Refrigeration – Processes – Circulating external gas
Reexamination Certificate
1999-10-08
2001-03-27
Wayner, William (Department: 3744)
Refrigeration
Processes
Circulating external gas
C062S271000, C062S175000
Reexamination Certificate
active
06205797
ABSTRACT:
TECHNICAL FIELD
This invention relates to air conditioning systems, and relates in particular to an air conditioning system that can operate continually air dehumidifying process by a desiccant and regeneration of the desiccant by heat pump.
BACKGROUND ART
FIG. 10
shows a system based on the conventional technology disclosed in a U.S. Pat. No. 4,430,864, which is comprised by: process air passage A; regeneration air passage B; two desiccant beds
103
A,
103
B; a heat pump
200
for regeneration of desiccant and cooling of process air. The heat pump
200
uses heat exchangers
220
,
210
embedded in the desiccant beds
103
A,
103
B as high and low temperature heat sources respectively, in which one desiccant bed performs dehumidifying by passing process air, and the other desiccant bed performs regeneration of desiccant beds by passing regeneration air. After air conditioning is carried out for a specific time interval, four-way switching valves
105
,
106
are operated to perform reverse processes in respective desiccant beds by flowing regeneration air and process air in the opposite desiccant beds.
In the conventional technology described above, high/low heat source of the heat pump
200
and each desiccant are integrated in each unit, and, an amount of heat equivalent to the cooling effect &Dgr;Q, is totally loaded on the heat pump (vapor compression cycle). That is, cooling effect cannot exceed the capability of the heat pump (vapor compression cycle) used. Therefore, there is no benefit resulting from making the system complex.
Therefore, to resolve such problems, it is possible to consider a system, such as the one shown in
FIG. 11
, to heat the regeneration air by placing a high temperature source
220
in the regeneration air passage B, and placing a low temperature air source
240
in the process air passage A to cool the process air, as well as to provide a heat exchanger
104
for exchanging sensible heat between the post-desiccant process air and pre-desiccant regeneration air. In this case, the desiccant
103
uses a desiccant wheel which rotates so as to straddle the process air passage A and the regeneration air passage B.
This system can provide cooling effects (&Dgr;Q), which is a sum of the cooling effects produced by the heat pump and the cooling effects produced by sensible heat exchange performed between process air and regeneration air, as shown in the psychrometric chart presented in
FIG. 12
, thus producing a system of more compact design and capable of generating a higher cooling effects than that produced by the system shown in FIG.
10
.
However, even in this type of air conditioning system, when processing a relatively low sensible heat load, as may happen during the rainy season, producing a relatively low temperature and a high humidity, it is difficult to obtain a heat balance between the heat produced by the heat pump needed for desiccant regeneration and the cooling load for sensible heat processing, resulting that, if priority is given to obtain dehumidification, the temperature of the conditioning space may become too low because cooling of supply air in the low-temperature heat source heat exchanger
240
can cause excessive cooling.
This invention has been made to solve the problems outlined above by providing an air conditioning system that can produce continual dehumidification of supply air and desiccant regeneration, by developing a system that enables to adjust the heat transfer process in the sensible heat exchanger disposed between the post-desiccant process air that has not yet flowed into the low-temperature heat source heat exchanger and regeneration air that has not yet flowed into the high-temperature heat source heat exchanger. When air conditioning is aimed primarily at dehumidification of process air with a low sensible heat fraction, heat transfer processes in the sensible heat exchanger are controlled so as to retain the sensible heat load in the low-temperature heat source heat exchanger, thereby increasing the temperature of supply air into the conditioning space. Such a system, when operated according to the method presented, conserves energy while exhibiting superior dehumidifying capability and flexibility in processing a variety of cooling loads.
DISCLOSURE OF INVENTION
This invention has been made to achieve the objectives stated above, and the invention according to claim
1
is an air conditioning system comprising: a desiccant for adsorbing moisture from process air; and a heat pump, including a compressor, that operates by using process air as a low-temperature heat source and regeneration air as a high-temperature heat source so as to supply heat to regeneration air for regenerating the desiccant; wherein processes of heat transfer in a sensible heat exchanger are made adjustable, for exchanging heat between post-desiccant process air that has not flowed into the low temperature heat source heat exchanger and pre-desiccant regeneration air that has not yet regenerated the desiccant.
Accordingly, by adjusting the heat transfer rate in the sensible heat exchanger, the system is able to adapt itself flexibly to dehumidify or cool the conditioning load with various sensible heat fraction so that dehumidifying mode of operation does not lead to excessive cooling.
The invention according to claim
2
is an air conditioning system comprising: a desiccant for adsorbing moisture from process air; and a heat pump, including a compressor, that operates by using process air as a low-temperature heat source and regeneration air as a high-temperature heat source so as to supply heat to regeneration air for regenerating the desiccant; wherein post-desiccant process air that has passed through the desiccant exchanges heat in a first sensible heat exchanger with regeneration air that has not yet flowed into a high-temperature heat source heat exchanger of the heat pump; and regeneration air that passed through the first sensible heat exchanger but has not yet entered the high temperature heat source heat exchanger exchanges heat in a second sensible heat exchanger with post-desiccant regeneration air; and heat transfer processes in the first sensible heat exchanger are made adjustable.
Accordingly, by adjusting the heat transfer in the sensible heat exchanger, the system is able to adapt flexibly to a variety of cooling requirements dictated by the sensible heat fraction in the conditioning load, and when operating in the dehumidifying mode, cooling of process air in the first sensible heat exchanger is suppressed before it enters into the low-temperature heat source heat exchanger so that the process air can serves as the source of low-temperature heat for desiccant regeneration, thereby securing sensible heat load for the low-temperature heat source heat exchanger, and avoiding excessive cooling in the room to be air conditioned. If the sensible heat load is high, the first sensible heat exchanger can be operated to lower the temperature of process air at the outlet of the heat pump, therefore, the system can be used in the cooling mode also.
The invention according to claim
3
is an air conditioning system according to claim
2
, wherein at least the first sensible heat exchanger is a rotary heat exchanger, whose heat exchange processes are made adjustable by varying a rotational speed. Accordingly, by adjusting the speed of rotation of rotary heat exchanger that is easy to control its heat transfer process, the system can be used for either dehumidification or cooling.
The invention according to claim
4
is an air conditioning system comprising: a desiccant for adsorbing moisture in process air; and a heat pump, including a compressor, that operates by using process air as a low-temperature heat source and regeneration air as a high-temperature heat source so as to supply heat to regeneration air for desiccant regeneration; wherein paths of process air and regeneration air that pass through the desiccant are divided into a first zone for dehumidifying process air and a second zone for regenerating the desiccant usi
Armstrong, Westerman Hattori, McLeland & Naughton
Ebara Corporation
Wayner William
LandOfFree
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