JP2002130863A - Dehumidification method - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] To provide a dehumidification method capable of lowering the minimum dew point temperature of an apparatus to around 0 ° C. to increase the amount of dehumidification. SOLUTION: This is solved by a dehumidifying method characterized in that moisture in an air stream is dropped and condensed on the surface of an evaporator 12, and dehumidified. In order to condense water in the air in the form of droplets on the surface of the evaporator 12, a preheater 11 constituted by dividing the condenser on the windward side of the evaporator 12 is disposed.
The method of raising the temperature of the air passing through the evaporator 12 by 1 is preferred. As a result, the condensation load on the condensers 11 and 13 is reduced, so that the condensation temperature is reduced and the evaporation temperature is also reduced. Therefore, the temperature difference between the air flow and the surface of the evaporator increases, and the condensation of moisture is promoted, and the amount of dehumidification is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehumidification method for cooling and dehumidifying indoor air with an evaporator, and more particularly, to a dehumidification method capable of greatly increasing the amount of dehumidification as compared with a conventional dehumidification method. .

[0002]

2. Description of the Related Art Conventionally, a dehumidifier has a cooling method,
There are various types such as a compression type, an absorption type and an adsorption type.
Of these, the cooling type is also called a direct expansion coil type, and the principle of dehumidification is to reduce the saturated steam pressure and condense moisture in the air by cooling the air with a compression refrigerator. This method has an advantage that the equipment cost is low, and is widely applied as a home dehumidifier or a commercial dehumidifier.

As shown in FIG. 5, a conventional cooling type dehumidifier comprises an evaporator 1 arranged on the windward side, a condenser 2 arranged on the leeward side, and an air flow from the evaporator 1 to the condenser 2. And an air blower (not shown) that forms air-cooled air, and the air in the room is cooled and dehumidified by the evaporator 1, and then the air is reheated by the condenser 2.

Normally, the amount of dehumidification can be obtained from a psychrometric chart shown in FIG. For example, when air at the standard point (temperature 27 ° C., relative humidity 60%) indicated by the point I in the drawing is cooled at the evaporator 1 at the outlet at the point O (temperature 17 ° C.), The dehumidification amount is x1-x2
= 3.67 g / kg (DR).

[0005] A straight line connecting the points I and O is called an air operation line, and if it follows an extension line, it comes into contact with the saturation temperature curve. Is called the dew point temperature (evaporation temperature). As the dew point temperature (evaporation temperature) is lower, the temperature at the point O is lower, and a large amount of dehumidification can be obtained.

The sensible heat ratio (SHF: Sensible Heat Factor) of the apparatus can also be determined from the psychrometric chart. The sensible heat ratio is the ratio of the amount of sensible heat to the total amount of heat when cooling a certain space, and sensible heat ratio = sensible heat amount QS / (sensible heat amount QS)
+ Latent heat quantity QL). The sensible heat QS is the heat required to change the temperature of the air, and the latent heat QL is the heat required to condense the moisture in the air. Here, in the case of the above example, the sensible heat ratio is about 0.54, and the amount of heat (sensible heat amount QS) required for temperature change among the heat amounts of air is 54% of the total heat amount.
%, And the remaining 46% is the amount of latent heat QL for taking moisture.

[0007]

The lowest possible dew point temperature obtained by the conventional cooling type dehumidifying method as described above is up to about 5 ° C. from a psychrometric chart, and should be set to 0 ° C. or less. Can not. This is because when the air operation line deviates from the saturation temperature curve, the operation state (refrigeration cycle) becomes unstable. In order to increase the amount of dehumidification by the cooling type dehumidification method, it is necessary to lower the minimum dew point temperature of the apparatus, increase the latent heat amount (QL) taken from the air, and lower the sensible heat ratio (SHF). In the conventional method of dehumidifying by arranging the heat exchangers (evaporator 1 and condenser 2) as described above, it was impossible to lower the minimum dew point temperature of the apparatus to 5 ° C. or less.

The present invention has been made in view of the above problems, and has as its object to provide a dehumidifying method capable of reducing the minimum dew point temperature of an apparatus to around 0 ° C. to increase the amount of dehumidifying.

[0009]

An object of the present invention is to provide an evaporator and a condenser arranged in this order from the windward side, and cooling the air flow to a dew point temperature by the evaporator to remove moisture. Is dehumidified by reheating the water to a predetermined temperature in the condenser, wherein the moisture in the air stream is dropped and condensed on the surface of the evaporator to dehumidify. .

