Heat exchanger utilizing device to vary cross section of header

A heat exchanger that effectively distributes a refrigerant by varying the cross-sectional area of a header and an air conditioner having the same. The heat exchanger includes a plurality of refrigerant tubes disposed spaced apart from each other, a header joined to both ends of each of the refrigerant tubes, at least one baffle to divide the refrigerant tubes into a plurality of mutually adjacent groups and block a longitudinal flow of a refrigerant flowing in the header, each of the groups causing the refrigerant to flow in one direction, and a booster installed to vary a cross-sectional area of the header to uniformly distribute the refrigerant to refrigerant tubes in the same group among the refrigerant tubes. The booster to vary the cross-sectional area of the header may allow a refrigerant flowing through a header to be effectively distributed to the refrigerant tubes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2013-0125406, filed on Oct. 21, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Embodiments of the present disclosure relate to a heat exchanger that effectively distributes a refrigerant by varying the cross-sectional area of a header and an air conditioner having the same.

2. Description of the Related Art

An air conditioner generally uses a refrigeration cycle to adjust temperature, humidity, airflow direction and air distribution, and also removes dust from the air to provide an environment suitable for humans. Main constituents configuring the refrigeration cycle include a compressor, a condenser, an evaporator, an expansion valve, and a fan.

Air conditioners may be classified into split type air conditioners having an indoor unit and an outdoor unit separately installed, and integrated type air conditioners having an indoor unit and an outdoor unit installed together in one cabinet. For a split type air conditioner, the indoor unit thereof includes a heat exchanger to exchange heat with air suctioned through a panel, and a fan to suction the indoor air and blow the suctioned air out to the indoor space.

A heat exchanger, a device constituting an air conditioner, may function as a condenser or an evaporator. The heat exchanger may be provided with a refrigerant pipe to guide a refrigerant, and the refrigerant pipe may be coupled to multiple heat exchange fins to increase heat exchange efficiency.

A heat exchanger having a microchannel refrigerant tube is known to have a better heater transfer property than other types of heat exchangers, and is thus used for air conditioners. However, since the refrigerant undergoes phase change as it flows along the microchannel refrigerant tube, the refrigerant may not be uniformly distributed throughout the refrigerant tube.

Moreover, ineffective distribution of the refrigerant throughout the refrigerant tube may prevent complete use of the refrigerant tube provided to the heat exchanger. As a result, the heat exchange efficiency and performance of the heat exchanger may be degraded, and the air conditioner may not be optimally operated.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a heat exchanger that may effectively distribute a refrigerant to a plurality of refrigerant tubes, and an air conditioner having the same.

Another aspect of the present disclosure is to provide a heat exchanger provided, at one side of a header, with a booster to vary the cross-sectional area of the header, and an air conditioner having the same.

In accordance with one aspect of the present disclosure, a heat exchanger includes a plurality of refrigerant tubes disposed spaced apart from each other, a header joined to both ends of each of the refrigerant tubes, at least one baffle to divide the refrigerant tubes into a plurality of mutually adjacent groups and block a longitudinal flow of a refrigerant flowing in the header, each of the groups causing the refrigerant to flow in one direction, and a booster installed to vary a cross-sectional area of the header to uniformly distribute the refrigerant to refrigerant tubes in the same group among the refrigerant tubes.

The booster may include a casing installed at one side of the header, a blocking plate positioned inside the casing and installed to be movable into the header, and an elastic unit to elastically bias the blocking plate.

The blocking plate may be positioned at a location where the refrigerant tubes are divided into different groups.

The booster may include an introduction port connecting the header to the casing to allow the refrigerant flowing in the header to enter the casing.

The booster may further include a connection plate to move according to introduction of the refrigerant into the casing through the introduction port, wherein one side of each of the blocking plate and the elastic unit may be fixed to the connection plate such that the blocking plate and the elastic unit move along with the connection plate.

