JPS63273775A - Thermo-hygrostat - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a constant temperature and humidity device that can set the humidity in a storage room where the internal temperature is between 125°C and the outside temperature to any desired humidity without a humidifier. It is related to the device.

Conventional technology As shown in Fig. 7, a conventional constant temperature and humidity device uses a heater 5 to heat the inside of a pan 7 in a storage chamber 4 covered with a casing 1 made of a heat insulating material and a door body 2 made of a heat insulating material. Humidifier that heats water and releases water vapor 6. A type of refrigerating cycle in which an 8° evaporator, a heater 10, and a blower 12 are respectively installed is known.

The evaporator 8 of the refrigeration cycle is of a fixed evaporation pressure type and is configured such that the temperature difference between the refrigerant temperature t and the air outlet temperature tA of the evaporator 8 is 5 to IGdeg.

In order to maintain the inside of the storage room 4 at a predetermined temperature t0 and humidity Ra, the following method has been used.

First, the humidifying heater 5 is heated to release the water from the flat tire as water vapor (the air becomes highly humid).

Next, the humidified air is cooled by the evaporator 8 of the refrigeration cycle, thereby allowing dehumidification.

The cooled and dehumidified air is again heated by the heater 10 to a predetermined temperature t0° C., and the heated air is blown into the storage chamber 4 by the blower 12.

Problems to be Solved by the Invention However, with such conventional devices, it is easy to adjust the indoor temperature to a predetermined temperature t,'C, but in order to adjust the indoor humidity to R0%RH, It is necessary to control the amount of water evaporated by heating by the heater and the amount of dehumidification by the evaporator. A commonly used method is to adjust the power of the humidifying heater 5, determine the amount of transpiration based on the water temperature in the pan 7, and adjust the relative humidity to the humidity. It was detected by the meter. According to such a method, an amount of power several times the output of the refrigerator is consumed to adjust the amount of humidification.

Furthermore, when trying to control the humidity in the storage room by setting the temperature in the storage room to 0° C. or lower, the water in the humidifier 6 freezes, making it virtually impossible to control the humidity.

In addition, when controlling the temperature in the storage room 4 to a temperature above 0°C and below the outside temperature, the saturated evaporation temperature of the evaporator 8 will be below 0°C due to cooling efficiency, so the condensed moisture will become frost. There is a risk that frost will form and the cooling capacity will decrease, making it impossible to cool down to a predetermined temperature.

When controlling the humidity at a temperature of 10°C or higher, the humidified air that has been cooled by the evaporator 8 is heated, which requires a heater with a considerable capacity, resulting in the inconvenience of increased power consumption. be.

Furthermore, there is a problem in that it is not possible to quickly respond when changing the temperature and humidity settings.

Therefore, the present invention was developed in view of the drawbacks of the conventional technology, and it is possible to control humidity in a wide temperature range, quickly respond to changes in set temperature and humidity, and maintain a constant temperature that is resistant to frost formation. The purpose is to provide a constant temperature device.

Means for solving the problem, that is, the present invention provides a storage chamber covered with a casing made of a heat insulating material and a door body made of a heat insulating material, a compressor, a condenser, an expansion valve installed in the storage room, In a device comprising an evaporator of a refrigeration cycle connected in circulation to an evaporator and an evaporation pressure regulating valve, a heater for heating the cooled air, and a blower for circulating the air, the heater is installed in a storage room. The evaporator is connected to a temperature control device that supplies power to the heater while detecting the temperature inside the storage chamber through a temperature sensor. This objective is achieved by a constant temperature and humidity device that has a heat exchange area larger than that of a normal device and has an expansion valve that has an opening degree of about two to three times that of a normal device.

The evaporator and expansion valve of the refrigeration cycle according to the present invention include:
We have selected the following:

The expansion valve is selected so that the evaporation pressure is adjusted to be higher than usual using the evaporation pressure regulating valve so that the refrigerant temperature t is close to the temperature tA near the outlet of the evaporator.

If the evaporation pressure is high, there is a risk of insufficient capacity when flowing refrigerant into the evaporator.

Then, the area near the refrigerant outlet becomes superheated and there is a part that does not contribute to cooling.

