JPS5989965A - Evaporator with corrugated fin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a heat pump outdoor heat exchanger, an evaporator for the purpose of air cooling, and a heat exchanger whose fin surface is frosted.
In particular, the present invention relates to a water droplet removal or defrosting method suitable for corrugated fin evaporators used as car air conditioner evaporators.

[Prior art]

In conventional evaporators for car air conditioners, when the inlet air temperature is low and frost forms on the fin surface, the compressor is stopped intermittently and the ice or frost on the fin surface is warmed by the air passing through it, melting it and releasing it to the outside of the evaporator. I'm taking it out. In this case, depending on the shape of the fins and heat transfer tubes of the evaporator, water droplets may easily fall on the surface of the fins, while others may not. The corrugated fin evaporator targeted by the present invention is difficult for water droplets to fall, so if the compressor is operated intermittently for a long time,
If the operation continues without water droplets being sufficiently removed to the outside of the evaporator, there is a drawback that ice may accumulate particularly on the surface of the bottom fins of the evaporator.

[Purpose of the invention]

In order to prevent water droplets from collecting and refreezing at the location of the evaporator outlet where the air temperature v is lowest, the corrugated fin shape allows water droplets to be removed in a dispersed state so that they do not collect at the evaporator outlet. The amount of water droplets generated on the fin surface increases on the evaporator inlet side and decreases as it approaches the evaporator outlet side. However, since the fins are tilted downward, there is a problem in that water droplets on the inlet side flow to the protruding end face.

The present invention aims to remove water droplets before they reach the evaporator outlet by making the drain plate have the effect of completely preventing the flow of water droplets surrounding the evaporator from the evaporator inlet side to the outlet side by effectively applying surface tension and gravity. It is something to do.

[Practice of invention? vinegar〕

Figure 1 shows a corrugated fin evaporator used in car air conditioners. The evaporator 1 consists of a zigzag-shaped fin 2 inserted between flat tubes 30, and a refrigerant inlet header 4 and an outlet 5 at the ends of the flat tubes. Note that the upper surface of the fin 2 is shown in Fig. 2 (Fig. 1 A-AU).
It is customary to provide a large number of cutouts called louvers 6, as shown in the T-side). Further, the flat tube 3 is often made of a drawn tube, and a large number of independent passages 7 are provided within the tube (FIG. 3). Next, the operation of the evaporator will be described with reference to FIG. The air flowing between the fins 3 (middle part) is
It circulates between the single chamber and the evaporator. When the pressurizer is rotated to cool this circulating air, low-temperature liquid refrigerant is supplied to the evaporator inlet header 4. Here, the dispersed refrigerant branches into an independent refrigerant passage 7 in a flat cage, and while flowing, it absorbs heat from the air and becomes a gas refrigerant, reaching the outlet header 5. Note that since the temperature of the second surface of the fin is usually below the dew point temperature, moisture in the flowing air condenses and adheres to the surface of the fin as water droplets. When the attached water droplets grow to a certain extent, they flow by gravity toward the lower surface of the evaporator 1 and are expelled to the outside.

However, even though the air temperature inside the vehicle is low and the load on the evaporator is small, if the vehicle speed is high and the compressor is running at full speed, the evaporation temperature will be extremely low and the evaporator will adhere to the fin surface. The water droplets that are present will freeze. When freezing progresses significantly, the ice reduces the air passage, and in extreme cases, the air may stop flowing and cooling power may not be obtained. To avoid this situation, the evaporator outlet air temperature or fin wall surface temperature is detected by the antifreeze thermometer 8, and the compressor is stopped intermittently to melt the ice and expel it to the outside of the generator. . Here, the flow of water droplets attached to the fin surface will be explained in the case of a corrugated fin using FIG. 2.3.

The water droplets that have grown on the fins follow a zigzag path along the fins 2 as shown in FIG. 2, collecting small diameter water droplets on the fin surfaces and falling while growing rapidly. On the other hand, in FIG. 3, the louvers 6 are arranged downward downstream of the air,
In addition, the higher the wind speed, the more water droplets flow downstream along the louvers 6. It was confirmed through observation and measurement that when the fin surface is repeatedly frozen and thawed due to the above flow, the amount of water retained on the fin surface is the highest at the fin tip downstream of the air.

