and promoting the stirring effect. Consequently, there can be provided a heat transfer tube for a zeotropic refrigerant mixture which exhibits a high heat transfer performance, and a heat exchanger of a cross-fin tube type, a refrigerator and an air conditioner which include such heat transfer tubes.

Refrigeration cycle

In an inner surface-grooved heat transfer tube, a plurality of fins is formed on the inner surface thereof along a line forming a first predetermined angle with respect to the longitudinal axis of the tube, a plurality of notches is defined on the fins along a line forming a second predetermined angle with respect to the longitudinal axis, and the depth Hf' of the notches is specified to be 20% or more and below 40% (0.2.ltoreq.Hf'/Hf&lt;0.4) with respect to the height Hf of the fins, to provide an inner surface-grooved heat transfer tube which can suppress pressure loss of a refrigerant, and by which improvements in performance of condensation and evaporation are intended. In addition no increase of power consumption is required for the pump.

Inner surface grooved heat transfer tube

A modified cross-section material having a thin part and a thick part in its widthwise direction is manufactured through a plurality of roll stages. Each rolling stage comprises of a set of a convex roll and a flat roll, wherein the convex roll has a convex part. The thin part is formed in accordance with the lengthwise expansion by the convex part of the convex roll, and the thick part is formed in accordance with the lengthwise expansion by a part other than the convex part of the convex roll.

Method of manufacturing modified cross-section material

A method for producing a strip of material having a non-uniform cross section is carried out by passing a strip of material in the longitudinal direction through a first set of working rolls, at least one of which is provided with an annular slot intermediate the ends thereof so that a reducing force is applied only to those portions of the strip engaging said roll on opposite sides of the slot whereby the excess material flows toward that portion of the strip opposed to the slot to cause the strip to buckle outwardly into the slot. The strip is subsequently passed through a set of smooth rolls to flatten the buckled portion. This procedure is repeated any desired number of times with the width of the slot becoming progressively smaller. The strip may then be passed through one or more sets of finishing rolls and a heating and annealing operation can take place before each passage through a set of finishing rolls.

Method of producing a strip having a non-uniform cross section by a

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Ibaraki-ken, Japan

Tadao Otani