US 6,684,637 B2 · Parallel slot heat exchanger

Abstract

A heat exchanger in which a fluid and a surface transfer thermal energy effectively with a smaller pressure drop than is conventionally realized. In a preferred embodiment, gas at one end of a piston flows into a piston chamber and passes radially through a plurality of axial slots formed through the piston sidewall and into a gap between the piston sidewall and the surface of the housing in which the piston slidably mounts. Between each pair of through-slots, longer axial slots are formed that extend only partially through the sidewall radially, and almost the entire length of the piston. Thus, around the circumference of the piston the slots alternate in structure between through-slots and longer slots. Gas that enters the gap through the through-slots flows circumferentially through the gap and into the longer slots. The gas exits the longer slots at the opposite end of the piston from the first gas space.

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Drawings

Claims32

Dependent claims

A heat exchanger apparatus for transferring thermal energy between a fluid and a first wall surface, the apparatus comprising:

(a) a wall having a wall surface spaced from and facing the first wall surface forming an occupied fluid gap between the first wall surface and the second wall surface;
(b) a first elongated slot formed in the second wall surface, the first slot opening into the unoccupied fluid gap and being in direct fluid communication with a fluid source;
and
(c) a second elongated slot formed in the second wall surface and spaced laterally from the first elongated slot, the second slot opening into the unoccupied fluid gap and being in direct fluid communication with a fluid destination.

1 more element

A heat exchanger apparatus for transferring thermal energy between a gas and a housing, the housing having a circular cylindrical surface in which a piston is slidably mounted, the piston having a hollow cylindrical sidewall and first and second endwalls mounted to opposite ends of the sidewall defining a piston chamber within the piston sidewall and endwalls, said first and second endwalls defining first and second gas spaces, respectively, on opposite ends of the piston, and an annular gap formed between the housing surface and the sidewall, the heat exchanger apparatus comprising:

(a) at least one gas passageway formed through the first endwall forming a gas flow passage between the first gas space and the piston chamber;
(b) a first slot formed in a radially outwardly facing surface of the sidewall, said first slot having an axial component and a depth equal to a piston sidewall thickness forming a gas flow path between the piston chamber and the annular gap, the first slot extending along the piston sidewall from near the first endwall to near the second endwall;
(c) a second slot formed in the radially outwardly facing surface of the sidewall spaced from the first slot and substantially parallel thereto, the second slot having an axial component and a depth less than the piston sidewall thickness, the second slot extending along the piston sidewall from near the first endwall to and through the second endwall forming a gas flow path between the annular gap and the second gas space;
(d) a third slot formed in the radially outwardly facing surface of the sidewall spaced from the second slot and substantially parallel thereto, said third slot having an axial component and a depth equal to the piston sidewall thickness forming a gas flow path between the piston chamber and the annular gap, the third slot extending along the piston sidewall from near the first endwall to near the second endwall;
and
(e) a fourth slot formed in the radially outwardly facing surface of the sidewall spaced from the first and third slots and substantially parallel thereto, the fourth slot having an axial component and a depth less than the piston sidewall thickness, the fourth slot extending along the piston sidewall from near the first endwall to and through the second endwall forming a gas flow path between the annular gap and the second gas space.

3 more elements

Dependencies are inferred from the claim text.

Description4,363 words

Summary992 words

#(Not Applicable)

#1. Field of the Invention

Brief description of the drawings16 figures

#FIG. 1 is a side view in perspective illustrating a preferred embodiment of the present invention.

#FIG. 2 is an end view in section through the line 2—2 of FIG. 1.

#FIG. 3 is an end view in section through the line 3—3 of FIG. 1.

Detailed description3,137 words

#In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or term similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art.

#A preferred embodiment is shown in FIG. 1 in which a moveable piston, such as the displacer 6 of a free piston Stirling cycle engine, is slidably mounted in a housing wall 10, having an annular radially inwardly facing surface 12. Of course, there is no need to limit the invention to free piston Stirling cycle engines, because it can be used on Stirling cycle coolers, and any mechanism in which a fluid and a wall surface must exchange thermal energy efficiently. The person having ordinary skill will understand the breadth of application of the invention from the description. The displacer 6 has a circular cylindrical sidewall 8, having a radially outwardly facing surface 14. The sidewall 8 defines the radial extremes of an interior piston chamber 16, shown in FIG. 2. A pair of disk-shaped end walls 18 and 20 are mounted to opposite ends of the sidewall 8 and defining the axial ends of the chamber 16. In the preferred embodiment, the housing wall surface 12 is smooth and contiguous, because it is preferably a machined metal surface over which fluid passes to transfer heat between the surface and the fluid. However, the term “surface” includes broken and rough surfaces, including screen and mesh surfaces.

#The radially outwardly facing annular surfaces 22 and 24 of the end walls 18 and 20, respectively, seat against the radially inwardly facing annular surface 12, or are at least positioned in such close proximity that the passage of gas between the annular surface 12 and the annular surfaces 22 and 24 is effectively eliminated or reduced to only a nominal amount. An annular gap, G, is formed between the inwardly facing annular surface 12 and the outwardly facing surface 12, through which gas can flow.

Facts

Application

10/056,833Filed 25 Jan 2002

Published

US 2003/0141044 A131 Jul 2003

Granted

3 Feb 2004

Term ended

25 Jan 2022

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification4 codes

F02G 1/057
Component parts or details: regenerators
F28F 13/06
Arrangements for modifying heat-transfer, e.g. increasing, decreasing: by affecting the pattern of flow of the heat-exchange media
F02G
Hot gas or combustion-product positive-displacement engine plants
F28F
Details of heat-exchange and heat-transfer apparatus, of general application

Parallel slot heat exchanger

Life of this patent

Parallel slot heat exchanger

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims32

Description4,363 words

Drawings

Classification4 codes

Life of this patent

Description4,363 words