Heat exchanger bottom plate structure

Abstract

To provide a fin-and-tube heat exchanger that has a bottom plate structure in which in order to reduce pressure loss of an airflow, drain holes are provided in a bottom plate of the heat exchanger to drain condensation water from the drain hole, and which prevents deterioration in heat exchange performance.SOLUTION: In a bottom plate that receives condensation water from coils and fins of a fin-and-tube heat exchanger, drain holes are provided in the bottom plate for condensation water generated during cooling, where the drain holes include at least drain holes near a center part of the bottom plate and drain holes near a downstream terminal, where a diameter of the drain holes near the terminal is made larger than a diameter of the drain holes near the center part; the number of drain holes near the terminal is made larger than the number of drain holes near the center part; or both of these are combined.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a fin-and-tube heat exchanger, and particularly to a bottom plate structure of the heat exchanger, which reduces the pressure loss of the air flow.

Background Art

[0002] As shown in FIG. 1, a conventional fin-and-tube heat exchanger has a structure in which the coil is covered with a frame body to protect the main pipes of the fins and coils and to ensure the passage of target fluids such as air. Generally, as shown in Patent Document 1, a drain pan (see the dotted line portion 212 in FIG. 1) for collecting condensed water such as dew condensation is arranged under the coil, and the condensed water falling from the coil bottom plate is drained exclusively from the drain pan. In such a fin-and-tube heat exchanger, in order to drain the condensed water condensed on the cooled fins and the main pipes of the coil during the operation of cooling or dehumidifying, drain holes are provided in the bottom plate, and the condensed water is drained from the drain holes. However, on the surface of the coil bottom plate of the heat exchanger, if the condensed water stays on the bottom plate surface or the coil, there are disadvantages that the condensed water staying in the most downstream part of the air scatters, or the condensed water accumulates on the bottom plate and the pressure loss increases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a bottom plate structure that provides drain holes in the bottom plate of the fin-and-tube heat exchanger, drains condensed water from the drain holes, and reduces the pressure loss without degrading the heat exchange performance.

Means for Solving the Problems

[0005] To achieve the above objective, the bottom plate structure of the heat exchanger is provided with drainage holes for the condensate water generated during cooling, in the bottom plate that receives condensate water from the coils and fins of the heat exchanger coil. Furthermore, the number and grouping of drainage holes provided in the bottom plate increase as you go downstream, and / or the diameter of the drainage holes increases as you go downstream. Moreover, the bottom plate structure of the heat exchanger is such that drainage holes are provided at least near the center of the bottom plate and near the downstream end, with the diameter of the drainage holes near the end being larger than the diameter of the drainage holes near the center. Furthermore, the size of the drainage holes and the number of drainage holes should be appropriately combined to efficiently discharge condensed water and suppress the amount of bypass air. [Effects of the Invention]

[0006] According to the heat exchanger bottom plate structure of the present invention, the bottom plate that receives condensed water from the main pipes and fins of the heat exchanger coil is provided with drainage holes for condensed water generated during cooling, and the number of drainage holes increases and / or the hole diameter increases as you go downstream. As a result, the condensed water that accumulates on the bottom plate can be properly discharged while maintaining the heat exchange performance of the heat exchanger. This makes it possible to reduce pressure loss (approximately 5% in Figure 6) while maintaining heat exchange performance. [Brief explanation of the drawing]