Therefore, in the expansion valve of the present invention, its opening degree is set to about two to three times that of the conventional one, thereby solving the problem of insufficient capacity. The selection of the evaporator is as follows: The cooling capacity Q is Q=lC-A-ET: Heat transfer coefficient A of the evaporator: Heat exchange area ST: Logarithmic average temperature difference Here, the device of the present invention has the following equation: saturated evaporation temperature t, Since the evaporation pressure is made high so that the air temperature at the evaporator outlet is equal to A, ST is extremely low.

Technically, it is possible to do this by increasing the airflow, but if the items stored in the storage room are prone to drying, such as foodstuffs, there is a problem with them drying out if the airflow is too high, so in principle, The heat transfer coefficient remains unchanged.

Therefore, assuming that the heat exchange area of the evaporator that can be used in a conventional refrigeration cycle is 80, an evaporator with a heat exchange area that is inversely proportional to the logarithmic average temperature difference δT is used so that the cooling capacity remains unchanged. .

Function Desired storage room temperature t0°C1 Relative humidity R0% Based on the absolute humidity R, the evaporator air outlet temperature tA equal to the absolute humidity R, and the saturation of the evaporator when cooling to the evaporator air outlet temperature. Calculate the evaporation temperature ta.

Next, the evaporation pressure is adjusted to a predetermined pressure using the evaporation pressure adjustment valve so that the saturated evaporation temperature of the refrigeration cycle becomes ta.

Further, the control device is adjusted so that the air temperature after heating by the heater becomes wrinkled, and the refrigeration cycle and the control device are operated.

Then, the temperature range (11>1) flowing in from the air inlet of the evaporator
A) For air with absolute humidity R'(R'>R), an evaporator with a large heat exchange area is used, and the opening degree of the expansion valve is twice that of the normal one to avoid insufficient capacity. Since the air outlet is about 3 times wider, air with a temperature tA''C1 and an absolute humidity R flows out from the air outlet of the evaporator.

The outflowing air is heated to a predetermined temperature t0° C. by a heater controlled by a control device, and is completely blown into the storage chamber by a blower.

As a result, the air blown out by the blower has a temperature t0
℃ and relative humidity R0.

At this time, in the refrigeration cycle according to the present invention, the air cooled by the evaporator is difficult to frost because the saturated evaporation temperature tA and the temperature tA near the air outlet of the evaporator are very close to each other.

Also, when changing the set temperature tl + relative humidity R1,
Similarly to the above, if the set temperature of the control device is changed to t, and the set evaporation pressure of the evaporation pressure regulating valve is changed in accordance with the dew point temperature equal to the absolute humidity of R1, the predetermined temperature 1. and the relative humidity can be maintained at R1.

Embodiments The present invention will be explained in detail below according to embodiments shown in the drawings.

In the figure, 24 is a storage chamber covered with a casing 20 made of a heat insulating material and a door body 22 made of a heat insulating material, and a compressor 26. Condenser 28. Expansion - 7 = Valve 30. Evaporator 32. A refrigerating cycle evaporator 32, which is connected in circulation to a variable evaporation pressure regulating valve 34 and an accumulator 36, a heater 38, and an air blower 40 are installed.

The refrigeration cycle used in this embodiment is different from a normal one, and the expansion valve 30 and evaporator 32 are set so that the temperature difference between the refrigerant temperature i and the air temperature tA at the outlet of the evaporator is 05 to 1 Odag. The selection is based on the following criteria.

In a conventional evaporator, the refrigerant temperature t8 and the evaporator air outlet □
Cooling was performed so that the temperature difference from the temperature tA was 5 to 10 degrees.

However, in the refrigeration cycle of the present invention, this temperature difference is 0.5 to 1
．． Odeg, the logarithmic average temperature difference ET of the evaporator is small.

Therefore, the logarithmic average temperature difference in a conventional evaporator is 8 units. ,
When the heat exchange area is A0, the heat exchange area A of the evaporator is set to A- in order to prevent the refrigerating capacity of the evaporator of this embodiment from decreasing and to reliably lower the air to the refrigerant temperature of the evaporator, t. A, .delta.T0/ST, which is inversely proportional to the average temperature difference, is used.

Generally, an evaporator with a heat exchange area about 2 to 3 times larger is used.

Next, the expansion valve 30 is used because the evaporation pressure of the refrigerant is increased by the evaporation pressure adjustment valve 34, and the evaporator 32 has a larger heat exchange area than before.
If refrigerant is allowed to flow through 2, there is a risk that the capacity will be insufficient.