The booster may further include a guide plate installed inside the casing in a protruding manner to allow the refrigerant introduced through the introduction port to apply pressure to the connection plate to cause the connection plate to stably move.

The booster may include a guide protrusion positioned at upper and lower portions of the blocking plate and protruding into the header to allow the blocking plate to stably move.

In accordance with another aspect of the present disclosure, an air conditioner includes a compressor to compress and discharge a gaseous refrigerant, an expansion valve to expand a condensed liquid refrigerant, and a heat exchanger provided with a plurality of refrigerant tubes disposed spaced apart from each other and a header joined to both ends of each of the refrigerant tubes, wherein the header may include at least one baffle to block a longitudinal flow of a refrigerant flowing in the header and a booster installed to vary a cross-sectional area of the header.

The booster may include a blocking plate installed to move using pressure of the refrigerant flowing in the header.

The booster may further include an elastic unit to elastically bias the blocking plate.

The blocking plate may be positioned at one side of the header and arranged between the refrigerant tubes disposed spaced apart from each other.

DETAILED DESCRIPTION

FIG. 1is a view illustrating a refrigerant cycle of air conditioner according to one embodiment of the present disclosure.

A refrigerant cycle constructing the air conditioner1includes a compressor7, a condenser, an expansion valve3, and an evaporator. The refrigerant cycle may cause a refrigerant circulating through a series of processes of compression, condensation, expansion, and evaporation to exchange heat with air to supply conditioned air to the indoor space.

The compressor7compresses a gaseous refrigerant to a high temperature and a high pressure and then discharges the same. The discharged gaseous refrigerant is introduced into the condenser. The condenser may condense the compressed refrigerant into liquid and dissipate heat into surroundings through the condensation process, thereby achieving heating.

The expansion valve3expands the liquid refrigerant of high temperature and high pressure produced through condensation in the condenser such that the liquid refrigerant of lower pressure is produced. The evaporator evaporates the refrigerant having expanded through the expansion valve3, and returns the gaseous refrigerant of lower temperature and low pressure to the compressor7. The evaporator may achieve cooling effect through heat exchange with an object to be cooled using the latent heat of evaporation of the refrigerant. Through such refrigeration cycle, the air conditioner1may adjust the temperature of air in an indoor space.

The outdoor unit200aof the air conditioner1is a part of the refrigeration cycle provided with a compressor7and an outdoor heat exchanger5a. The expansion valve3may be arranged in one of the indoor unit200band the outdoor unit200a, and the indoor heat exchanger5bmay be arranged in the indoor unit200bof the air conditioner1.

The indoor heat exchanger5band the outdoor heat exchanger5amay be the same type of heat exchangers5. When the refrigerant changes from gas to liquid, the heat exchangers5may be used as condensers. When the refrigerant changes from liquid to gas, the heat exchangers5may be used as evaporators. Each of the outdoor heat exchanger5aand the indoor heat exchanger5bmay be used as one of the condenser and the evaporator. In the case that the outdoor heat exchanger5afunctions as a condenser, the indoor heat exchanger5bis used as an evaporator. In the case that the outdoor heat exchanger5afunctions as an evaporator, the indoor heat exchanger5bmay be used as a condenser.

The refrigerant cycle indicated by a solid line inFIG. 1represents a cooling cycle of cooling the indoor space. In this cycle, the outdoor heat exchanger5aserves as a condenser, and the indoor heat exchanger5bserves as an evaporator. The refrigerant compressed into a high-temperature and high-pressure gaseous refrigerant by the compressor7is introduced into the outdoor heat exchanger5a. The outdoor heat exchanger5aserves as a condenser to condense the gaseous refrigerant into a liquid refrigerant and dissipate the produced heat to the indoor air. After the outdoor heat exchanger5a, the liquid refrigerant expands at the expansion valve3and flows into the indoor heat exchanger5b. The indoor heat exchanger5bevaporates the liquid refrigerant in a gaseous refrigerant, absorbing heat from the indoor air to cool the indoor space.

