KR101795770B1 - vacuum dryer using heat pump and drying method - Google Patents

Abstract

The present invention relates to a vacuum dryer using a heat pump and a drying method using the same and, more specifically, relates to a vacuum dryer using a heat pump and a drying method using the same, wherein after high humidity air discharged from a drying chamber is cooled in an evaporator, the air is heated by heat generated in a condenser to dry an object to be dried, and at the same time, the flow of the air is alternately changed to improve drying efficiency.

Description

[0001] The present invention relates to a vacuum dryer using a heat pump and a drying method using the same,

The present invention relates to a vacuum dryer using a heat pump and a drying method using the same. More particularly, the present invention relates to a vacuum dryer using a heat pump, And a drying method using the same. [0002] The present invention relates to a vacuum dryer using a heat pump, and more particularly, to a vacuum dryer using a heat pump capable of increasing drying efficiency by alternately changing the flow of air.

Generally, agricultural products such as rice, barley harvested in mountain areas, and fish products such as fish caught in fishing villages have a large moisture content, so drying is essential for storage and transportation until reaching consumers.

In other words, various agricultural and marine products are easy to multiply microorganisms and easily corroded. Therefore, in order to improve the preservability of such agricultural and marine products, agricultural and marine products must be dried at a predetermined temperature and for a certain period of time.

As a method of drying a small amount of agricultural and marine products, there is a method in which a drying band formed as a mesh is installed in a certain area, and then various agricultural and marine products are displayed on the installed drying bed and naturally dried with sunlight and wind.

However, the natural drying method not only occupies a large occupied area but also has a very low drying speed, and it is inconvenient to quickly collect agricultural and marine products in case of snow or rain.

As a result, the natural drying method is disadvantageous in that the drying speed, the drying amount, and the dryness of the agricultural and marine products can not be kept constant due to the restriction on the climate conditions, which leads to a decrease in productivity and a decrease in commerciality.

In view of this, in recent years, there has been a tendency to use a dryer capable of rapidly drying a large amount of foodstuffs as a means for drying and transporting or drying foodstuffs for a long period of time.

The dryer is an electric heater or a gas burner type drier, which uses electricity or oil to raise the temperature inside and raise the temperature of the dried material to evaporate moisture to dry. In addition, a method of heating the air by removing the moisture in the air is also applied so as to increase the drying efficiency.

Korean Patent No. 10-1314156 discloses a system for drying agricultural products and a method thereof.

In the agricultural product drying system, dried agricultural products such as cereals, vegetables, fruits, and the like are put into a drying chamber and dry air dehumidified by a dehumidifier for a predetermined time is supplied into the drying chamber to dry agricultural products.

However, in the conventional drying system, since the discharge port through which the humid air is discharged is fixed through the inlet port and the drying chamber where the hot dry air flows, the dry material close to the inlet port is dried well, but the dry material close to the discharge port is well dried .

Korean Patent No. 10-1314156: Agricultural Product Drying System and Method Thereof

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method and apparatus for cooling a humid air discharged from a drying chamber by an evaporator of a heat pump, And more particularly, to a vacuum dryer using a heat pump capable of uniform drying by introducing dry air into a drying chamber while alternately changing the drying air and drying efficiency, and a drying method using the same.

According to an aspect of the present invention, there is provided a vacuum dryer using a heat pump, the drying apparatus including a drying chamber in which a drying table is installed and in which a first air inlet and a second air inlet are formed, A circulation duct having one side connected to the first vent and the other side connected to the second vent; An outside air inflow damper installed at one side of the circulation duct to introduce outside air into the circulation duct; An exhaust vent damper installed on the other side of the circulation duct to discharge air passing through the drying chamber to the outside of the circulation duct; A forward fan installed inside the circulation duct for moving the air in one direction; A reverse fan installed inside the circulation duct for moving the air in a direction opposite to the direction of movement of the air by the forward fan; A heat pump for cooling the air passing through the circulation duct and then heating the air; A vacuum pump for maintaining the inside of the drying chamber in vacuum; And a controller for selectively activating either the forward fan or the reverse fan.

