JPH0972674A - Counter flow type cooling tower and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a counter flow type cooling tower which satisfies demanded characteristics (pressure loss and cooling performance) and the best manufacturing process of the counter blow type cooling tower. SOLUTION: This invention relates to a counter flow type cooling tower where Hin /W=0.3 to 0.5 in which Hin represents the height of an air intake and W represents the width of a tower when no louver is provided on the air intake. When a louver is provided on the air intake, the counter flow type cooling tower is expressed by Hin /W=0.4 to 0.8. Furthermore, if the height of a plenum area is assumed to be HP and tower width is assumed to be W, the counter flow type is expressed by HP/W=0.2 to 0.4. The relationship between the shape and the characteristics of the tower is determined based on a numerical analytical method, thereby manufacturing the counter flow type cooling tower according to a specified process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counter-flow type cooling tower for cooling hot water discharged from factory equipment, air-conditioning equipment and the like with high efficiency, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a cooling tower used to cool and circulate hot water discharged from factory equipment, air-conditioning equipment of buildings, etc. has a hot water cooling system in view of the hot water cooling system. The so-called "cross flow method" where the air flow intersects at right angles and the hot water and the cooling air flow face each other,
There is a so-called "counterflow type", and the present invention relates to a counterflow type cooling tower. Therefore, in order to facilitate understanding of the present invention, FIG. 7 shows a schematic configuration of a counterflow type cooling tower.

In FIG. 7, a filler block 2 is installed above an air intake section 1 through which outside air (F) taken in from the side of the tower passes, and a cooling fan 4 via a plenum section 3 above it. Is installed. Filler block 2
Is supplied with hot water from a hot water supply pipe 5 through a branch pipe 6 and a sprinkling nozzle 7, and the supplied hot water flows down in the filler block. On the other hand, the hot water that is taken into the air intake section 1 by the cooling fan 3 and flows down through the filler block 2 is cooled by the air flow rising in the tower. The air after the heat exchange with the hot water is separated into water droplets by the eliminator 8 and is then discharged to the outside. As described above, in the counter flow type cooling tower, the warm water flowing down is cooled by the airflow supplied from the opposite direction. Thus, the hot water that has passed through the filler block becomes cold water and is stored in the cold water tank 9. In addition, the cooling tower shown in FIG.
There is no louver at the air intake that sucks in air, but this louver has "the effect of smoothly introducing the outside air into the tower" and "the effect of suppressing the scattering of the cooled water flowing down in the tower to the outside". Expected and can be installed as needed.

[0004]

By the way, in manufacturing a cooling tower, the air intake height (H _in , see FIG. 8) and the plenum height (which are important dimensions of the counterflow type cooling tower) are important. H _P, see Fig. 8) and towers width (W, see FIG. 8), of that has been determined empirically is a reality. The empirical value is obtained by investigating the pressure loss and cooling performance of the actually manufactured cooling tower. Therefore, it is unclear whether the height of the air inlet or the height of the plenum is the proper size (shape) for the characteristics (pressure loss, cooling performance) required for the cooling tower. The effect of the attached louvers is also unknown.

The present invention has been made in view of the above problems in a counter flow type cooling tower, and an object thereof is a counter flow type cooling which satisfies required characteristics (pressure loss, cooling performance). To provide a tower. Another object of the present invention is to provide the best manufacturing process for a counter flow type cooling tower.