The refrigerant cycle indicated by a dotted line inFIG. 1represents a heating cycle of heating the indoor space. In this cycle, the outdoor heat exchanger5aserves as an evaporator, and the indoor heat exchanger5bserves as a condenser. In this cycle, the refrigerant moves in the direction opposite to that of movement of the refrigerant in the refrigeration cycle indicated by the solid line. The gaseous refrigerant leaving the compressor7is introduced into the indoor heat exchanger5b. Accordingly, the indoor heat exchanger5bmay dissipate heat into indoor air to heat the indoor space. The indoor heat exchanger5bcondenses the gaseous refrigerant into liquid refrigerant and sends the condensed refrigerant to the expansion valve3. After passing through the expansion valve3, the refrigerant undergoes phase change in the outdoor heat exchanger5band turns into gaseous refrigerant.

A refrigerant diversion unit60may divert the direction of flow of the refrigerant such that the refrigerant cycle is used as a heating cycle and a cooling cycle. The refrigerant diversion unit60allows the refrigerant to flow clockwise or counterclockwise, and accordingly the air conditioner1may be used as a cooling/heating air conditioner for both cooling and heating of the indoor air. The refrigerant diversion unit60may be disposed between the compressor7and the outdoor heat exchanger5a. The refrigerant diversion unit60may be arranged adjacent to the compressor7, which is the most influential part of the refrigerant cycle of the air conditioner1, to more easily divert the flow direction of the refrigerant.

FIG. 2is a view illustrating a heat exchanger5according to one embodiment of the present disclosure.

The heat exchanger5includes a plurality of refrigerant tubes20spaced apart from each other and headers41and42coupled to both ends of each of the refrigerant tubes20. Refrigerant pipes43and44connected to another refrigerant cycle unit to allow inflow and outflow of the refrigerant therethrough may be joined to one side of the headers41and42.

The headers41and42may include a first header41and a second header42joined to both ends of each of the refrigerant tubes20. The refrigerant pipes43and44may include a first refrigerant pipe43installed at one side of the upper portion of the second header42and a second refrigerant pipe44installed at one side of the lower portion of the second header42. One side of the first refrigerant pipe43may be connected to the compressor7, and one side of the second refrigerant pipe44may be connected to the expansion valve3.

In the case that the refrigerant is introduced through the first refrigerant pipe43and discharged through the second refrigerant pipe44, the heat exchanger5may function as a condenser. On the other hand, in the case that the refrigerant is introduced through the second refrigerant pipe44and discharged through the first refrigerant pipe43, the heat exchanger5may function as an evaporator.FIG. 2shows a heat exchanger5used as an evaporator in which the refrigerant is introduced through the second refrigerant pipe44for heat exchange and discharged through the first refrigerant pipe43.

The first header41and the second header42are joined to both ends of each of the refrigerant tubes20. The refrigerant may flow along the refrigerant tubes20communicating with each other through the first header41and the second header42. The refrigerant tubes20extend as long as possible to increase the area for heat exchange between the refrigerant and the external air, but extension thereof in a longitudinal direction is spatially restricted. Accordingly, the first header41and the second header42may be provided with baffles50a,50,50cjoined to both ends of the refrigerant tubes20to divert the refrigerant.

At least one of the baffles50a,50b,50cmay be installed to block the longitudinal flow of the refrigerant flowing in the headers41and42. The baffles50a,50b,50cmay be installed in the first header41and the second header42and spaced a certain distance from each other. As shown inFIG. 2, the baffles50a,50b,50cmay be alternately arranged in the first header41and the second header42to allow the refrigerant to flow along the refrigerant tubes20in alternating directions and then pass through the heat exchanger5. By the baffles50a,50b,50cdiverting the flow direction of the refrigerant, refrigerant tubes20may be divided into a plurality of adjacent groups. In the refrigerant tubes from the same group, the refrigerant flows in the same direction.

