WO2003087683A1

WO2003087683A1 - Dehumidifying method

Info

Publication number: WO2003087683A1
Application number: PCT/JP2002/003717
Authority: WO
Inventors: Chikayoshi Sato
Original assignee: Chikayoshi Sato
Priority date: 2000-10-19
Filing date: 2002-04-15
Publication date: 2003-10-23
Also published as: CN100365359C; TW517149B; JP2002130863A; CN1483131A

Abstract

A dehumidifying method capable of increasing a dehumidification amount by lowering the lowest dew point temperature of a device to near 0 ° C, comprising the steps of disposing a preheat condenser (11), an evaporator (12), and a reheat condenser (13) so that a sensible heat factor is less than 0.5, and condensing, dropwise, the moisture in the air on the surface of the evaporator (12) for dehumidification, whereby, since the condensation load of the condenser is lowered and, accordingly, a condensation temperature and an evaporation temperature are lowered, a temperature difference between an air flow and the surface of the evaporator is increased, and the dropwise condensation of the moisture is promoted to increase the dehumidification amount.

Description

Description 湿 Dehumidification method Technical field

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 improving the amount of dehumidification as compared with a conventional dehumidification method. Background art

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

As shown in Fig. 5, the conventional cooling type dehumidifier forms 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. In general, a blower (not shown) is provided, and the air in the room is cooled and dehumidified by the evaporator 1, and then the air is reheated by the condenser 2.

Usually, the amount of dehumidification can be obtained from the psychrometric chart shown in Fig. 6. For example, when air at the standard point (temperature 27 ° C, relative humidity 60%) indicated by point I in the figure is cooled by the evaporator 1, the air at the outlet at point O (temperature 17 ° C ), The dehumidification amount is calculated as xl—x 2 = 3.67 g / kg (DR).

The straight line connecting the points I and 0 is called the air operation line.Following the extension line, the line touches the saturation temperature curve, and the temperature F (10 ° C in this example) at this time is usually It is called the dew point temperature (evaporation temperature). The lower the dew point temperature (evaporation temperature), the more O The temperature at the point decreases, and a large amount of dehumidification can be obtained.

From this psychrometric chart, the sensible heat factor (SHF) of the device can also be obtained. The sensible heat ratio is the ratio of the sensible heat to the total heat when cooling a certain space, and sensible heat ratio = sensible heat QS / (sensible heat QS + latent heat QL). Sensible heat QS is the amount of heat required to change the temperature of the air. Latent heat QL is the amount of 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 required for temperature change (sensible heat QS) of the heat of air is 54% of the total heat, and the remaining 46% is Latent heat QL to take moisture.

Now, the lowest possible dew point temperature obtained by the conventional cooling type dehumidification method as described above is up to about 5 ° C from the psychrometric chart, and cannot be reduced to 0 ° C or less. If the air operating line deviates from the saturation temperature curve, the operating 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 device, increase the latent heat (QL) taken from the air, and lower the sensible heat ratio (SHF). However, it was impossible to lower the minimum dew point temperature of the equipment to 5 or less by the conventional method of arranging the heat exchangers (evaporator 1 and condenser 2) as described above to dehumidify.

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

The above problem is to arrange an evaporator and a condenser in order from the windward side, cool the air flow to the dew point temperature by the evaporator to remove moisture, and then reduce the air flow to a predetermined temperature by the condenser. A dehumidifying method for reheating, characterized in that moisture in the air stream is dropped and condensed on the surface of the evaporator to dehumidify. In the conventional dehumidification method, the condensate (moisture in the air) becomes film-like condensation that covers the surface of the evaporator (condensation surface) in a film form, and the heat transfer on the condensation surface is performed through this liquid film. The liquid film has a large heat transfer resistance. In contrast, the present invention condenses water in the air in the form of droplet condensation in which the condensed liquid covers the condensing surface in a droplet form, so that the air flow comes into direct contact with the condensing surface as compared with film condensation. Increase the area of the part and increase the heat transfer 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 reduced. 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 a droplet form on the surface of the evaporator, a preheater composed of a split condenser is placed on the windward side of the evaporator, and the temperature of the air passing through the evaporator is set by this preheater. Is preferable. This reduces the condensation load on the condenser, lowering the condensation temperature and lowering the evaporation temperature. Therefore, the temperature difference between the air flow and the surface of the evaporator is increased to promote the condensation of water in a droplet form, thereby improving the amount of dehumidification.