[0006]

In order to achieve the above object, the present invention comprises a cooling fan above the filler block via a plenum portion, and a cold water tank below the filler block via an air intake portion, In a counter-flow type cooling tower that cools the hot water flowing down through the filler block by the airflow taken into the air intake section by the cooling fan, if the louver is not provided at the air intake port, the height of the air intake port is set to H. H _in / W when _in and the tower width is W
= 0.3 to 0.5 is a counter flow type cooling tower as the first invention, and in the above first invention, when a louver is provided at the air intake port, H _in / W
= 0.3 to 0.5, H _{in /} W = 0.4 to 0.6
The second aspect of the present invention is a counter-flow type cooling tower characterized in that a cooling fan is provided above the filler block via a plenum part, and a cold water tank is provided below the filler block via an air intake part to fill. the hot water flowing down in the wood block, the counter flow system cooling tower for cooling the air flow taken into the air intake portion by the cooling fan, the plenum height and H _P, when the tower width is W, H _P / W = 0.2 to 0.4 is a counterflow type cooling tower as a third invention, the counterflow type cooling tower is divided into a plurality of elements, and the movement of the air flow in the cooling tower is divided. Replacing the continuous equation and the motion equation that governs the equation with a difference equation, the pressure is repeatedly calculated until the pressure reaches a constant value under the prescribed boundary conditions, and The resulting flow rate to obtain the pressure loss or cooling performance of the cooling tower based on the pressure or flow rate, the presence or absence of the louver in the inlet air, the air intake of the height H _in,
A fourth invention is a method for producing a counterflow type cooling tower by determining the shape of the cooling tower based on the relationship between the plenum height H _P or the tower width W and the pressure loss or the cooling performance, and performing the predetermined steps. And

In order to manufacture a counterflow type cooling tower having an appropriate size (shape) according to the required characteristics of the cooling tower, it is indispensable to elucidate the air flow in the cooling tower, and it is necessary to understand the existing velocity meter and pressure. Although it is conceivable to actually measure the flow using a meter, it is often difficult to accurately measure the air flow in the tower due to the complicated structure inside the tower as shown in FIG. 7. In such a case, a method of analyzing the air flow in the tower by using a numerical flow analysis method is advantageous, and a large amount of data can be obtained by changing the calculation conditions and repeating the calculation. In the flow numerical analysis, partial differential equations (continuity equation and motion equation) that govern the motion of the air flow are analyzed under predetermined boundary conditions.

The method for obtaining the air flow in the tower by numerical analysis of the flow will be briefly described. First, the area to be analyzed is divided into small elements. Although it depends on the analysis conditions, the area is divided into approximately 70 to 150,000 pieces. Regarding the fluid elements inside and outside the created tower structure, it is convenient to use a computer under predetermined boundary conditions and replace the partial differential equation with a differential equation to obtain an approximate solution. The specific method is described below.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A counterflow type cooling tower of appropriate size (shape) that satisfies desired characteristics (pressure loss, cooling performance) and a best process for manufacturing such a cooling tower will be described.

(1) Calculation range Ratio of air intake height H _in (m) to tower width W (m) [H _in / W] 0.2 <H _in /W<0.7 Plenum height the ratio of the H _P and Tohaba W (m) [H _P /
W] 0.1 <H _P /W<0.6 Average wind velocity in the tower 2.9 m / sec Even if the wind velocity condition is changed considerably, the air flow in the tower is in a completely turbulent state. The results obtained in (1) can be hydrodynamically correlated to different wind speed conditions. Air physical properties (density, viscosity coefficient) Operating temperature (0 to 40 ° C) was adopted.

(2) Analytical method The continuous equation and the equation of motion are replaced by a difference equation, and repeated calculation is performed until the pressure reaches a constant value under a predetermined boundary condition. Ask. The obtained pressure and flow velocity values almost represent the actual operating conditions. The following processing is performed based on this local pressure value and flow velocity value.

(3) Effect of air intake height / tower width (H _in / W) on air intake pressure loss: The pressure loss of the air intake means that the outside air is the inlet of the air intake. This is the loss of air pressure from the inlet to the bottom of the filler block 2, and is due to the bending loss accompanying the expansion and contraction of the flow path. Therefore, in order to obtain the pressure loss in the target section, the difference between the sectional average pressures at the start point and the end point of the section may be calculated. Here, if the pressure of the outside air (P _atoms [Pa]) is the starting point and the average pressure of the cross section of the lower part of the filler block 2 is the end point, the air intake port pressure loss ΔP _in [Pa] can be obtained by the following equation. ΔP _in = P _atoms −∫PdA / AP is the pressure [P _a ] of the element obtained by the above numerical analysis, and A is the column cross-sectional area [m ² ]. FIG. 1 shows the relationship of ΔP _in with respect to H _in / W when there is no louver, and FIG. 3 shows the relationship of ΔP _in with respect to H _in / W when there is a louver. In FIG. 3, L _P indicates the louver installation pitch.