In the conventional dehumidifying method, the condensed liquid (moisture in the air) forms a film-like condensation covering the surface (condensation surface) of the evaporator in a film form, and the heat transfer on the condensation surface is performed through this liquid film.
This liquid film has a large heat transfer resistance. In contrast, the present invention condenses the water in the air in the form of droplet condensation in which the condensed liquid covers the condensing surface in a droplet form, whereby the air flow comes into direct contact with the condensing surface as compared with the film-shaped condensation. Increase the area of the part,
Increase the heat transmission coefficient (heat transfer coefficient).

Therefore, according to the present invention, the condensation of water is promoted by the improvement of the heat transmission coefficient, the amount of latent heat taken from the air flow is increased, and as a result, the dew point temperature is lowered.
As a result, the dew point temperature can be reduced to around 0 ° C., and the amount of dehumidification can be significantly improved.

In order to condense water in the air in the form of droplets on the surface of the evaporator, a preheater constituted by dividing the condenser is arranged on the windward side of the evaporator, and the preheater is passed through the evaporator by the preheater. A method of increasing the temperature of the air is preferred. As a result, the condensation load of the condenser is reduced, the condensation temperature is reduced, and the evaporation temperature is also reduced. Therefore, the temperature difference between the air flow and the surface of the evaporator increases, and the condensation of moisture is promoted, and the amount of dehumidification is improved.

In particular, by arranging the preheater, the evaporator and the condenser so that the sensible heat ratio is less than 0.5, it is possible to promote the droplet condensation of the air flow.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
In the present embodiment, a configuration is adopted in which a preheat condenser 11, an evaporator 12, and a reheat condenser 13 are vertically arranged in order from the windward side to dehumidify indoor air. Although not shown, the preheat condenser 1 is located on the lee side of the reheat condenser 13.
A blower is provided for forming an air flow from 1 to the reheat condenser 13. Reference numeral 14 in the figure denotes a shield that blocks passage of air.

The preheat condenser 11 and the reheat condenser 13 are obtained by dividing one condenser into two parts and disposing them on the upstream and downstream sides of the evaporator 12, respectively, as shown in FIG. Are in a parallel relationship with respect to the flow of the refrigerant from the compressor 27. In FIG. 2, reference numeral 32 indicates a capillary tube for adjusting the flow rate of the refrigerant.

The preheat condenser 11, the evaporator 12, and the reheat condenser 13 have the same configuration, and include a plurality of radiation fins 111, 121, 131 arranged at equal pitches.
The refrigerant circulating pipes 112, 122, and 132 are arranged so as to penetrate through the radiation fins.

In particular, in this embodiment, the area of the evaporator 12 is smaller than the area of the evaporator 1 of the conventional dehumidifier described with reference to FIG. Comparing the evaporation area with the number of hairpin portions of the pipe 122, the evaporator 12 of the present embodiment is two, and the conventional evaporator 1 is seven, and the area of the evaporator 12 of the present embodiment is: It is 3.5 times smaller than the area of the conventional evaporator 1.

Next, the operation of the present embodiment will be described. The air in the room is guided to the preheating condenser 11 by driving a blower (not shown), and the air whose temperature has been raised by a predetermined temperature (5 ° C. in the present embodiment) is cooled by the evaporator 12 to remove water. It is reheated to a predetermined temperature by the reheat condenser 13 at the subsequent stage, and is discharged into the room.

In this embodiment, the air passes through the preheating condenser 11 and contacts the surface of the evaporator 12 in a state where the temperature is raised by a predetermined temperature. And comes into contact with the evaporator 12. In addition, the condensation temperature is reduced by the split arrangement of the condenser,
Dew point temperature (evaporation temperature) decreases. As described above, the droplet condensation of moisture is promoted, and the amount of latent heat taken from the air is increased to improve the dehumidification amount.

The lowering of the dew point temperature will be described with reference to the psychrometric chart shown in FIG.
° C, 60% relative humidity).
After being preheated to 32 ° C. by cooling, it is cooled by the evaporator 12, and at this time, the operation line contacts the saturation temperature curve at 0 ° C. or less (−1 ° C. in this example), Temperature (evaporation temperature).

The sensible heat ratio (SHF) of the apparatus cannot be represented from the psychrometric chart. However, as will be described later, it is possible to calculate the sensible heat ratio by calculation from the evaporating temperature (dew point temperature) of the apparatus, the amount of dehumidification, and the capacity table of the compressor.

