Refrigeration – Atmosphere and sorbent contacting type
Reexamination Certificate
1999-06-25
2001-03-13
McDermott, Corrine (Department: 3744)
Refrigeration
Atmosphere and sorbent contacting type
C062S094000
Reexamination Certificate
active
06199394
ABSTRACT:
TECHNICAL FIELD
The present invention relates to air conditioning systems, and relates in particular to a combined air conditioning unit combining a room air conditioner to process recirculated room air and a ventilation air conditioner to process and admit outdoor air into indoors.
BACKGROUND ART
FIG. 8
shows an example of a conventional air conditioning system. This is a combination system in which an indoor air conditioner unit
3
for processing room air by recirculating the indoor air is combined with a ventilation air conditioner
11
to process outdoor air and admit processed outdoor air into indoors. The system is based on an enthalpy heat exchanger, and undertakes heat exchange processes for both humidity and sensible heat in outdoor air and indoor air. Processing load on the air conditioner generated in the conditioned space is extracted by a heat pump system and discharged to outdoors.
The operation of such a system will be explained with reference to a psychrometric chart shown in FIG.
9
. During a cooling period, outdoor air (at a state K) and indoor air (at a state Q) exchange enthalpy and outdoor air reaches a state L and indoor air reaches a state T, and respectively become a supply air to indoor space and an exhaust air to be discharged to outdoors. Enthalpy exchange efficiency for this process is as low in the currently available products as in a range of 60~70%, so that an enthalpy difference AH is produced between the supply air (at a state L) and room air (at a state Q). The result is that air having excess humidity (i.e., difference in moisture content, &Dgr;X) is supplied to the room so as to introduce moisture corresponding to 30~40% of humidity ratio difference between untreated outdoor air and indoor air. This moisture must be removed by the air conditioning system, by cooling the indoor air to 5~10° C., which is lower than its dew point (15~16° C.).
Of the air processing loads on the air conditioner based on an enthalpy heat exchanger, the latent heat load required for dehumidification is about 10~15% of the total load and the remaining 85~90% is a sensible heat load. This sensible heat load can be removed at about 15~20° C. without cooling the air temperature to the dew point. However, in the conventional systems, because the admitted outdoor air is mixed with the indoor air and the whole air has to be processed, the latent heat is removed only by cooling the air to well below the dew point, to about 10° C. Therefore, the temperature difference (temperature lift) between the evaporator temperature and the condenser temperature in the air conditioner needs to be set the same as in a case when not using the enthalpy heat exchanger, meaning that although the conditioning load on the air conditioner can be reduced, the temperature lift for pumping up the heat cannot be reduced.
It can be seen in that, in the conventional systems, a large amount of temperature lift is necessary for pumping and discharging the heat, therefore, energy consumption in the heat pump for removing sensible heat has been high and wasteful. Also, the facility becomes cumbersome because of the necessity of providing a drain to discharge condensed moisture.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a high efficiency air conditioning apparatus and an air processing system incorporating such an air conditioning apparatus to enable energy conservation by preventing sensible heat as well as latent heat from outdoor air.
The object has been achieved in an air conditioning apparatus comprising: a first air passage for directing air from a first space to a second space, and a second air passage for directing air from the second space to the first space; a desiccant device alternatingly communicating with the first air passage and with the second air passage so as to perform a regeneration process in the first air passage and to perform a dehumidification process in the second air passage; a heat pump device having a high temperature heat source for heating air flowing through the first air passage and a low temperature heat source for cooling air flowing through the second air passage; and an enthalpy heat exchanger for performing enthalpy heat exchange between air in the first and second air passages; wherein, air flowing in the first air passage exchanges heat in the enthalpy heat exchanger with air flowing in the second air passage, is then heated by contacting the high temperature heat source, and flows into the desiccant device so as to desorb and regenerate the desiccant device and flows into the second space, and wherein, air flowing in the second air passage exchanges heat in the enthalpy heat exchanger with air flowing in the first air passage, is then dehumidified by passing through the desiccant device, is cooled by contacting the low temperature heat source and flows into the first space.
Accordingly, for a cooling operation, the conditioning space to be air conditioned becomes the first space and the outdoor space becomes the second space for supplying outdoor air into indoor space through the second air passage. Outdoor air admitted from the second air passage is processed to reduce its humidity ratio compared with that for the indoor air, therefore, excess moisture is not brought into indoors so that there is no need to be dehumidified by the indoor air conditioner. Also, reduction of moisture content in the supply air means that temperature lift for driving the heating/cooling cycles of the indoor air conditioner can be lowered to achieve a significant energy conservation. Because the indoor air conditioner does not have to dehumidify ventilation air, there is no need for a drain to remove condensate.
In the above apparatus, the heat pump device may be a vapor compression type heat pump or an absorption type heat pump.
During a cooling operation, the first space becomes an indoor conditioning space and the second space becomes an outdoor space. During a heating operation, the first space becomes an outdoor space and the second space becomes an indoor conditioning space.
In the apparatus presented above, the ventilation air conditioning unit can be used in combination with an indoor air conditioning unit which performs cooling on a sensible heat load in the conditioning space. In such a system, during a cooling operation, outdoor air is led into the ventilation air conditioning unit so that the humidity ratio of the incoming air is lower than that of the air in the indoor conditioning space. Therefore, excess moisture is not brought into indoors, and the inside air conditioning units do not need to dehumidify the inside air. Temperature lift to drive the inside conditioners can be lowered and a significant energy saving can be achieved. Because there is no need to dehumidify, no drain is needed to remove condensate.
The apparatus may be arranged so that the heat pump device processes a sensible heat cooling load in a conditioning space. In such a system, sensible heat is recovered during the cooling operation to utilize the recovered heat in moisture removal and regeneration of desiccant material. Regenerated desiccant works more efficiently, and coupled with sensible heat recovery, contributes to conservation of energy and high operating efficiency.
The object has also been achieved in an air conditioning apparatus comprising: a first air passage for directing air from a first space to a second, and a second air passage for directing air from the second space to the first space; an enthalpy heat exchanger for exchanging heat between air flowing in the first air passage and air flowing in the second air passage; a heat pump device having a high temperature heat source for heating air, which has passed through the enthalpy heat exchanger, flowing in one of the first air passage or the second air passage, and a low temperature heat source for cooling air, which has passed through the enthalpy heat exchanger, flowing through the other of the first air passage or the second air passage; and a desiccant device undergoing moisture adsorption a
Armstrong, Westerman Hattori, McLeland & Naughton
Ebara Corporation
Jiang Chen-Wen
McDermott Corrine
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