The heat pump includes a first heat exchanger installed in the circulation duct, a second heat exchanger installed inside the circulation duct and spaced apart from the first heat exchanger by a predetermined distance, and a second heat exchanger installed in the first heat exchanger or the second heat exchanger A four-way valve for selectively introducing the gaseous refrigerant compressed by the compressor into any one of the first heat exchanger and the second heat exchanger, A first expansion line connecting the first heat exchanger and the second heat exchanger and a second check valve installed in the first expansion line so that the refrigerant can flow only in the direction of the second heat exchanger from the first heat exchanger, A first expansion valve installed in the first expansion line for expanding a refrigerant condensed by the first heat exchanger, and a second expansion valve installed in the first expansion line and the second heat exchanger, A second check valve installed in the second expansion line so that the refrigerant can flow only in the direction of the first heat exchanger from the second heat exchanger, and a second check valve installed in the second expansion line And a second expansion valve for expanding the refrigerant condensed by the second heat exchanger.

Wherein the heat pump includes a solenoid valve installed in a branch pipe branched from a pipe connecting the compressor and the four-way valve, the opening and closing being controlled by the control unit, Lt; RTI ID = 0.0 > condenser < / RTI >

And a condensed water collection unit connected to the circulation duct to collect condensed water generated from the air cooled by the heat pump.

The condensed water collecting unit includes a first water receiving part installed in the circulating duct at a position corresponding to the first heat exchanger, a second water receiving part installed in the circulating duct at a position corresponding to the second heat exchanger, A condensing water reservoir connected to the water receiving portion and the first drain pipe and connected to the second water receiving portion and the second drain pipe; and a first solenoid valve installed in the first drain pipe and the second drain pipe, And a second solenoid valve.

And an electric heater installed inside the circulation duct to heat the air flowing into the drying chamber.

According to another aspect of the present invention, there is provided a drying method for drying an object to be dried using a vacuum dryer, wherein the vacuum dryer includes a drying table in which the object is placed, A circulation duct in which one side is connected to the first ventilation hole and the other side is connected to the second ventilation hole; and a circulation duct installed on one side of the circulation duct, An outside air inflow damper for introducing outside air into the inside of the circulation duct, an exhaust vent damper installed at the other side of the circulation duct for discharging air passing through the drying chamber to the outside of the circulation duct, A forward fan installed in the circulation duct for moving the air in one direction, A reverse fan for moving the air in a direction opposite to the direction of the circulation duct, a heat pump for cooling the air passing through the circulation duct and heating the air, a vacuum pump for maintaining the inside of the drying chamber in vacuum, The heat pump includes a first heat exchanger installed inside the circulation duct and a second heat exchanger installed inside the circulation duct to separate the first heat exchanger from the first heat exchanger by a predetermined distance A first heat exchanger, a second heat exchanger, a second heat exchanger, and a second heat exchanger. The first and second heat exchangers are connected to the first heat exchanger and the second heat exchanger. A four-way valve for selectively introducing the refrigerant into any one of the first heat exchanger, the second heat exchanger, A first check valve installed in the first expansion line such that the refrigerant can flow only in the direction of the second heat exchanger from the first heat exchanger, and a second check valve installed in the first expansion line A first expansion valve for expanding the refrigerant condensed by the first heat exchanger, a second expansion line connecting the first heat exchanger and the second heat exchanger, and a second expansion line connecting the first expansion valve to the first heat exchanger And a second expansion valve installed in the second expansion line for expanding the refrigerant condensed by the second heat exchanger, wherein the second expansion valve is installed in the second expansion line, An initial drying step of operating the heat pump to dry the laundry while introducing outside air into the drying chamber while the damper and the air discharge damper are opened; Drying the drying object by operating the heat pump and the vacuum pump while the outside air inflow damper and the inside air discharge damper are closed and alternately operating the forward fan and the reverse fan to change the flow of air, Wherein the initial drying step comprises the steps of: a) switching the flow path of the four-way valve so that the refrigerant compressed in the compressor can be introduced into the first heat exchanger, and b) operating the forward- The air introduced through the damper is cooled by the second heat exchanger, heated by the first heat exchanger, then introduced into the drying chamber through the first vent, To the outside through the exhaust damper.

