Formed sheet heat exchanger

Abstract

A formed sheet heat exchanger is provided for exchanging heat between fluids is provided. The apparatus includes flow divider sheets that are positioned in a stacked configuration and extend in a longitudinal direction so that adjacent pairs of the sheets define flow passages therebetween for receiving first and second fluids. Each of the sheets is nonuniform in the longitudinal direction, having a manifold portion and a corrugated portion. The corrugated portions of each adjacent pair of sheets define a plurality of fluid channels therebetween that are connected to the portion of the flow passage defined between the manifold portions. The fluid channels are configured to receive the first or second fluids and transfer thermal energy therebetween through the flow divider sheets.

Description

BACKGROUND OF THE INVENTION [0001] 1) Field of the Invention [0002] The present invention relates to apparatuses and methods for exchanging heat between fluids and, more particularly, to a counter-flow heat exchanger with passages defined by nonplanar sheets. [0003] 2) Description of Related Art [0004] Heat exchangers, which are used in numerous applications and industries, generally define two sets of passages that are at least substantially fluidly disconnected. A relatively hot fluid flows through a first set of passages of the heat exchanger, and a relatively cool fluid flows through a second set of passages of the exchanger. The two sets of passages thermally communicate so that thermal energy is transferred from the hot fluid to the cool fluid. The fluids can flow in the same direction, perpendicular directions, or opposite directions. Heat exchangers characterized by opposite flow of the fluids are typically referred to as counter-flow devices. [0005] One application for whic...

AI Technical Summary

Benefits of technology

[0007] The present invention provides an apparatus for exchanging heat between fluids. The apparatus includes a plurality of flow divider sheets that are positioned in a stacked configuration to define flow passages therebetween. Each sheet is nonuniform in a longitudinal direction and, in particular, defines a corrugated portion and at least one manifold portion. The corrugated portions of each sheet correspond to the corrugated portions of the adjacent sheets in the stack so that adjacent sheets define fluid channels therebetween in the flow passages. First and second fluids can be delivered through the flow passages, e.g., in an alternating fashion, so that the first and second fluid thermally communicate. The corrugated portions of the sheets can provide relatively large common boundary areas between the fluids in adjacent passages, thereby increasing the thermal efficiency of the heat transfer therebetween. Advantageously, the flow divider sheets can provide efficient thermal communication between the two flow streams without requiring extensive internal joints or complex parts. For example, the geometrical configuration of the apparatus can provide efficient heat exchange between hot and cold fluids by minimizing the path of thermal conduction therebetween. The close proximity of the fluids can also result in a reduction in structural loads that are induced by temperature differences. Further, the elimination of certain rigid connections typically formed in conventional heat exchanging devices can reduce the thermal stress in the apparatus. In some cases, the apparatus of the present invention can be configured with many fluid passages, which can be relatively small in cross-sectional size, and yet can be made using a relatively simple and inexpensive fabrication process.

[0008] The corrugated portions of adjacent flow divider sheets can contact one another along a plurality of interfaces extending in the longitudinal direction of the sheets, thereby substantially preventing transverse flow of the fluids between adjacent channels. Further, the corrugated portions of adjacent flow divider sheets can be substantially disconnected throughout the corrugated portions of the flow passages so that the adjacent sheets are relatively adjustable during operation of the apparatus, e.g., to accommodate nonuniform expansion or contraction of the sheets. Elongate members extending transversely can be disposed between the flow divider sheets so that the elongate members support the divider sheets and maintain the flow passages between the sheets.

Problems solved by technology

Preburners are sometimes used to heat the incoming airflow via partial combustion, but a preburner can reduce the efficiency of the turbine, and byproducts such as nitrogen oxides and carbon monoxide can be formed in the preburner.

However, the structural configuration required for such heat exchangers is generally complex.

The assembly of such a heat exchanger is typically labor intensive, and the exchanger is often subjected to large thermal strains that limit the operating life of the device.

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