JP3720208B2 - Heat exchanger and air-conditioning refrigeration apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger for performing heat exchange between a refrigerant and a gas or the like, and an air-conditioning refrigeration apparatus using the heat exchanger.
[0002]
[Prior art]
FIG. 12 is a partial side view showing a fin tube type heat exchanger used in an air conditioning refrigeration apparatus disclosed in, for example, Japanese Patent Laid-Open No. 63-3188. This heat exchanger is generally called a plate fin tube type, is arranged at regular intervals, and air flows between them (wind direction is indicated by an arrow in the figure), and to each of these plate fins 1 There is a heat transfer tube 2 inserted at a right angle and through which a refrigerant flows, and the plate-like fins 1 between the adjacent ones in the step direction perpendicular to the gas passage direction of the heat transfer tube 2 are cut off. Three groups of wakes are provided.
[0003]
In recent years, from the viewpoint of global warming prevention, energy saving of air-conditioning refrigeration equipment and reduction of the amount of refrigerant used as working fluid are strongly demanded, and this type of heat exchanger is also required to have high performance and small internal volume. ing.
On the other hand, in order to ensure comfort, the gas passing wind speed is kept low from the viewpoint of suppressing noise increase, and the heat transfer rate on the air side is lower than the heat transfer rate inside the heat transfer tube. Therefore, the air side heat transfer is increased by increasing the air side heat transfer area.
[0004]
However, due to the requirement for downsizing the heat exchanger and the limitation of installation space, it is not possible to increase the heat transfer area by increasing the size of the heat exchanger by changing the number of heat exchangers installed in the stage direction or the length in the heat transfer tube longitudinal direction. However, a method of increasing the heat transfer area of the heat exchanger by reducing the diameter of the heat transfer tube, reducing the fin pitch, or increasing the number of rows installed in the row direction of the heat transfer tubes is employed.
[0005]
Previously, for example, heat exchanger tube diameter was about 10 mm, fin pitch was about 1.5 mm, and heat exchangers with two rows were commercialized, but recently, heat transfer tube diameter is about 7 mm, The fin pitch is narrowed to about 1.1 mm, and heat exchangers with three or more rows have been commercialized.
[0006]
In FIG. 12, the heat transfer tube outer diameter Do is in the range of 3 mm ≦ Do ≦ 7.5 mm, and the row pitch L1 in the gas passage direction of the heat transfer tube 2 is in the range of 1.2 Do ≦ L1 ≦ 1.8 Do, In addition, the publication discloses that the step pitch B in the direction perpendicular to the gas passage direction of the heat transfer tube 2 (step direction) is in the range of 2.6 Do ≦ L2 ≦ 3.5 Do.
[0007]
[Problems to be solved by the invention]
However, Japanese Patent Laid-Open No. 63-3188, which describes the above-described conventional fin tube heat exchanger, does not mention fin pitch and fin thickness. For example, when the fin pitch is narrowed to about 1.1 mm, the row pitch L1 in the gas passage direction of the heat transfer tube 2 is too small in the conventional heat exchanger, the pressure loss of the air flow increases extremely, and the blower driving force increases. In addition, there is a problem that the noise level is increased, the energy saving of the air-conditioning refrigeration apparatus is reversed, and it is difficult to ensure comfort.
[0008]
In addition, when attempting to increase the heat transfer area by increasing the number of rows, for example, if a heat exchanger of 2 to 3 rows is used, the pressure loss of the air flow increases about 1.5 times, and the fin pitch is increased. As with the narrowing, there is a problem that it increases the driving force of the blower and the noise level and goes back to energy saving of the air-conditioning refrigeration system, making it difficult to ensure comfort.
[0009]
Furthermore, Japanese Patent Laid-Open No. 63-3188, which describes the above-described conventional fin tube heat exchanger, does not mention the internal volume of the heat exchanger. If the heat transfer tube outer diameter, row pitch, and step pitch shown in the same publication are used, the heat transfer tube arrangement density in the heat exchanger will increase, and the internal volume of the heat exchanger will increase, increasing the amount of refrigerant used. It is against the viewpoint of preventing global warming.
[0010]
In addition, because the air conditioning refrigeration system is used in combination with an indoor heat exchanger and an outdoor heat exchanger, it is not necessary to reduce the internal volume of either one of the heat exchangers. It is necessary to reduce the amount used. In addition, since the air-conditioning refrigeration system is also used as a heat pump type, the internal volume of the indoor heat exchanger and the outdoor heat exchanger is reduced so that the amount of refrigerant required for cooling operation and heating operation is reduced and the difference between them is zero. Need to design.
[0011]
The present invention has been made to solve such a problem, and is a heat exchanger having a small ventilation resistance and a good heat transfer performance, and an air conditioner designed to reduce the amount of refrigerant used by using this heat exchanger. An object is to provide a refrigeration apparatus.