A first direction A is defined as the direction in which the refrigerant is directed from the second header42toward the first header41, and a second direction B is defined as the direction in which the refrigerant is directed from the first header41to the second header42. As shown inFIG. 2, the refrigerant introduced through the second refrigerant pipe44flows through the refrigerant tubes20in the first direction A. The first baffle50apositioned in the second header42causes the refrigerant to move along the refrigerant tubes20in the first direction A without flowing to the upper portion of the second header42. After moving to the first header41positioned at the end of the path in the first direction A, the refrigerant is introduced into the first header41by pressure, and then caused to flow in the second direction B by the second baffle50bpositioned in the first header41.

The refrigerant flowing in the second direction B moves again to the second header42, and is prevented from moving to the lower portion of the second header42by the first baffle50a. The third baffle50cpositioned over the first baffle50ain the second header42may divert the refrigerant again to the first direction A. That is, in the inner space of the second header having the lower portion closed by the first baffle50aand the upper portion closed by the third baffle50c, the refrigerant enters the inner space in the second direction B and leaves the space in the first direction A. Flowing out of the second header42in the first direction A, the refrigerant enters the first header41and is prevented from flowing downward by the second baffle50b. The refrigerant diverted by the closed end portion41aof the first header41flows in the second direction B and leaves the first header41through the first refrigerant pipe43.

The number and positions of the baffles positioned in the first header41and the second header42are selectable. The baffles may be alternately positioned in the first header41and the second header42such that the refrigerant moves alternately in the first direction A and the second direction B.

The refrigerant tubes20of the heat exchanger5shown inFIG. 2may be divided, by the baffles50a,50b,50c, into four groups in which the refrigerant flows in the first direction A or the second direction B. A group of the refrigerant tubes in which the refrigerant introduced into the heat exchanger5through the second refrigerant pipe44flows in the first direction A is defined as a first group a. In sequential order of flow directions of the refrigerant, the other refrigerant tubes may be divided into a second group b having the refrigerant flowing in the second direction B, a third group having the refrigerant in the first direction A, and the fourth group d having the refrigerant flowing to the first refrigerant pipe43in the second direction B.

The refrigerant introduced through the second refrigerant pipe44in a liquid state changes to gas through heat exchange and flows out to the first refrigerant pipe43as a gaseous refrigerant. On the other hand, when refrigerant is introduced through the first refrigerant pipe43and discharged to the second refrigerant pipe44, the refrigerant undergoes phase change from gas to liquid.

Since the liquid refrigerant has a smaller volume than a gaseous refrigerant of the same mass, the number of refrigerant tubes20mostly containing liquid refrigerant may be set to be small. That is, the same amount of refrigerant flows through the refrigerant tubes20of each group to perform heat exchange, but the first group a in which a major portion of the refrigerant flowing through the refrigerant tubes20is liquid refrigerant has a smaller number of refrigerant tubes20. On the other hand, the fourth group d in which a major portion of the refrigerant flowing through the refrigerant tubes20is gaseous refrigerant has the greatest number of refrigerant tubes20among all groups. The heat exchanger5is disposed such that the number of refrigerant tubes20increases in order from the first group a to the fourth group.

FIG. 3is a view illustrating the refrigerant tubes20of the heat exchanger5according to one embodiment of the present disclosure.

The refrigerant tubes20include a plurality of flow channels21hollowed to allow the fluid refrigerant to flow therethrough, and partition walls22to divide the flow channels21. The flow channels21are spaced apart from each other in the widthwise direction of the refrigerant tubes20.

Microchannel refrigerant tube may be used as the refrigerant tubes20. The microchannel refrigerant tubes20are tubes whose hydraulic diameter is equal to or less than 3 mm. The hydraulic diameter may be found by dividing the cross-sectional area of a tube by the circumference thereof.

