JP2704451B2 - Stacked heat exchanger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laminated heat exchanger used for an air conditioner or the like, and particularly to a laminated heat exchanger suitable as an evaporator for a car air conditioner.

[Conventional technology]

A conventional laminated heat exchanger used as an evaporator has a rib protruding two heat transfer tube plates having ribs protruding into a refrigerant passage as described in JP-A-63-2149. X
It has a structure in which a number of flat heat transfer tubes and zig-zag refrigerant flow passages are formed so as to intersect in a cross shape, and a plurality of cooling air side heat transfer fins are alternately stacked. Is provided with a refrigerant inlet and an outlet tank so that adjacent heat transfer tubes communicate with each other.

[Problems to be solved by the invention]

The refrigerant that has branched and flowed into each of the flat heat transfer tubes via the inlet tank portion exchanges heat with air while passing through the tubes, and the liquid refrigerant evaporates. The evaporated gas refrigerant merges again at the outlet tank and flows out. However, in the conventional heat exchanger, the protruding ribs have a zigzag flow path structure in which the protruding ribs intersect in an X-shape over the entire flow path. There is a problem that the pressure loss of the road becomes large. On the other hand, as disclosed in Japanese Patent Application No. 1-258782, according to the heat exchanger in which the inner fin is disposed in the pipe, the refrigerant flows straight along the inner fin, so that the pressure loss is greatly reduced. However, in the heat transfer tube where the refrigerant flows downward in the direction of gravity due to the low resistance of the refrigerant passage, the liquid refrigerant having a high density instantaneously drops by the action of gravity in the heat transfer tube, so that the contact time with the inner fin is short, and Since there is almost no diffusion to the surroundings, there is a problem that the cooling capacity of the liquid refrigerant cannot be sufficiently exhibited.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to a transmission molded by extruding a hollow part to be a refrigerant flow path and an inlet / outlet tank part connected to the hollow part, at least leaving a joining rib part for sealing the refrigerant flow path. A flat heat transfer tube is formed by inserting and fixing an inner fin in the refrigerant flow path formed by combining two hot plates and meandering downward multiple times. The inlet and outlet tanks of the flat heat transfer tube communicate with each other. In a stacked heat exchanger in which a number of flat heat transfer tubes and air-side heat transfer fins are alternately stacked so that the refrigerant flowing in the tubes rises, the fin pitch of the inner fin arranged in the passage in which the refrigerant flows down in the direction of gravity rises. Is smaller than the fine pitch of the inner fins arranged in the flow path that flows through.

Further, in order to improve the heat transfer performance, the inner fin arranged in the pipe is an inner fin having a cutout portion interrupted by a predetermined pitch along the longitudinal direction.

[Action]

Since the pitch of the inner fin arranged in the heat transfer tube through which the refrigerant flows in the same direction as the direction of gravity is set to be small, the droplet of the refrigerant instantaneously falls between the inner fins by the action of gravity. As a result, the time during which the droplet contacts the inner fin can be maintained for a long time, so that the cooling capacity of the liquid refrigerant can be sufficiently exhibited. Further, since the liquid refrigerant can be diffused in the direction crossing the flow path through the cutout portion provided intermittently in the longitudinal direction of the inner fin, the cooling capacity is further improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a flat heat transfer tube 1 of a laminated heat exchanger according to the present invention.
Is a plan view in which the inner fins 3 are arranged in the channel recesses 2 of the heat transfer tube plate 1a, FIG. 2 is a perspective view of the flat heat transfer tube plate 1a, FIG. 3 is a perspective view of the inner fins 3, and FIG. FIG. 5 is a perspective view of a main part of the inner fin 3, FIG. 6 is an overall configuration diagram of a laminated heat exchanger, and FIG. 7 is an overall view schematically showing a flow of a refrigerant. It is.

The heat transfer tube plate 1a pushes out the U-shaped concave portion 2 which is to be a refrigerant flow passage while leaving the joining rib portion 40 for forming a closed flow passage over the entire circumference of the material flat plate, and further deepens the U-shaped depression portion. The inlet tank 4 and the outlet tank 5 are formed by extrusion. At the middle of the U-shaped flow path, a flow path partitioning portion 6 connected to the joining rib 4 is provided. Communication holes a and b are punched out at the inlet and outlet tank portions of the U-shaped flow passage, respectively, and the folded portions for maintaining the interval of the flat heat transfer tubes 1 when stacked and assembled at the end opposite to the tank side. Part 7
Is provided. Fuinpitsuchi P _D of In'nafuin 3a disposed on the inlet side refrigerant passage 2a leading to the inlet tank portion 4 is smaller than Fuinpitsuchi P _U of In'nafuin 3b disposed on the outlet side refrigerant passage 2b, P _D <is set such that P _U. Normally, P _D = 1.0 for P _U = 2.0 mm
It is preferably set to about 1.5 mm. As shown in FIG. 5, the inner fin 3 is provided with an intermittent cut-out portion C of a predetermined pitch along the longitudinal direction of the fin, and the cut-out portion extends in a direction crossing the fin. It is also possible to flow a refrigerant. As shown in FIG. 4, the heat transfer tube plate 1b combined with the heat transfer tube plate 1a has a symmetrical shape as shown in a mirror with respect to 1a.

FIG. 6 shows the overall configuration of the laminated heat exchanger according to the present invention. A flat heat transfer tube 1 is inserted and fixed in a U-shaped refrigerant passage formed by combining the heat transfer tube plates 1a and 1b with an insert fin.
Is configured. A plurality of flat heat transfer tubes 1 are stacked so that the inlet tank portion 4a and the outlet tank portion 5 of the flat heat transfer tube 1 communicate through the respective communication holes a and b, and a space formed between the adjacent flat tubes 1 The heat transfer fins 8 to be cooled are inserted and fixed to the flat tubes, and side plates 9 are fixed to the flat tubes located at both left and right ends via side fins 8a. An inlet header tank 4a is disposed downstream of the cooled air A, and an outlet header tank 5a is disposed upstream thereof.
0, the outlet pipe 11 is connected.

As shown in FIG. 7, the refrigerant flowing into the inlet header tank 4a from the inlet pipe 10 is branched into a flat heat transfer tube connected to the inlet heat pipe 4a, and the refrigerant is sequentially branched in the direction of gravity as indicated by an arrow D in the direction of gravity. Flows into the inlet-side refrigerant flow path 2a flowing down as described above. In the refrigerant flow path 2a, a fine pitch is P _D = 1.0 to
The liquid refrigerant flows down with the gas refrigerant while making good contact with the liquid droplets between the fins due to the capillary action based on the surface tension because the inner fin with a clogging of about 1.5 mm is inserted, so that the liquid refrigerant has The cooling capacity can be exhibited. In addition, since the notched portion C is provided on the inner fin, the contact with the coolant droplets is intermittent, so that the heat transfer performance is further improved and the liquid refrigerant flows through the notched portion in the width direction of the flow channel. Therefore, the cooling capacity of the liquid refrigerant can be more fully exhibited. The flowing-down refrigerant bends and reverses at the U-turn portion at the lower end of the flow path and flows into the downstream-side refrigerant flow path 2b. In the downstream-side refrigerant flow path 2b, the refrigerant flows upward as indicated by an arrow U, and the liquid refrigerant having a high density is blown up from below by the gas refrigerant so as to oppose gravity. Therefore, the flow resistance increases as much as the liquid refrigerant is blown up against the gravity, but the inner fins located here
Fuinpitsuchi P _U and 3b is increased flow resistance is suppressed because it is larger than Fuinpitsuchi P _D of In'nafuin 3a of about 2mm and the upstream flow channel 2a. In addition, the behavior of the refrigerant droplets blown up by the refrigerant gas is unstable, and diffuses laterally in the refrigerant flow path through the notch C provided in the inner fin, so that contact with the inner fin is evenly distributed. The cooling capacity of the liquid refrigerant is exhibited more efficiently.

The flow of the refrigerant in the heat exchanger of the first embodiment is the seventh.
As shown in the figure, the refrigerant flowing in all of the laminated flat tubes uniformly forms an orthogonal counterflow with respect to the air flow A. The operation effect of the present invention is as shown in FIG. In addition, the flat tube is divided into a plurality of tube groups, and at least, a refrigerant path is formed so that the refrigerant flowing in the most downstream tube group connected to the outlet pipe 11 has an orthogonally opposed flow to the air flow. Even if it does not change.

In the above-described embodiment, one U-shaped refrigerant flow path is provided by providing one flow path partitioning portion 6 in the refrigerant flow path.
As shown in FIG. 10 and FIG. 10, the effect of the present invention does not change even in a heat exchanger having a refrigerant flow path meandering in a W shape by providing two or more partitions in parallel.

Further, in this embodiment, the header tank is arranged at the upper side, but the operation and effect of the present invention do not change for the heat exchanger arranged at the lower side.

〔The invention's effect〕

According to the present invention, the pitch of the inner fin arranged in the heat transfer tube in which the refrigerant flows down in the same direction as the direction of gravity is set to be small, so that the space between the fins is formed by the capillary action based on the surface tension of the refrigerant droplet. The droplets are held by the liquid refrigerant, which prevents the droplets of the refrigerant from instantaneously falling between the inner fins due to the action of gravity, and can keep the droplets in contact with the inner fins for a long time. Can be fully demonstrated. Further, since the liquid refrigerant can be diffused in the direction crossing the flow path through the cutout portion provided intermittently in the longitudinal direction of the inner fin, the cooling capacity is further improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a laminated heat exchanger according to one embodiment of the present invention,
2 is a perspective view of the flat heat transfer tube plate, FIG. 3 is a perspective view of the inner heat transfer tube, FIG. 4 is a perspective view of the flat heat transfer tube plate, FIG. 5 is a perspective view of a main portion of the inner heat transfer tube, and FIG. FIG. 7 is a perspective view of the heat exchanger, FIG. 7 is an explanatory view schematically showing how the refrigerant flows, FIG. 8 is an explanatory view of the refrigerant flow of the second embodiment of the present invention,
FIG. 9 is a plan view of a flat heat transfer tube according to the third embodiment of the present invention, and FIG. 10 is a perspective view showing a heat exchanger of the third embodiment of the present invention. 3a …… Innafin, 3b …… Innafin.

Claims (1)

(57) [Claims] 1. A combination of two heat transfer plates formed by extruding a hollow portion to be a refrigerant flow channel and an inlet / outlet tank portion connected to the hollow portion, at least leaving a joining rib portion for sealing the refrigerant flow channel. A flat heat transfer tube is formed by inserting and fixing the inner fin in the formed refrigerant flow path meandering up and down a plurality of times,
In the laminated heat exchanger in which a plurality of the flat heat transfer tubes and the air-side heat transfer fins are alternately stacked so that the inlet and the outlet tank portions of the flat heat transfer tubes are interlocked, the refrigerant flowing in the tubes has a gravity. A laminated heat exchanger wherein the fine pitch of the inner fin disposed in the passage flowing down in the direction is set smaller than the fine pitch of the inner fin disposed in the refrigerant flow path flowing upward.