[0012]
[Means for Solving the Problems]
  The heat exchanger according to the present invention includes a plurality of plate-like fins arranged in parallel and through which gas flows, and inserted into the plate-like fins at right angles, through which the working fluid passes and the gas passes. Outer diameter D provided in a plurality of rows in a row direction perpendicular to the direction and provided in a plurality of rows in the row direction of the gas passage directionIs 3mm ≦ D ≦ 7mmA heat transfer tube and a cut-and-raised portion provided on the plate-like fin surface and having an opening facing the gas flow, the step pitch Dp in the step direction of the heat transfer tube being 2D ≦ Dp ≦ 3D, The row pitch Lp in the row direction is 2D ≦ Lp ≦ 3.5D, and the fin pitch Fp of the plate-like fins is0.15D ≦ Fp ≦ 0.27DIt is what.
[0013]
  In addition, a plurality of plate-like fins arranged in parallel and through which gas flows, and inserted into each plate-like fin at a right angle, the working fluid passes through the inside and is perpendicular to the direction in which the gas passes. Outer diameter D provided in a plurality of rows in the row direction and in a plurality of rows in the row direction of the gas passage directionIs 3mm ≦ D ≦ 7mmA heat transfer tube and a cut-and-raised portion provided on the plate-like fin surface and having an opening facing the gas flow, the step pitch Dp in the step direction of the heat transfer tube being 2D ≦ Dp ≦ 3D, The column pitch Lp in the column direction is 2D ≦ Lp ≦ 3.5D,When the fin pitch in the stacking direction of the plate-like fins is Fp,The fin thickness Ft of the plate-like fin is 6 ≦ Fp / Ft ≦ 18.
[0014]
  In addition, a plurality of plate-like fins arranged in parallel and through which gas flows, and inserted into each plate-like fin at a right angle, the working fluid passes through the inside and is perpendicular to the direction in which the gas passes. Outer diameter D provided in a plurality of rows in the step direction and in a plurality of rows in the row direction of the gas passage directionIs 3mm ≦ D ≦ 7mmA heat transfer tube and a cut-and-raised portion provided on the plate-like fin surface and having an opening facing the gas flow, the step pitch Dp in the step direction of the heat transfer tube being 2D ≦ Dp ≦ 3D, The row pitch Lp in the row direction is 2D ≦ Lp ≦ 3.5D, and the fin pitch Fp of the plate-like fins is0.15D ≦ Fp ≦ 0.27DAnd the fin thickness Ft of the plate-like fin is 6 ≦ Fp / Ft ≦ 18.
[0015]
The air-conditioning refrigerating apparatus according to the present invention includes a compressor as a working fluid, a compressor, a throttle device, a condensing heat exchanger, and an evaporating heat exchanger, wherein the heat exchanger according to any one of claims 1 to 3 is used. It is.
[0016]
The refrigerant is a working fluid, and includes a compressor, a four-way valve, a throttle device, an indoor heat exchanger, and an outdoor heat exchanger, and the heat exchanger according to any one of claims 1 to 3 is used for the indoor heat exchanger. Is.
[0018]
The refrigerant is a working fluid, and includes a compressor, a four-way valve, a throttle device, an indoor heat exchanger, and an outdoor heat exchanger, and the heat exchanger according to any one of claims 1 to 3 is used for the indoor heat exchanger. In this case, the internal volume of the indoor heat exchanger is Vi, the internal volume of the outdoor heat exchanger is Vo, and Vi and Vo satisfy the relationship of 1.4 ≦ Vo / Vi ≦ 1.8.
[0019]
Further, any one of R407C, R410A, R32, isobutane, propane, carbon dioxide, and ammonia is used as the refrigerant.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 shows the first embodiment, and is a partial side plan view and a side view of a heat exchanger. As shown in the figure, a plate-like fin 1 and a heat transfer tube 2 inserted perpendicularly to the plate-like fin 1 and between adjacent heat transfer tubes in a step direction perpendicular to the gas passage direction. Cut and raised 3 is provided on the plate-like fin surface.
[0021]
In the heat exchanger in this embodiment, the pitch Fp in the stacking direction of the plate-like fins 1 is Fp = 0.001 m, the fin thickness Ft is Ft = 0.0001 m, and the length of one row along the gas passage direction of the heat exchanger The row pitch Lp is Lp = 0.012 m, and the step pitch Dp, which is the distance between the centers of the heat transfer tubes adjacent in the step direction perpendicular to the gas passage direction of the heat exchanger, is Dp = 0.014 m. The outer diameter D of the heat tube is D = 0.005 m, and the number Ln of rows in the gas passage direction of the heat exchanger is Ln = 3.
[0022]
The qualitative tendency of the shape parameters described above will be described below for the heat transfer performance and the ventilation resistance of the heat exchanger.
When the row pitch Lp and the step pitch Dp are increased, the heat transfer coefficient on the fin surface is improved, but the fin efficiency defined by the relationship between the distance from the outer periphery of the heat transfer tube 2 to the fin end and the heat transfer is lowered. . Further, since the ventilation resistance is reduced, the air volume can be increased.
On the other hand, if the row pitch Lp and the step pitch Dp are reduced, the fin efficiency is improved, but the airflow resistance is increased, so that the air volume cannot be increased.
[0023]
Further, if the fin pitch Fp is increased, the airflow resistance is reduced, so that the air volume can be increased, but the heat transfer area is reduced.
