Method and Materials for Improving Evaporative Heat Exchangers

Abstract

A corrugated laminate material (44) for use in an evaporative heat exchanger, said material including a water retaining medium having a wettable surface (40) and an opposed vapour resistant surface (42).

Description

FIELD OF THE INVENTION[0001]The present invention relates to improvements in heat exchange capacity of evaporative heat exchangers. In particular, one aspect of this invention relates to a material suited to use in forming heat exchange surfaces of evaporative heat exchangers. Additional inventions are disclosed that relate to the operation of evaporative coolers. For ease of understanding, the aspects of this invention will be described in connection with the heat exchange core of counter flow evaporative coolers, as well as to methods, equipment and systems for the ventilation and cooling of enclosed spaces. The various aspects of this invention can be applied to self-contained air conditioning units suitable for supplying cooled air to an enclosed space, and to self-contained conditioning units suitable for supplying cooled water for use in heat exchange units forming part of a system for the cooling of enclosed spaces.DESCRIPTION OF THE PRIOR ART[0002]Throughout this description...

AI Technical Summary

Benefits of technology

[0025]In an eighth aspect of the present invention there is provided a method of operating an evaporative cooler which includes a heat exchange core wherein adjacent wet and dry airflow channels are in counter current airflow heat exchange relationship with water being supplied to the wet channels in a descending flow pattern, characterised in that water is supplied to the wet channels over a plurality of segments from an air entry end to an air outlet end of said core during operation of said cooler and wherein water is circulated through each segment relatively separately from adjacent segments such that an appropriate temperature gradient is established from an air inlet end to an air outlet end of the core by maintaining different circulating water temperatures in each segment.

[0031]The inventive aspects of the present invention when combined can result in an indirect evaporative cooler which fully utilises the characteristics of corrugated media to produce a compact, efficient and economical cooler. Such an indirect evaporative air cooler typically comprises a fan means for the delivery of air, an indirect evaporative heat exchanger and an air delivery means including an airflow resistance means.

Problems solved by technology

This limitation in achievable temperature and the addition of moisture to the air severely limits the degree of cooling available by this method, as well as limiting the use of this means of cooling to relatively hot, dry climates.

However, the construction suffers a number of deficiencies.

Heat transfer between the wet and dry air passages is inefficient due to the air boundary layers at both sides of the medium between the passages, requiring large surface areas for effective transfer of heat.

The available delivered airflow for a given size of heat exchanger is therefore low, resulting in an unacceptably large and costly construction for practical airflows.

There are also considerable practical difficulties with the construction and operation of such an indirect evaporative cooler.

Manifolding of air streams to the respective wet and dry ducts requires individual separation of the ducts with laborious and expensive sealing systems.

When used with normal potable water supplies, water evaporated from the wet duct leaves behind salts, which cannot be easily removed, eventually clogging the heat exchanger.

The interaction of air streams within the adjacent corrugations in this construction of wetted media results in intense evaporation from the wet surfaces and intense heat transfer from the cold surfaces formed as a result of that evaporation.

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