In particular, by arranging the preheater, the evaporator, and the condenser so that the sensible heat ratio is less than 0.5, the droplet-like condensation of the air stream can be promoted. BRIEF DESCRIPTION OF THE FIGURES

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 heat exchanger. FIG. 3 is a 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, and FIG. Fig. 6 is a psychrometric chart explaining the dew point temperature (evaporation temperature) by the conventional dehumidification method. BEST MODE FOR CARRYING OUT THE INVENTION '' Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

The preheated condenser 11 and the reheated condenser 13 consist of a single condenser divided into two and placed on the upwind side and downwind side of the evaporator 12, respectively, as shown in Fig. 2. There is a parallel relationship with respect to the flow of the refrigerant from the compressor 27. In FIG. 2, reference numeral 32 denotes a capillary tube for adjusting the flow rate of the refrigerant.

The preheating condenser 11, the evaporator 12 and the reheating condenser 13 have the same configuration, respectively, and a plurality of radiating fins 1 1 1 1 2 1 These are composed of refrigerant circulation pipes 112, 122, 132, which are arranged so as to penetrate through the radiation fins.

In particular, in the present embodiment, the area of the evaporator 12 is configured to be smaller than the area of the evaporator 1 of the conventional dehumidifier described with reference to FIG. Comparing the evaporating area with the number of hairpins of the pipe 122, the evaporator 12 of the present embodiment has two evaporators and the conventional evaporator 1 has seven evaporators. 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 to a predetermined temperature (5 ° C in this embodiment) is cooled by the evaporator 12 to remove water. After that, it is reheated to a predetermined temperature by the reheat condenser 13 at the subsequent stage, and is discharged indoors.

In this embodiment, the air is heated to a predetermined temperature by passing through the preheating condenser 11. Since it contacts the surface of evaporator 12 in this state, it comes into contact with evaporator 12 with a larger temperature difference than when the preheat condenser 11 is not provided. In addition, the condensation temperature decreases due to the split arrangement of the condenser, and the dew point temperature (evaporation temperature) decreases. From the above, the droplet condensation of water is promoted, and the amount of latent heat taken from the air is increased to improve the amount of dehumidification. Explaining the drop in dew point temperature on the psychrometric chart shown in Fig. 3, if the indoor air is at a standard point (temperature 27 ° (:, relative humidity 60%), the preheat condenser 11 After it is preheated to 32 ° C, it is cooled by the evaporator 12.At this time, the operating line contacts the saturation temperature curve at 0 ° C or less (11 ° C in this example). This temperature becomes the dew point temperature (evaporation temperature).

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

Table 1 shows the standard points, 2 mm. The relationship between the rising temperature of the air by the preheating condenser 11 and the lowest attained evaporation temperature based on the relative humidity (60%) is shown as an example. Setting the condensing temperature of the preheat condenser to raise the air by more than 3 ° C (for example, 40 ° C) will result in a minimum reached evaporation temperature of 11 ° C.

(table 1)

Also, 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 condensing capacity of the conventional condenser 2 is reduced. Since the condensing capacity is increased from the condensing capacity of (1) and the condensing pressure (condensing temperature) can be lowered by reducing the condensing load so as not to lower the capacity of the compressor 27 (40 ° C in the present embodiment). However, the amount of dehumidification can be improved without lowering the refrigerating capacity. At the same time, an increase in 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, points A1 and A2 represent data of the invented device and the conventional device at a temperature of 22.5 and a relative humidity of 47.6%, respectively. Comparing the dehumidification amount, it is 190 cc / h in the conventional machine, but 300 ccZh in the invented machine, 1.58 times that of the conventional machine. From this, when the sensible heat ratio (SHF) of the inventor is found, Assuming that the sensible heat ratio (QS) of the machine is 0.54 (described above), the QL is 0.46, and therefore 0.46X1.58 = 0.73. Becomes 0.27.

In the figure, points B1 and B2 represent data of the invented device and the conventional device at a temperature of 24.5 ° C and a relative humidity of 93.3%, respectively. Comparing the amount of dehumidification, the conventional machine is 520 cCh, whereas the invented machine is 950 cc / h, which is 1.8 times that of the conventional machine. From this, when the sensible heat ratio (SHF) of the invented machine is obtained, assuming that the sensible heat ratio (QS) of the conventional machine is 0.54, QL is 0.46 and therefore 0.46 X 1. From 8 = 0.83, the sensible heat ratio of the invented machine is 0.17.

