JPH07127975A - Cold air drying machine - Google Patents

Abstract

PURPOSE:To prevent drying capability from being lowered even upon changeover from a cooling operation to a reheating operation by increasing the number of condensers activated as the temperature in a drying machine rises upon using a drying operation function. CONSTITUTION:Capacity control of a compressor is effected by feeding back a refrigerant from a compressor 103 to a location of intermediate pressure of the compressor 103 or a suction side (S) of the same. An expansion valve 15 adjusts the amount of injection to the compressor in response to the temperature of a refrigerant fedback to the compressor. An accumulator 16 and a high/low pressure switch 17 are provided. A solenoid opening/closing valve 18 and a check valve 19 are provided, and when the solenoid opening/closing valve 18 is opened, a refrigerant flowing from a three-way valve 104 can pass through a reheater 6b. More specifically, the refrigerant flows through the reheaters 6a, 6b whereby they are operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold air dryer used for drying and preserving foods and agricultural products.

[0002]

2. Description of the Related Art Conventionally, in this type of cold air dryer, a refrigerant circuit as shown in FIG. 4 has been tried. That is, the cold air dryer is provided with an indoor unit 101 and an outdoor unit 102, which are provided inside a cabinet for storing foods to be dried (materials to be dried).
And a compressor 103 provided on the drying chamber 101 side.
A three-way valve 104 is connected to the discharge side of, and one outlet of the three-way valve 104 is connected to a condenser 105 provided in the outdoor unit 102. Reference numeral 106 denotes a blower for forcibly cooling the condenser 105, and the amount of blown air is controlled according to the temperature of the condenser.

The condenser 105 is connected to a liquid receiver 108 via a check valve 107 provided on the side of the indoor unit 101, and the liquid receiver 108 is provided with a cooler provided in the storage via an expansion valve 109. It is connected to 110. Cooler 110
Is connected to the suction side of the compressor 103 to form an annular refrigeration cycle. The expansion valve 109 detects the temperature on the outlet side of the cooler 110 and automatically adjusts the opening so as to maintain the temperature of the cooler 110 at a predetermined value.

The other outlet of the three-way valve 104 is connected to a reheater 112 which is provided inside the refrigerator together with the cooler 110 and constitutes a heat exchanger. The reheater 112 has a check valve 113. It is connected to the liquid receiver 108 through.
Both the check valve 113 and the check valve 107 have the liquid receiver 108 side in the forward direction. Further, 114 is a blower for forcibly circulating the air that has exchanged heat with the cooler 110 and the reheater 112 in the chamber.

The compressor 10 in front of the three-way valve 104
The discharge side of 3 is connected between the expansion valve 109 and the cooler 110 via the on-off valve 116 and the pressure adjusting valve 122 to form a defrost circuit. The on-off valve 116 detects the temperature on the outlet side of the evaporator 110, and opens the flow path to defrost the cooler 110 when this temperature falls below a set value. Further, the flow of the three-way valve 104 is switched depending on the temperature inside the refrigerator. Incidentally, 120 is an open / close valve which is always open. Reference numeral 121 is an opening / closing valve that controls a liquid injection circuit for cooling the compressor 103.

The operation of the above conventional cold air dryer will be described. The temperature inside the cold air dryer is, for example, + 10 ° C to + 30 ° C.
The temperature inside the refrigerator is set to, for example, the above + 10 ° C. Then, the compressor 103 is operated, and the flow path of the three-way valve 104 is set to the one outlet direction until the temperature inside the refrigerator decreases to the set temperature. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 103 passes through the three-way valve 104 as shown by the solid line arrow and passes through the condenser 10.
5, heat is dissipated there and condensed, and then enters the liquid receiver 108 via the check valve 107 and the expansion valve 1 via the on-off valve 120.
09. As described above, the expansion valve 109 adjusts the opening degree based on the temperature on the outlet side of the cooler 110, throttles the condensed and liquefied refrigerant, and supplies it to the cooler 110. The refrigerant flowing into the cooler 110 evaporates, absorbs heat from the surroundings, exerts a cooling effect, and is then sucked into the compressor 103.