Wherein the drying step comprises the steps of: c) operating the forward fan in a state where the flow path of the four-way valve is switched so that the refrigerant compressed in the compressor can be introduced into the first heat exchanger, Cooling the inner air of the second heat exchanger through the first heat exchanger and then heating the first heat exchanger through the first vent and into the drying chamber; d) The reverse fan is operated in a state in which the flow path of the four-way valve is switched so that it can be introduced into the heat exchanger, the air in the drying chamber flowing out through the first air vent is cooled by the first heat exchanger, And then introduced into the drying chamber through the second ventilation hole.

As described above, according to the present invention, the drying of the laundry is performed by a heat pump while introducing outside air at the initial stage of drying, and the drying of the laundry is performed by the heat pump while circulating the inside air in the latter stage of drying. have.

In addition, in the latter stage of drying, the refrigerant flow is alternately switched by the four-way valve, and the forward fan and the reverse fan are alternately operated according to the flow direction of the refrigerant to change the inflow position of the hot air flowing into the drying chamber So that the drying object can be uniformly dried and the drying efficiency can be increased.

FIG. 1 is a schematic view showing the construction of a drying apparatus according to an embodiment of the present invention,
Figure 2 is an example of the operation of the drying apparatus of Figure 1,
Figure 3 is another example of the operation of the drying apparatus of Figure 1,
Figure 4 is another example of the operation of the drying apparatus of Figure 1;

Hereinafter, a vacuum dryer using a heat pump according to a preferred embodiment of the present invention and a drying method using the vacuum dryer will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a vacuum dryer using a heat pump according to the present invention includes a drying chamber 7 having a first ventilation hole 3 and a second ventilation hole 5, 1), a circulation duct 10 having one side connected to the first vent 3 and the other side connected to the second vent 5, and a circulation duct 10 installed on one side of the circulation duct 10, And an air discharge damper 15 for discharging the air that has passed through the drying chamber 1 to the outside of the circulation duct 10. The air discharge damper 15 is provided on the other side of the circulation duct 10, A forward fan 20 installed inside the circulating duct 10 for moving the air in one direction and a fan 20 installed inside the circulating duct 10 for moving the air by the forward fan 20, A reverse fan 25 for moving the air in the direction opposite to the moving direction, and a cooling fan 25 for cooling the air passing through the circulating duct 25 A vacuum pump 90 for maintaining the inside of the drying chamber 1 under vacuum and a control unit for selectively activating either the forward fan 20 or the reverse fan 25 Respectively.

The drying chamber (1) is provided therein with a drying table (7). The drying rack 7 has a structure in which the trays are stacked up and down. The drying object to be dried is put on the drying table 7. Agricultural products, aquatic products, and other foods may be applied to the building.

The drying chamber (1) is provided with a first vent hole (3) and a second vent hole (5) through which air can pass. In the illustrated example, the first air vent 3 is provided on the upper right side of the drying chamber 1 and the second air vent 5 is provided on the lower left side of the drying chamber 1.

The present invention introduces the dry air produced by the heat pump (30) into the inside of the drying chamber (1) through either the first vent hole (3) or the second vent hole (5). The humid air containing moisture evaporated from the drying object passing through the drying table 7 is discharged to the outside of the drying chamber 1 through one of the first air vent 3 and the second air vent 5. For example, when dry air flows into the drying chamber 1 through the first air vent 3, moist air containing moisture evaporated from the drying object is discharged to the outside of the drying chamber 1 through the second air vent 5 do. When the dry air is introduced into the drying chamber 1 through the second air vent 5, humid air containing moisture evaporated from the drying object is discharged to the outside of the drying chamber 1 through the first air vent 3 .

