US 4,570,700 AGranted

Flat, multi-luminal tube for cross-flow-type indirect heat exchanger, having greater outer wall thickness towards side externally subject to corrosive inlet gas such as wet, salty air

AssigneeNippondenso Co., Ltd.

InventorsToshio Ohara, Sigenobu Fukumi, Yoshiyuki Yamauchi

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Abstract

A transversally corrugated multi-luminal flat tube for circulating the refrigerant of an evaporator for an automotive air conditioner in indirect heat exchange relation with air is provided with one laterally marginal portion, being the one which faces inlet air flow in a transverse cross-flow system, that is so thick-walled about its outer perimeter, that inlet air, which is corrosive because it contains moisture and salt, will be prevented for a sufficiently long time from corroding pinholes through that part of the tube, the remaining part of the outer periphery of the flat tube, because it is less subject to corrosive attack being thinner walled, so as to maximize durability and mass flow rate, while minimizing weight and cost.

Claims20

Dependent claims

In a heat exchanger flat tube for use in a cross-flow indirect heat exchanger:

(a) in which a corrosive vapor to be cooled is passed externally, transversally of the flat tube, while a fluid capable of absorbing heat conducted through an outer peripheral sidewall of the tube extending perimetrically of the tube is circulated longitudinally of the tube through longitudinal passageway means of the tube,
(b) in which the tube is made of a metal having a relatively high heat conductivity, but one which is, over time, capable of being corrosively attacked by said vapor to such a degree as to eventually produce pinholes through said outer peripheral wall, at least at vapor inlet conditions to the heat exchanger,
(c) in which said outer peripheral wall of the tube is constructed and arranged to have two opposite relatively broad faces and two opposite narrow edges, and
(d) in which said tube is constructed and arranged to have one of said narrow edges be a leading edge thereof as respects said vapor inlet,
the improvement wherein:
said outer peripheral wall of said tube is substantially thicker over a portion thereof which includes all of said leading edge and respective adjoining parts of said opposite faces, than it is over the remainder thereof.

3 more elements

In a cross-flow indirect heat exchanger including at least one flat tube constructed and arranged to have a corrosive vapor to be cooled passed externally, transversally of the tube, while a fluid capable of absorbing heat conducted through an outer peripheral sidewall extending perimetrically of the flat tube is circulated longitudinally of the tube through longitudinal passageway means of the tube, the tube being made of a metal having a relatively high heat conductivity but being capable, over time, of being corrosively attacked by said vapor to such a degree as to eventually produce pinholes through said outer peripheral wall, at least at vapor inlet conditions to the heat exchanger, said heat exchanger being so constructed and arranged that said tube has two opposite relatively broad faces and two opposite narrow edges with one of said narrow edges being presented as a leading edge as respects said vapor inlet,

the improvement wherein:
said outer peripheral wall of said tube is substantially thicker over a portion thereof which includes all of said leading edge and respective adjoining parts of said opposite faces, than it is over the remainder thereof.

Dependencies are inferred from the claim text.