When the internal cold storage temperature is lowered to the set temperature by the cooling operation, the flow path of the three-way valve 104 is switched to the other outlet direction. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 103 enters the reheater 112 via the three-way valve 104 as shown by the dotted arrow, and is condensed there to exert a heating effect. On the other hand, the refrigerant is condensed there, then enters the liquid receiver 108 through the check valve 113, and thereafter flows as described above. If the internal temperature rises due to the drying operation (reheating operation), the cooling operation is switched to the cooling operation again, and thereafter, the cooling operation and the reheating operation are repeated. Since the air cooled by the cooler 109 and heated by the reheater 112 is circulated in the refrigerator by the blower 114, the articles stored in the refrigerator are dried by repeating the cooling / reheating operation.

Here, when the temperature in the refrigerator is + 15 ° C. or higher, the evaporation temperature of the refrigerant in the cooler 110 is 0 ° C. or higher, so that no frost is formed, but when the temperature in the refrigerator is + 10 ° C., cooling is performed. Since the evaporation temperature of the refrigerant in the cooler 110 is −5 ° C., frost grows on the cooler 110. When frost grows on the cooler 110, heat exchange is not performed and the temperature of the cooler 110 decreases. The on-off valve 116 provided in the defrost circuit opens the flow path and expands the high-temperature high-pressure gas refrigerant discharged from the compressor 103 when the outlet temperature of the cooler 110 decreases to, for example, -3 ° C. due to the frost formation. It is made to flow to the downstream side of 109 and directly made to flow into the cooler 110. Due to the inflow of the high-temperature and high-pressure gas refrigerant, the cooler 110
Is heated and defrosted.

When the cold storage operation in the refrigerator is selected, the cooling operation as described above is performed.

[0010]

In the conventional cold air dryer having such a structure, the drying operation and the cooling operation can be selected.

FIG. 5 is a characteristic diagram of a high pressure on the high pressure side (for example, a pressure in the refrigeration cycle on the discharge side of the compressor) in the refrigeration cycle when the cold air dryer shown in FIG. 4 is operated.
In addition, the measurement conditions are an outside temperature of 32 degrees and a power source of three-phase 200V.
Is. In this characteristic diagram, the dotted line shows the change in the high pressure with respect to the temperature inside the refrigerator during the cooling operation, and the solid line shows the change in the high pressure with respect to the temperature inside the refrigerator during the reheat operation.

In this figure, the high-pressure pressure during the cooling operation has a constant air inlet temperature of the condenser 105 (the outside temperature is 32 ° C).
Since this temperature is constant at 32 degrees, this temperature is also constant at 32 degrees), so that it changes depending on the evaporation temperature of the evaporator 110, which mainly depends on the internal temperature, and the change range of the high pressure is about 2.5 Kg.
/ Square centimeter (internal temperature range of 15 to 30 degrees).

On the other hand, the high pressure during the reheat operation is the same as the reheater 1
12 Air inlet temperature (15-30 degrees) and evaporator 11
Depending on the evaporation temperature of 0, the variation range of the high pressure is about 7 kg / square centimeter (internal temperature range of 15 to 30 degrees).

Each component of the refrigeration cycle is designed so that the high pressure during the cooling operation and the high pressure during the reheating operation match at about 19 kg / square centimeter when the temperature inside the refrigerator is 30 degrees.

When the cooling operation is switched to the reheat operation (the high pressure characteristic during the cooling operation is changed to the high pressure characteristic during the heat operation), the high pressure during the refrigeration cycle sharply drops. For example, when the cooling temperature (high pressure = 16.5 kg / square centimeter, refrigerant temperature = 45 degrees) is switched to the reheat operation (high pressure = 12 kg / square centimeter, refrigerant temperature = 32 degrees) when the internal temperature is 15 degrees, The high-pressure pressure sharply dropped, but the refrigerant temperature could not drastically fall, and during this period (2.5 minutes to 3 minutes), flash gas was generated and the refrigerating capacity, that is, the drying capacity was lowered.

The present invention provides a cold air dryer that does not cause a decrease in drying capacity even when switching from cooling operation to reheat operation in order to solve such problems.

[0017]

The present invention comprises a refrigeration cycle using a compressor, a condenser, a decompression device, and an evaporator, and supplies air cooled by the evaporator to the inside of a chamber containing a material to be dried. In a dryer having a cooling operation function to perform and a drying operation function to reheat the air cooled by the evaporator by the condenser and then supply the air to the inside of the refrigerator, a plurality of condensers are used for the reheating. When the drying operation function is used, the number of condensers to be operated increases as the temperature inside the storage chamber increases.