The refrigerant may dissipate or absorb heat to or from the surroundings by compressing or expanding as it flows along the flow channels21formed in the refrigerant tubes20. To allow the refrigerant to efficiently dissipate or absorb heat through compression or expansion, heat exchange fins30are joined to the refrigerant tubes20.

A plurality of heat exchange fins30may be disposed spaced a predetermined distance from each other in a direction C perpendicular to the direction in which the refrigerant tubes20extend. The direction C, in which the heat exchange fins30are inserted into the refrigerant tubes20, the first direction A, and the second direction B are perpendicular to each other. The heat exchange fins30may be formed of an aluminum alloy having a high thermal conductivity. The heat exchange fins30may be bonded to the outer surface of the refrigerant tubes20, thereby serving to substantially increase the area of the refrigerant tubes20for exchange of heat with external air.

When the space between the stacked heat exchange fins30is narrowed, a larger number of the heat exchange fins30may be disposed. However, in the case the space between the heat exchange fins30is excessively narrow, they may resist inflow of external air toward the heat exchanger5. This may result in pressure loss. Accordingly, space between the heat exchange fins30may be properly adjusted.

The heat exchange fins30may include a plurality of insertion grooves31into which the refrigerant tubes20are inserted, and a plurality of the bonding plates32bonded to refrigerant tubes20with the refrigerant tubes20inserted into the insertion grooves31.

The insertion grooves31may be formed in a shape corresponding to a portion of the heat exchange fins30to allow at least one portion of the heat exchange fins30to be inserted thereinto. In addition, they may be formed between the bonding plates32spaced apart from each other in the direction of extension of the heat exchange fins30. The heat exchange fins30may be formed in any shape allowing efficient dissipation or absorption of heat by the refrigerant tubes20.

FIG. 4is a view illustrating a booster100of a heat exchanger5according to one embodiment of the present disclosure.

Since each of the refrigerant tubes20has a plurality of flow channels21having a relatively small diameter as discussed above, the refrigerant introduced into the headers41and42may not be uniformly distributed to the refrigerant tubes20. Particularly, when dryness increases according to phase change of the refrigerant, distribution of the refrigerant to the refrigerant tubes20may become difficult.

In the case of a variable rate-of-rotation compressor7, the velocity of flow of the refrigerant may vary depending on operation of the compressor7. When the compressor7is operated at a relatively low rate of rotation, the internal pressure of the header41increases and the velocity of flow of the refrigerant decreases. On the other hand, when the compressor7is operated at a relatively high rate of rotation, the internal pressure of the header41decreases and the velocity of flow of the refrigerant increase.

As such, distribution of the refrigerant to the refrigerant tubes20may vary depending on the velocity of flow of the refrigerant. When the velocity of flow of the refrigerant is high, the refrigerant may be concentrated in the upper refrigerant tubes20among the refrigerant tubes20from the same group. On the other hand, when the velocity of flow of the refrigerant is low, the refrigerant may be concentrated in the lower refrigerant tubes20among the refrigerant tubes20from the same group.

A property of distribution of the refrigerant to the refrigerant tubes20from the same group is associated with the mass flow rate of the refrigerant and the effective cross-sectional areas of the headers41and42. According to this embodiment, by using the booster100to adjust the effective cross-sectional areas of the headers41and42the distribution property of the refrigerant may be enhanced.

The booster100may include a casing115installed at one side of the headers41and42, a blocking plate110positioned inside the casing115and installed to move into the headers41and42, and an elastic unit112to elastically bias the blocking plate110.

The booster100may be installed at the upper side of the headers41and42containing a large amount of the gaseous refrigerant having a degraded distribution property. Particularly, the booster100may be positioned at a place where the refrigerant tubes20are divided into different groups. As shown inFIG. 2, the booster100may be attached to one side of the first header41at which the refrigerant tubes20are divided into the third group c and the fourth group d. Hereinafter, the first header41will be referred to as the header for simplicity of description.