As described above, the inlet for introducing heated dry air into the drying chamber 1 is not fixed, but one of the first and second vents 3 and 5 can be used as an inlet, The position of the inlet where air is introduced can be freely adjusted.

The circulating duct (10) is installed outside the drying chamber (1). One side of the circulating duct (10) is connected to the first vent hole (3) and the other side is connected to the second vent hole (5).

At one side of the circulating duct (10), an outside air inflow damper (15) is installed. It is possible to open and close the outside air inlet 11 connected to the circulating duct 10 through the outside air inflow damper 15. When the outside air inflow damper 15 is opened, the outside air flows into the inside of the circulating duct 10. As shown in FIG. 2, when the outside air inlet 11 is opened, the outside air inlet damper 15 blocks the internal passage of the circulating duct 10 connected to the outside air outlet 13.

On the other side of the circulating duct (10), an air discharge damper (16) is installed. It is possible to open and close the air outlet 13 formed on the other side of the circulating duct 10 through the air discharge damper 16. When the air discharge damper 16 is opened, the humid air having passed through the drying chamber 1 can be discharged to the outside of the circulating duct 10. As shown in FIG. 2, when the air outlet 13 is opened, the air outlet damper 16 blocks the internal passage of the circulating duct 10 connected to the outside air inlet 11.

The outside air inflow damper 15 and the inside air discharge damper 16 are opened and closed by a control unit.

A forward fan (20) and a reverse fan (25) are installed apart from each other in the circulating duct (10). One or more forward fans 20 may be installed. Also, one or more reverse fans 25 may be installed.

The direction of air movement by the forward fan 20 and the reverse fan 25 is opposite. When the forward fan 20 moves the air in one direction, the reverse fan 25 moves the air in the direction opposite to the direction of movement of the air by the forward fan 20. In the illustrated example, the forward fan 20 moves the air in the direction of the first vent 3 and the reverse fan 25 moves in the direction of the second air 5.

The forward fan (20) and the reverse fan (25) are controlled to be operated by the control unit. The controller selectively activates either the forward fan (20) or the reverse fan (25).

A heat pump (30) is provided to introduce the heated gun air into the drying chamber (1).

The heat pump 30 cools the air passing through the circulation duct 20 to reduce moisture in the air and then heats the air.

The heat pump 30 applied to the present invention is configured such that each heat exchanger can serve as a condenser or an evaporator depending on the direction of movement of the refrigerant passing through the two heat exchangers 33 and 35. The moving direction of the refrigerant is changed in accordance with the flow direction of the air moving in the circulating duct 10.

The illustrated heat pump 30 includes a first heat exchanger 33 installed inside the circulation duct 10 and a second heat exchanger 33 installed inside the circulation duct 10 and spaced apart from the first heat exchanger 33 by a predetermined distance A compressor 32 for compressing the refrigerant evaporated in the first heat exchanger 33 or the second heat exchanger 35 and a compressor 32 for switching the flow path by the control unit, A four-way valve 31 for selectively introducing gaseous refrigerant into any one of the first heat exchanger 33 and the second heat exchanger 35; a first heat exchanger 33 and a second heat exchanger 35; A first check valve (not shown) installed in the first expansion line (40) so that the refrigerant can flow only in the direction of the second heat exchanger (35) from the first heat exchanger (33) A first expansion valve 43 installed in the first expansion line 40 for expanding the refrigerant condensed by the first heat exchanger 33 and a second expansion valve 43 for expanding the refrigerant condensed by the first heat exchanger 33 and the second heat exchanger 33. [ Lt; RTI ID = 0.0 > 35 < / RTI & A second check valve 47 installed in the second expansion line 45 so that the refrigerant can flow only in the direction of the first heat exchanger 33 from the second heat exchanger 35, And a second expansion valve (49) installed in the second expansion line (45) for expanding the refrigerant condensed by the second heat exchanger (35).

When the four-way valve 31 switches the flow path so that the gaseous refrigerant compressed by the compressor 32 flows into the first heat exchanger 33, the refrigerant flows from the compressor 32 to the four-way valve 31 through the first heat exchanger 33 ) → the first check valve 41 → the first expansion valve 43 → the second heat exchanger 35 → the four-way valve 31 → the compressor 32.