(4) Effect of air intake height / tower width (H _in / W) and plenum height / tower width (H _P / W) on heat exchange performance (cooling performance) Air flow in the cooling tower The flow of the water affects the cooling performance. If the airflow is unevenly distributed in the tower or if there is a dead space in the tower to which the airflow does not reach, the cooling performance is deteriorated. The size of these drift and dead volume is dependent on the air inlet height H _in or plenum height H _P, to grasp the cooling performance in each tower body structure is extremely in the manufacture of cooling tower is important. In obtaining the cooling performance, first, a parameter α representing the state of the flow in the column is defined. α becomes zero when the airflow is uniformly flowing in the tower in an ideal state (plug flow), and is calculated by the following equation. α = Qdev / QT [Qdev = ∫ (U−U _ave ) dA: U> U _ave ] [QT = total air flow in the tower, U = local wind speed in the tower, U
_ave = cross-section average wind speed] The cooling performance of the tower has a peak value when α is zero, that is, when plug flow occurs. However, there is a wind speed distribution in the majority tower in the air flow of the wind speed distribution tower body structure conditions (H _in / W and H _P /
W). That is, since α changes with H _in / W and H _P / W, it is important to obtain the cooling performance in an arbitrary flow state (α ≠ 0). Specifically, it can be performed as follows. That is, the following relationship is established between the heat exchange coefficient K _a [kcal / m ³ hr Δi] (reference state: α = 0) of the filler, the cooling water amount L [kg / hr], and the air flow rate G [kg / hr]. There is. K _a = β (L / A) ^m (G / A) ⁿ [β = constant, m = 0.3 to 1.0, n = 0 to 1.0, A
= Tower cross-sectional area [m ² ]] β, m and n are numerical values determined for each packing material, and K _a in the standard state (α = 0) is obtained from the formula.
From the equation, if the cooling water amount L is constant, K _a is the air flow rate G
It turns out that it depends on. Since the flow rate of the air flowing locally in the tower can be clarified by the above-mentioned numerical analysis of the airflow in the tower, by calculating K _a in the tower local and integrating the area in the entire tower, an arbitrary flow state (α The total K _a (α) in the tower when ≠ 0 can be obtained.

That is, K _a (α) is obtained from the following equation. K _a (α) = ∫ β (L / A) ^m (G / A) ⁿ dA / A The ratio of the formula to the formula is calculated, and H in the case of no louver is calculated.
_in / W, in the case of there louver H _in / W, and H _P /
The plots for W are shown in FIGS. 2, 4, and 6, respectively.

(5) Effect of Plenum Height / Tower Width (H _P / W) on Plenum Pressure Loss Plenum pressure loss is the air pressure from the top of the packing block 2 to the bottom of the cooling fan 3. The loss of
This is due to the expansion and contraction of the flow path. Therefore, in order to obtain the pressure loss in the target section, the difference between the cross-sectional average pressures at the start point and the end point of the section may be calculated. Here, the cross-sectional average pressure (P ₁ [P
a)) as the starting point and the sectional average pressure (P ₂ [Pa]) below the cooling fan 3 as the ending point, the plenum pressure loss ΔP _out [Pa] can be calculated by the following equation. ΔP _out = P ₂ −P ₁ [P ₂ , P ₁ = ∫PdA / A, P = element pressure [P
a], the A = Todan area [m ^2]] contraction flow ratio as a parameter, [Delta] P for H _P / W
FIG. 5 shows the relationship of _out . In addition, in FIGS. 5 and 6, the contraction ratio is (cross-sectional area of the cooling fan installation portion) /
(Filler block installation section cross-sectional area) ratio.