On the other hand, when the fin pitch Fp is reduced, the heat transfer area increases, but the ventilation resistance increases and the air volume cannot be increased.
In addition, when the fin thickness Ft is increased, the fin efficiency is improved, but the ventilation resistance is increased. On the other hand, when the fin thickness Ft is reduced, the fin efficiency is reduced, but the ventilation resistance is reduced.
As described above, each of the above-described shape parameters has an optimum value, and in order to quantitatively evaluate this, the heat transfer performance and the ventilation resistance of the heat exchanger are calculated by the method described below.
[0024]
Heat transfer coefficient α [w / m between air and plate fins²K] is generally defined by the following equation:
α = Nu × λ / De
Nu = C1 × (Re × Pr × De / Lp / Ln)^C2
Re = U × De / ν
Here, Nu is the Nusselt number and Re is the Reynolds number. Pr is the Prandtl number, λ is the thermal conductivity of air, ν is the kinematic viscosity coefficient of air, and Pr = 0.72, λ = 0.0261 [w / m · k], ν at room temperature and normal pressure, respectively. = 0.000016 [m² / S]. C1 and C2 are constants.
[0025]
Here, the representative length De [m] is defined by the following equation.
De = 4 × (Lp × Dp−π × D² / 4) × (Fp−Ft) / {2 × (Lp × Dp−π × D² / 4) + π × D × (Fp−Ft)}
The wind speed U [m / s] based on the free passing volume between the plate fins and the front wind speed Uf [m / s] of the heat exchanger are defined by the following equations.
U = Uf * Lp * Dp * Fp / {(Lp * Dp- [pi] * D² / 4) × (Fp−Ft)}
[0026]
Further, the fin efficiency η is defined by the following equation.
η = 1 / (1 + ψ × α)
ψ = {(4 × Lp × Dp / π)^0.5 -D}² × (4 × Lp × Dp / π)^0.5 / D^0.5 / 6 / Ft / λf
Here, λf [w / m · k] is the thermal conductivity of the plate fin.
[0027]
On the other hand, the ventilation resistance ΔP [Pa] between the air and the plate-like fin is defined by the following equation.
ΔP = 2 × F × Lp × Ln × ρ × U² / De
F = C3 × De / Lp / Ln + C4 × Re^C5× (De / Lp / Ln)^{1 + C5}
Here, F is a friction loss coefficient, and C3, C4, and C5 are constants. Also, ρ is the density of air, 1.2 [kg / m at normal temperature and normal pressure.^Three ].
[0028]
Further, in order to reduce the blower driving force when the heat exchanger in Embodiment 1 is used in an air conditioning refrigeration apparatus, the blower driving force is added to the performance evaluation item of the heat exchanger.
The blower driving force Pf [w] is defined by the following equation.
Pf = ΔP × Q
Here, Q is the air flow rate [kg / s] passing through the heat exchanger, where the length in the longitudinal direction of the heat transfer tube is W [m] and the number of stages is Dn, the front wind speed Uf [m / [s] has the following relationship.
Uf = Q / ρ / (W × Dp × Dn)
[0029]
Hereinafter, ΔP is calculated using each of the step pitch Dp, the row pitch Lp, the fin pitch Fp, the fin thickness Ft, and the outer diameter D of the heat transfer tube as parameters, and the air flow rate Q is determined under the condition that the fan driving force Pf is constant. The heat exchange capacity E of the heat exchanger at this time was calculated. The heat exchange capacity is evaluated by the heat exchange amount E [w / k] per unit temperature difference, and is based on the following formula.
E = Q × H × ε
ε = 1−exp (−T)
T = Ao × K / (Q × H)
K = 1 / (1 / αo + Ao / Ai / αi)
αo = 1 / (Ao / (Ap + η × Af) / α)
Ao = Ap + Af
Where H [w / kg · k] is the specific heat of the air, ε is the temperature efficiency, and K [w / m²・ K] is the heat transfer rate, Ao [m²] Is the total heat transfer area on the air side of the heat exchanger, Ap [m²] Is the heat transfer area of the air side pipe of the heat exchanger, Af [m²] Is the air side fin heat transfer area of the heat exchanger, Ai [m²] Is the heat transfer area on the refrigerant side of the heat exchanger, and the dimensions depending on the shape of the heat exchanger, the step pitch Dp, the row pitch Lp, the fin pitch Fp, the fin thickness Ft, and the outer diameter D of the heat transfer tube are determined. This is a value that can be calculated. Note that the heat transfer coefficient αi [w / m] of the fluid flowing in the pipe of the heat exchanger²・ K] is constant.
[0030]
Hereinafter, the relationship between the shape parameter and the heat exchange capacity E is shown in FIGS. In these figures, the heat exchange amount E [w / k] is a value when the number of stages is one and the length W in the longitudinal direction of the heat transfer tube is a unit length.
FIG. 2 shows that the outer diameter D, the row pitch Lp, the fin pitch Fp, and the fin thickness Ft of the heat transfer tube are substantially constant within the optimum value range (not necessarily within the optimum value range), and the step pitch Dp is set as a parameter. Is the result of calculating the heat exchange amount E.
