Heat exchanger for cooling tower

Abstract: The heat exchanger has a zig-zagged liquid-flowing passage (14) and an overflowed-liquid escaping conduit (17). When an excessive amount of cooling water is supplied to the heat exchanger, a part of cooling water flows into the overflowed-liquid escaping conduit (17) through a dam formed between the liquid-flowing passage and the escaping conduit (17). The heat exchanger is formed by assembling a plurality of heat exchanging partition plates formed by molding, which have the same shape and the same dimensions, and which are easily engageable with and detachable form each other.

Description: The present invention relates to a heat exchanger for a cooling tower used for apparatuses such as air conditioners, refrigerators and so on. Particularly, it relates to an indirect contact type heat exchanger for the cooling tower in accordance with the preamble of claim 1. Such a heat exchanger is known from DE-C-414269. An indirect contact type heat exchanger for a cooling tower is widely used as a closed type heat exchanger or such a type of heat exchangers that it is mounted on a packing material consisting of a large number of corrugated plates in a parallel arrangement to prevent generation of whitish smoke or mist. An example of the inner structure of the heat exchanger is shown in Figures 16 to 18 in which air passages for feeding air in the horizontal direction are separated by metallic plates or synthetic resin plates from liquid-flowing passages for feeding liquid in the vertical direction so that the two kinds of passages are arranged alternately. Heat-exchanging efficiency is increased by reducing the space of the liquid-flowing passages as possible. In each of the liquid-flowing passages, there are formed a number of deflectors projecting from the partition plates in the liquid-flowing passages to reduce a flow speed of the liquid to thereby further increase heat-exchanging efficiency. Japanese Unexamined Patent Publication No. 100370/1976 discloses a heat exchanger for cooling tower which comprises a plurality of thin, flat liquid-flowing passages arranged vertically and in parallel to each other and a plurality of thin, flat air-flowing passages extending vertically which are alternately interposed between the adjacent liquid-flowing passages, wherein each of the liquid-flowing passages is separated from each of the air-flowing passages by a heat exchanging partition plate made of a synthetic resin so that the liquid and air are fed in the passages in a non-contact state. Both walls for forming of each of the air-flowing passages are formed by an inverse U-shaped member. The adjacent inverse U-shaped members are connected to each other by means of ribs projecting from the side walls so that a liquid-flowing passage is formed between the connected inverse U-shaped members. The heat exchanger disclosed in the above-mentioned publication is mounted on a cooling tower by hanging a plurality of the inverse U-shaped members above the packing material held in the cooling tower by means of a horizontal supporting beam as shown in Figure 19, or it is mounted on a cooling tower by hanging a plurality of vertically arranged heat exchangers inside the packing material which is disposed at an outer air inlet port of the cooling tower as shown in Figure 20. This arrangement of the heat exchangers is to prevent generation of whitish smoke or mist in the winter season. In the conventional heat exchangers, however, there is such a disadvantage that when it is used for a long time, dust or microorganisms deposit on the wall surface of the liquid-flowing passages which are generally narrow and are curved in order to reduce the falling speed of the liquid flowing by the action of gravity. As a result, the optimum flow rate of liquid can not be obtained, and there often causes flooding of the liquid at the liquid supplying side of the heat exchanger. This results in not only wetting the heat exchanger but also reduction of an amount of a refrigerant circulated in the heat exchanger. In a case that the heat exchanger is used for a cooling tower by disposing it above the packing material to disperse the liquid discharged from the heat exchanger onto the packing material, the quantity of the dispersed liquid (water) becomes short to thereby invite the shortage of liquid circulating in the cooling tower. In such a type of cooling tower that a plurality of the heat exchangers are supported by hanging them in a multi-stage at the inside of the packing material which is disposed at the outer air inlet port of the cooling tower (Figure 20), the shortage of the liquid in the cooling tower results in the generation of whitish smoke or mist. It is an object of the present invention to provide an indirect contact type heat exchanger for cooling tower or a heat exchanger unit as the major component of the heat exchanger which has a simple structure and is capable of maintaining the optimum flowing rate of liquid even when there causes clogging in a part of the heat exchanger or the heat exchanger unit. In accordance with the present invention, there is provided a heat exchanger for cooling tower plurality of thin, flat air-flowing passages which are alternately interposed between the adjacent liquid-flowing passages, each of the liquid-flowing passages being separated from each of the air-flowing passages by a heat exchanging partition plate made of a metallic plate or a synthetic resin