[0007] [Figure 1] A perspective view of the overall appearance of the heat exchanger of the given embodiment. [Figure 2] Figure 2(a) is a diagram illustrating the state of condensed water in a conventional bottom plate without drainage holes, and Figure 2(b) is a diagram illustrating the state of condensed water in one embodiment of the present invention, in which drainage holes are provided only near the center of the bottom plate. [Figure 3] Figure 3(a) is a diagram illustrating the state of condensation when there are many rows of coil main tubes (direction of airflow on the bottom plate) and only drainage holes are provided near the center of the bottom plate, and Figure 3(b) is a diagram illustrating the state of condensation when only drainage holes are provided near the leeward end of the bottom plate. [Figure 4] Figures 4(a) to (c) illustrate another embodiment of the present invention, showing a case where drainage holes 27 of the same diameter are provided at least near the center and leeward end of the bottom plate, while Figures 4(d) to (f) illustrate another embodiment of the present invention, showing a case where drainage holes 27 of different diameters are provided at least near the center and leeward end of the bottom plate. [Figure 5] This diagram illustrates the bottom plate structure of an embodiment of the present invention, showing the state of the bypass airflow and the state of condensed water. [Figure 6] Graph 1 compares the coil performance and pressure loss of a conventional bottom plate structure with a drain hole in the center (bottom plate in Figure 2(b)) and a bottom plate structure in which the drain holes shown in Figure 5 of the present invention are provided near the center and near the leeward end. [Modes for carrying out the invention]

[0008] The present invention relates to a bottom plate structure for a fin-and-tube heat exchanger that, in order to prevent a decrease in coil performance, has drainage holes in the bottom plate of the heat exchanger to drain condensed water such as condensation from the drainage holes, and reduces pressure loss without reducing heat exchange performance. A preferred embodiment of the present invention will be described with reference to the figures. [Examples]

[0009] First, let me explain the necessity of drainage holes. Figure 1 shows a fin-and-tube heat exchanger 1. The heat exchanger 1 has a coil 2 mounted on a frame 21, with a header 22 on one side of the coil 2. The main pipe 25 of the coil is connected to this header 22, and on the other side, the main pipe 25 is folded back into the header 22 by a U-bend 26. A bottom plate 211 is provided on the coil frame 21. The header 22 has a chilled / hot water inlet 221 side and a chilled / hot water outlet 222 side. Chilled / hot water inlets 23 and chilled / hot water outlets 24 are provided on the chilled / hot water inlet 221 side and chilled / hot water outlet 222 side of the header, and are connected to the main pipe 25. If necessary, a drain pan 212 for temporarily storing condensation and other drainage is provided further below the bottom plate 211.

[0010] In the absence of conventional drainage holes, as shown in Figure 2(a), condensed water A accumulates on the bottom plate 211 below the two coil groups of the heat exchanger 1, restricting the airflow path and causing problems such as reduced heat exchange performance and increased pressure loss. There is also a concern that the accumulated condensed water may scatter downstream, causing problems such as water leakage. In this case, as shown in Figure 2(b), providing drainage holes 27 near the center of the bottom plate 211 is effective when there are few rows of coils, as the water is constantly drained. However, with only one row of drainage holes near the center, the air that should be cooled flows along with the drained water and bypasses the drainage, which also causes problems such as reduced heat exchanger performance. However, as the number of coil rows increased, the drainage holes located only near the center became insufficient for draining condensed water. This resulted in condensed water being retained on the bottom plate 211, hindering air from passing through the fin surface, and consequently leading to increased pressure loss and reduced heat exchange performance of the coils. If we consider the case where there are many rows perpendicular to the airflow, when the drainage holes 27 are located near the center of the bottom plate 211, as shown in Figure 3(a), the amount of condensed water A increases. The condensed water A near the center is drained, but the condensed water A on the downwind side is not drained, so a pool of condensed water A forms, obstructing the airflow, leading to increased pressure loss, and also increasing the possibility of condensed water A scattering. Furthermore, if the drain hole 27 is located on the leeward side, as shown in Figure 3(b), the condensed water A on the leeward side will be discharged, but conversely, the condensed water A will accumulate from near the center to the leeward side, leading to an increase in pressure loss.