As described above, the influence of H _in / W on the pressure loss of the air intake portion with and without the louver, the influence of H _in / W on the cooling performance with and without the louver, and the pressure loss or cooling performance of the plenum. Since the influence of _HP / W was sought, the proper cooling tower shape is then determined based on these relationships.

(6) Appropriate cooling tower shape without louver The proper cooling tower shape is determined from two points of pressure loss and cooling performance. Regarding the pressure loss, from FIG. 1, ΔP _in is H _in /
When W = about 0.5, the value is almost constant, and even if H _in /W>0.5, the effect of reducing ΔP _in is small. Also, H _in / W =
At 0.3 to 0.5, ΔP _in tends to slightly increase, but the degree is small. On the other hand, when H _in /W<0.3, ΔP _in rapidly increases and an excessive cooling fan is required, which is not preferable. Therefore, when the proper shape of the cooling tower is determined from the viewpoint of pressure loss, H _in /W=0.3 to
It becomes 0.5. Next, regarding the cooling performance, from FIG.
When H _in / W = about 0.5, 98% of the cooling performance in the plug flow is reached, and even if H _in /W>0.5, the cooling performance is not further improved. On the other hand, when H _in / W = about 0.3, it becomes 96% of the cooling performance in the plug flow, and H
_{When in /} W <0.3, the decrease in cooling performance cannot be ignored, which is not preferable.

As described above, in the case of no louver, H _in
It can be said that /W=0.3 to 0.5 satisfies both characteristics of pressure loss and cooling performance.

(7) Appropriate cooling tower shape with louver The proper cooling tower shape is determined from two points of pressure loss and cooling performance. Regarding the pressure loss, from FIG. 3, ΔP _in is H _in /
When W = about 0.6, the value is almost constant, and even if H _in /W>0.6, the effect of reducing ΔP _in is small. Also, H _in / W =
At 0.4 to 0.6, ΔP _in tends to increase slightly, but the degree is small. On the other hand, when H _in /W<0.4, ΔP _in rapidly increases and an excessive cooling fan is required, which is not preferable. Therefore, when the proper shape of the cooling tower is determined from the viewpoint of pressure loss, H _in /W=0.4 to
0.6. Next, regarding the cooling performance, from FIG.
When H _in / W = about 0.6, the cooling performance reaches 96% in the plug flow, and even if H _in /W>0.6, the cooling performance is not further improved. On the other hand, when H _in / W = about 0.4, the cooling performance is 93% in the plug flow, and H
_{When in /} W <0.4, the cooling performance sharply deteriorates, which is not preferable.

As described above, when the louver is present, H _in
It can be said that /W=0.4 to 0.6 satisfies both characteristics of pressure loss and cooling performance.

Thus, it can be seen that the presence of the louver not only increases the pressure loss but also reduces the cooling performance. In other words, if louvers are installed, the air flow in the tower may become uneven, so care should be taken to minimize the number of louvers installed.

[0022] (8) the pressure loss of the plenum portion height and proper cooling tower shaped plenum portion, as shown in FIG. 5, are different by contraction flow ratio, it decreases with increasing H _P / W,
H _P / W When is above a certain value in converges substantially constant value. When determining the scope of the preferred H _P / W within the range of practical contraction flow ratio it is believed to be 0.2 to 0.4. That is, when H _P / W is about 0.4, ΔP _out has a substantially constant value, and the effect of reducing ΔP _out is small even when H _P /W>0.4. On the other hand, when H _P /W<0.2, ΔP _out increases, which is not preferable.

