US20120210745A1

US20120210745A1 - Drier and refrigerating cycle

Info

Publication number: US20120210745A1
Application number: US13/401,085
Authority: US
Inventors: Naofumi Ikeda; Takuya Kondo
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2011-02-22
Filing date: 2012-02-21
Publication date: 2012-08-23
Also published as: JP2012189309A; JP5488575B2

Abstract

A drier for a refrigerating cycle includes an adsorbent adsorbing moisture contained in refrigerant. The refrigerant has a molecular formula of C₃H_mF_n(m=1-5, n=1-5, and m+n=6) and has one double bond in a molecular structure. The refrigerating cycle is a vapor compression refrigerating cycle through which the refrigerant flows. The adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2011-35986 filed on Feb. 22, 2011 and Japanese Patent Application No. 2011-270128 filed on Dec. 9, 2011, the disclosures of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a drier and a refrigerating cycle having the drier.

BACKGROUND

If moisture is contained in refrigerant of a vapor compression refrigerating cycle, the moisture is frozen by being cooled rapidly when the refrigerant has an adiabatic expansion. At this time, a decompressor that decompresses the refrigerant such as expansion valve or capillary tube may be plugged with the frozen moisture. Moreover, when the moisture is precipitated (condensed) in the refrigerating cycle, components of the refrigerating cycle have internal corrosion. For this reason, the refrigerating cycle includes a drier having adsorbent. The drier is arranged in a receiver that separates the refrigerant flowing out of a condenser into gas refrigerant and liquid refrigerant and that stores the liquid refrigerant.
The adsorbent of the drier adsorbs the moisture in the refrigerant, and may be made of zeolite (molecular sieve) or silica gel having high adsorption property even in a state where a concentration of the moisture in the refrigerant is low.
An adsorption capacity of the adsorbent such as zeolite or silica gel is small, that is, an amount of moisture absorbed by the adsorbent is small relative to a weight of the adsorbent. If the moisture-adsorbing amount is required to be increased, it is necessary to increase the amount (volume) of the adsorbent. In this case, a space for the adsorbent in the receiver is required to be increased.
JP-U-H1-136862 describes a water-adsorbing resin as the adsorbent of the drier. The adsorption capacity of the water-adsorbing resin is larger than that of zeolite or silica gel.
In a case where a refrigerating cycle is mounted to a vehicle, it is difficult to produce all the pipes in the refrigerating cycle with metal, because vibration is generated while the vehicle is driving, so that a rubber hose and an O-ring are used for the pipes. In such refrigerating cycle, moisture may permeate the rubber hose or the O-ring, other than the mixing of water into the refrigerant.
The moisture has a permeation speed permeating the refrigerating cycle (hereinafter referred to moisture permeation speed). When a water vapor has a partial pressure Pwin in the refrigerant of the refrigerating cycle, and when a water vapor has a partial pressure Pwout in atmospheric air outside of the refrigerating cycle, the moisture permeation speed tends to be proportional to a difference (Pwout-Pwin) between the partial pressure Pwin in the refrigerant and the partial pressure Pwout in the atmospheric air.
In a case where zeolite is used as the adsorbent, the moisture concentration in the refrigerant is lowered, and the partial pressure Pwin in the refrigerant is lowered, because zeolite has high adsorption property when the moisture concentration is low. At this time, the moisture permeation speed may be raised.
When zeolite is saturated with the moisture, the difference between the partial pressure Pwin in the refrigerant and the partial pressure Pwout in the atmospheric air becomes small, so that the moisture permeation speed is made slow.
That is, when zeolite is used as the adsorbent, the moisture amount in the refrigerant cannot efficiently be lowered.
In contrast, if the water-adsorbing resin of JP-U-H1-136862 is used as the adsorbent, the moisture permeation speed is restricted from becoming high, compared with zeolite, because the adsorption property of the resin is low when the moisture concentration is low.
However, refrigerant of R22 or R134a that is currently used for a refrigerating cycle reacts with moisture, and an inclusion compound (clathrate) is generated. The clathrate promotes the freezing in the refrigerant of the refrigerating cycle, so that it is necessary to lower the moisture concentration in the refrigerant to or below a predetermined value.
That is, when the water-adsorbing resin of JP-U-H1-136862 is used as the adsorbent, the moisture concentration cannot sufficiently be lowered because the adsorption property of the water-adsorbing resin is low in the state where the moisture concentration is low, so that freezing may be generated in the refrigerant of the refrigerating cycle.
When the water-adsorbing resin is used as the adsorbent, similarly to the case of zeolite or silica gel, it is necessary to increase the amount of the adsorbent so as to prevent the freezing in the refrigerant by raising the adsorption property in the state where the moisture concentration is low.

SUMMARY

According to a first example of the present invention, a drier for a refrigerating cycle includes an adsorbent adsorbing moisture contained in refrigerant. The refrigerant has a molecular formula of C₃H_mF_n(m=1-5, n=1−5, and m+n=6) and has one double bond in a molecular structure. The refrigerating cycle is a vapor compression refrigerating cycle through which the refrigerant flows. The adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased.
According to a second example of the present invention, a refrigerating cycle includes: a compressor that compresses and discharges refrigerant; a condenser that condenses the refrigerant flowing out of the compressor; a decompressor that decompresses the refrigerant flowing out of the condenser; an evaporator that evaporates the refrigerant decompressed by the decompressor;
and a drier having an adsorbent that adsorbs moisture contained in the refrigerant. The adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased. The drier is located in a refrigerant passage extending from a refrigerant outlet of the decompressor to a refrigerant inlet of the compressor, at a position where the refrigerant having liquid phase exists.
According to a third example of the present invention, a vapor compression refrigerating cycle includes: a condenser that condenses refrigerant; a receiver that separates the refrigerant flowing out of the condenser into gas refrigerant and liquid refrigerant and that discharges the liquid refrigerant; and a drier having an adsorbent that adsorbs moisture contained in the refrigerant. The refrigerant has a molecular formula of C₃H_mF_n(m=1−5, n=1−5, and m+n=6) and has one double bond in a molecular structure. The drier is arranged inside of the receiver. The adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic view illustrating a refrigerating cycle according to a first embodiment;

FIG. 2 is a schematic cross-sectional view illustrating a drier for the refrigerating cycle;

FIG. 3 is a front view illustrating the drier;

FIG. 4 is a result of experiment for confirming a condition at which a freezing is generated in refrigerant;

FIG. 5 is an explanatory view illustrating a moisture permeation into a refrigerant pipe of the refrigerating cycle;

FIG. 6 is a graph illustrating adsorption characteristics of adsorbents in the drier;

FIG. 7A is a graph illustrating a relationship between an elapsed time and a partial pressure of water vapor when zeolite is used as the adsorbent, and FIG. 7B is a graph illustrating a relationship between an elapsed time and a moisture permeation amount when zeolite is used as the adsorbent;

FIG. 8A is a graph illustrating a relationship between an elapsed time and a partial pressure of water vapor when a water-adsorbing resin is used as the adsorbent, and FIG. 8B is a graph illustrating a relationship between an elapsed time and a moisture permeation amount when the water-adsorbing resin is used as the adsorbent;

FIG. 9A is a graph illustrating a relationship between an elapsed time and a partial pressure of water vapor when a water-adsorbing resin is used as the adsorbent in a refrigerating cycle according to a second embodiment, and FIG. 9B is a graph illustrating a relationship between an elapsed time and a moisture permeation amount when the water-adsorbing resin is used as the adsorbent in the refrigerating cycle of the second embodiment;

FIG. 10 is a schematic view illustrating a refrigerating cycle according to a third embodiment;

FIG. 11 is a schematic cross-sectional view illustrating an accumulator of the refrigerating cycle of the third embodiment;

FIG. 12 is a graph illustrating a relationship between a temperature of refrigerant and a concentration of saturated water;

FIG. 13 is a graph illustrating a result of comparison in which an adsorption property is compared between a low pressure region and a high pressure region in the refrigerating cycle of the third embodiment;

FIG. 14 is a schematic perspective view illustrating a drier arranged in a refrigerant pipe of a low pressure region of a refrigerating cycle according to other embodiment; and

FIG. 15 is a schematic perspective view illustrating a drier arranged in an evaporator of a refrigerating cycle according to other embodiment.

DETAILED DESCRIPTION

First Embodiment

A first embodiment will be described with reference to FIGS. 1-7B.
A vapor compression refrigerating cycle according to the first embodiment is applied to an air-conditioner for a vehicle. As shown in FIG. 1, the refrigerating cycle is defined by a closed circuit having a refrigerant pipe that connects a compressor 1, a condenser 2, a temperature expansion valve 4 and an evaporator 5 in this order. The compressor 1 compresses and discharges refrigerant. Refrigerant flowing out of the compressor 1 is condensed by the condenser 2. The expansion valve 4 corresponds to a decompressor, and decompresses refrigerant flowing from the condenser 2. The evaporator 5 evaporates the refrigerant decompressed by the expansion valve 4. A part of the refrigerant pipe is constructed of a rubber hose so as to absorb vibration of the vehicle. The rubber hose has a moisture permeability.
In the refrigerating cycle of the first embodiment, refrigerant having molecular formula C₃H_mF_n(m=1−5, n=1−5, and m+n=6) and having one double bond in the molecular structure is adopted. The refrigerant of C₃H_mF_nhas a structure in a manner that a clathrate cannot be easily generated, compared with R22 or R134a which is generally (currently) used in a refrigerating cycle. The clathrate is generated by reaction with water, and promotes freezing in the refrigerant. If the clathrate is generated, the freezing becomes easy to be generated in the refrigerant inside of the expansion valve and the like.
In a case where R22 (HFC-22) or R134a (HFC-134a) is used as the refrigerant, it is important that the moisture concentration in the refrigerant is lowered as much as possible, so as not to produce the clathrate, thereby avoiding the freezing in the refrigerant.
In contrast, the refrigerant of C₃H_mF_nis used in the present embodiment. In this case, the clathrate is difficult to be generated even if the moisture concentration is high in the refrigerant, so that the freezing is difficult to be generated in the refrigerant, compared with the case of HFC-22 or HFC-134a
For example, HFO-1234yf (C₃H₂F₄: CF₃CF=CH₂) is adopted as the refrigerant of C₃H_mF_n. A global warming potential (GWP) of HFO-1234yf is low. The refrigerant may be made of only HFO-1234yf or mixed refrigerant containing HFO-1234yf.
An experiment is performed for checking the freezing generated in the refrigerant using a refrigerating cycle with refrigerant of HFC-134a and a refrigerating cycle with refrigerant of HFO-1234yf. In the experiment, the refrigerating cycles have the same construction, and an equivalent amount of moisture is input into the refrigerating cycles so as to check a generation of the freezing in the refrigerant.
As shown in FIG. 4, when 2.0 g or more amount of the moisture is input in the refrigerating cycle using HFC-134a, freezing is generated in the refrigerant. In contrast, even when about 20 g of the moisture is input in the refrigerating cycle using HFO-1234yf, freezing is not generated in the refrigerant.
Thus, the freezing is less generated in the refrigerant of the refrigerating cycle using HFO-1234yf, compared with the refrigerating cycle using HFC-134a. That is, the freezing is restricted from being generated in the refrigerant by using an adsorbent that has a low adsorption property in a state where the moisture concentration is low in the refrigerant.
The condenser 2 of FIG. 2 is attached to a chassis of the vehicle using a mount member (not shown) at a position easy to receive a running wind in an engine compartment of the vehicle. For example, the condenser 2 is located on a front side of a radiator which cools engine cooling water.
The condenser 2 integrally has a receiver 3 that separates refrigerant flowing out of the condenser 2 into gas refrigerant and liquid refrigerant. The receiver 3 introduces the liquid refrigerant into the expansion valve 4.
The condenser 2 is a sub-cool condenser performing condensation and super-cooling by exchanging heat in a heat exchange portion 20 of the condenser 2 between the high temperature and high pressure gas refrigerant flowing out of the compressor 1 and outside air. The heat exchange portion 20 integrally has a condensation part 21 and a super-cooling part 22. The condensation part 21 is located upstream of the heat exchange portion 20 in the refrigerant flow, and the super-cooling part 22 is located downstream of the heat exchange portion 20 in the refrigerant flow.
More specifically, as shown in FIG. 2, the condensation part 21 is arranged on the upper side of the heat exchange portion 20, and the super-cooling part 22 is arranged on the lower side of the heat exchange portion 20. Each of the condensation part 21 and the super-cooling part 22 has plural tubes 201 and plural corrugated fins 202, both of which extend in a horizontal direction and are joined with each other by brazing.
The tube 201 is produced by extruding a metal material made of aluminum, for example, and has a flat ellipse cross-section. The tube 201 defines a refrigerant passage therein, and refrigerant flows through the refrigerant passage.
A cylindrical first header tank 23 is connected to longitudinal ends of the tubes 201 of the heat exchange portion 20. The first header tank 23 extends in the up-and-down direction, and the longitudinal end of the tube 201 is inserted and fitted to the first tank 23.
A cylindrical second header tank (not shown) is connected to the other longitudinal ends of the tubes 201. The second header tank extends in the up-and-down direction, and the other longitudinal end of the tube 201 is inserted and fitted to the second tank.
The first tank 23 has a partition board 231 therein so as to divide the inside space of the first tank 23 into an upper space and a lower space. The condensation part 21 is arranged in the upper space, and the super-cooling part 22 is arranged in the lower space.
The second tank has a partition board (not shown) therein so as to divide the inside space of the second tank into an upper space and a lower space. The partition board of the second header tank is located at the similar position as the partition board 231 of the first header tank 23.
The first header tank 23 has a first through hole 232 directly upper side of the partition board 231. The first through hole 232 makes the tube 201 of the condensation part 21 to communicate with the inside of the receiver 3 through the first header tank 23. In addition, as shown in an arrow direction A of FIG. 2, refrigerant is introduced into the receiver 3 through the first through hole 232 from the condensation part 21.
The first header tank 23 has a second through hole 233 directly lower side of the partition board 231. The second through hole 233 makes the tube 201 of the super-cooling part 22 to communicate with the inside of the receiver 3 through the first header tank 23. The first through hole 232 may correspond to a refrigerant inlet which introduces refrigerant into the receiver 3. The second through hole 233 may correspond to a refrigerant outlet which discharges the refrigerant from the receiver 3.
The receiver 3 is a gas-liquid separator that divides the refrigerant into gas refrigerant and liquid refrigerant and that discharges the liquid refrigerant into the super-cooling part 22.
The receiver 3 has a based cylindrical tank 31 and a tank cap 32 (lid part). The tank 31 extends in the up-and-down direction, and has an opening 31 a on the lower end. The tank cap 32 closes the opening 31 a of the tank 31.
The first through hole 232 is located on the upper side of the second through hole 233, so that the refrigerant flows from the upper side to the lower side in the tank 31. The opening 31 a of the tank 31 has a female thread part threaded with a male thread part 321 defined on an outer circumference of the tank cap 32. The tank 31 is sealed by fitting the tank cap 32 to the opening 31 a.
As shown in FIG. 3, the tank cap 32 has a filter holder 323 on the upper side of the male thread part 321. A side face of the holder 323 has a frame that holds a filter 322. The filter 322 removes foreign matters such as dust from the refrigerant. In addition, as shown in an arrow direction B of FIG. 2, the liquid refrigerant is drawn from the receiver 3 to the super-cooling part 22 through the filter 322 and the second through hole 233.
A drier 10 for the refrigerating cycle is arranged in the receiver 3, and has an adsorbent 11 that adsorbs moisture contained in the refrigerant. The drier 10 has an accommodation bag 12 which accommodates the adsorbent 11.
The drier 10 is located in a lower end portion of the receiver 3 through which the liquid refrigerant flows so as to efficiently adsorb the moisture contained in the refrigerant. If a large amount of the liquid refrigerant retains in the receiver 3, the drier 10 may float on the liquid face of the refrigerant. According to the present embodiment, the drier 10 is integrally arranged on the upper side of the filter holder 323 of the tank cap 32 so as to prevent the floating.
Because a part of the refrigerant pipe is made of the rubber hose, moisture may permeate the rubber hose from outside, as shown in FIG. 5.
Moisture permeates the refrigerating cycle with a permeation speed W_H. The permeation speed W_His generally proportional to a difference (Pwout-Pwin) between a partial pressure Pmin of water vapor in the refrigerant and a partial pressure Pwout of water vapor in atmospheric air, as shown in the following formula F1.
W _H =k _H ×L×(Pwout−Pwin) (F1)
k_Hrepresents a moisture permeation coefficient, and L represents a length of the pipe having the moisture permeation.
The partial pressure Pwin in the refrigerant is generally proportional to a moisture concentration X in the refrigerant (X∝Pwin). If the moisture concentration X is low, the difference between the partial pressure Pwin in the refrigerant and the partial pressure Pwout in atmospheric air is increased. At this time, the moisture permeation speed W_His raised, and the amount of moisture permeating from outside is increased.
By focusing on the change in the moisture permeation speed W_H, an adsorbent having characteristics that a lowering degree of moisture adsorption rate is increased as a relative humidity of the refrigerant is lowered is suitable for the adsorbent 11 of the drier 10. In other words, the adsorbent 11 has characteristics that an increasing degree (gradient) in the moisture adsorption rate is increased as the relative humidity is increased, which is seen in a region where the relative humidity is high in FIG. 6. While the moisture adsorption rate of the adsorbent 11 is low in a region where the relative humidity is low, the moisture adsorption rate is increased as the moisture in the refrigerant is increased so as to be saturated.
In the present embodiment, a water-adsorbing resin having high water-adsorbing property is adopted as the adsorbent 11 of the drier 10. The water adsorbing resin has the adsorption characteristics shown in a solid line of FIG. 6. In FIG. 6, a single chain line represents the adsorption characteristics of zeolite (molecular sieve), and a double chain line represents the adsorption characteristics of silica gel.
As shown in FIG. 6, zeolite and silica gel have high adsorption property in a state where the moisture concentration is low in the refrigerant. In contrast, the water-adsorbing resin has low adsorption property in the state where the moisture concentration is low in the refrigerant.
Therefore, the moisture permeation speed W_Hcan be restricted from increasing by adopting the water-adsorbing resin as the adsorbent 11, compared with the case where zeolite or silica gel is adopted. Thus, the amount of moisture permeating from outside can be restricted from increasing when the water-adsorbing resin is adopted.
Moreover, the adsorption capacity of the water-adsorbing resin is large in a state where the humidity is high, compared with zeolite or silica gel. Therefore, the moisture in the refrigerant can be adsorbed without increasing the amount of the resin filled in the drier 10. Specifically, the water-adsorbing resin may be made of hydrophilic polymer used as a sanitary material such as disposable diaper or feminine sanitary item, for example.
The accommodation bag 12 of the drier 10 may be made of polyamide synthetic fiber, and has a mesh sate that allows the moisture in the refrigerant to permeate the bag 12. An opening of the bag 12 used for accommodating the adsorbent 11 is closed using a method of heat sealing, for example.
Operation of the refrigerating cycle will be described below.