Table 1 shows the standard points (27 ° C., relative humidity 60
The relationship between the rising temperature of the air by the preheating condenser 11 and the lowest attained evaporation temperature on the basis of%) is exemplarily shown. If the condensing temperature of the preheating condenser is set so that the air is raised by 3 ° C. or more (for example, 40 ° C.), a minimum ultimate evaporation temperature of −1 ° C. can be obtained.

[0024]

[Table 1]

In the present embodiment, the conventional condenser 2
(See FIG. 5) is divided into a preheat condenser 11 and a reheat condenser 13, so that the condensation capacity thereof is greater than that of the conventional condenser 1, and the capacity of the compressor 27 is increased. The condensing load can be reduced so as not to lower the condensing pressure (condensing temperature) (40 ° C. in the present embodiment), so that the amount of dehumidification can be improved without lowering the refrigerating capacity. At the same time, an increase in the ambient temperature can be suppressed by reducing the condensation load.

FIG. 4 shows the amount of dehumidification performed in a prefabricated warehouse without temperature and humidity adjustment in the dehumidifier configured as described above, in comparison with a conventional home dehumidifier. here,
The solid line indicates the invented machine, and the dashed line indicates the conventional machine.

In the figure, the points A1 and A2 correspond to the temperature 2
The data of the invention machine and the conventional machine at 2.5 ° C. and 47.6% relative humidity are shown, respectively. Comparing the dehumidification amount, the conventional machine is 190 cc / h, while the inventive machine is 300 cc / h, which is 1.58 times that of the conventional machine.
From this, the sensible heat ratio (SHF) of the invented machine is calculated. Assuming that the sensible heat ratio (QS) of the conventional machine is 0.54 (described above),
QL is 0.46 and therefore 0.46 × 1.5
From 8 = 0.73, the sensible heat ratio of the invention machine is 0.27.

In the figure, points B1 and B2 are:
The data of the invention machine and the conventional machine at a temperature of 24.5 ° C. and a relative humidity of 93.3% are shown, respectively. Comparing the dehumidification amount, the conventional machine is 520 cc / h, whereas the inventive machine is 950 cc / h, which is 1.8 times that of the conventional machine. When the sensible heat ratio (SHF) of the invented machine is calculated from this,
Assuming that the sensible heat ratio (QS) of the conventional machine is 0.54, Q
L is 0.46, so 0.46 × 1.8 =
From 0.83, the sensible heat ratio of the invention machine is 0.17.

In the figure, points C1 and C2 are:
The graph shows the dehumidification amount of the invention machine and the conventional machine at the temperature of 27 ° C. and the relative humidity of 60%, that is, the standard point. However, since the measurement is not actually performed at this point, the details are unknown, but it is estimated that the invented device has a dehumidification amount about twice that of the conventional device. Therefore, the sensible heat ratio of the invented machine is 0.5 or less, as in the case of the points A1 and B1.

In particular, in this embodiment, the area of the evaporator 12 is 3.5 times smaller than the area of the conventional evaporator 1, and as described above, the dehumidification amount is about twice the dehumidification amount of the conventional machine. Since the amount of dehumidified water can be obtained, if the dehumidified water has a film shape on the surface of the evaporator 1 of the conventional machine on average, the thickness of the film of the dehumidified water of the evaporator 12 of the present embodiment is There will be a water film about 7 times thicker of the dehumidified water of the evaporator 1. Therefore,
If the water film is about seven times that of the conventional machine, it can be expressed as a water droplet rather than a film. That is, in this embodiment, it can be said that the moisture in the air is dehumidified in the form of droplet condensation.

Further, since the specific volume of the refrigerant increases due to the decrease in the condensing temperature and the evaporating temperature, which causes a decrease in the circulation amount of the refrigerant, the power consumption is reduced, the evaporator 12 is downsized, and the dehumidifier as a whole is reduced. Can be reduced in size.
That is, according to the present embodiment, the amount of dehumidification can be improved with a smaller evaporation area (capacity) than in the related art.