As shown in FIG. 2, when the step pitch Dp is in the range of 2D ≦ Dp ≦ 3D, the heat exchange amount E is sufficiently large, and the heat exchanger has excellent heat transfer characteristics.
[0031]
FIG. 3 shows that the step pitch Dp, the outer diameter D of the heat transfer tube, the fin pitch Fp, and the fin thickness Ft are substantially constant within the optimum value range (not necessarily within the optimum value range), and the column pitch Lp is used as a parameter. It is the result of calculating the heat exchange amount E.
From FIG. 3, if the row pitch Lp is in the range of 2D ≦ Lp ≦ 3.5D, the heat exchange amount E is sufficiently large and the heat exchanger is excellent in heat transfer characteristics.
[0032]
FIG. 4 shows that the row pitch Lp, the step pitch Dp, the outer diameter D of the heat transfer tube, and the fin thickness Ft are substantially constant within the optimum value range (not necessarily within the optimum value range), and the fin pitch Fp is used as a parameter. It is the result of calculating the heat exchange amount E.
From FIG. 4, when the fin pitch Fp is in the range of 0.15D ≦ Fp ≦ 0.27D, the heat exchange amount E is sufficiently large, and the heat exchanger has excellent heat transfer characteristics.
[0033]
FIG. 5 shows that the row pitch Lp, the step pitch Dp, the outer diameter D of the heat transfer tube, and the fin pitch Fp are substantially constant within the optimum value range (not necessarily within the optimum value range), and the fin thickness Ft is used as a parameter. It is the result of calculating the heat exchange amount E.
As shown in FIG. 5, when the fin thickness Ft is in the range of 6 ≦ Fp / Ft ≦ 18, the heat exchange amount E is sufficiently large and the heat exchanger is excellent in heat transfer characteristics.
[0034]
FIG. 6 shows the heat exchange amount E calculated using the outer diameter D of the heat transfer tube as a parameter in the range of the row pitch Lp, the step pitch Dp, the fin pitch Fp, and the fin thickness Ft, which are almost optimum values (not necessarily optimum values). It is the result.
From FIG. 6, when the heat transfer tube outer diameter D is in the range of 3 mm ≦ D ≦ 7 mm, the heat exchange amount E is sufficiently large, and the heat exchanger has excellent heat transfer characteristics. The actual measurement results are shown by white circles in FIGS. 2 to 6, and in all cases, the calculation results are accurately reproduced.
[0035]
Although FIG. 1 shows an example in which three rows of heat transfer tubes are provided in the gas passage direction, the number of rows is not limited to three, and any number of rows can provide the effect of the present invention.
In addition, the example in which three cut-and-raised portions 3 provided on the plate-like fin surface are provided between the heat transfer tubes 2 is shown, but the number is not limited to three, and any number may be used. Even if it does not exist, there exists an effect of this invention.
[0036]
FIG. 7 is a partial side view of a heat exchanger that is a modification of the first embodiment. In FIG. 7, the arrangement of the heat transfer tubes in the second row with respect to the first row is not a staggered arrangement that is ½ of the step pitch Dp, but is, for example, １ ／ of the step pitch Dp. Thus, even if the arrangement of the heat transfer tubes is not staggered, the effects of the present invention are exhibited.
In the non-staggered heat exchanger, the draft resistance is reduced by reducing the projected area of the heat transfer tube in the air flow direction. Moreover, the air-side heat transfer performance is improved by reducing the dead water area behind the heat transfer tube 2.
[0037]
Moreover, although the example of air and a refrigerant | coolant was shown as a working fluid, even if it uses other gas, liquid, and gas-liquid mixed fluid, there exists the same effect.
[0038]
Moreover, since the outer diameter of the heat transfer tube is smaller than the conventional 10 mm, the internal volume of the heat exchanger is reduced, and the amount of working fluid used in the tube can be reduced. In particular, when using HC refrigerants (butane, isobutane, ethane, propane, propylene, etc., or some mixed refrigerants of these refrigerants) or toxic ammonia refrigerants that are flammable as working fluids, The safety of the equipment can be improved.
[0039]
Embodiment 2. FIG.
FIG. 8 is a diagram showing the second embodiment and is a refrigerant circuit diagram of the air-conditioning refrigeration apparatus. The refrigerant circuit shown in the figure includes a compressor 11, a condensation heat exchanger 12, an expansion device 13, and an evaporating heat exchanger 14. By using the heat exchanger according to the first embodiment for the condensation heat exchanger 12 or the evaporative heat exchanger 14 or both, an air-conditioning refrigeration apparatus with high energy efficiency can be realized.
Here, energy efficiency is defined by the following equation.
Heating energy efficiency = indoor heat exchanger (condenser) capacity / all inputs
Cooling energy efficiency = indoor heat exchanger (evaporator) capacity / total input
[0040]
FIG. 9 is a refrigerant circuit diagram of an air conditioning refrigeration apparatus according to a modification of the second embodiment. The refrigerant circuit shown in the figure is an example of a heat pump type air-conditioning refrigeration apparatus, and includes a compressor 11, a four-way valve 15, an outdoor heat exchanger 16, an expansion device 13, and an indoor heat exchanger 17. By using the heat exchanger according to the first embodiment for the outdoor heat exchanger 16, the indoor heat exchanger 17, or both, an air-conditioning refrigeration apparatus with high energy efficiency can be realized.