When the air-conditioner is started, refrigerant is discharged out of the compressor 1. The high-temperature and high-pressure refrigerant discharged from the compressor 1 flows into the condensation part 21 in the heat exchange portion 20 through the second header tank. Heat is exchanged between the refrigerant in the condensation part 21 and air outside of the passenger compartment, so that the refrigerant is condensed by being cooled. Thus, the refrigerant becomes saturated liquid refrigerant which partially contains gas phase refrigerant. The saturated liquid refrigerant is introduced into the receiver 3 through the first header tank 23 and the first through hole 232, and is separated into gas refrigerant and liquid refrigerant in the receiver 3. Further, the moisture in the refrigerant is adsorbed by the adsorbent 11 of the drier 10, in the receiver 3.
After the filter 322 removes foreign matters from the liquid refrigerant in the receiver 3, the refrigerant is drawn to the super-cooling part 22 through the second through hole 233 and the first header tank 23. The refrigerant is cooled again (super-cooled) in the super-cooling part 22.
The refrigerant super-cooled in the super-cooling part 22 of the condenser 2 is decompressed by the expansion valve 4 and flows into the evaporator 5. The refrigerant flowing into the evaporator 5 is evaporated by absorbing heat from air to be blown into the passenger compartment. The evaporated refrigerant is again drawn and compressed by the compressor 1.
Advantages obtained in the case where the water-adsorbing resin is used as the adsorbent 11 will be explained by comparing with the case where zeolite is used as an adsorbent.
If the water-adsorbing resin of 2 g is used as the adsorbent, the maximum adsorption capacity of the water-adsorbing resin is 20 g (ten times of the self weight). If zeolite of 40 g is used as the adsorbent, the maximum adsorption capacity is 8 g (0.2 times of the self weight).
FIGS. 7A and 7B explain a moisture permeation action when zeolite is used as the adsorbent. FIG. 7A shows a change of the partial pressure of water vapor in refrigerant and atmospheric air, and FIG. 7B shows a change in the moisture permeation amount.
FIGS. 8A and 8B explain a moisture permeation action when the water-adsorbing resin is used as the adsorbent. FIG. 8A shows a change of the partial pressure of water vapor in refrigerant and atmospheric air, and FIG. 8B shows a change in the moisture permeation amount.
As shown in FIG. 7B, when zeolite is used as the adsorbent, before the moisture permeation amount exceeds the maximum adsorption capacity (8 g), the moisture in the refrigerant is adsorbed by zeolite, so that the partial pressure of water vapor in the refrigerant becomes low in the initial stage, as shown in FIG. 7A. As a result, the moisture permeation speed becomes high, and the moisture permeation amount is increased.
When the moisture permeation amount exceeds the maximum adsorption capacity (8 g) in FIG. 7B, the moisture in the refrigerant is not adsorbed by zeolite, and the partial pressure of water vapor in the refrigerant is raised in FIG. 7A. As a result, the partial pressure of water vapor in the refrigerant becomes high, and the moisture permeation speed becomes slow.
When the moisture permeation amount exceeds the maximum adsorption capacity (8 g) in FIG. 7B, the moisture dissolved in the refrigerating cycle is precipitated, and may be separated from the refrigerant. If the precipitated moisture remains in the refrigerating cycle, the freezing becomes easy to be generated in the refrigerant of the refrigerating cycle.
In contrast, when the water-adsorbing resin is used as the adsorbent, the adsorption property is low in the state where the moisture concentration is low in the refrigerant, compared with zeolite, so that the partial pressure of water vapor in the refrigerant becomes high in the initial stage of FIG. 8A. As a result, the moisture permeation speed is slow, and the moisture permeation amount is restricted from increasing, as shown in FIG. 8B.
Moreover, the maximum adsorption capacity (20 g) of the water-adsorbing resin is larger than that (8 g) of zeolite. Therefore, even if the moisture dissolved in the refrigerating cycle is precipitated and separated from the refrigerant, the precipitated moisture can be adsorbed by the water-adsorbing resin. Thus, the freezing can be restricted from being generated in the refrigerant of the refrigerating cycle, and components of the refrigerating cycle can be restricted from having internal corrosion.
Furthermore, when the water-adsorbing resin is used as the adsorbent, compared with the case of zeolite, the volume of the adsorbent occupied in the receiver 3 can be reduced. Therefore, the size of the adsorbent can be reduced in the receiver 3.
According to the first embodiment, in the refrigerating cycle through which HFO-1234yf (C₃H₂F₄) flows as the refrigerant, the resin having the high water-adsorbing property is used as the adsorbent 11. As the relative humidity is raised, the increasing degree in the adsorption rate of the moisture is increased, as the characteristics of the resin.
Therefore, freezing can be restricted from being generated in the refrigerant, while the amount of the adsorbent 11 filled in the drier 10 is restricted from increasing. Moreover, because the moisture permeation speed is restricted from increasing, compared with zeolite, the amount of the moisture in the refrigerant can be reduced efficiently.
When the resin absorbs the moisture, the resin becomes to have gel state. If the water-adsorbing resin is simply arranged in the refrigerating cycle, the gel-state water-adsorbing resin may circulate through the refrigerating cycle.
According to the present embodiment, the drier 10 has the mesh-state accommodation bag 12 accommodating the water-adsorbing resin. Even if the water-adsorbing resin becomes to have the gel state, the gel-state water-adsorbing resin is restricted from circulating through the refrigerating cycle by the bag 12.
The water-adsorbing resin is disposed in the lower end portion of the tank 31 of the receiver 3, and is located on the upper part of the filter holder 323 of the tank cap 32. Therefore, the moisture contained in the liquid refrigerant retained in the receiver 3 can be adsorbed efficiently.
The present invention is especially effective when being applied to the air-conditioner for the vehicle in which a part of the refrigerant pipe is made of the material having the water permeability. In this case, the moisture permeation amount is large, so that it is necessary to select the adsorbent 11 by considering the moisture permeation amount.