Therefore, in order to resolve the lack of capacity, and furthermore to eliminate the superheat part near the refrigerant outlet and improve cooling efficiency, we have adopted an opening that is approximately two to three times larger than normal.

The operation of the heater 38 is controlled by a control device 42, and the heater 38 is operated so as to maintain the inside of the storage chamber 24 at t0°C according to the temperature t0°C input from an installation temperature input knob 44 provided on the control device 42. 38. This control device 42 is installed in the storage chamber 24 or in the evaporator 3.
Feedback control is performed in which the indoor temperature is detected by a temperature sensor 46 provided at the air inlet section of No. 2, and the supply of tolerance to the heater 38 is adjusted.

In the apparatus of the embodiment according to the present invention in the above-described loose configuration, the temperature inside the storage chamber 24 is +14°C2 relative humidity 60%RH.
When you want to set the temperature to +14°C, turn the set temperature input knob 44.

Next, the relative humidity at +1460 (95% R
Read H). - On the other hand, determine the absolute humidity R of water vapor from the installation temperature and relative humidity, and from the relationship diagram between temperature and absolute humidity shown in Figure 3, find the temperature t* that is the intersection of the absolute humidity R and the curve of relative humidity 90°C RH. (+', z°C) is determined, and the opening degree of the evaporation pressure regulating valve 34 is adjusted so that the evaporation pressure corresponds to the saturated evaporation temperature, so that the saturated evaporation temperature becomes +7.2°C.

After each device is set as described above, the refrigeration cycle and heater 38 are activated.

Then, as shown in Figure 3, the relative humidity is 60% at +14°C.
Air above RH is cooled in the evaporator 32 to +7.2°C.

The air becomes 95% RH and flows out from the air outlet of the evaporator 32.

The air at +72°C and 95% RH that flows out is sent to the heater 3.
8 until it reaches +14°C.

As a result of heating, the absolute humidity of the air at +7.2° C. and 95% RH is equal to the absolute humidity of the air at +14° C. and 960% RH, so the humidity in the storage chamber 24 becomes 60% RH.

Once the specified temperature and humidity (+14℃, relative humidity 60
%RH), the absolute humidity corresponding to +14° C. 260% RH is maintained without being dehumidified because the dew point temperature of the air is very close to the saturated evaporation temperature.

Next, when changing the temperature inside the storage chamber 24 to -3°C and 60% RH, the temperature setting input knob 44 of the control device 42 is turned to set the set temperature to -3°C in the same manner as described above.

From the characteristic diagram in FIG. 2, the relative humidity of the evaporator 32 corresponding to -3° C. is determined (90% RH).

This curve for relative humidity 90%RH and -3℃, 60%R)
The intersection (-10 DEG C.) of the absolute humidity with the straight line corresponding to I is determined from FIG. 3, and the evaporation pressure of the evaporation pressure regulating valve 34 is set so that the saturated evaporation temperature is 110 DEG C.

When the device is operated, the air in the storage chamber 24 is cooled by the evaporator 32 and dehumidified to -10° C. and 90% RH.

The heated air is heated to a predetermined temperature of −3° C. by the heater 38.

As a result, the air inside the storage chamber 24 becomes 960% air at 13°C.

Next, FIG. 4 shows another embodiment of the refrigeration cycle to be installed, in which the compressor 26. Condenser 28. Expansion valve 30. Evaporator 32. Evaporation pressure adjustment valve 34. In the evaporator 32 which is connected in circulation to the accumulator 36, the refrigerant passage is connected to the evaporator 32 so that the refrigerant flows from the bottom to the top. This allows the refrigerant to flow through the evaporator 32 in a semi-full state in order to increase the heat transfer coefficient.

However, in the case of a half-channel liquid type, depending on the type of refrigerant, lubricating oil in the refrigerant may be separated and accumulate at the bottom of the evaporator 32 pipe. A first bypass pipe 50 is connected to the refrigerant outlet of the evaporator 32 via a solenoid valve 48, and a first bypass pipe 50 is connected to the refrigerant outlet of the evaporator 32 via a solenoid valve 52. The solenoid valves 48 and 52 are connected by a double bypass pipe 55, and the solenoid valves 48 and 52 are opened periodically. .52, and the defrost start time is set to timer 5.
It is controlled by 6.