Here, the relationship between the capacity of the evaporator 12 of the present invention and the capacity of the conventional evaporator 1 will be confirmed by the following calculation formula from the theoretical design formula of the evaporator. Qe = K · F · td (1) Qe: Cooling capacity of the evaporator (kcal / h), K: Heat transmission coefficient of the evaporator (kcal / ° C. m ² h), F: Surface area of the evaporator (m ² ) td = (ta + tb) / 2−te (2) ta: air temperature at the inlet of the evaporator (° C.), tb: air temperature at the outlet of the evaporator (° C.), te: evaporation temperature of the evaporator (° C.) As the design conditions of the inventor, the same compressor as that of the conventional machine is used, and the cooling capacity is almost the same. If the cooling capacity of the evaporator of the conventional machine is Qe1 and the cooling capacity of the evaporator of the invention machine is Qe2, Qe1 = Qe2. Regarding the relationship between the heat transfer coefficient K1 of the conventional evaporator and the heat transfer coefficient K2 of the inventor's evaporator, K1 is the heat transfer coefficient in the film condensation and K2 is the heat transfer coefficient in the droplet condensation. Therefore, K
1 <K2. Therefore, from the equation (2), the conventional machine td1 =
(Ta1 + tb1) / 2-te1, invention machine td2 = (t
a2 + tb2) / 2−te2, then ta1 = 27
° C, ta2 = 32 ° C, tb1 = 17 ° C, tb2 = 14
° C, te1 = 10 ° C, te2 = 7 ° C, td1
= 12 ° C, td2 = 16 ° C, and td1 <td2. Therefore, Qe1 = Qe2, K1 <K2, td1
From the relationship of <td2>, the surface area F of the evaporator is F1> F2 from the equation (1), and consequently, unless the capacity of the evaporator of the inventor is smaller than the capacity of the evaporator of the conventional apparatus. It turns out that it does not become.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical concept of the present invention.

For example, in the above-described embodiment, as a method of lowering the evaporation temperature of the evaporator 12 in order to achieve the droplet condensation of moisture in the air, a method of reducing the capacity of the evaporator 12 as compared with the conventional method is employed. Alternatively, the evaporating temperature can be reduced even if the air volume by the blower is reduced as compared with the conventional case.

Further, in the above embodiment, the capillary tube 32 is used as the refrigerant flow rate adjusting means. However, in order to surely adjust the flow rate of the refrigerant due to the lowering of the evaporation temperature, electronic expansion is performed instead of the capillary tube 32. A valve may be employed.

[0036]

As described above, according to the dehumidifying method of the present invention, the amount of latent heat deprived from air is increased by condensing water in the air in a droplet form to improve the heat transmission coefficient of the evaporator. In addition, the amount of dehumidification can be significantly improved.

According to the second aspect of the present invention, the temperature difference between the air flow and the surface of the evaporator is increased to promote the droplet-like condensation of water. Improvement, that is, improvement in the amount of dehumidification can be achieved.
Further, the increase in the ambient temperature is suppressed by reducing the condensation load, and the amount of circulating refrigerant is reduced, so that the heat exchanger can be reduced in size and power consumption can be reduced.

Further, according to the third aspect of the present invention, it is possible to improve the heat transmission coefficient of the evaporator, promote the droplet condensation of water, and improve the dehumidification amount.

[Brief description of the drawings]

FIG. 1 is a side view of a heat exchanger illustrating a dehumidification method according to an embodiment of the present invention.

FIG. 2 is a piping system diagram of the same.

FIG. 3 is a psychrometric chart illustrating the dew point temperature (evaporation temperature) according to the embodiment of the present invention.

FIG. 4 is a diagram showing a comparison of the amount of dehumidification between a dehumidifier to which the present invention is applied and a conventional dehumidifier.

FIG. 5 is an arrangement diagram of each heat exchanger for explaining a conventional dehumidification method.

FIG. 6 is a psychrometric chart explaining the dew point temperature (evaporation temperature) according to the conventional dehumidifying method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Preheat condenser 12 Evaporator 13 Reheat condenser 27 Compressor 120 Evaporator 122 Circulation pipe

Claims (3)

[Claims] 1. An evaporator and a condenser are arranged in this order from the windward side. After the air flow is cooled to a dew point temperature by the evaporator to remove water, the air flow is returned to a predetermined temperature by the condenser. A dehumidifying method for heating, wherein moisture in the air stream is dropped and condensed on the surface of the evaporator to perform dehumidification. 2. A preheater, which is configured by dividing the condenser, is arranged on the windward side of the evaporator, and the temperature of an air flow passing through the evaporator is increased by the preheater. The dehumidification method according to claim 1. 3. The dehumidifying method according to claim 2, wherein the preheater, the evaporator, and the condenser are arranged so that a sensible heat ratio is less than 0.5.