The blocking plate110may be movably installed inside the header41to vary the cross-sectional area of the header41. The blocking plate110may be positioned between the refrigerant tubes20spaced apart from each other. Particularly, the blocking plate110may be disposed between the refrigerant tube20apositioned at the uppermost part of the third group c and the refrigerant tube20bpositioned at the lowermost part of the fourth group d. That is, the blocking plate110is installed in the passage in which the refrigerant having passed through the third group c is collected to move to the fourth group d.

To allow the refrigerant flowing through the header41to enter the casing115, the booster100may include an introduction port125connecting the header41to the casing115. The refrigerant introduced through the introduction port125may move a connection plate113to which the blocking plate110and the elastic unit112are connected by applying pressure to the connection plate113. One side of each of the blocking plate110and the elastic unit112may be fixed to the connection plate113. Accordingly, the blocking plate110and the elastic unit112may move along with the connection plate113.

To ensure that the refrigerant introduced though the introduction port125applies pressure to the connection plate113to stably move the connection plate113, the booster100may include a guide plate120installed inside the casing115in a protruding manner. The guide plate120may have a length corresponding to the distance by which the connection plate113moves. In addition, to form a passage124of flow of the refrigerant, one side of the guide plate120may not be attached to the casing115.

To ensure that the blocking plate110stably moves to vary the cross-sectional area of the header41, the booster100may include guide protrusions117and118protruding into the header41. The guide protrusions117and118may include an upper guide protrusion118supporting the upper portion of the blocking plate110and a lower guide protrusion117supporting the lower portion of the blocking plate110. The guide protrusions117and118may horizontally fix the blocking plate110pressed upward or downward by the refrigerant moving upward or downward.

The booster100may be fabricated as an assembly separate from the header41and attached to one side of the header41. The header41may be provided with an opening into which the introduction port125and the blocking plate110are inserted for installation of the booster100. By inserting the blocking plate110into the opening and attaching the casing115to the header41, the booster100may be installed at the header41.

The blocking plate110is designed to have a length shorter than the diameter of the header41such that the refrigerant may flow in the header41even when the blocking plate110is maximally inserted into the header41. The refrigerant flowing along the header41passes through the introduction port125and applies pressure to the connection plate113via the passage124. Thereby, the blocking plate110and the elastic unit112may move to vary the cross-sectional area of the header41. The modulus of elasticity of the elastic unit112may be designed to adjust the range of variation of the cross-sectional area of the header41.

In the case that the compressor7is operated at a relatively low rate of rotation, the internal pressure of the header41increases and, accordingly, the internal pressure of the casing115also increase. Therefore, a relatively high pressure is applied to the connection plate113, the elastic unit112contracts, and the blocking plate110narrows the passage through which the refrigerant in the header41passes. The velocity of flow of the refrigerant passing through the narrowed passage may increase, causing a larger amount of the refrigerant to move upward to allow uniform distribution of the refrigerant.

On the other hand, when the compressor7is operated at a relatively high rate of rotation, the internal pressure of the header41decreases, and the internal pressure of the casing115also decreases. Accordingly, a relatively low pressure is applied to the connection plate113, and the elastic unit112extends. Accordingly, the blocking plate110widens the passage through which the refrigerant in the header41passes. The velocity of flow of the refrigerant passing through the widened passage may decrease, causing a larger amount of the refrigerant to move downward to allow uniform distribution of the refrigerant.

The space in which the elastic unit112is positioned may contain a gas that may expand and contract depending on pressure, and may communicate with the first refrigerant pipe43or a suction pipe of the compressor7.

As is apparent from the above description, a booster to vary the cross-sectional area of a header according to one embodiment of the present disclosure may allow a refrigerant flowing through a header to be effectively distributed to a plurality of refrigerant tubes.

In addition, the booster operated using fluid pressure of the refrigerant may eliminate necessity of a separate control device.