Refrigeration – Processes – Circulating external gas
Reexamination Certificate
2002-02-28
2004-01-06
Jones, Melvin (Department: 3744)
Refrigeration
Processes
Circulating external gas
49
Reexamination Certificate
active
06672082
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a heat pump and a dehumidifying apparatus, and more particularly to a heat pump with a high COP and a dehumidifying apparatus which has such a heat pump and a high moisture removal per energy consumption.
BACKGROUND ART
As shown in
FIG. 11
, there has heretofore been available a dehumidifying apparatus having a compressor
1
for compressing a refrigerant, a condenser
2
for condensing the compressed refrigerant with outside air, an evaporator
3
for depressurizing the condensed refrigerant with an expansion valve
5
and evaporating the refrigerant to cool process air from an air-conditioned space
10
to a temperature equal to or lower than its dew point, and a reheater
4
for reheating the process air, which has been cooled to a temperature equal to or lower than its dew point, at the downstream side of the condenser
2
with the refrigerant upstream of the expansion valve
5
. The refrigerant is condensed in the condenser and the reheater. With the illustrated dehumidifying apparatus, a heat pump HP is constituted by the compressor
1
, the condenser
2
, the reheater
4
, the expansion valve
5
, and the evaporator
3
. The heat pump HP pumps heat from the process air which flows through the evaporator
3
into the outside air which flows through the condenser
2
.
Here, operation of the heat pump HP shown in
FIG. 11
will be described below with reference to a Mollier diagram shown in FIG.
12
. The diagram shown in
FIG. 12
is a Mollier diagram in the case where HFC134a is used as the refrigerant. A point a represents a state of the refrigerant evaporated by the evaporator
3
, and the refrigerant is in the form of a saturated vapor. The refrigerant has a pressure of 0.34 Mpa, a temperature of 5° C., and an enthalpy of 400.9 kJ/kg. A point b represents a state of the vapor drawn and compressed by the compressor
1
, i.e., a state at the outlet port of the compressor
1
. In the point b, the refrigerant is in the form of a superheated vapor. The refrigerant vapor is cooled in the condenser
2
and reaches a state represented by a point c in the Mollier diagram. In the point c, the refrigerant is in the form of a saturated vapor and has a pressure of 0.94 MPa and a temperature of 38° C. Under this pressure, the refrigerant is cooled and condensed to reach a state represented by a point d. In the point d, the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c. The saturated liquid has an enthalpy of 250.5 kJ/kg. The refrigerant liquid is depressurized by an expansion valve
5
to a saturation pressure of 0.34 MPa at a temperature of 5° C. A mixture of the refrigerant liquid and the vapor at a temperature of 5° C. is delivered to the evaporator
3
, in which the mixture removes heat from process air and is evaporated to reach a state of the saturated vapor, which is represented by the point a in the Mollier diagram. The saturated vapor is drawn into the compressor
1
again, and the above cycle is repeated.
Operation of the dehumidifying apparatus shown in
FIG. 11
will be described below with reference to a psychrometric chart shown in FIG.
13
. In
FIG. 13
, the alphabetical letters K, L, M correspond to the encircled letters in FIG.
11
. Air (in a state K) from the air-conditioned space
10
is cooled to a temperature equal to or lower than its dew point to lower the dry bulb temperature thereof and lower the absolute humidity thereof, and reaches a state L. The state L is on a saturation curve in the psychrometric chart. The air in the state L is reheated by the reheater
4
to increase the dry bulb temperature thereof and keep the absolute humidity thereof constant, and reaches a state M. Then, the air is supplied to the air-conditioned space
10
. The state M is lower in both of absolute humidity and dry bulb temperature than the state K.
With the conventional heat pump and dehumidifying apparatus described above, since it is necessary to considerably cool the air to its dew point, about half of the refrigerating effect of the evaporator in the heat pump is consumed to remove a sensible heat load from the air, so that the moisture removal (the dehumidifying performance) per electric power consumption is low. If a single-stage compressor is used as the compressor in the heat pump, then it produces a one-stage compression-type refrigerating cycle, resulting in a low coefficient of performance (COP) and a large amount of electric power consumed per amount of moisture removal.
It is therefore an object of the present invention to provide a heat pump with a high coefficient of performance (COP) and a dehumidifying apparatus which consumes a small amount of energy per amount of moisture removal.
DISCLOSURE OF INVENTION
According to an aspect of the present invention, as shown in
FIG. 1
, for example, there is provided a heat pump comprising: a pressurizer
260
for raising a pressure of a refrigerant; a condenser
220
for condensing the refrigerant to heat a high-temperature heat source fluid; an evaporator
210
for evaporating the refrigerant to cool a low-temperature heat source fluid; and heat exchanging means
300
disposed in a refrigerant path connecting the condenser
220
and the evaporator
210
, for evaporating and condensing the refrigerant under an intermediate pressure between the condensing pressure of the condenser
220
and the evaporating pressure of the evaporator
210
to cool the low-temperature heat source fluid by evaporation of the refrigerant under the intermediate pressure and to heat the low-temperature heat source fluid by condensation of the refrigerant under the intermediate pressure; wherein the low-temperature heat source fluid is successively cooled by the heat exchanging means
300
, cooled by the evaporator
210
, and heated by the heat exchanging means
300
in the order named.
Preferably, the heat exchanging means
300
is arranged such that the refrigerant is repeatedly evaporated and condensed alternately under the intermediate pressure. Typically, the refrigerant condensed by the condenser
220
to heat the high-temperature heat source fluid is the refrigerant pressurized by the pressurizer
260
, and the refrigerant evaporated by the evaporator
210
to cool the low-temperature heat source fluid is pressurized by the pressurizer
260
.
With the above arrangement, the heat pump comprises the heat exchanging means for evaporating and condensing the refrigerant under an intermediate pressure between the condensing pressure of the condenser and the evaporating pressure of the evaporator to cool the low-temperature heat source fluid by evaporation of the refrigerant under the intermediate pressure and to heat the low-temperature heat source fluid by condensation of the refrigerant under the intermediate pressure. Therefore, the low-temperature heat source fluid is successively cooled by the heat exchanging means, cooled by the evaporator, and heated by the heat exchanging means in the order named. Hence, the low-temperature heat source fluid can be precooled by the heat exchanging means prior to cooling in the evaporator, and the low-temperature heat source fluid which flows out of the evaporator can be heated with use of the heat in precooling.
According to another aspect of the present invention, there is provided a heat pump, wherein the intermediate pressure includes at least a first intermediate pressure and a second intermediate pressure lower than the first intermediate pressure, and the heat exchanging means
300
cools the low-temperature heat source fluid successively by evaporation of the refrigerant under the first intermediate pressure and by evaporation of the refrigerant under the second intermediate pressure in the order named, and the heat exchanging means heats the low-temperature heat source fluid successively by condensation of the refrigerant under the second intermediate pressure and by condensation of the refrigerant under the first intermediate pressure in the order named.
With the above arra
Inaba Hideo
Maeda Kensaku
Nishiwaki Shunro
Ebara Corporation
Jones Melvin
Westerman Hattori Daniels & Adrian LLP
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