[0011] Therefore, the present invention provides rows of drainage holes 27 at least near the central part and near the leeward end, and some embodiments thereof are illustrated in Figure 4. Figures 4(a) to 4(c) are plan views of the base plate 211, showing arrangements of drainage holes 27 with the same diameter. Figure 4(a) shows six drainage holes 27 near the center and eleven near the leeward end. Figure 4(b) shows six near the center and eleven near the leeward end, the only difference from Figure 4(a) being the wider base plate. Figure 4(c) shows three rows of drainage holes 27, with six near the center and eleven in the area between the leeward end and the center.

[0012] Similarly, in Figures 4(d) to (e), the diameter of the drainage holes 27 near the leeward end is larger than that of the drainage holes 27 near the center. In Figures 4(d) to (f), 11 drainage holes 27 with larger diameters than those near the center are arranged near the leeward end, and the width of the bottom plate is varied, similar to Figures 4(a) to (c). Furthermore, the reason for increasing the number of holes or the diameter of the drainage holes 27 on the leeward side is that, since the mass of water is greater than that of air, air can easily pass through the first drainage hole 27, while the area near the end is suitable for the discharge of water, which has a larger mass due to the wind speed.

[0013] Based on these findings, as shown in Figure 5, in a fin-and-tube type heat exchanger, by appropriately adjusting the number of drainage holes 27 near the center and near the leeward end, the diameter of the holes, and their arrangement (density), the amount of bypass air B can be suppressed, thereby suppressing a decrease in heat exchange performance. Furthermore, the drainage of condensate 27 is improved, preventing water accumulation, thus reducing pressure loss and allowing condensate A to be properly discharged.

[0014] Graph 1 in Fig. 6 compares the number and size of the drain holes 27 of the present invention with those of a conventional bottom plate 211 having a row of drain holes provided in the middle part. Specifically, for this example, the number of drain holes 27 in the central part is 6, the number of drain holes 27 near the ends is 11, and the hole diameter of the drain holes 27 near the ends is larger. While suppressing the decrease in heat exchange performance due to the increase in the airflow (bypass air B) that does not pass through the heat exchanger 1, the drainage performance is improved, and the pressure loss can be reduced by suppressing water pooling. That is, the drainage performance by the drain holes is improved, the heat exchange performance equivalent to that of the conventional product is maintained, and the pressure loss is reduced by about 5%.

[0015] As described above, according to the bottom plate structure of the heat exchanger of the embodiment of the present invention, in the bottom plate that receives the condensed water of the coils and fins provided in the coil of the heat exchanger, drain holes are provided for the condensed water generated on the bottom plate. The drain holes are arranged such that the number increases and the hole diameter becomes larger towards the downstream. Therefore, while maintaining the heat exchange performance of the heat exchanger, the condensed water staying on the bottom plate can be appropriately discharged. Also, while maintaining the heat exchange performance, the pressure loss can be reduced (Fig. 6: about 5%).

Explanation of Signs

[0016] A... Condensed water, B... Bypass air 1... Heat exchanger, 2... Coil, 21... Coil frame, 211... Bottom plate, 212... Drain pan 22... Header, 221... Cold / hot water inlet side header, 222... Cold / hot water outlet side header, 23... Cold / hot water inlet, 24... Cold / hot water outlet, 25... Main pipe, 26... U-bend, 27... Drain hole, 3... Fin

Claims

[Claim 1] A heat exchanger bottom plate structure that includes drainage holes for draining condensed water from the coils and fins of a fin-and-tube heat exchanger, Multiple drainage holes are provided in a line perpendicular to the airflow being heated by the heat exchanger, forming a row of drainage holes. A heat exchanger bottom plate structure characterized by having rows of drainage holes in the center of the bottom plate in the direction of airflow and at the leeward end, with the number of drainage holes in the row of drainage holes at the leeward end being greater than the number of drainage holes in the row of drainage holes at the center in the direction of airflow, and the diameter of the drainage holes in the row of drainage holes at the leeward end being larger than the diameter of the drainage holes in the row of drainage holes at the center in the direction of airflow.

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