[0041]
Embodiment 3 FIG.
FIG. 10 is a diagram showing the third embodiment, and is a refrigerant circuit diagram of a heat pump type air-conditioning refrigeration apparatus. As shown in the figure, the compressor 11, the four-way valve 15, the outdoor heat exchanger 16, the expansion device 13, and the indoor heat exchanger 17 are configured. And let the internal volume of the outdoor heat exchanger 16 be Vo, and let the internal volume of the indoor heat exchanger 17 be Vi.
Hereinafter, the size of the indoor / outdoor heat exchanger and the amount of refrigerant required for cooling and heating in the heat pump type air-conditioning refrigeration apparatus will be described.
[0042]
In the heat pump type air-conditioning refrigeration apparatus, it is required that the outdoor heat exchanger 16 can be continuously operated without frost formation during normal heating operation, specifically, when the outside air temperature is 7 [° C.]. At this time, if the evaporating temperature of the refrigerant is 0 [° C.] or higher, frost is not formed. Therefore, the outdoor heat exchanger 16 having an evaporating heat exchanging performance with a temperature difference within 7 [° C.] from the outside air temperature is required. Here, the heat exchange amount G [w / k] per unit temperature difference is considered as an index representing the performance of the heat exchanger.
[0043]
The evaporation capacity required for the heating capacity (= condensing capacity) is generally about 2/3 to 3/4 of the capacity, and is required for the outdoor heat exchanger 16 in an air conditioner having a heating capacity of 4000 [w], for example. If the evaporation capacity is 3000 [w] and the temperature difference from the outside air temperature is 7 [° C.], an outdoor heat exchanger with G = 428.6 [w / k] is required.
On the other hand, in the indoor heat exchanger 17, when the room temperature is 20 [° C.] and the condensation temperature is 40 [° C.], the temperature difference is 20 [° C.] and the indoor heat exchanger 17 with G = 200 [w / k] Necessary.
[0044]
Therefore, in the heat pump type air-conditioning refrigeration apparatus, the outdoor heat exchanger 16 is required to have a heat exchange capacity twice or more that of the indoor heat exchanger 17.
In other words, if the heat exchanger has the same performance, the outdoor heat exchanger 16 needs to be twice as large as the indoor heat exchanger 17.
Here, for example, if the condensation temperature is 30 [° C.], the temperature difference from the room temperature is 10 [° C.], the indoor heat exchanger 17 with G = 400 [w / k] is required, and the outdoor heat exchanger 16 However, the temperature of the air blown out from the indoor heat exchanger 16 is 30 [° C.] or less, and heating is performed at a temperature lower than the body temperature. The condensation temperature has a lower limit of about 40 [° C.] in terms of comfort. Therefore, the outdoor heat exchanger 17 is also required to have a heat exchange capacity more than twice that of the indoor heat exchanger 16.
[0045]
On the other hand, during cooling operation, for example, in an air conditioner with a cooling capacity (= evaporation capacity) of 3000 [w], if the room temperature is 27 [° C.] and the evaporation temperature of the indoor heat exchanger is 13 [° C.], the temperature difference is 14 [ ° C] and the indoor heat exchanger 16 having G = 24.3 [w / k] is required.
Further, when the condensation capacity required for the outdoor heat exchanger 17 is 4000 [w], the outside air temperature is 35 [° C.], and the condensation temperature of the outdoor heat exchanger 17 is 45 [° C.], the temperature difference is 10 [° C. Therefore, the outdoor heat exchanger 17 with G = 400 [w / k] is required. Accordingly, in the cooling operation, the outdoor heat exchanger 17 is required to have a heat exchange capacity about twice that of the indoor heat exchanger 16, and if the heat exchanger has the same performance, the outdoor heat exchanger 17 is About twice as large as the indoor heat exchanger 16 is required.
[0046]
Generally, when the refrigerant is excessive in the condenser, the degree of supercooling is increased, and the heat transfer area of the supercooled liquid part having a low refrigerant side heat transfer performance is increased, so that the heat exchange capability is lowered. In addition, when the refrigerant becomes insufficient, the degree of supercooling decreases, and the difference in enthalpy cannot be obtained, so the heat exchange capacity is reduced.
On the other hand, in the evaporator, generally, when the refrigerant is excessive, the evaporator outlet dryness is lowered, and the enthalpy difference cannot be taken, so that the heat exchange ability is lowered. Further, when the refrigerant becomes insufficient, the degree of superheat at the evaporator outlet increases, and the heat transfer area of the superheated steam section having a low refrigerant side heat transfer performance is increased, so that the heat exchange capability is reduced.
Therefore, both the condenser and the evaporator have an optimum refrigerant amount that maximizes the heat exchange capacity and maximizes the energy efficiency.