The present invention was devised based on the above results, focusing on the fact that if the movement of water droplets from the air upstream to the downstream fin tip can be completely prevented, the fin tip will not refreeze. Next, a specific example of an evaporator for a car air conditioner will be described with reference to FIGS. 4 and 5.

In FIG. 4, according to the present invention, a drain plate 9 is arranged between adjacent flat tubes 3.degree. 3'. In other words, the height of the fin is
It is set to 1/2H of the height H of conventional fins. in this case,
The shape of the draining plate 9 is characterized in that the front view seen from the direction of arrow B in FIG. 4 is as shown in FIG. 5.

In Figure 6, the types of draining plates are 9 depending on the behavior of water droplets.
Three types are used: a, 9b, and 9c. That is, the triangular area 9C extending from the bottom surface 1/2L (L-depth dimension) of the draining plate to the air outlet end is a tilted corrugated plate with a coarse wave pitch pw. Also, the area 9b obtained by removing 90 from the area from the bottom of the draining plate to 1/3H (H - total height of the draining plate) is the wave pitch pW.

It is a rough vertical corrugated plate. Further, an area 9a obtained by removing areas 9b and 9c from the total area of the draining plate is a vertical flat plate with dense wave pinches. Here, wave height hW and wave pitch p
w is experimentally and empirically hwki 1-2 mm,
1.5 to 2.5 inches in pw (surface 9a) and 2 to 6 inches in pw (surfaces 9b, 9c) are suitable for corrugated fin evaporators for car air conditioners.

The above-mentioned draining plate made of a corrugated plate is formed by press forming in advance and then fixed between the fins by melting the surface of the fins 2 made of plating sheet in a high-temperature furnace.

By using the above-described drain plate in an evaporator with corrugated fins, water droplets on the fins adjacent to the surface 9a flow toward the bottom surface of the drain plate due to capillary action. However, the amount of water falling near the bottom of the drain plate is large, so
The dense corrugated plate used in this section lacks the passage area necessary for water droplets to fall. Therefore, 1/3 from the bottom of the draining board
H'1. Now, a coarse corrugated plate with a wave pitch pw of 2 to 6 rrrm is used to secure a passage V1 for water droplets, and guide them to the bottom surface of the draining plate with a weight of 7 J & 1.

The state shown above is established under normal conditions where the evaporation pressure is relatively high and the fin surface does not freeze. However, if the evaporation pressure is low and the fin surface freezes, and the antifreeze thermostat is activated, the ice or the box melts all at once, so the amount of water droplets on the fin adjacent to surface 9a becomes larger than the amount of water directed toward the bottom surface by the capillary tube. Therefore, some of the water droplets flow downstream of the air. The water droplets flowing downstream of the air are collected by a rough corrugated plate with a wave pitch pw of 2 to 6 on the surface 9C, and fall by gravity. Since the baffle surface 9c is slanted, the air reaches the position of the bottom surface of the draining plate returned to the upstream side. In other words, water droplets do not collect at the evaporator outlet end.

Figures 6 and 9 show examples of car air conditioners.

The present invention is characterized in that a heat vibrator is used to forcibly apply heat to the curved p part of the flat tube to melt the ice, and the gap between the fins and vibrator and the flat tube is made appropriate to make it easier for the drain to fall. .

FIG. 7 shows the condenser 21. This is an antifreeze pipe composed of a heat vibrator 22 and a thawing fin 23. The high heat source side 22 of the heat vibe 22 is fixed to the flat tube of the condenser 21, and the low heat source side 22b of the heat vibe 22 is fixed to the defrosting fins 23 by brazing or the like.

The refrigerant gas in the heat vibrator 22 taken from the condenser 21 by latent heat of vaporization moves to the evaporator 1, where it is cooled by the defrosting fins and condensed. Thereafter, the refrigerant liquid returns to the high heat source side again due to gravity and capillary action caused by the wick material provided inside the heat pipe tube. By utilizing the characteristics of the heat vibe 22, it becomes possible to constantly supply heat to the bent portion of the flat tube, and it is possible to completely prevent water accumulated during thawing from refreezing. Here, the thawing fins 23 of the antifreeze pipe are
As shown in FIG. 8, plate-shaped fins are fixed to the heat vibrator 22 at appropriate intervals so that they can be inserted into the bent portion of the flat tube. In addition, the installation positions of the antifreeze pipe and the evaporator are as shown in FIG.
The gap S1 between the heat vibrator 22 and the flat tube 3 and the gap S2'Q between the heat vibrator 22 and the flat tube 3 are each about 1 to 2 mm. small gap 8
1.82, the melted water is easily transmitted through the gap and flows into the drain tray 19 shown in FIG. 4, so the amount of water that accumulates in the bent portion of the flat tube is smaller than in the past.

