# US 2014/0150769 A1 · Heat Exchanger for Oven > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150769 A1 - Document ID: US20140150769A1 - Status: Published application - Kind: A1 - Application number: 13/690,098 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Alto-Shaam, Inc. - Applicants: Alto-Shaam, Inc. - Inventors: J. K. Raghavan; Jan Bartelick - Web page: https://patentgrep.com/patent/US20140150769A1 ## CPC - F24C 15/322: {with forced circulation} - F28D 1/024: {with an air driving element} - F28D 1/047: the conduits being bent, e.g. in a serpentine or zig-zag - F28F 1/006: {with variable shape, e.g. with modified tube ends, with different geometrical features (F28F1/025, F28F1/06, F28F1/08, F28F9/16, F28F9/18 take precedence)} - F28F 13/08: by varying the cross-section of the flow channels - F24C: DOMESTIC STOVES OR RANGES (exclusively for solid fuels F24B); DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION - F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general) - F28F: DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION (water and air traps, air venting F16) ## Abstract An oven includes a heat exchanger with flattened segments providing low thermal resistance between flue gases being conveyed through the heat exchanger and a peripheral wall of the heat exchanger to increase the efficiency of heating of the peripheral wall of the heat exchanger to facilitate increasing a temperature of heated air that is delivered by a fan, across an outer surface of the peripheral wall of the heat exchanger, and through a cooking volume of the oven. ## Claims ### Claim 1 An oven comprising: an oven housing defining a cooking volume; a fan communicating with the cooking volume for directing heated air through the cooking volume; a heat exchanger providing at least one tube extending around the fan for heating the heated air being directed by the fan through the cooking volume, the heat exchanger tube including: a first tube segment having a first passage extending longitudinally along an axis therethrough and having a width that is defined transversely across and through a middle portion of the first passage, and a second tube segment connected to the first tube segment and having a second passage communicating with the first passage and extending longitudinally along the axis through the second tube segment and having a width that is defined transversely across and through a middle portion of the second passage, wherein the width of the second tube segment is smaller than the minimum width of the first tube segment; wherein the first and second tube segments have substantially the same surface area per unit distance along the axis. ### Claim 2 (depends on 1) The oven of claim 1 wherein the second tube segment defines a flattened portion that provides a minor axis that extends across the middle portion of the second passage in a first direction and a major axis that is longer than the minor axis and extends across the middle portion of the second passage in a second direction that is different than the first direction, such that the width of the second passage is defined by the minor axis and a height of the second passage is defined by the major axis. ### Claim 3 (depends on 2) The oven of claim 2 wherein the width of the second passage is smaller than the width of the first passage and wherein the height of the second passage is greater than a height of the first passage. ### Claim 4 (depends on 3) The oven of claim 3 wherein the length of the major axis of the second passage is at least about twice the length of the minor axis of the second passage. ### Claim 5 (depends on 4) The oven of claim 4 wherein the flattened portion defines an oval cross-sectional shape. ### Claim 6 (depends on 1) The oven of claim 1 wherein the first passage of the first tube segment defines a circular cross-sectional perimeter shape and the second passage of the second tube segment defines a non-circular cross-sectional perimeter shape. ### Claim 7 (depends on 6) The oven of claim 6 wherein the cross-sectional perimeter shape of the second passage is a flattened round shape. ### Claim 8 (depends on 6) The oven of claim 6 wherein the second passage defines a cross-sectional perimeter shape that is generally oval. ### Claim 9 (depends on 8) The oven of claim 8 wherein each of the first and second tube segments is made from a piece of round tubing and wherein at least part of a length of the second tube segment is flattened so that the second tube segment defines a pair of side walls that extend in a generally common direction and a pair of curved end walls that interconnect respective ends of the side walls to each other, and wherein the minimum width of the second tube segment is defined between the side walls of the second tube segment. ### Claim 10 (depends on 9) The oven of claim 9 wherein the first and second passages of the first and second tube segments have substantially identical perimeter lengths. ### Claim 11 (depends on 1) The oven of claim 1 wherein the heat exchanger includes straight sections and curved sections and wherein the second tube segment is arranged within one of the straight sections of the heat exchanger. ### Claim 12 (depends on 11) The oven of claim 11 wherein an axis of the maximum width of the second tube segment is tipped with respect to an adjacent oven wall. ### Claim 13 (depends on 12) The oven of claim 12 wherein the minimum width of the second tube segment is defined between the side walls of the flattened portion of the second tube segment. ### Claim 14 (depends on 1) The oven of claim 1 wherein the first and second tube segments longitudinally abut each other and are arranged in a first straight section of the heat exchanger. ### Claim 15 (depends on 14) The oven of claim 14 further including a splitter separating the two of the heat exchanger into two substantially parallel tubes each having a first and second tube segment each first tube segment having a first passage extending longitudinally along an axis therethrough and having a width that is defined transversely across and through a middle portion of the first passage, and each second tube segment connected to the first tube segment and having a second passage communicating with the first passage and extending longitudinally along the axis through the second tube segment and having a width that is defined transversely across and through a middle portion of the second passage, wherein the width of the second tube segment is smaller than the minimum width of the first tube segment; wherein the first and second tube segments have substantially the same surface area per unit distance along the axis, and wherein the second tube segments are positioned to be adjacent and parallel with axes of maximum width tipped with respect to an oven wall. ### Claim 16 (depends on 15) The oven of claim 15 wherein the wherein the axes of maximum width of the second tube segments are parallel. ### Claim 17 (depends on 15) The oven of claim 15 wherein the axes of maximum width of the second tube segments are not parallel.