[0047]
On the other hand, when considering the amount of refrigerant used in the actual machine, it is natural that the amount of refrigerant in the heat exchanger with a smaller internal volume is smaller in the evaporator than in the condenser. Here, if the heat exchanger has the same performance, the outdoor heat exchanger 17 needs to be about twice as large as the indoor heat exchanger 16 (= internal volume). In the cooling operation in which a condenser is used, the amount of refrigerant used is larger than that in the heating operation. Therefore, in a heat pump type air-conditioning refrigeration system, if the refrigerant amount that maximizes the energy efficiency based on the cooling operation standard is charged, the refrigerant becomes excessive during the heating operation and the energy efficiency is lowered.
[0048]
In addition, if the refrigerant amount that maximizes the energy efficiency based on the heating operation standard is charged, the refrigerant becomes insufficient during the cooling operation, and the energy efficiency decreases. Therefore, it is necessary to fill the refrigerant amount that maximizes the energy efficiency for both cooling and heating by adjusting the performance and internal volume of the heat exchanger.
[0049]
If the refrigerant circuit is equipped with a refrigerant amount adjustment container that absorbs the difference in the amount of refrigerant between cooling and heating, it is possible to operate with maximum energy efficiency. The amount of refrigerant cannot be reduced. Providing the refrigerant quantity adjusting container leads to an increase in the cost of the equipment, and a storage space for the container is also required, which is against the downsizing of the equipment and is not a good idea.
[0050]
Refrigerant abundance Mo in the heat exchanger is determined by dividing the heat exchanger into three parts, a superheated steam part, a supercooling liquid part, and a two-phase part, and the refrigerant abundance Mgsh, Mlsc, Mtp of each part. Total Mo = Mgsh + Mlsc + Mtp.
Here, Mgsh, Mlsc, and Mtp are calculated by the following equations, respectively.
Mgsh = Vgsh × ρgsh
Mlsc = Vlsc × ρlsc
Mtp = Vtp × ρtp
ρtp = F × ρg + (1−F) × ρl
F = 1 / {1-S × (ρg / ρl)} + S × (ρg / ρl) × LN {Xi + (Xo−Xi) S × (ρg / ρl)} / (Xo−Xi) / {1-S × (ρg / ρl)}²
S = (Ug / Ul)^C6
Here, M [kg] is the refrigerant abundance, V [m^Three] Is the internal volume, ρ [kg / m^Three] Is the refrigerant density, U [m / s] is the refrigerant flow velocity, subscript o is the whole heat exchanger, gsh is the superheated steam, lsc is the supercooled liquid, tp is the two-phase part, g is the saturated steam, l is It is a saturated liquid.
[0051]
The superheated steam part and the supercooled liquid part, which are single-phase parts, calculate the refrigerant density from the degree of superheat or supercooling that is the refrigerant state at that time, and calculate the amount of refrigerant together with the internal volume of the heat exchanger occupied by that part. Can be calculated.
For the two-phase region, a dimensionless number such as a void fraction F and a slip ratio S is introduced, and the refrigerant density ρtp is calculated to calculate the refrigerant amount. Here, C6 is a constant relating the ratio of the flow rates of the saturated vapor refrigerant and the saturated liquid refrigerant, that is, the slip ratio S. Xi is the dryness of the two-phase part inlet, and Xo is the dryness of the two-phase part outlet. Here, in the case of a condenser, generally, Xi = 1 and Xo = 0, and in the case of an evaporator, Vlsc = 0.
[0052]
FIG. 11 shows the ratio Vo / Vi between the internal volume Vi of the indoor heat exchanger and the internal volume Vo of the outdoor heat exchanger at a certain amount of refrigerant on the horizontal axis and the energy efficiency of cooling and heating at that time on the vertical axis. FIG. The energy efficiency was obtained by calculating the degree of supercooling and the degree of superheat from the amount of refrigerant, the internal volume Vi of the indoor heat exchanger 16, and the internal volume Vo of the outdoor heat exchanger 17 based on the above-described formula.
From FIG. 11, the energy efficiency change of heating is moderate with respect to the change of the internal volume ratio Vo / Vi, but the energy efficiency change of the cooling is large, and the internal volume ratio Vo / Vi is 1.4 ≦ Vo / Vi ≦ 1. If it is in the range of .8, the energy efficiency is expected to be sufficiently high for both cooling and heating. The actual machine test results are shown as white circles, but they are in good agreement.
[0053]
Therefore, the adjustment of the internal volume of the indoor / outdoor heat exchanger 16 enables an operation that maximizes the energy efficiency for both cooling and heating, and there is no need to provide a refrigerant amount adjustment container that absorbs the refrigerant amount difference between the cooling and heating. Reduction of the amount, cost of the equipment, and storage space for the container are also required, so that the equipment can be miniaturized. At this time, if the heat exchanger described in Embodiment 1 is used as the heat exchanger, the energy efficiency can be further increased.