Next, the cooling performance of the plenum portion is shown in FIG. 6, cooled in H _P /W=0.3~0.4 performance is almost reached a certain value, H _P / W> Even if it is 0.4, improvement of cooling performance cannot be expected. Moreover, the cooling performance becomes H _P /W<0.2 is gradually decreased, and further, the plenum must be installed sprinkler nozzle and eliminator, it is necessary for the plenum portion above a certain size. Above, H _P /
It can be said that W = 0.2 to 0.4 is a preferable range in consideration of both characteristics of pressure loss and cooling performance.

The cooling tower having the shape determined as described above can be manufactured according to the manufacturing process generally performed.

[0025]

According to the invention described in claim 1, 2 or 3, it is possible to provide a cooling tower which satisfies the main characteristics required for the cooling tower such as pressure loss and cooling performance. Further, the invention according to claim 4 discloses the best process for producing the cooling tower according to claim 1, 2 or 3, and according to the present production method, any shape satisfying the required characteristics can be obtained. It is possible to manufacture a cooling tower. Further, since it is possible to design a compact shape with no wasted portion, it is possible to reduce the total height of the cooling tower by about 10%.

[Brief description of drawings]

FIG. 1 is a diagram showing the influence of air inlet height / tower width (H _in / W) on air inlet pressure drop (ΔP _in ) in a louver-less counterflow cooling tower.

FIG. 2 Air inlet height / tower width (H _in
It is a figure which shows the influence of / W).

FIG. 3 is a diagram showing the influence of air inlet height / tower width (H _in / W) on air inlet pressure loss (ΔP _in ) in a counter flow type cooling tower with louvers.

FIG. 4 Air inlet height / tower width (H _in
It is a figure which shows the influence of / W).

FIG. 5: Plenum height / tower width (H _P / W) that affects plenum pressure loss in a counter flow type cooling tower
It is a figure which shows the influence of.

FIG. 6 is a diagram showing the effect of plenum height / tower width (H _P / W) on the cooling performance ratio in a counter flow type cooling tower.

FIG. 7 is a partially cutaway perspective view of a counterflow type cooling tower.

FIG. 8 is a diagram schematically showing a counter flow type cooling tower.

[Explanation of symbols]

 1 ... Air intake part 2 ... Filler block 3 ... Plenum part 4 ... Cooling fan 5 ... Hot water supply pipe 6 ... Branch pipe 7 ... Sprinkling nozzle 8 ... Eliminator 9 ... Cold water tank

Claims (4)

[Claims] 1. A cooling fan is provided above the filling material block via a plenum portion, and a cold water tank is provided below the filling material block via an air intake portion. Hot water flowing down in the filling material block is aired by the cooling fan. In a counter-flow type cooling tower that cools by the airflow taken into the intake part, when the louver is not provided at the air intake port, the height of the air intake port is set to H _in , and the tower width is set to W _in / W
= 0.3 to 0.5, a counter flow type cooling tower. 2. When a louver is provided at the air intake,
Instead of H _in /W=0.3 to 0.5, H _in /W=0.4
The counterflow type cooling tower according to claim 1, wherein the cooling tower has a flow rate of about 0.6. 3. A cooling fan is provided above the filling material block via a plenum portion, and a cold water tank is provided below the filling material block via an air intake portion. Hot water flowing down in the filling material block is aired by the cooling fan. in counter-flow system cooling tower for cooling by incorporating the intake portion stream, the plenum height and H _P, when the tower width is is W, that is H _P /W=0.2~0.4 Characteristic counter flow type cooling tower. 4. A counter flow type cooling tower is divided into a plurality of elements, and the continuous equation and the equation of motion that govern the motion of the air flow in the cooling tower are replaced with a difference equation to reduce the pressure under a predetermined boundary condition. Obtain the pressure and flow velocity of each of the above dividing elements in a steady state by repeating the calculation until it becomes a constant value, and determine the pressure loss or cooling performance of the cooling tower based on this pressure or flow velocity, and whether there is a louver at the air intake, of the air intake height H _in, plenum height H _P or tower width W
And the pressure loss or the cooling performance, the shape of the cooling tower is determined, and a counterflow type cooling tower is manufactured through predetermined steps.