At this time, the gaseous refrigerant compressed by the compressor 32 is condensed in the first heat exchanger 33, and the refrigerant expanded while passing through the first expansion valve 43 absorbs the latent heat of vaporization in the second heat exchanger 35 And evaporated. Accordingly, the first heat exchanger (33) serves as a condenser and the second heat exchanger (35) serves as an evaporator.

On the other hand, when the four-way valve 31 switches the flow path so that the gaseous refrigerant compressed by the compressor 32 flows into the second heat exchanger 35, the refrigerant flows from the compressor 32 to the four- The refrigerant is circulated through the path of the second check valve 35 → the second check valve 47 → the second expansion valve 49 → the first heat exchanger 33 → the four-way valve 31 → the compressor 32.

At this time, the gaseous refrigerant compressed by the compressor 32 is condensed in the second heat exchanger 35, and the refrigerant expanded while passing through the second expansion valve 49 absorbs the latent heat of vaporization in the first heat exchanger 33 And evaporated. Accordingly, the first heat exchanger (33) serves as an evaporator and the second heat exchanger (35) serves as a condenser.

The first and second heat exchangers (33, 35) are installed inside the circulating duct (10). The first and second heat exchangers 33 and 35 are spaced apart from each other. The first heat exchanger (33) is installed near the first air vent (3), and the second heat exchanger (35) is installed near the second air vent (5).

The forward fan 20 is operated while the reverse fan 25 is stopped and the four-way valve 31 switches the flow path so that the gaseous refrigerant compressed by the compressor 32 flows into the first heat exchanger 33 The air passes through the second heat exchanger 35 and then through the first heat exchanger 33. [ The moist air passes through the second heat exchanger (35) serving as an evaporator, and is cooled and dehumidified to be in a dry air state at a low temperature (5 to 10 ° C).

The dehumidified dry air having passed through the second heat exchanger (35) is heated while passing through the first heat exchanger (33). Heat emitted from the first heat exchanger (33) is used to heat the air. The dehumidified dry air is heated to a room temperature or a warm temperature (25 to 35 DEG C) when it passes through a first heat exchanger (33) serving as a condenser.

The operation of the forward fan 20 is stopped and the reverse fan 25 is operated and the four-way valve 31 switches the flow path so that the gaseous refrigerant compressed by the compressor 32 flows into the first heat exchanger 33 The air passes through the first heat exchanger 33 and then through the second heat exchanger 35. In this case, In this case, while passing through the first heat exchanger (33), the air is cooled to remove moisture, and is heated while passing through the second heat exchanger (35).

When the direction of the refrigerant is changed by the four-way valve 31, the roles of the first and second heat exchangers 33 and 35 change each other.

On the other hand, the heat pump 30 may further include an auxiliary condenser. In the illustrated example, a branch pipe 50 branched from a pipe connecting the compressor 32 and the four-way valve 31 is provided, and a solenoid valve 51 whose opening and closing is controlled by a control unit is installed in the branch pipe 50 do. An auxiliary condenser (55) is connected to the branch pipe (50) so that a part of the refrigerant compressed in the compressor can pass through when the electromagnetic valve (51) opens the branch pipe (50).

When the pressure of the first or second heat exchanger serving as the condenser during the operation of the heat pump 30 becomes high, the solenoid valve 51 is opened by the control unit and a part of the refrigerant passes through the auxiliary condenser 55.

A vacuum pump (90) is installed so that the inside of the drying chamber (1) can be maintained in vacuum and dried. The vacuum pump 90 may be installed in the condensate collection unit.