plate so as not to have air contact with liquid passed therethrough, the heat exchanger being characterized in that deflectors are arranged on the surface of each of the partition plates in the direction of its width so as to project toward the liquid-flowing passages to thereby form a liquid-falling speed reducing part, and a vertically extending overflowed-liquid escaping conduit is formed adjacent the liquid-falling in accordance with claim 1. A preferred embodiment is claimed in claim 2. In the drawings: Figure 1 is a front view partly broken of a first embodiment of the heat exchanger according to the present invention; Figure 2 is a front view partly omitted of a second embodiment of the present invention; Figure 3 is a front view partly broken of a third embodiment according to the present invention; Figures 4 through 8 are respectively cross-sectional views taken along lines 4-4, 5-5, 6-6, 7-7, and 8-8 in Figure 1; Figure 9 is a bottom view partly omitted of the heat exchanger shown in Figure 1; Figure 10 is a front view partly broken of a fourth embodiment of the heat exchanger according to the present invention; Figures 11 through 15 are respectively cross-sectional views of the heat exchanger unit taken along lines 4-4, 5-5, 6-6, 7-7, and 8-8 in Figure 10; Figure 16 is a schematic view showing a conventional heat exchanger; Figure 17 shows the conventional heat exchanger from the front part; Figure 18 is a diagram showing another conventional heat exchanger; and Figures 19 and 20 are respectively diagrams showing conventional heat exchangers used for a cooling tower to prevent the generation of whitish smoke or mist. Preferred embodiments of the present invention will be described with reference to the drawings. A first embodiment of the present invention will be described with reference to Figure 1 and Figures 4 through 9. In the Figures, a simbol A shows as a whole a heat exchanger for cooling tower. The heat exchanger A is provided with a plurality of thin, flat liquid-flowing passages 50 arranged in the vertical direction and in parallel to each other, and a plurality of thin, flat air-flowing passages 51 interposed between adjacent two liquid-flowing passages 50 of the plurality of liquid-flowing passages 50, wherein a plurality of heat exchanging partition plates 52 are interposed between the adjacent liquid-flowing passage 51 and the air-flowing passage 50 to provide a partition to render the two kinds of fluids to be in a non-contact state. The two adjacently placed heat exchanging partition plates 52, which constitutes walls for a single air-flowing passage 51, form a single heat exchanger unit B by connecting the upper edges of the plates in their entire width direction. A plurality of the heat exchanger units B are arranged in a single and same casing C in parallel to each other to form each liquid-flowing passage 50 between each adjacently placed two heat exchanger units B. In the third embodiment, the heat exchanger A is constituted by arranging the plurality of heat exchanger units B so that they are engageable with and detachable from each other at the planes where the liquid-flowing passages are formed. Each of the heat exchanging partition plates 52 is formed by a molding method so as to have the same size and the same dimensions. The heat exchanger unit B is formed by opposing a couple of the heat exchanging partition plates 52, i.e. one being reversed, followed by connecting their upper edges. The heat exchanging partition plate 52 has a number of deflectors 54 in an expanded form at the area except the edge portions. Namely, the deflectors 54 are distributed in a discrete and alternate manner in the horizontal and vertical direction in the partition plate 52. The heat exchanger units B are assembled in such a manner that the deflectors 54 projecting from a first heat exchanger unit B are fitted to recesses formed in a second heat exchanger unit B while the deflectors projecting from the second heat exchanger unit extend toward the first heat exchanger unit, whereby a zig-zagged liquid-flowing passages is formed between the first and second heat exchanger units B. The deflectors 54 will be explained in more detail. Referring to Figures 4 through 8. Of the two adjacent heat exchanging plates 52 to form a liquid-flowing passage 50 therebetween, the tip of each of the deflectors 54 of the heat exchanging plate 52 of the first heat exchanger unit B is fitted into each corresponding sharrow recess formed in the heat exchanging partition plate 52 of the second heat exchanger unit B, while the tip of each of the deflectors 54 formed on the heat exchanging partition plate 52 of the second heat exchanging unit B is fitted into each corresponding sharrow recess formed in the heat exchanging partition plate of the first heat exchanger unit B. Thus, the deflectors 54 functions not only to provide curved liquid-flowing passages but also to provide spacers for the liquid-flowing passages defined by the first and second heat exchanger units B. In the first embodiment, the distance of the liquid-flowing passages 50 defined by the two heat exchanger units B is in a range from 2 mm - 5 mm, preferably, about 2 mm. The thickness of the partition plate 52 is in a range from 0.2 mm to 0.4 mm. At both side portions of each of the heat exchanging partition plates 52, a plurality of stripe-like projections and recesses 55 are formed over the entire length. These stripe-like projections and recesses 