Second Embodiment

A second embodiment will be described with reference to FIGS. 9A and 9B.
In the second embodiment, the accommodation bag 12 which accommodates the water-adsorbing resin is made of film, and water vapor can permeate the film. Only the water vapor in the liquid refrigerant is adsorbed using the moisture absorption action of the water-adsorbing resin.
An advantage of the second embodiment will be described using an example in which the water-adsorbing resin of 10 g is used as the adsorbent. The maximum adsorption capacity of the water-adsorbing resin is 10 g (the same as the self weight).
FIGS. 9A and 9B explain a moisture permeation action when the water-adsorbing resin is used as the adsorbent. FIG. 9A shows a change of the partial pressure of water vapor in refrigerant and atmospheric air, and FIG. 9B shows a change in the moisture permeation amount.
As shown in FIGS. 9A and 9B, when the moisture (water vapor) dissolved in the refrigerant is adsorbed by the water-adsorbing resin, the amount of moisture dissolved in the refrigerant is reduced, so that the moisture dissolved in the refrigerating cycle becomes difficult to be precipitated. Thus, the freezing can be restricted from being generated in the refrigerant of the refrigerating cycle, because the moisture is restricted from being precipitated in the refrigerating cycle, so that components of the refrigerating cycle can be restricted from having internal corrosion.
According to the second embodiment, the accommodation bag 12 which accommodates the water-adsorbing resin is made of film, and water vapor can permeate the film. Therefore, only the water vapor is adsorbed by the resin, so that the resin is restricted from becoming the gel state.