In the figure, points C1 and C2 indicate the dehumidification amounts of the inventive machine and the conventional machine, respectively, at a temperature of 27 ° C and a relative humidity of 60%, that is, at a standard point. However, the details are not known because measurement was not actually performed at this point, but it is presumed that the invented machine has about twice the amount of dehumidification as compared to the conventional machine. 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 the present embodiment, the area of the evaporator 12 is 3.5 times smaller than the area of the conventional evaporator 1, and the dehumidification amount is about twice as large as that of the conventional machine as described above. Therefore, if it is assumed that the dehumidified water has a film shape on the surface of the evaporator 1 of the conventional machine on average, the film thickness of the dehumidified water of the evaporator 12 of the present embodiment is There will be a water film about 7 times thicker than 1 dehumidified water. 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 moisture in the air is dehumidified in the form of droplet condensation.

Further, the specific volume of the refrigerant increases due to a decrease in the condensing temperature and the evaporating temperature, which leads to a decrease in the amount of the circulating refrigerant. Can be achieved. That is, according to the present embodiment, For example, the amount of dehumidification can be improved with a smaller evaporation area (volume) than before. Here, from the theoretical design formula of the evaporator, the relationship between the capacity of the evaporator 12 of the present invention and the capacity of the conventional evaporator 1 is confirmed by the following formula.

Qe = K · F · t d …… (1)

Qe: Evaporator cooling capacity (kcal / h),

K: heat transfer coefficient of the evaporator (kcal / ° Cm ² h),

F: Evaporator surface area (m ² )

t d = (t a + t b) / 2- t e (2)

t a: Air temperature at evaporator inlet (C),

t b: Air temperature at evaporator outlet (° C),

t e: Evaporator evaporation temperature (° 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 invented machine is Qe2, then Qel = 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 film-form condensation, and K2 is the drop-rate condensation. Because of the heat transfer coefficient, it becomes 1 ^ 2.

Therefore, from equation (2), if the conventional machine td 1 = (ta 1 + t 1) Z2—tel and the inventor t d2 = (ta 2 + tb 2) Z2—te 2, then ΐ & 1 = 27, ta 2 = 32 ° C, tb 1 = 17 ° C, tb 2 = 14 ° C> te 1 = 10 ° C, te 2 = 7 ° C, tdl = 12 ° (, td 2 = 16 ° C , Td l <td 2. Therefore, from the relation of Qe l = Qe 2, K1 and K2, and td 1 <td 2, the surface area F of the evaporator becomes F 1> F2 from the equation (1). In conclusion, it can be seen that the capacity of the evaporator of the invented machine must be smaller than the capacity of the evaporator of the conventional machine. Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these, and various modifications can be made based on the technical idea 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 the moisture in the air, a method of reducing the capacity of the evaporator 12 compared to the conventional method is adopted. Alternatively, the evaporating temperature can be reduced by reducing the air volume from the blower as compared with the conventional case.

Further, in the above embodiment, the capillary tube 32 was used as the refrigerant flow rate adjusting means. However, in order to surely adjust the refrigerant flow rate due to the decrease in the evaporation temperature, the refrigerant tube 32 was replaced with the capillary tube 32. Alternatively, an electronic expansion valve may be employed. The invention's effect

As described above, according to the dehumidification 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, thereby reducing the amount of dehumidification. Significant improvement can be achieved.

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 condensation of the water, and the condensation temperature is reduced together with the evaporation temperature to reduce the refrigeration capacity. Improvement, that is, improvement in the amount of dehumidification can be achieved. Furthermore, it is possible to suppress the rise in the ambient temperature by reducing the condensing load, and to reduce the amount of refrigerant circulating, thereby reducing the size of the heat exchanger and reducing power consumption.

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

Claims

The scope of the claims

1. An evaporator and a condenser are arranged in order from the windward side. After the air flow is cooled to the dew point temperature by the evaporator to remove moisture, the air flow is reheated to a predetermined temperature by the condenser. -.

A dehumidifying method, characterized in that moisture in the air stream is dropped and condensed on the surface of the evaporator to dehumidify.

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. 2. The dehumidifying method according to item 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.