55 provide sealing portions at both side areas 50a, 50b of the zig-zagged liquid-flowing passages 50 by the mutual engagement of the projections and the recesses 55 when the heat exchanger is assembled (Figure 9). At least one engageable and detachable notch or fastener may be provided at a part of the stripe-like projections and recesses 55 to secure the engagement of the projections and recesses 55, if necessary. A second embodiment of the heat exchanger according to the present invention will be described with reference to Figure 2. In Figure 2, the same reference numerals as in Figure 1 designate the same or corresponding parts and therefore, description of these parts is omitted. In the second embodiment, the lower edge 56 of the heat exchanger unit B is integrally connected over its entire width, whereby there is provided a heat exchanger Al for cooling tower in which air-flowing passages are closed at their upper and lower ends; the upper parts of the passages are connected to a common liquid supplying port; and their lower parts are connected to a common discharge port. A third embodiment of the heat exchanger will be described with reference to Figure 3. In Figure 3, the same reference numerals designate the same or corresponding parts as in Figure 1, and therefore, description of these parts is omitted. In the third embodiment of the present invention, a heat exchanger A2 for cooling tower has a liquid-flowing passage section 50A which comprises in general a liquid-falling speed reducing part E in the central area, overflowed-liquid escaping conduit parts F at both sides of the liquid-falling speed reducing part E and stripe-like projections and recesses 59 provided between the liquid-falling speed reducing part E and the overflowed-liquid escaping conduit parts F. The liquid-falling speed reducing part E is formed by a number of the deflectors 54 in the heat exchanging partition plate 52 in the same manner as described with reference to the third embodiment. A plurality of the heat exchanger units B comprising a couple of the heat exchanging partition plates 52 are assembled by mutually fitting the deflectors 54 in the recesses formed in the heat exchanging partition plates 52. The liquid-falling speed reducing part E is separated from the overflowed-liquid escaping conduit parts F by the vertically extending stripe-like projections and grooves 59. The upper edges of the stripe-like projections and recesses 59 extend to the upper part of the heat exchanger unit B to form dams G for liquid overflowed, whereby when cooling water is excessively supplied to the heat exchanger, a part of cooling water escapes through the conduit parts F. Reference numerals 55 designates sealing parts at both edges of the heat exchanger and the sealing means may be in a form of the stripe-like projections and grooves. In the first to third embodiments of the present invention, each of the heat exchanging partition plates 52 has the same size and the the same dimensions. Accordingly, it is easily manufactured by a molding method. Further, in storage and transportation of the heat exchaing partition plates before assembling work, they are not bulky and save a space. When the heat exchanging partition plates 52 are assembled to form to heat exchanger units B, assembling working can be easy by simply opposing a couple of the partition plates 52, followed by connecting their upper edges 53. Figures 10 through 14 show a modified embodiment of each of the first to third embodiments as shown in Figures 1 through 9. In the Figures the same reference numerals designate the same or corresponding parts. A number of expanded projections 60 are formed in each of the heat exchanging partition plates 52 at same positions. The expanded projections 60 function as spacers for air-flowing passages 51 when a couple of the heat exchanging partition plates 52 are assembled to form a heat exchanger unit B. Each of the expanded projections 60 may take a shape of cone 62 with a bottom 61 opened and a flat apex portion. The inner surface 62 of the conical-shaped expanded projection 60 functions as a vortex-flow-generating means in the liquid-flowing passages. Of the a couple of the heat exchanging partition plates 52 constituting a single heat exchanger unit B, a small projection 64 is formed in the top surface of each of the expanded projections 60 of the first heat exchanging partition plate 52. On the other hand a small recess 65 is formed in the top surface of each of the expanded projections 60 of the second heat exchanging partition plate 52. Thus, position adjustment of the first and second heat exchanging partition plates 52 is effected. It is clear that the above-mentioned structure can also be applied to the embodiments shown in Figures 2 and 3. In the embodiment described with reference to Figures 10 through, the danger of deposition of dust or microorganisms can be reduced because vortex flows are resulted due to the vortex-flow-generating means when the cooling water flows in the liquid-flowig passages. Further, by engaging the small projections and the small recesses, accurate positioning of the heat exchanger unit in an assembled heat exchanger can be obtained. In the embodiments shown in Figures 1 through 14, the upper edge portion 52a of each of the heat exchanging partition plates 52 may be bent to the same side as the expanded projections 53 into an L shape so that it is flush with the top of the expanded projections 53. In