In the embodiment shown in FIG. 7, a condenser is used as the high heat source of the heat vibrator 22, but in a car air conditioner, a condenser is used as the high heat source.
Any of the engine room, radiator, heater, etc. may be used.

Figure 10.11 shows another embodiment. In the present invention, a bimetal plate 29 is disposed on the upper surface of the flat tube 3 facing the air outlet side of the refrigeration inlet header 4, and a valve action is applied to the air outlet side in the ↓ direction shown in FIG. The feature is that the flow rate of refrigerant flowing through the refrigerant passage is adjusted. The opening degree of the bimetal plate 29 is determined by the spring 30.
And the adjustment screw 31 is set so that it will be fully closed when the temperature of the liquid refrigerant in the refrigerant inlet header reaches -10 to -5C, and similarly, it will be fully open when it reaches 0 to 5C. It is knotted.

By adding the above-mentioned device to the evaporator, the fin surface temperature near the tip on the air outlet side can be maintained at 0.00 or higher even during freezing conditions when the compressor is operated intermittently. Become. In other words, while the liquid refrigerant temperature in the refrigerant inlet header reaches -10C to -50C and the fully closed state is maintained, the liquid refrigerant remaining in the closed refrigerant passage flows when the compressor is stopped. Evaporates in hot air and water droplets. After the remaining liquid refrigerant has completely evaporated, the fin surface temperature i is always kept above 00, so the water droplets that have gathered at the tip on the air outlet side will fall without floating, so they will stay on the fins. It can prevent ice from accumulating.

〔Effect of the invention〕

By using the corrugated draining plate shown above in a corrugated fin evaporator, water droplets can fall from any location on the bottom of the draining plate along the direction of air flow, unlike conventional methods. Water droplets do not collect at the location at the evaporator outlet where the air temperature is lowest. In addition, the amount of water held inside the fins is smaller than before, and there is no possibility of freezing even under operating conditions where the antifreeze thermostat is activated.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the evaporator with corrugated fins, Figure 2 is the front box seen from the air outlet side in Figure 1, Figure 3 is a cross-sectional view of A and -A in Figure 1, and Figure 4 is the book. FIG. 5 is a perspective view of the Corrugated-Toffin evaporator of the invention, and is a front view of the drain plate seen from arrow B in FIG. 4. Fig. 6 is a perspective view of another embodiment of the corrugated fin evaporator of the present invention, Fig. 7 is a perspective view of heat pipe piping, Fig. 8 is a perspective view of the heat pipe evaporator side, and Fig. 9 is a perspective view of the third embodiment of the corrugated fin evaporator. It is an enlarged view of the heat pipe attachment part of a figure. FIG. 10 is a perspective view of an inlet header section according to another embodiment of the present invention, and FIG. 11 is a sectional view taken along the line BB in FIG. 10. 1... Evaporator, 2... Fin, 3... Flat tube, 4
...Inlet header, 5...Fern to outlet, 6...Louver, 7...Refrigerant passage, butt...Anti-freeze thermo, 9...
・Draining board. ■ 1 Figure 2 Yu 3 Figure S 11 Figure 5 Ward Pw Akira ni mouth 307- ■ 3 Figure 3 No 9 Figure j S2

Claims (1)

[Claims] 1. In an evaporator with corrugated fins inserted between flat tubes having a large number of independent passages formed by a large number of zigzag bent fin '11 extraction pipes, etc. , A drain plate is installed between adjacent flat tubes.
An evaporator with corrugated fins, characterized in that 31 is provided with fins. 2. The shape of the draining plate is triangular or wavy with multiple tentative pitches; 2. The draining board according to item 1, characterized in that it has a pitch. 3. Regarding the direction of the waves on the draining plate, in Figure 5, the air outlet side and the paper surface (9c) are slanted so that the water droplets flow toward the upstream side of the air, while the other parts are oriented vertically. The draining board according to item 1, characterized in that: