JP2005009827A - Fin tube type heat exchanger and heat pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fin tube type heat exchanger excellent in frost formation resisting performance with a large heat exchange and a heat pump device using it. <P>SOLUTION: This fin tube type heat exchanger comprises a number of fins arranged substantially in parallel to each other with a space so that a fluid A flows in the space, and a number of heat exchange tubes inserted substantially vertically to the fins, in the inner part of which a fluid B flows. The tube outer diameter D of the heat exchange tube is set to 1 mm≤D<5 mm, the tube line pitch L1 in the flowing direction of the fluid A of the heat exchange tube is 2.5D<L1≤3.4D, and the tube stage pitch L2 vertical to the flowing direction of the fluid A is 3.0D<L2≤3.9D, whereby the fin tube type heat exchanger and the heat pump device can have excellent frost formation resisting performance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a finned tube heat exchanger and a heat pump device that are used for air conditioning, refrigeration, refrigeration, hot water supply and the like, and transfer heat between fluids such as refrigerant and air.
[0002]
[Prior art]
In recent years, fin tube type heat exchangers and heat pump devices are required to increase the amount of heat exchange and to be miniaturized in order to improve the performance and size of the applied products. In order to increase the amount of heat exchange, it is known that it is effective to reduce the diameter of the heat transfer tube.
[0003]
As a conventional fin tube type heat exchanger, the outer diameter of the heat transfer tube has become mainstream around 5 mm to 8 mm (see, for example, Patent Document 1).
[0004]
Hereinafter, the conventional fin tube heat exchanger will be described with reference to the drawings.
[0005]
FIG. 5 is a schematic perspective view of the conventional fin tube heat exchanger. As shown in FIG. 5, the conventional fin tube type heat exchanger 1 is arranged in parallel at a predetermined interval, and a large number of fins 2 configured to allow airflow to flow therebetween, and the fins 2 are orthogonal to each other. And the heat transfer tube 3 having a circular outer periphery in section, the tube outer diameter of the heat transfer tube 3 is D, the tube row pitch in the air flow direction of the heat transfer tube 3 is L1, and the air flow direction of the heat transfer tube 3 When the pipe step pitch in the direction orthogonal to L2 is L2, 2 mm ≦ D ≦ 8 mm, 1.9D ≦ L1 ≦ 2.5D, 2.3D ≦ L2 ≦ 3.7D, the pipe outer diameter, the air flow rate, It is said that the maximum heat exchange amount can be obtained when the fin pitch or the like is kept constant, and the compactness can be achieved.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-257383
[Problems to be solved by the invention]
However, the conventional configuration described above has the same pipe pitch definition formula 1.9D ≦ L1 ≦ 2.5D and 2.3D ≦ L2 with the tube outer diameter as a parameter when the tube outer diameter of the heat transfer tube is 2 mm ≦ D ≦ 8 mm. Since ≦ 3.7D is used, the maximum heat exchange amount is obtained in the range of the tube row pitch L1 when the tube outer diameter is 8 mm. However, as the tube diameter becomes smaller, the tube row pitch L1 that obtains the maximum heat exchange amount is obtained. The range slides, and the maximum heat exchange amount is obtained over 2.5D when the tube diameter is 2 mm. Since the range of the pipe outer diameter to which the pipe pitch definition formula is applied is wide, there is a problem that the maximum heat exchange amount is not necessarily obtained by the same pipe pitch definition formula. Moreover, the said conventional structure is not examined from a viewpoint of anti-frosting performance at the time of being used as an evaporator. For this reason, there exists a subject that anti-frosting performance is low.
[0008]
The present invention solves the above-described conventional problems, and an object thereof is to provide a finned tube heat exchanger having a large heat exchange amount and excellent anti-frosting performance, and a heat pump device using the same.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, a large number of fins, which are arranged in parallel at intervals and through which the fluid A flows, are inserted substantially vertically into the fins, and the fluid B flows inside. In the finned tube heat exchanger composed of a large number of heat transfer tubes, the tube outer diameter D of the heat transfer tubes is 1 mm ≦ D <5 mm, and the tube row pitch L1 in the flow direction of the fluid A of the heat transfer tubes is 2.5D. <L1 ≦ 3.4D, a tube tube pitch L2 in the direction perpendicular to the flow direction of the fluid A is 3.0D <L2 ≦ 3.9D, and is a finned tube heat exchanger characterized in that the tube outer diameter D is By setting 1 mm ≦ D <5 mm, the dead water area generated in the rear portion in the flow direction of the fluid A flowing outside the heat transfer tube is reduced as compared with the conventional heat transfer tube having a diameter of 5 mm to 8 mm. The pipe pitch can be reduced, increasing fin efficiency It has the effect of that. In addition, since the tube thickness with the same pressure resistance is thinner than that of a conventional heat transfer tube having an outer diameter of 5 mm to 8 mm, the material input amount of the heat transfer tube is reduced. Further, if the tube row pitch is reduced, the fin efficiency is improved, but with the same number of rows, the heat transfer area of the fins is reduced, and the anti-frosting performance is also lowered. Conversely, when the tube row pitch is widened, the fin efficiency is lowered, but with the same number of rows, the heat transfer area of the fins is increased and the frost resistance is improved. A well-balanced design point is that the tube pitch is approximately an equilateral triangle. Furthermore, if the tube step pitch is reduced, the speed of the fluid A between the heat transfer tubes increases, and the fin efficiency increases, but the flow resistance of the fluid A increases. Therefore, there is an optimum relationship between the outer diameter of the pipe and the pipe pitch that maximizes the amount of heat exchange. The pipe row pitch L1 is 2.5D <L1 ≦ 3.4D, and the pipe stage pitch L2 is 3 By setting 0.0D <L2 ≦ 3.9D, the balance between the heat exchange amount and the anti-frosting performance is improved.
[0010]
The invention according to claim 2 of the present invention is the finned tube heat exchanger according to claim 1, wherein the fin shape is a flat fin or a corrugated fin. By using a fin with no shape, dust and condensed water are less likely to adhere to the surface of the fin, and clogging of the fin gap can be reduced.
[0011]
The invention according to claim 3 of the present invention is the finned tube heat exchanger according to claim 1 or 2, wherein carbon dioxide is used for the fluid B. Due to the high density refrigerant characteristics, the speed is slower than other refrigerants at the same mass flow rate, and the increase in pressure loss in the heat transfer tube due to the diameter reduction is small. Moreover, it has the effect | action that the influence which the pressure loss in a heat exchanger tube has on a temperature change is small.
[0012]
According to a fourth aspect of the present invention, the fin tube according to any one of the first to third aspects is characterized in that the fluid A and the fluid B are caused to flow in opposite directions. As a result, the fluid A and the fluid B have a function of performing stable heat exchange while maintaining a temperature difference as compared with the parallel flow.
[0013]
The invention according to claim 5 of the present invention is a heat pump device in which a compressor, a radiator, an expansion device, and an evaporator are connected in order, and the evaporator according to any one of claims 1 to 4. It is a heat pump apparatus characterized by using the described finned tube heat exchanger, and has an effect of obtaining an evaporator having a compact, high withstand voltage and a stable heat exchange amount.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a fin tube type heat exchanger and a heat pump water heater using the fin tube type heat exchanger according to the present invention will be described with reference to the drawings. In addition, about the same structure as the past, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
[0015]
(Embodiment 1)
FIG. 1 is a partial cross-sectional view seen from the side of a finned tube heat exchanger in an embodiment of the present invention.
[0016]
In FIG. 1, the fin tube type heat exchanger 1 is arranged substantially parallel to each other at intervals, and a large number of fins 2 in which air flows and gaps flow through the gaps. It is comprised from many heat exchanger tubes 3 inserted in. The heat transfer tubes 3 are connected to each other so that the airflow direction and the refrigerant flow direction are opposed to each other, and the rows adjacent at equal intervals are shifted by a half pitch and arranged in a staggered pattern. Further, assuming that the tube outer diameter of the heat transfer tube 3 is D, the tube row pitch in the airflow direction is L1, and the tube step pitch in the direction perpendicular to the airflow direction is L2, 1 mm ≦ D <5 mm, 2.5D <L1 ≦ 3.4D. 3.0D <L2 ≦ 3.9D. Moreover, the shape of the fin 2 is comprised by a flat fin or a waveform fin. The fins 2 and the heat transfer tubes 3 are made of a material having good thermal conductivity such as aluminum or copper.
[0017]
FIG. 2 is a circuit diagram of a heat pump water heater using the finned tube heat exchanger in the same embodiment, and is configured by a heat pump circuit and a hot water circuit.
[0018]
2, the heat pump circuit of the heat pump water heater 4 includes a compressor 5 that compresses refrigerant, a radiator 6 that exchanges heat between water and refrigerant, an expansion device 7 that expands refrigerant, and an evaporator 8 that exchanges heat between air and refrigerant. An accumulator 9 that performs gas-liquid separation of the refrigerant is connected in a ring shape, and the fin tube heat exchanger 1 is used as the evaporator 8. Hereinafter, the evaporator 8 is referred to as a fin tube type heat exchanger 1. The hot water circuit includes a hot water storage tank 10 that stores water heated by the radiator 6 and a circulation pump 11 that circulates the water in the hot water storage tank 10 through the radiator 6.
[0019]
The operation of the fin-tube heat exchanger 1 and the heat pump water heater 4 configured as described above will be described below.
[0020]
FIG. 3 is a numerical analysis result of the heat exchange amount change of the finned tube heat exchanger 1, where the vertical axis represents the heat exchange amount Q, and the horizontal axis represents the row pitch L1 divided by the tube outer diameter D (L1 / D). is there. The heat exchange amount Q is a heat exchange amount per unit opening area of the finned tube heat exchanger 1 under the same wind speed. The tube row pitch L1 is set to 1.0D ≦ L1 ≦ 4 under the condition that the number of steps in the direction perpendicular to the air flow direction of the heat transfer tube 3 is 6, the tube outer diameter D is D = 3.15 mm, and the tube step pitch L2 is L2 = 10 mm. Varying in the 8D range. The analysis result for each row when the number of rows in the airflow direction of the heat transfer tubes 3 is changed from 3 rows to 6 rows is shown.
[0021]
In FIG. 3, when the row pitch is changed under the above conditions, the heat exchange amount increases as the row pitch is increased. This is because the fin efficiency decreases, but the heat transfer area of the fin increases. Here, L1 / D = 2.8 is a tube pitch at which the tube arrangement is approximately an equilateral triangle. The amount of heat exchange increases as the row pitch is increased, but the degree of improvement decreases from the point where the tube arrangement passes a pitch that is approximately a regular triangle. Therefore, it is uneconomical to increase the row pitch by a certain value or more in the same number of rows, because an increase in heat exchange amount corresponding to an increase in cost accompanying an increase in the material input amount of fins cannot be expected. Moreover, if the tube row pitch is reduced, the anti-frosting performance also decreases. From these facts, a design point with a good balance is a point where the tube pitch is approximately an equilateral triangle. For this reason, the tube row pitch L1 in the airflow direction of the heat transfer tube 3 is in the range of 2.5D <L1 ≦ 3.4D under the condition that the tube outer diameter D is D = 3.15 mm and the tube step pitch L2 is L2 = 10 mm. By setting, it is possible to obtain a finned tube heat exchanger having a good balance between the heat exchange amount and the anti-frosting performance.
[0022]
FIG. 4 is a numerical analysis result of the heat exchange amount change of the finned tube heat exchanger 1, where the vertical axis represents the heat exchange amount Q, and the horizontal axis represents the step pitch L2 divided by the tube outer diameter D (L2 / D). is there. The heat exchange amount Q is the heat exchange amount per unit opening area of the finned tube heat exchanger 1 under the same wind speed as in FIG. Under the condition that the number of stages in the direction perpendicular to the air flow direction of the heat transfer tubes 3 is 6, the number of rows in the air flow direction of the heat transfer tubes 3 is 3, and the tube outer diameter D is D = 3.15 mm, the tube step pitch L2 is 1.9D. It was changed in the range of ≦ L2 ≦ 5.7D. At this time, the tube row pitch L1 was also changed in conjunction with the tube step pitch L2 so that the tube pitch was approximately a regular triangle pitch.
[0023]
In FIG. 4, when the tube outer diameter D is D = 3.15 mm, the heat exchange amount reaches a peak when the tube step pitch L2 in the airflow direction of the heat transfer tube 3 is in the range of 3.0D <L2 ≦ 3.9D. This is due to the following reason. When the tube step pitch is reduced, the air velocity between the heat transfer tubes is increased and the fin efficiency is improved. On the other hand, the tube row pitch is reduced in conjunction with the tube step pitch, so the heat transfer area of the fin is reduced. Conversely, when the tube step pitch is widened, the air velocity between the heat transfer tubes and the fin efficiency decrease, but the heat transfer area of the fins increases. For this reason, there exists an optimum relationship between the tube outer diameter and the tube pitch, and the heat exchange amount shows a peak value in the optimum relationship.
[0024]
Therefore, under the condition that the outer diameter D of the tube is D = 3.15 mm, the tube row pitch L1 and the tube step pitch L2 are set in the ranges of 2.5D <L1 ≦ 3.4D and 3.0D <L2 ≦ 3.9D. Thus, a fin tube type heat exchanger having a good balance between the heat exchange amount and the anti-frosting performance is obtained.
[0025]
Furthermore, as a result of performing the same numerical analysis even when the pipe outer diameter D is in the range of 1 mm ≦ D <5 mm, the tube row pitch L1 is 2.5D <L1 ≦ 3.4D, and the tube stage pitch L2 is 3.0D <L2 ≦. It was found that the range setting of 3.9D is to obtain a finned tube heat exchanger with a sufficiently good balance between the heat exchange amount and the frosting resistance. Here, by changing the tube diameter D from 1 mm to 5 mm, the dead water area generated in the rear portion in the airflow direction flowing outside the heat transfer tube is reduced as compared with the conventional heat transfer tube having a tube diameter of 5 mm to 8 mm. The pipe pitch can be reduced with the same air resistance, and the fin efficiency is increased. For this reason, the amount of heat exchange can be increased, and the thickness of the tube with the same pressure resistance is reduced, so that the amount of material input to the heat transfer tube 3 can be reduced. The overall size of the heat exchanger can be reduced, and the total weight can be reduced.
[0026]
Since the fins 2 are flat fins or corrugated fins, there are no openings or end surfaces on the surface of the fins, so that dust and condensed water are less likely to adhere, and clogging of the fin gaps can be reduced. For this reason, the reduction | decrease of the heat exchange amount by clogging of a fin clearance can be suppressed.
[0027]
In the above embodiment, the refrigerant is preferably carbon dioxide. Carbon dioxide has a high-pressure, high-density refrigerant characteristic, and has a lower speed than other refrigerants at the same mass flow rate, and the increase in pressure loss in the heat transfer tube due to the reduction in diameter is small. Moreover, the influence which the pressure loss in the heat exchanger tube 3 has on a temperature change is small. For this reason, the influence which the increase in the pressure loss in the heat exchanger tube 3 by diameter reduction has on the heat exchange amount reduction | decrease is suppressed compared with another refrigerant | coolant, and much heat exchange amount is carried out in the said fin tube type heat exchanger 1. Obtainable.
[0028]
By configuring the tube arrangement of the heat transfer tubes 3 of the finned-tube heat exchanger 1 in a counter flow, a stable heat exchange amount can be obtained as an evaporator. This is because the heat exchange is performed while maintaining a temperature difference between the air and the refrigerant on average in the entire heat exchanger compared to the parallel flow, and the parallel flow has a larger heat exchange amount as the degree of superheat of the evaporator outlet is increased. Although it decreases, the amount of heat exchange in the counterflow is almost constant even when the evaporator outlet superheat degree is changed.
[0029]
By using the above fin tube type heat exchanger 1 for the evaporator 8, in order to obtain the evaporator 8 with a compact and high pressure resistance and a stable heat exchange amount, the water heater 4 itself is also compact and has a high pressure resistance. In addition, the heat pump water heater 4 has stable performance.
[0030]
In the embodiment, an example in which the fin tube heat exchanger is applied to a water heater has been shown. However, the present invention is not limited to a heat pump water heater, but is applied to an evaporator of an air conditioner or an evaporator of a heat pump washer / dryer. However, the same effect is achieved.
[0031]
【The invention's effect】
As described above, the invention according to claim 1 is arranged substantially parallel to each other at intervals, and a plurality of fins in which the fluid A flows through the gaps, and the fins are inserted substantially perpendicularly into the fins. In the finned tube heat exchanger composed of a large number of heat transfer tubes, the tube outer diameter D of the heat transfer tubes is 1 mm ≦ D <5 mm, and the tube row pitch L1 in the flow direction of the fluid A of the heat transfer tubes is 2 0.5D <L1 ≦ 3.4D, and the tube step pitch L2 in the direction perpendicular to the flow direction of the fluid A is 3.0D <L1 ≦ 3.9D.
[0032]
By configuring in this way, since the tube diameter of the heat transfer tube is narrower than that of the conventional fin tube heat exchanger, the dead water area behind the heat transfer tube is reduced, and the tube pitch is reduced with the same air resistance. Fin efficiency can be improved and a large amount of heat exchange can be obtained. Moreover, since the tube thickness with the same pressure resistance is reduced, the amount of material input can be reduced. The overall size of the heat exchanger can be reduced, and the total weight can be reduced. In addition, since the pipe pitch is roughly a regular triangle, the balance between fin efficiency, fin heat transfer area, and anti-frosting performance is good, and the pipe pitch in the above range has a balance between fin efficiency and fin heat transfer area. As a result, a compact and high pressure resistant heat exchanger having a good balance between the heat exchange amount and the anti-frosting performance can be obtained.
[0033]
Since the fin shape of the fin tube type heat exchanger according to claim 1 is a flat fin or a corrugated fin, there is no opening or end face on the surface of the fin. Condensed water is less likely to adhere and clogging of the fin gap can be reduced, and a reduction in heat exchange amount due to clogging of the fin gap can be suppressed.
[0034]
In the invention of claim 3, in the invention of claim 1 or claim 2, since carbon dioxide is used for the fluid B, the refrigerant characteristics are high pressure and high density. Compared to other refrigerants, the speed is slow, the increase in pressure loss in the heat transfer tube due to the smaller diameter is small, and the effect of the pressure loss in the heat transfer tube on the temperature change is small, so a large amount of heat exchange is obtained be able to.
[0035]
The invention according to claim 4 is the invention according to any one of claims 1 to 3, in which the fluid A and the fluid B are caused to flow in a counterflow, so that compared to the parallel flow A stable heat exchange amount can be obtained by performing a stable heat exchange while maintaining a temperature difference between the fluid A and the fluid B on the whole heat exchanger.
[0036]
The invention according to claim 5 is the heat pump apparatus according to any one of claims 1 to 4, wherein the compressor, the radiator, the expansion device, and the evaporator are connected in order. Since the finned tube heat exchanger according to any one of claims 1 to 4 is used as a condenser, a heat pump device is provided in order to obtain a compact, high withstand pressure and stable heat exchange amount evaporator. The device itself is compact, has a high withstand voltage, and can obtain stable performance.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a fin tube heat exchanger according to the present invention as viewed from the side of a first embodiment. FIG. 2 is a circuit diagram of a heat pump water heater using the fin tube heat exchanger of the first embodiment. FIG. 3 is a characteristic diagram of heat exchange amount change with respect to the row pitch of the heat transfer tube. FIG. 4 is a characteristic diagram of heat exchange amount change with respect to the substantially regular triangle pitch of the heat transfer tube. Perspective view 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Fin tube type heat exchanger 2 Fin 3 Heat transfer tube 5 Compressor 6 Radiator 7 Expansion device 8 Evaporator

Claims (5)

Fin tube type comprising a large number of fins that are arranged substantially in parallel with an interval and fluid A flows through the gaps, and a large number of heat transfer tubes that are inserted substantially vertically into the fins and in which fluid B flows. In the heat exchanger, the tube outer diameter D of the heat transfer tube is 1 mm ≦ D <5 mm, the tube row pitch L1 in the flow direction of the fluid A of the heat transfer tube is 2.5D <L1 ≦ 3.4D, and the flow direction of the fluid A A fin tube heat exchanger characterized in that the vertical tube stage pitch L2 is 3.0D <L2 ≦ 3.9D. The fin-tube heat exchanger according to claim 1, wherein the fin has a flat fin shape or a corrugated fin shape. The fin tube type heat exchanger according to claim 1 or 2, wherein carbon dioxide is used for the fluid B. The fin tube type heat exchanger according to any one of claims 1 to 3, wherein the fluid A and the fluid B are caused to flow in a counterflow. In the heat pump apparatus formed by sequentially connecting a compressor, a radiator, an expansion device, and an evaporator, the fin tube type heat exchanger according to any one of claims 1 to 4 is used for the evaporator. A heat pump device.

Images