Third Embodiment

A third embodiment is described with reference to FIGS. 10-13. As shown in FIG. 10, the refrigerating cycle has an accumulator 6 located between the evaporator 5 and the compressor 1 in the refrigerant flow.
The decompressor is constructed by a fixed throttle 4 such as capillary tube or orifice, instead of the temperature expansion valve of the first embodiment.
A high pressure region is defined by a refrigerant passage extending from a refrigerant outlet of the compressor 1 to a refrigerant inlet of the fixed throttle 4. A low pressure region is defined by a refrigerant passage extending from a refrigerant outlet of the fixed throttle 4 to a refrigerant inlet of the compressor 1.
The accumulator 6 is a separator separating the refrigerant flowing out of the evaporator 5 into gas refrigerant and liquid refrigerant. The accumulator 6 stores the liquid refrigerant, and discharges the gas refrigerant to the refrigerant inlet of the compressor 1.
As shown in FIG. 11, the accumulator 6 has a tank 60, a separator 61, and a pipe 62 constructed by a double tube having an internal pipe 62 a and an external pipe 62 b coaxially arranged with each other. The separator 61 has an umbrella shape, and divides the liquid refrigerant and the gas refrigerant inside the tank 60. The pipe 62 introduces the gas refrigerant to the refrigerant inlet of the compressor 1.
The tank 60 has a based cylinder shape, and has an inlet 60 a and an outlet 60 b in the upper face of the tank 60. Refrigerant flowing out of the evaporator 5 is introduced into the tank 60 through the inlet 60 a. The outlet 60 b is connected to the internal pipe 62 a, and the gas refrigerant is discharged from the tank 60 through the outlet 60 b to the refrigerant inlet of the compressor 1.
Thereby, the gas-liquid refrigerant flowing into the accumulator 6 through the inlet 60 a is separated into the gas refrigerant and the liquid refrigerant by the separator 61. The liquid refrigerant is stored in a storage part 60 c located on the lower side of the tank 60. The gas refrigerant flows through the pipe 62, and is drawn to the refrigerant inlet of the compressor 1 through the outlet 60 b. A filter 63 for removing sludge from oil contained in the refrigerant is arranged in the lower part of the pipe 62.
FIG. 12 is a characteristics view showing a relationship between temperature of the refrigerant and concentration of saturated moisture in the refrigerant. As shown in FIG. 12, the concentration of saturated moisture in the refrigerant is raised as the temperature of the refrigerant is raised.
In the refrigerating cycle, the concentration of saturated moisture becomes low in the low pressure region, compared with the high pressure region. For example, the temperature of the refrigerant is 20° C. or less in the low pressure region. The relative humidity of the refrigerant corresponds to a ratio of an average moisture concentration in the refrigerating cycle to the concentration of saturated moisture. Therefore, the relative humidity becomes high in the low pressure region where the temperature of the refrigerant is low, compared with the high pressure region.
In addition, the concentration of saturated moisture is low in the liquid refrigerant, compared with the gas refrigerant, so that the relative humidity of the liquid refrigerant becomes high compared with the gas refrigerant.
According to the present embodiment, by considering the above characteristics, the adsorbent 11 constructed by the water-adsorbing resin is arranged in the low pressure region at a position where the liquid refrigerant exists. As the relative humidity is raised, the increasing degree in the moisture adsorption rate is increased in the water-adsorbing resin. Specifically, as shown in FIG. 11, the drier 10 is arranged in the storage part 60 c of the accumulator 6.
FIG. 13 shows a comparison of the adsorption property of the adsorbent between the low pressure region and the high pressure region of the refrigerating cycle. As shown in FIG. 13, when the adsorbent 11 is arranged in the low pressure region of the refrigerating cycle, the adsorption property of the adsorbent 11 is higher than that in the case where the adsorbent 11 is arranged in the high pressure region.
In addition, the adsorption property represented by an ordinate axis of FIG. 13 corresponds to a ratio of an adsorption property in the refrigerating cycle to an adsorption property in atmospheric air. As the value of the ratio becomes high, the adsorption property becomes high.
According to the third embodiment, the drier 10 is arranged in the accumulator 6 in the low pressure region of the refrigerating cycle. Therefore, the amount of moisture contained in the refrigerant can be more efficiently reduced, compared with the first embodiment.
The drier 10 may be integrated with the filter 63 that is arranged in the lower end portion of the tank 60 of the accumulator 6, for example. The decompressor is not limited to the fixed throttle 4. The decompressor may be a valve having a variable throttle mechanism, for example.

Other Embodiments

The present invention is not limited to the above embodiments.
The adsorbent 11 is not limited to the water-adsorbing resin. Alternatively, a fiber having high moisture (water vapor) absorption property or a fiber having high water adsorption property may be used as the adsorbent 11, if the fiber has the same property as the water-adsorbing resin.
The refrigerant is not limited to HFO-1234yf. For example, HFO-1234ze (C₃H₂F₄: CF₃CH=CHF) may be used as the refrigerant, because HFO-1234z8 has a structure where a clathrate cannot be easily generated by the reaction with water, similar to HFO-1234yf. Moreover, the refrigerant may be made of a mixture of HFO-1234yf and HFO-1234ze.
In the third embodiment, the adsorption property of the adsorbent 11 of the drier 10 is markedly raised, so that refrigerant may be R22 or R134a which has the structure where a clathrate is easily generated, for example.
The drier 10 is not limited to be arranged inside of the accumulator 6 in the third embodiment. The drier 10 is just arranged in the low pressure region of the refrigerating cycle at a position where the liquid refrigerant exists.
For example, the drier 10 may be arranged in the refrigerant passage extending from the refrigerant outlet of the fixed throttle 4 to the refrigerant inlet of the evaporator 5, or may be arranged inside the evaporator 5. These arrangements are effective for being applied in a refrigerating cycle not having the accumulator 6.
If the drier 10 is arranged in the refrigerant passage extending from the refrigerant outlet of the fixed throttle 4 to the refrigerant inlet of the evaporator 5, for example, as shown in FIG. 14, a part of the refrigerant pipe has an enlarged part between the fixed throttle 4 and the evaporator 5, and the drier 10 is arranged in the enlarged part.
Moreover, if the drier 10 is arranged inside the evaporator 5, as shown in FIG. 15, the drier 10 may be arranged in a header tank 50 of the evaporator 5 into which the refrigerant flows from the fixed throttle 4.
The adsorbent 11 is not limited to be accommodated in the mesh bag or the film bag. Alternatively, the adsorbent 11 may be accommodated in the accommodation bag 12 made of felt.
The drier 10 may be arranged in the refrigerant pipe without being accommodated in the bag 12.
The accommodation bag 12 may be closed by a method other than the heat sealing. A downstream end of the accommodation bag 12 may be closed while an upstream end of the bag 12 is opened in the refrigerant flow.
The condenser 2 and the receiver 3 may be separated from each other.
The condenser 2 is not limited to the sub-cool condenser. Alternatively, the drier 10 may be applied to a condenser having a condensation part 21 in a heat exchange portion 20.
The air-conditioner is not limited to perform the cooling by using the evaporator 5. Alternatively, the air-conditioner may perform a heating using the condenser 2, or both of the cooling and the heating may be performed by switching a refrigerant circuit of the refrigerating cycle.
The present invention may be applied to a refrigerating cycle (heat pump cycle) used for a heating device for a vehicle, a stationary type hot water supplier or indoor heating device.
Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.