A valve mechanism for preventing the refrigerant from flowing into the condenser that is not functioning when the drying function is used is provided.

[0019]

In the cold air dryer configured as described above, the number of condensers functioning according to the temperature in the refrigerator during the reheating operation is changed to change the reheating ability, so that the flash gas generated due to the temperature difference of the refrigerant is generated. By shortening the time, it is possible to shorten the time for the drying ability to drop.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a front view of a use side unit of a cold air dryer, and FIG. 2B is a partially sectional side view of the same. 1
Is a unit and is installed in the refrigerator. An air suction port 2 sucks the air in the refrigerator into the unit 1 by driving the blower 3. The air sucked into the unit 1 is cooled and heated by the heat exchanger 4 and then supplied again to the inside of the refrigerator by the blower 3. This air flows in the unit 1 along the solid line shown in FIG.

FIG. 1 (c) is an explanatory view of the heat exchanger 4 shown in FIG. 1 (b). This heat exchanger has an evaporator 5 and a secondary side located on the air intake side (primary side). Located in 1st
Reheater (first condenser) 6a, second reheater (second condenser)
6b and.

FIG. 2 is a refrigerant circuit diagram showing a refrigeration cycle used in the cold air dryer shown in FIG. In this figure,
Since the basic configuration and the basic operation of the refrigeration cycle are the same as those shown in the fourth example, the components that perform the same operation are designated by the same reference numerals and the description thereof will be omitted.

10 is dry, 11 is an indicator, 1
An oil separator 2 separates oil from the refrigerant discharged from the compressor 103 and returns it to the compressor 103. 1
3 and 14 are solenoid valves for controlling the capacity of the compressor 103,
The capacity of the compressor is controlled by returning the refrigerant discharged from the compressor 103 to the intermediate pressure position of the compressor 103 or to the suction side (S). Reference numeral 15 is an expansion valve, which adjusts the injection amount into the compressor according to the temperature of the refrigerant returned to the compressor. Reference numeral 16 is an accumulator, and 17 is a high / low pressure switch.

Reference numeral 18 is an electromagnetic opening / closing valve, 19 is a check valve,
When the electromagnetic opening / closing valve 18 is open, the refrigerant flowing from the three-way valve 104 can pass through the reheater 6b. That is, the refrigerant flows through the reheater 6a and the reheater 6b, and the two reheater 6a,
6b is functional. When the electromagnetic opening / closing valve 18 is closed, the refrigerant does not flow to the reheater 6b, and the check valve 19
Prevents the refrigerant from flowing backward, so that the refrigerant does not lie in the reheater 6b.

The solenoid on-off valve 18 is controlled by a control unit (not shown) so that it opens when the following conditions are satisfied. At the time of reheat operation, when the temperature inside the refrigerator is 23 degrees or higher (when the temperature sensor inside the refrigerator determines that the temperature is 23 degrees or higher.

The control unit is a conventional control circuit (Japanese Patent Application No.
116109 reference), the temperature sensor for detecting the temperature inside the refrigerator is compared with the temperature detected by this temperature sensor and the set temperature (23 degrees in this embodiment), and a signal is output when the detected temperature is equal to or higher than the set temperature. A circuit and a driver circuit for opening the electromagnetic on-off valve 18 by the output signal of this comparison circuit may be added. Needless to say, an appropriately selected differential is set in the comparison circuit.

Further, although the set temperature is set to 23 degrees in this embodiment, it is not limited to this temperature but the capacity of the compressor,
It is set appropriately according to the size of each heat exchanger and the size of the interior.

FIG. 3 is a characteristic diagram similar to the characteristic diagram shown in FIG. 5, and is a high pressure on the high pressure side in the refrigeration cycle when the cold air dryer is operated (for example, the pressure in the refrigeration cycle on the discharge side of the compressor). ) Is a characteristic diagram of FIG. The measurement conditions are the same as in FIG. 3, where the outside temperature is 32 degrees and the power source is three-phase 200V. In this characteristic diagram, the dotted line shows the change in the high pressure with respect to the temperature inside the refrigerator during the cooling operation, and the solid line shows the change in the high pressure with respect to the temperature inside the refrigerator during the reheat operation.