[0054]
In addition, about the heat exchanger described in Embodiment 1 to Embodiment 3 and the air-conditioning refrigeration apparatus using the heat exchanger, HCFC (R22, etc.) and HFC (R116, R125, R134a, R14, R143a, R152a, R227ea, R23, R236ea, R236fa, R245ca, R245fa, R32, R41, RC318, etc., and some mixed refrigerants R407A, R407B, R407C, R407D, R407E, R410A, R410B, R404A, R507A, R508A, R508B) HC (butane, isobutane, ethane, propane, propylene, etc., and some mixed refrigerants of these refrigerants), natural refrigerant (air, carbon dioxide, ammonia, etc., and some mixed refrigerants of these refrigerants), Several mixed refrigerants Be used any type of refrigerant, it can achieve its effect. In addition, when flammable HC refrigerant or toxic ammonia refrigerant is used, reducing the amount of refrigerant used can improve the safety of the apparatus.
[0055]
In addition, about the heat exchanger described in Embodiments 1 to 3 and the air-conditioning refrigeration apparatus using the heat exchanger, mineral oil, alkylbenzene oil, ester oil, ether oil, fluorine oil, and the like can be used. The effect can be achieved with any refrigeration oil, whether the oil is soluble or not. In particular, with respect to refrigerating machine oil having zero or poor solubility in the refrigerant, the effect can be achieved by setting the oil circulation rate of the air-conditioning refrigerating apparatus to a solubility of 0.5% or less.
[0056]
【The invention's effect】
  In the heat exchanger according to the present invention, the outer diameter D of the heat transfer tube is 3 ≦ D ≦ 7 mm, the step pitch Dp in the step direction of the heat transfer tube is 2D ≦ Dp ≦ 3D, and the column pitch Lp in the column direction of the heat transfer tube is 2D ≦ Lp ≦ 3.5D, and the fin pitch Fp of the plate fins0.15D ≦ Fp ≦ 0.27DAs a result, a heat exchanger having high heat transfer performance and low ventilation resistance can be configured without increasing the fan driving force, so that a significant improvement in heat exchange can be achieved.
[0057]
  Further, the outer diameter D of the heat transfer tube is set to 3 ≦ D ≦ 7 mm, the step pitch Dp in the step direction of the heat transfer tube is set to 2D ≦ Dp ≦ 3D, and the column pitch Lp in the column direction of the heat transfer tube is set to 2D ≦ Lp ≦ 3.5D. age,When the fin pitch in the stacking direction of the plate-like fins is Fp,Since the fin thickness Ft of the plate-like fin is 6 ≦ Fp / Ft ≦ 18, a heat exchanger having high heat transfer performance and low ventilation resistance can be configured without increasing the fan driving force in the same manner. An improvement in the amount of heat exchange can be achieved.
[0058]
  Further, the outer diameter D of the heat transfer tube is set to 3 ≦ D ≦ 7 mm, the step pitch Dp in the step direction of the heat transfer tube is set to 2D ≦ Dp ≦ 3D, and the column pitch Lp in the column direction of the heat transfer tube is set to 2D ≦ Lp ≦ 3.5D. And the fin pitch Fp of the plate fins0.15D ≦ Fp ≦ 0.27DSince the fin thickness Ft of the plate-like fins is 6 ≦ Fp / Ft ≦ 18, a heat exchanger with high heat transfer performance and low ventilation resistance can be configured without further increasing the fan driving force. A significant improvement in heat exchange can be achieved.
[0059]
Since the air-conditioning refrigerating apparatus according to the present invention uses the heat exchanger according to any one of claims 1 to 3, a heat exchanger having high heat transfer performance and low ventilation resistance without increasing the fan driving force. Since it can be configured, a significant improvement in heat exchange can be achieved, and the energy efficiency of the device can be dramatically improved.
[0060]
Moreover, since the refrigerant is the working fluid and the heat exchanger according to any one of claims 1 to 3 is used for the indoor heat exchanger, the heat transfer performance is high and the ventilation resistance is small without increasing the fan driving force. Since the heat exchanger can be configured, it is possible to achieve a significant improvement in the amount of heat exchange and to dramatically improve the energy efficiency of the device.
[0062]
The refrigerant is a working fluid, and includes a compressor, a four-way valve, a throttle device, an indoor heat exchanger, and an outdoor heat exchanger, and the heat exchanger according to any one of claims 1 to 3 is used for an indoor heat exchanger. In this case, the internal volume of the indoor heat exchanger is Vi, the internal volume of the outdoor heat exchanger is Vo, and Vi and Vo satisfy the relationship of 1.4 ≦ Vo / Vi ≦ 1.8. The energy efficiency of the device can be dramatically improved while achieving reduction, cost reduction of the device, and downsizing of the device.
[0063]
In addition, any type of refrigerant such as R407C, R410A, R32, isobutane, propane, carbon dioxide, ammonia, etc. can be used as the refrigerant, and the energy efficiency of the equipment can be dramatically improved and flammable HC When a refrigerant or a toxic ammonia refrigerant is used, reducing the amount of refrigerant used can improve the safety of the apparatus.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment, and is a partial side plan view and a side view of a heat exchanger.
FIG. 2 shows the first embodiment, and is a characteristic diagram showing the relationship between the stage pitch of the heat transfer tubes and the heat exchange amount.
FIG. 3 shows the first embodiment and is a characteristic diagram showing the relationship between the row pitch of the heat transfer tubes and the heat exchange amount;
FIG. 4 is a diagram showing the first embodiment and is a characteristic diagram showing a relationship between a fin pitch and a heat exchange amount.