The condensed water collecting unit includes a first water receiving portion 70 installed in a circulating duct at a position corresponding to the first heat exchanger 33 and a second water receiving portion 70 installed in the circulating duct at a position corresponding to the second heat exchanger 35. [ A condensed water storage tank 80 connected by a first water receiving portion 70 and a first drain pipe 73 and connected by a second water receiving portion 71 and a second drain pipe 77, And a first solenoid valve (75) and a second solenoid valve (79) installed in the first drain pipe and the second drain pipe and selectively opened and closed by the control unit. A drain pipe (81) for discharging condensate water is provided in the condensate water reservoir (80), and a solenoid valve (83) is installed in the drain pipe (81). The condensate water reservoir 80 is provided with a water level sensor, and the control unit can control the electromagnetic valve 83 installed in the drain pipe 81 by a signal output from the water level sensor.

The first solenoid valve 75 is opened when the first heat exchanger 33 serves as an evaporator and the second solenoid valve 79 is opened when the second heat exchanger 35 serves as an evaporator So that the condensed water is collected in the condensed water storage tank 80. At the same time, the vacuum pump 90 installed in the condensate storage tank 80 is controlled by the control unit so that the drying chamber 1 can be maintained at a constant vacuum pressure. Since the object to be dried can be dried at a vacuum pressure by the vacuum pump 90, evaporation of moisture becomes active and drying is performed more quickly.

Meanwhile, an electric heater 60 may be installed inside the circulating duct 10. The electric heater 60 can heat the air flowing into the drying chamber 1 to a higher temperature. The electric heater (60) is installed between the first air vent (3) and the first heat exchanger (33). The electric heater (60) can be controlled to be operated by the control unit.

The control unit is constituted by a microprocessor and various drive circuits as a typical configuration.

The controller selectively activates either the forward fan 20 or the reverse fan 25. It goes without saying that the control unit controls the operation of the outside air inflow damper 15, the inside air discharge damper 16, the various solenoid valves, the four-way valve 31, the vacuum pump 90 and the electric heater 60.

Hereinafter, the drying method using the above-described vacuum dryer will be described.

The drying method largely consists of an initial drying step and a later drying step.

In the initial drying step, the outside air is introduced into the drying chamber 1 while the outside air inflow damper 15 and the inside air discharge damper 16 are opened, and the humid air having passed through the drying chamber 1 is discharged to the outside The heat pump 30 is operated to discharge the dried material.

 The initial drying step includes a step of switching the flow path of the four-way valve 31 so that the refrigerant compressed in the compressor 32 can be introduced into the first heat exchanger 33 and the step of operating the forward fan 20 to start the outside air inflow damper 15 are cooled by the second heat exchanger 35 and then heated by the first heat exchanger 33 and then introduced into the drying chamber 1 through the first vent 3 And air discharged through the second air vent 5 may be discharged to the outside through the air discharge damper 16.

Such an initial drying step is shown in Fig.

In the initial drying step, the outside air inflow damper 15 opens the outside air inflow opening 11 so that outside air can be introduced into the inside of the circulating duct 10. The exhaust vent damper 16 also opens the exhaust outlet 13 so that the highly humid air having passed through the drying chamber 1 can be discharged to the outside.

When the four-way valve 31 switches the flow path so that the gaseous refrigerant compressed by the compressor 32 flows into the first heat exchanger 33, the refrigerant flows from the compressor → the four-way valve → the first heat exchanger → the first check valve → the first And circulates through the expansion valve, the second heat exchanger, the four-way valve, and the compressor.

At this time, the gaseous refrigerant compressed by the compressor (33) is condensed in the first heat exchanger (33), and the refrigerant expanded while passing through the first expansion valve (43) absorbs the latent heat of vaporization in the second heat exchanger And evaporated. Accordingly, the first heat exchanger (33) serves as a condenser and the second heat exchanger (35) serves as an evaporator.

When the forward fan 20 is operated, the outside air is introduced into the circulating duct 10 and the air introduced into the circulating duct 10 passes through the second heat exchanger 35 and the first heat exchanger 33, And then flows into the drying chamber 1.

The air introduced from the outside is cooled while passing through the second heat exchanger (35), and the moisture in the air is removed, resulting in a low-temperature (5 to 10 ° C) dry air state. Then, the dry air is heated to a normal temperature or a warm temperature (25 to 35 DEG C) when passing through the first heat exchanger (33).

The drying air having passed through the first heat exchanger (33) is heated to a higher temperature by the electric heater (60) and flows into the drying chamber (1) through the first air vent (3). The dry air introduced into the drying chamber 1 dries the laundry. In this process, moisture is evaporated from the object to be dried, and the evaporated moisture is contained in the air and is discharged to the outside through the second air vent (5).

When the pressure of the first heat exchanger (35) serving as a condenser in the initial drying step is increased, the solenoid valve (51) is opened and the auxiliary condenser (55) is operated to adjust the condensation pressure.

In the initial drying step, the drying of the laundry containing a lot of moisture is performed by hot air drying during the initial drying, and the air of high temperature and high humidity including moisture generated in the drying chamber is discharged to the outside, Method.

If the moisture content of the laundry is lowered through the initial drying step, the latter drying step is carried out.

The late drying step is performed in a state where the outside air inflow damper 15 and the inside air discharge damper 16 are closed so that the inside air circulates without inflow of outside air. In the latter drying step, the forward fan 20 and the reverse fan 25 are alternately operated to dry the air while changing the flow of the air. The later drying step proceeds while the vacuum pump 90 is operated. Therefore, evaporation of water becomes active and drying becomes faster.

In the latter drying step, the forward fan 20 is operated in a state where the flow path of the four-way valve 31 is switched so that the refrigerant compressed in the compressor 32 can be introduced into the first heat exchanger 33, Is cooled by the second heat exchanger (35) and then heated by the first heat exchanger (33). Then, the air in the drying chamber (1) flowing through the drying chamber A reverse fan 25 is operated in a state where the flow path of the four-way valve 31 is switched so that the refrigerant compressed in the compressor 32 can be introduced into the second heat exchanger 35 The inside air of the drying chamber 1 flowing out through the first air vent 3 is cooled by the first heat exchanger 33 and then heated by the second heat exchanger 35 and then the second air vent 5 is heated Into the interior of the drying chamber (1).

3, the flow path of the four-way valve 31 is switched so that the refrigerant compressed by the compressor 32 can be introduced into the first heat exchanger 33. As shown in FIG. Through this, the refrigerant circulates from the compressor → the four-way valve → the first heat exchanger → the first check valve → the first expansion valve → the second heat exchanger → the four-way valve → the compressor.

When the forward fan 20 is operated in this state, the air inside the drying chamber 1 flows out to the circulating duct 10 through the second air vent 5. The air is cooled while passing through the second heat exchanger (35) to remove moisture, and is heated while passing through the first heat exchanger (33). The heated dry air flows into the interior of the drying chamber (1) through the first air vent (3).

When air is dehumidified as it passes through the second heat exchanger (35), the condensed water collects in the condensed water storage tank (80) through the second water pipe (77).

When the condensing pressure of the first heat exchanger (33) serving as a condenser during operation is increased, the solenoid valve (51) is opened and the auxiliary condenser (55) is operated to regulate the condensation pressure.

The drying air heated by the first air vents 3 is flowed in, the drying air is dried for a predetermined period of time, and the heated air flows into the second air vents 5. For this, the flow path of the four-way valve 31 is switched so that the refrigerant compressed by the compressor 32 can be introduced into the second heat exchanger 35 as shown in FIG. Through this, the refrigerant circulates from the compressor → the four-way valve → the second heat exchanger → the second check valve → the second expansion valve → the first heat exchanger → the four-way valve → the compressor.

At this time, the gaseous refrigerant compressed by the compressor (33) is condensed in the second heat exchanger (35), and the refrigerant expanded while passing through the second expansion valve (49) absorbs the latent heat of vaporization in the first heat exchanger And evaporated. Accordingly, the first heat exchanger (33) serves as an evaporator and the second heat exchanger (35) serves as a condenser.

