Heat exchanger and method of operating the same

Abstract

An evaporative heat exchanger includes first and second stacked plates forming a first fluid flow path between a first end and a second end. The first stacked plate defines a plane. Third and fourth stacked plates define a second fluid flow path. A fluid flow plate is positioned between the first and second stacked plates, and has a plurality of flow channels extending substantially parallel to the plane between the first end and the second end. At least one of the first and second stacked plates defines slots that form a portion of the first fluid flow path so that fluid flowing along the first fluid flow path flows along the flow channels in the first direction, then flows along at least one of the slots, then flows into adjacent flow channels and then along the adjacent flow channels in a second direction parallel to the first direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is a continuation-in-part of U.S. application Ser. No. 12 / 572,310, filed Oct. 2, 2009 which claims priority to U.S. Provisional Patent Application Ser. No. 61 / 102,458, filed Oct. 3, 2008, the entire contents of both of which are hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to heat exchangers, and more particularly to evaporative heat exchangers having a number of stacked plates at least partially defining two separate and substantially adjacent fluid flow pathsSUMMARY OF THE INVENTION[0003]Attempts to use stacked plate style heat exchangers in applications where one of the fluids experiences a change of phase from a liquid to a vapor have been problematic. In such applications the fluid that is evaporating exists, over at least a portion of its flow path through the heat exchanger, as a two-phase fluid having both vapor and liquid fractions. The vapor fraction tends to ...

AI Technical Summary

Benefits of technology

[0008]In some embodiments, the pressure resistance and heat transfer performance of the heat exchanger may be improved by having a uniformly narrow channel width for the flow channels of the fluid flow plates. In some embodiments the second collection manifold can consist of one or more slots extending through the fluid flow plate. In some embodiments the one or more slots can each have a slot width that is approximately equal to the channel width.

Problems solved by technology

Attempts to use stacked plate style heat exchangers in applications where one of the fluids experiences a change of phase from a liquid to a vapor have been problematic.

The vapor fraction tends to separate from the liquid fraction due to the substantial differences in densities between the phases, making it difficult to achieve a uniform distribution of the fluid over the multiple parallel passages.

When the distribution is not uniform, the performance of the heat exchanger tends to suffer.

Separation of the phases of the evaporating fluid can result in liquid flooding of certain regions, with slugs of the liquid forced through the heat exchanger at a non-constant rate.

A disadvantage of using a tube and fin evaporator construction in such applications is the difficulties that it poses in arranging the hot and cold fluid flows in a circuiting arrangement other than cross-flow.

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