The evaporation pressure regulating valve 34 of this embodiment is provided with a setting device 58 for setting the saturated evaporation temperature 1R of the evaporator 32, and detects the temperature via a temperature sensor 60 provided at the air outlet of the evaporator 32. The opening degree of the evaporation pressure regulating valve 34 is finely adjusted so that the air outlet temperature tA of the evaporator 32 is maintained at the set temperature.

The operation of the apparatus when immediately maintaining the storage chamber 24 at a predetermined temperature and a predetermined humidity R0% is the same as in the first embodiment.

Next, FIG. 5 shows an embodiment configured to automatically control the refrigeration cycle and heater 38 shown in the first embodiment.

In this embodiment, the heater 3 is controlled by an automatic control device 62 having a temperature setting knob 64 and a relative humidity setting knob 66.
8 and the evaporation pressure regulating valve 34 of the refrigeration cycle are controlled.

As shown in FIG. 6, this control device 62 controls the heater 3 according to the temperature input from the temperature setting knob 64.
a temperature controller 68 that feeds back power to the heater 38 and controls the heater 38 via a temperature sensor 46 provided in the storage chamber 24 to keep the inside of the storage chamber 24 at temperatures t and ``c''; and a humidity setting knob. Humidity R0 input from 66
The absolute humidity is calculated from the %RH and the set temperature t0°C, and the evaporation pressure is calculated according to the temperature and humidity calculator 70 that calculates the evaporation temperature of the evaporator 32 according to the characteristics of the evaporator 32 and the output from the temperature and humidity calculator 70. It consists of a drive section 72 that adjusts the opening degree of the regulating valve 34.

Here, the temperature/humidity calculator 70 determines the evaporation temperature (evaporation pressure) by performing the following calculation.

First, set temperature t. ``Determine absolute humidity from C1C128%RH.

Since the relative humidity characteristic of the evaporator 32 is a linear function directly proportional to temperature as shown in FIG. 2, the set temperature t,
Relative humidity R near the evaporator outlet can be calculated using "c" as a reference and the set temperature as a variable.

Next, the intersection point between the relative humidity R1 curve and the absolute humidity straight line is calculated, and the saturated evaporation temperature t at the intersection point is calculated.

The opening degree of the evaporation pressure regulating valve 34 is adjusted via the drive device 72 so that the saturated evaporation temperature becomes tR'C.

When the device is operated in this state, the air that has been cooled and dehumidified by the evaporator 32 is heated again by the heater 38, and is blown into the storage chamber 24 at a predetermined temperature t6+predetermined humidity R0.

Effects As described above, the device according to the present invention is not suitable for controlling temperature and humidity below 10°C because the conventional device uses a humidifier. Since it is configured to control humidity, it is possible to control humidity at temperatures of 10° C. or lower, including subzero temperatures.

Furthermore, since an evaporator with a small logarithmic average temperature difference is used, there is no additional cooling compared to conventional devices, and less heating by the heater is required.

[Brief explanation of the drawing]

1 to 6 show embodiments of the device according to the present invention, FIG. 1 is a schematic diagram of the device showing the first embodiment, and FIG.
The figure is a graph showing the characteristics of the temperature and relative humidity of the evaporator.
The figure is an psychrometric diagram showing the relationship between temperature and absolute humidity, Figure 4 is a schematic diagram of the device showing the second embodiment, Figure 5 is a schematic diagram of the device showing the third embodiment, and Figure 6 is the automatic FIG. 2 is a block diagram showing a control device. FIG. 7 is a schematic diagram of a device showing the prior art.

Claims (1)

[Claims] a storage room covered with a casing made of a heat insulating material and a door body made of a heat insulating material; a compressor installed in the storage room;
A device comprising: an evaporator of a refrigeration cycle connected in circulation to a condenser, an expansion valve, an evaporator, and an evaporation pressure regulating valve; a heater for heating cooled air; and a blower for circulating the air. is connected to a temperature control device that supplies power to the heater while detecting the temperature inside the storage chamber through a temperature sensor installed in the storage chamber, and the evaporation pressure adjustment valve is a variable type that can change the evaporation pressure at will. A constant-temperature and constant-humidity device characterized by having an evaporator with a larger heat exchange area than a normal one, and an expansion valve with an opening that is about two to three times larger than a normal one. Device.