In this state, when the operation of the forward fan 20 is stopped and the reverse fan 25 is operated, the air inside the drying chamber 1 flows out to the circulating duct through the first air vent 3. The air is cooled while passing through the first heat exchanger (33) to remove moisture, and is heated while passing through the second heat exchanger (35). The heated dry air flows into the interior of the drying chamber 1 through the second air vent 5.

When the air passes through the first heat exchanger (33) and is dehumidified, the condensed water collects in the condensed water storage tank (80) through the first water pipe (73).

When the condensing pressure of the second heat exchanger (35) serving as a condenser during operation is increased, the solenoid valve (51) is opened and the auxiliary condenser (55) is operated to regulate the condensation pressure.

As described above, in the post-drying step, the flow of the refrigerant is alternately switched by the four-way valve 31, the forward fan 20 and the reverse fan 25 are alternately operated according to the flow direction of the refrigerant, The heated and dried air can be introduced into the second vent hole 5 for a predetermined period of time after flowing into the first vent hole 3 for a predetermined period of time. Therefore, even if the volume of the drying chamber 1 is large, the drying object can be uniformly dried and the drying efficiency can be increased.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention. . Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

1: drying chamber 7: drying zone
10: Circular duct 20: Forward fan
25: reverse fan 30: heat pump
33: first heat exchanger 35: second heat exchanger

Claims (8)

A drying chamber in which a drying table is installed and in which a first air inlet and a second air inlet are formed in which air can be introduced;
A circulation duct having one side connected to the first vent and the other side connected to the second vent;
An outside air inflow damper installed at one side of the circulation duct to introduce outside air into the circulation duct;
An exhaust vent damper installed on the other side of the circulation duct to discharge air passing through the drying chamber to the outside of the circulation duct;
A forward fan installed inside the circulation duct for moving the air in one direction;
A reverse fan installed inside the circulation duct for moving the air in a direction opposite to the direction of movement of the air by the forward fan;
A heat pump for cooling the air passing through the circulation duct and then heating the air;
A vacuum pump for maintaining the inside of the drying chamber in vacuum;
And a controller for selectively activating either the forward fan or the backward fan,
The heat pump includes a first heat exchanger installed in the circulation duct, a second heat exchanger installed inside the circulation duct and spaced apart from the first heat exchanger by a predetermined distance, and a second heat exchanger installed in the first heat exchanger or the second heat exchanger A four-way valve for selectively introducing the gaseous refrigerant compressed by the compressor into any one of the first heat exchanger and the second heat exchanger, A first expansion line connecting the first heat exchanger and the second heat exchanger and a second check valve installed in the first expansion line so that the refrigerant can flow only in the direction of the second heat exchanger from the first heat exchanger, A first expansion valve installed in the first expansion line for expanding a refrigerant condensed by the first heat exchanger, and a second expansion valve installed in the first expansion line and the second heat exchanger, A second check valve installed in the second expansion line so that the refrigerant can flow only in the direction of the first heat exchanger from the second heat exchanger, and a second check valve installed in the second expansion line And a second expansion valve for expanding the refrigerant condensed by the second heat exchanger,
And a condensed water collection unit connected to the circulation duct for collecting condensed water generated from the air cooled by the heat pump,
The condensed water collecting unit includes a first water receiving part installed in the circulating duct at a position corresponding to the first heat exchanger, a second water receiving part installed in the circulating duct at a position corresponding to the second heat exchanger, A condensed water storage tank connected to the water receiving portion and the first drain pipe and connected to the second water receiving portion and the second drain pipe and having the vacuum pump installed therein, A drain pipe installed in the condensed water storage tank for discharging condensed water, and a water level sensor provided in the condensed water storage tank,
Further comprising an electric heater installed in the circulation duct and installed between the first air vent and the first heat exchanger to heat the air flowing into the drying chamber, . delete The heat pump according to claim 1, wherein the heat pump comprises: a solenoid valve installed in a branch pipe branched from a duct connecting the compressor and the four-way valve, the solenoid valve being opened and closed by the control unit; Further comprising an auxiliary condenser for passing the refrigerant compressed by the compressor. delete delete delete delete delete

Images