Claims

1. A drier for a refrigerating cycle comprising:

an adsorbent adsorbing moisture contained in refrigerant, the refrigerant having a molecular formula of C₃H_mF_n(m=1−5, n=1−5, and m+n=6) and having one double bond in a molecular structure, the refrigerating cycle being a vapor compression refrigerating cycle through which the refrigerant flows, wherein

the adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased.

2. The drier according to claim 1, wherein

the adsorbent is made of water-adsorbing resin having high water-adsorbing property.

3. The drier according to claim 2, further comprising:

an accommodation bag accommodating the water-adsorbing resin, wherein the accommodation bag has a mesh state that allows the moisture to permeate the accommodation bag.

4. The drier according to claim 2, further comprising:

an accommodation bag accommodating the water-adsorbing resin, wherein the accommodation bag has a film state that allows a water vapor to permeate the accommodation bag.

5. The drier according to claim 2, further comprising:

an accommodation bag accommodating the water-adsorbing resin, wherein the accommodation bag is made of felt.

6. The drier according to claim 1, wherein

the adsorbent is made of a fiber having high moisture-adsorbing property.

7. The drier according to claim 1, wherein

the adsorbent is made of a fiber having high water-adsorbing property.

8. The drier according to claim 1, wherein

the refrigerant is HFO-1234yf.

9. A refrigerating cycle comprising:

a compressor that compresses and discharges refrigerant;

a condenser that condenses the refrigerant flowing out of the compressor;

a decompressor that decompresses the refrigerant flowing out of the condenser;

an evaporator that evaporates the refrigerant decompressed by the decompressor; and

a drier having an adsorbent that adsorbs moisture contained in the refrigerant, wherein

the adsorbent has adsorption characteristics in which an increasing degree of a moisture-adsorbing rate is increased as a relative humidity is increased, and

the drier is located in a refrigerant passage extending from a refrigerant outlet of the decompressor to a refrigerant inlet of the compressor, at a position where the refrigerant having liquid phase exists.

10. The refrigerating cycle according to claim 9, wherein

the refrigerant has a molecular formula of C₃H_mF_n(m=1−5, n=1−5, and m+n=6) and has one double bond in a molecular structure.

11. The refrigerating cycle according to claim 9, further comprising:

an accumulator that separates the refrigerant flowing out of the evaporator into gas refrigerant and liquid refrigerant and that discharges the gas refrigerant into the refrigerant inlet of the compressor, and

the drier is arranged inside of the accumulator.

12. The refrigerating cycle according to claim 9, wherein

the drier is located in a refrigerant passage extending from the refrigerant outlet of the decompressor to a refrigerant inlet of the evaporator.

13. The refrigerating cycle according to claim 9, wherein

the drier is arranged inside of the evaporator.

14. A refrigerating cycle comprising:

a condenser that condenses refrigerant;

a receiver that separates the refrigerant flowing out of the condenser into gas refrigerant and liquid refrigerant and that discharges the liquid refrigerant; and

the refrigerant has a molecular formula of C₃H_mF_n(m=1−5, n=1−5, and m+n=6) and has one double bond in a molecular structure,

the drier is arranged inside of the receiver, and

15. The refrigerating cycle according to claim 14, wherein

the receiver has

a based cylindrical tank portion extending in an up-and-down direction and having an opening at a lower end, and

a cover portion closing the opening,

the tank portion has a refrigerant outlet and a refrigerant inlet that is located on an upper side of the refrigerant outlet in a manner that the refrigerant flows from the upper side to a lower side, and

the drier is located on the lower side in the tank portion.

16. The refrigerating cycle according to claim 15, wherein

the drier is integrated with the cover portion.

17. The refrigerating cycle according to claim 9, wherein the adsorbent is made of water-adsorbing resin having high water-adsorbing property.

18. The refrigerating cycle according to claim 17, further comprising:

19. The refrigerating cycle according to claim 17, further comprising:

20. The refrigerating cycle according to claim 17, further comprising:

21. The refrigerating cycle according to claim 9, wherein

the adsorbent is made of a fiber having high moisture-adsorbing property.

22. The refrigerating cycle according to claim 9, wherein

the adsorbent is made of a fiber having high water-adsorbing property.

23. The refrigerating cycle according to claim 9, wherein

the refrigerant is HFO-1234yf.

24. The refrigerating cycle according to claim 9, wherein

the refrigerant flows through a refrigerant pipe, and

a part of the refrigerant pipe is made of a material having a moisture permeability.