Regenerative evaporative cooler

Details Regenerative evaporative cooler Regenerative evaporative cooler

2001-07-12

2002-01-15

Bennett, Henry (Department: 3744)

Refrigeration

Material cooling means including gas-liquid contactor

Fluid recirculating means

C062S305000, C062S314000, C062S121000

Reexamination Certificate

active

06338258

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to evaporative coolers designed to distribute cool air currents, having a temperature lower than that of atmospheric air, to a target room without using refrigerant, different from typical air conditioners, and, more particularly, to a regenerative evaporative cooler designed to reduce the temperature of inlet air using latent heat of vaporization of water prior to distributing the air to a target room.
2. Description of the Prior Art
As well known to those skilled in the art, evaporative coolers spray water to air flowing in a channel, thus allowing the water to vaporize absorbing the latent heat from the air and subsequently the air to become cool before it is distributed from the cooler to a target room. Several types of evaporative coolers have been proposed and used in the prior art. For example, Korean Patent Laid-open Publication No.
96-1649,
and U.S. Pat. Nos. 3,792,841 and 4,337,216 each disclose a direct-type evaporative cooler, which directly sprays water to inlet air and forms desired cool air prior to distributing the cool air to a target room. On the other hand, Korean Patent Laid-open Publication No. 2000-20820 discloses an indirect-type evaporative cooler, which primarily sprays water to processing air, and reduces the temperature of the processing air, and secondarily performs a heat exchanging process of reducing the temperature of inlet air by the low temperature processing air, thus indirectly cooling the inlet air prior to distributing the air to a target room. Korean Patent Laid-open Publication Nos. 1996-38336 and U.S. Pat. No. 4,566,290 each disclose another type of indirect-type evaporative cooler, which primarily reduces the temperature of processing water, and secondarily performs a heat exchanging process of reducing the temperature of inlet air by the low temperature processing water, thus indirectly cooling the inlet air prior to distributing the air to a target room. On the other hand, U.S. Pat. No. 5,664,433 discloses a combined-type evaporative cooler, which reduces the temperature of inlet air through a combined evaporative cooling system, formed by a combination of the direct- and indirect-type evaporative cooling systems.
When a conventional direct-type evaporative cooler is used within a closed room having poor ventilation, moisture is continuously generated from the vaporization process of the cooler and excessively increases the humidity of the room, thus making users in the room feel unpleasant, particularly when the cooler is used in an area of high temperature and high humidity. On the other hand, the indirect-type evaporative coolers do not change the humidity of a target room, thus being capable of distributing desired cool air currents making usersfeel pleasant, different from the direct-type evaporative coolers.
Such conventional evaporative coolers regardless of their types are advantageous in that they effectively conserve energy since they use energy only for operating blower fans during an operation. However, the temperature of cool air formed by the conventional evaporative coolers is undesirably limited by the wet-bulb temperature of inlet air, and so the evaporative coolers limitedly accomplish their desired operational effect in the case of an operation in an area of high temperature and low humidity; but they don't accomplish the desired operational effect in an area of high humidity.
In addition, a regenerative evaporative cooling system has been proposed, and used in the design of the prior art evaporative coolers. In a cooler using such a regenerative evaporative cooling system, it is ideally possible to reduce the temperature of air to a dew point of inlet air in place of the wet-bulb point of the inlet air. During a summer season of Korea, the dew point of atmospheric air is typically lower than the wet-bulb point of the atmospheric air by about 2~5° C., and so the regenerative evaporative cooler preferably reduces the temperature of cool air to a point lower than that of the other types of conventional evaporative coolers.
FIG. 1
a
is a view of a conventional regenerative evaporative cooler.
As shown in the drawing, during an operation of the regenerative evaporative cooler, hot inlet air
21
passes through a dry channel
31
of a heat exchanger while being reduced in its temperature through a heat exchanging process to form low temperature primary air
22
. The low temperature primary air
22
from the dry channel
31
is partially extracted into the wet channel
33
, arranged in parallel to the dry channel
31
, and flows in the wet channel
33
in a direction opposite to that of the primary air
22
within the dry channel
31
as shown by the arrow
23
of the drawing. The extracted air
23
flowing in the wet channel
33
is cooled by the vaporization of water
25
, thus being further reduced in its temperature. A temperature difference is formed between the two channels
31
and
33
. Due to the temperature difference, the wet channel
33
absorbs heat from the dry channel
31
, thus reducing the temperature of the air
21
flowing in the dry channel
31
. In the above regenerative evaporative cooler, the phase variations of air flowing in the two channels
31
and
33
are shown in the psychrometric temperature-enthalpy chart of
FIG. 1
b.
In the psychrometric temperature-enthalpy chart of
FIG. 1
b,
the phase variation of primary air flowing in the dry channel
31
is designated by the reference numeral
61
, while the phase variation of extracted air flowing in the wet channel
33
is designated by the reference numeral
62
. As shown in the chart of
FIG. 1
b,
the enthalpy variation 64 per unit mass flow rate of the extracted air is larger than the enthalpy variation 63 per unit mass flow rate of the primary air by about 3~5 times, and so the amount of extracted air, required to accomplish a desired energy balance between the two channels, is preferably set to {fraction (1/3~1/5)} of the amount of primary air. Therefore, the regenerative evaporative cooler can distribute cool air currents to a target room, with the amount of distributed cool air currents being set to {fraction (2/3~4/5)} of the primary air. As shown in the chart of
FIG. 1
b,
the regenerative evaporative cooler effectively reduces the temperature of the primary air to the dew point of the primary air. In order to enlarge the temperature difference of the primary air between the inlet and outlet ends of the dry channel, it is preferable to arrange the dry and wet channels for the primary air and extracted air such that the flowing direction of the primary air is completely opposite to that of the extracted air to form countercurrents.
U.S. Pat. No. 5,301,518 discloses a conventional regenerative evaporative cooler. The cooler of 5,301,518 has a plurality of flat panels, separating a dry channel from a wet channel, and accomplishes a heat transfer from the dry channel to the wet channel through the flat panels. Therefore, the flat panels act as heat transfer panels in the regenerative evaporative cooler. In order to reduce a pressure loss caused by an air flow within the channels, the gap between the flat panels is set to about 1~2 mm, thus forming a narrow gap capable of forming a laminar flow of air within the channels.
In order to improve the operational performance of such regenerative evaporative coolers, it is necessary to allow water to be actively vaporized within the wet channel
33
of
FIG. 1
a,
in addition to accomplishing an effective heat transferbetween the dry channel
31
and the wet channel
33
. However,the conventional regenerative evaporative cooler is designed to form a laminar flow of air within its channels by the heat transfer panels arranged with a gap of about 1~2 mm as described above, and so the cooler regrettably has a low heat transfer rate. It is thus necessary to sufficiently enlarge the size of the heat transfer panels in order to accomplish a desired heat transfer effect. However, when the heat transfer panels a

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