FIG. 5 is a diagram showing the first embodiment and is a characteristic diagram showing a relationship between a fin thickness and a heat exchange amount.
FIG. 6 shows the first embodiment and is a characteristic diagram showing the relationship between the outer diameter of the heat transfer tube and the amount of heat exchange.
7 is a diagram showing a modification of the first embodiment, and is a partial side plan view of the heat exchanger. FIG.
FIG. 8 is a diagram showing a second embodiment and is a refrigerant circuit diagram of an air-conditioning refrigeration apparatus.
FIG. 9 is a diagram showing a modification of the second embodiment, and is a refrigerant circuit diagram of an air conditioning refrigeration apparatus.
FIG. 10 shows the third embodiment and is a refrigerant circuit diagram of the air-conditioning refrigeration apparatus.
FIG. 11 shows the third embodiment and is a characteristic diagram showing the relationship between the internal volume and energy efficiency of the indoor heat exchanger and the outdoor heat exchanger.
FIG. 12 is a diagram showing a conventional heat exchanger, and is a partial side plan view of the heat exchanger.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plate-like fin, 2 Heat exchanger tube, 3 Cutting and raising, 11 Compressor, 12 Condensation heat exchanger, 13 Expansion device, 14 Evaporation heat exchanger, 15 Four-way valve, 16 Outdoor heat exchanger, 17 Indoor heat exchanger.

Claims (7)

A plurality of plate-like fins arranged in parallel and through which gas flows,
The plate-like fins are inserted at right angles, the working fluid passes through the inside, and a plurality of stages are provided in a step direction perpendicular to the gas passage direction, and a plurality of rows are provided in the row direction of the gas passage direction. A heat transfer tube having an outer diameter D of 3 mm ≦ D ≦ 7 mm ;
Provided on the plate-like fin surface, and provided with a cut-and-raised opening facing the gas flow,
The step pitch Dp in the step direction of the heat transfer tube is 2D ≦ Dp ≦ 3D,
The row pitch Lp in the row direction of the heat transfer tubes is 2D ≦ Lp ≦ 3.5D,
The heat exchanger according to claim 1 , wherein a fin pitch Fp of the plate fin is 0.15D ≦ Fp ≦ 0.27D . A plurality of plate-like fins arranged in parallel and through which gas flows,
The plate-like fins are inserted at right angles, the working fluid passes through the inside, and a plurality of stages are provided in a step direction perpendicular to the gas passage direction, and a plurality of rows are provided in the row direction of the gas passage direction. A heat transfer tube having an outer diameter D of 3 mm ≦ D ≦ 7 mm ;
Provided on the plate-like fin surface, and provided with a cut-and-raised opening facing the gas flow,
The step pitch Dp in the step direction of the heat transfer tube is 2D ≦ Dp ≦ 3D,
The row pitch Lp in the row direction of the heat transfer tubes is 2D ≦ Lp ≦ 3.5D,
A heat exchanger , wherein a fin thickness Ft of the plate-like fins is 6 ≦ Fp / Ft ≦ 18 when a fin pitch in the stacking direction of the plate-like fins is Fp. A plurality of plate-like fins arranged in parallel and through which gas flows,
The plate-like fins are inserted at right angles, the working fluid passes through the inside, and a plurality of stages are provided in the step direction perpendicular to the gas passing direction, and a plurality of lines are provided in the column direction in the gas passage direction. A heat transfer tube having an outer diameter D of 3 mm ≦ D ≦ 7 mm ;
Provided on the plate-like fin surface, and provided with a cut-and-raised opening facing the gas flow,
The step pitch Dp in the step direction of the heat transfer tube is 2D ≦ Dp ≦ 3D,
The row pitch Lp in the row direction of the heat transfer tubes is 2D ≦ Lp ≦ 3.5D,
The fin pitch Fp of the plate fin is 0.15D ≦ Fp ≦ 0.27D ,
A heat exchanger characterized in that a fin thickness Ft of the plate-like fins is set to 6 ≦ Fp / Ft ≦ 18.   A heat exchanger according to any one of claims 1 to 3 is used in an air-conditioning refrigeration apparatus using a refrigerant as a working fluid and including a compressor, an expansion device, a condensing heat exchanger, and an evaporating heat exchanger. Air conditioning refrigeration equipment.   An air-conditioning refrigeration system using a refrigerant as a working fluid and including a compressor, a four-way valve, a throttle device, an indoor heat exchanger, and an outdoor heat exchanger, wherein the heat exchanger according to any one of claims 1 to 3 is the indoor heat exchanger. An air-conditioning refrigeration apparatus characterized by being used in a container.   6. The internal volume of the indoor heat exchanger is Vi, the internal volume of the outdoor heat exchanger is Vo, and Vi and Vo satisfy a relationship of 1.4 ≦ Vo / Vi ≦ 1.8. The air-conditioning refrigeration apparatus described. The air-conditioning refrigerating apparatus according to any one of claims 4 to 6 , wherein any one of R407C, R410A, R32, isobutane, propane, carbon dioxide, and ammonia is used as the refrigerant.

Images