this case, a single heat exchanger unit B is formed by facing a couple of the heat exchanging partition plates 52 in which one of the partition plates 52 is reversed and by connecting the upper edges 52a along there entire width. In this case, the projections 53 of both the heat exchanging partition plates 52 are mutually met so that air-flowing passages having a constant distance can be realized by the spacing function of the projections 53. The heat exchanger A is assembled by the thus formed heat exchanger units B as follows. A plurality of the heat exchanger units B are disposed in parallel to each other in a casing C; the stripe-like projections and recesses 55 of a heat exchanging partition plate 52 of one heat exchanger unit B are engaged with those of an adjacent heat exchanger unit B to form a liquid-flowing passage part having sealing portions at both sides of it; engagement of these stripe-projections and recesses 55 are carried out for the other heat exchanger units successively; and a liquid supplying port is formed at the upper edges 52a of the heat exchanging partition plates 52 so as to be communicated with the liquid-flowing passages. In this case, each of the heat exchanger units B are connected at the plane for forming liquid-flowing passages so as to be freely engageable and detachable. When the heat exchanger of the present invention is used for a cooling tower in the condition as shown in Figure 19, i.e. the heat exchanger is disposed on the packing material, the cooling water is cooled in the heat exchanger by indirect contact with air passing therethrough and it is dispersed on the packing material. Then, the cooling water is brought in direct contact with air to be cooled. On the other hand, the temperature and the humidity of the air are increased, and the air is forced toward the outlet where it is mixed with air which has an elevated temperature but the same absolute humidity as the atmosphere, whereby the mixed air is discharged out the cooling tower without generating whitish smoke or mist. When the heat exchanger of the present invention is used for a cooling tower under the condition as shown in Figure 20, i.e. the heat exchangers are disposed in multi-stage inside the packing material, air having an elevated temperature and a high humidity is fed to the heat exchanger through the packing material in which the air is brought in direct contact with the cooling water. On the other hand, the cooling water falling through the zig-zagged liquid-flowing passages in the heat exchanger gradually enters into the lower heat exchangers during which heat exchanging is effected between the air and the cooling water, whereby the air having an elevated temperature is discharged out the cooling tower without causing whitish smoke or mist. In the heat exchanger of the present invention, even when an excessive amount of cooling water is supplied to the heat exchanger by any cause such as clogging in a part of liquid-flowing passages, a part of cooling water is escaped through the overflowed-liquid escaping conduit to be discharged outside the heat exchanger. Therefore, a continuous operation can be attained without limiting an amount of cooling water to be supplied to the heat exchanger.

Claims: A heat exchanger for cooling tower comprising a plurality of thin, flat liquid-flowing passages (50) and a plurality of thin, flat air-flowing passages (51) which are alternately interposed between the adjacent liquid-flowing passages (50), each of said liquid-flowing passages (50) being separated from each of said air-flowing passages (51) by a heat exchanging partition plate (52) made of a metallic plate or a synthetic resin plate so as not to have air contact with liquid passed therethrough, each adjacent two heat exchanging partition plates (52) constituting a single heat exchanger unit (B) by connecting the upper parts (52a) of said two adjacent partition plates (52); and a plurality of said heat exchanger units (B) are vertically arranged in parallel to each other in a casing (C) to thereby form said liquid-flowing passages (50) between the adjacent heat exchanger units (B); characterized in that said adjacent heat exchanger units (B) are disposed to have side portions along a liquid-flowing direction formed to be engageable with and detachable from those of an adjacent heat exchanger unit (B) and a position where each liquid-flowing passage (50) is located, whereby at least one engageable and detachable notch or fastener is provided at a part of strip-like projections and recesses (55) to secure the engagement of the projections and recesses (55). The heat exchanger according to Claim 1, wherein a number of expanded deflectors (54) are formed in said adjacent partition plates (52) constituting the heat exchanger unit (B) so that spacers are formed by butting the ends of each opposing pair of said expanded deflectors (54), and a number of recesses are formed to receive said expanded deflectors (54) in said partition plates (52), whereby the deflectors (54) and recesses are formed in the plane of the liquid-flowing passages (50).

Inventors: KASHIWADA KEN, MUTO TADANOBU, SASAKI TETSUO, KASHIWADA, KEN, MUTO, TADANOBU, SASAKI, TETSUO, KASHIWADA, KEN, SHINWA SANGYO CO., LTD., MUTO, TADANOBU, SHINWA SANGYO CO., LTD., SASAKI, TETSUO, SHINWA SANGYO CO., LTD.
Applicants: SHINWA SANGYO KK, SHINWA SANGYO CO., LTD.
Application year: 1988
Main classification: F28B1
IPC codes: F28C1, F28B1, F28D9, F28F21