In this figure, the high pressure during the cooling operation is the same as that in FIG. 3, and the change range of the high pressure is about 2.5K.
It is g / square centimeter (internal temperature range of 15 to 30 degrees).

On the other hand, the high pressure during the reheat operation is the same as the reheater 6
Depending on the air inlet temperature (15 to 30 degrees) of a and 6b and the evaporation temperature of the evaporator 5, the change width of the high pressure is about 4.5 kg / square centimeter (internal temperature 15 to 3 degrees).
0 degree range).

Each component of the refrigeration cycle is designed so that the high pressure during the cooling operation and the high pressure during the reheating operation match at about 19 kg / square centimeter when the temperature inside the refrigerator is 30 degrees.

In the present invention, the number of functioning heat exchangers increases from 1 to 2 when the temperature inside the refrigerator is 23 degrees. When the temperature inside the refrigerator is lower than 23 degrees, only the reheater 6a functions, so that the circulation amount of the refrigerant decreases and the high pressure during the refrigeration cycle increases. When the internal temperature is 15 degrees, the high pressure is 14.5 kg / square centimeter (refrigerant temperature is 39
Degree). The characteristics shown in FIG. 5 are the same when the inside temperature is 23 degrees or higher.

Accordingly, when the operation of the cold air dryer is switched from the cooling operation to the reheating operation when the temperature inside the refrigerator is 15 degrees, as in the previous term, the high pressure in the refrigeration cycle = 16.5 Kg / square centimeter (refrigerant temperature = 45 Is high pressure = 14.
It decreases by 5 kg / square centimeter (refrigerant temperature = 39 degrees). The temperature difference of the refrigerant during this period is as small as 6 degrees, and the flash gas generation period is also reduced to about 1 minute to 1 minute 10 seconds. In other words, the vocalization period of the flash gas can be reduced to about 40% as compared with the conventional case.

Further, since the high pressure difference is 2 kg / cm 2 at the maximum when switching from the cooling operation to the reheating operation when the inside of the refrigerator is 23 ° C. or less, the generation of flash gas is particularly reduced in the temperature range inside the refrigerator which is normally used. Therefore, it is possible to prevent the deterioration of the drying ability at the time of switching.

[0035]

According to the present invention, the condenser used for the reheating is divided into a plurality of condensers, and the number of condensers to be operated increases as the temperature in the refrigerator increases when the drying operation function is used. Therefore, the refrigerant circulation amount when the temperature inside the refrigerator is low can be reduced and the high pressure in the refrigeration cycle can be increased. Therefore, it is possible to shorten the temporary reduction time of the drying capacity when switching from the cooling operation to the reheating operation (drying operation).

Furthermore, the amount of refrigerant stagnation in this heat exchanger is minimized by providing a valve mechanism for preventing the refrigerant from flowing into the condenser that is not functioning when using the drying function. Is something that can be done.

[Brief description of drawings]

1A, 1B, and 1C are a front view, a partial cross-sectional side view, and a heat exchanger of a cold air dryer showing an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram showing a refrigeration cycle used in the cold air dryer shown in FIG.

3 is a characteristic diagram showing changes in high pressure when the refrigeration cycle shown in FIG. 2 is used.

FIG. 4 is a refrigerant circuit diagram showing a refrigeration cycle used in a conventional cold air dryer.

5 is a characteristic diagram showing changes in high pressure when the refrigeration cycle shown in FIG. 4 is used.

[Explanation of symbols]

 1 Cold Air Dryer 4 Heat Exchanger 5 Evaporator 6a First Evaporator 6b Second Evaporator 18 Electromagnetic Open / Close Valve 19 Check Valve

Claims (2)

[Claims] 1. A cooling operation function for supplying air cooled by an evaporator to a chamber containing a material to be dried, which comprises a refrigeration cycle using a compressor, a condenser, a pressure reducing device, and an evaporator. In a dryer having a drying operation function of supplying cooled air to the inside after reheating with a condenser, the condenser used for the reheating is divided into a plurality of condensers, and a drying operation function is provided. A cold air dryer characterized by increasing the number of condensers to be operated as the temperature inside the chamber increases when used. 2. The cold air dryer according to claim 1, further comprising a valve mechanism that prevents a refrigerant from flowing into a condenser that is not functioning while using the drying function.