阅读说明：本技术 空气换热器中换热翅片面积的校核方法 (The check method of heat exchange fin area in air heat exchanger ) 是由 石世信 姚建峰 林建忠 于 2019-09-21 设计创作，主要内容包括：本发明公开了一种空气换热器中换热翅片面积的校核方法,包括以下步骤：步骤一,换热器平均温差△T的计算；步骤二,空气侧所需的理论换热系数h<Sub>air</Sub>的核算；步骤三,实际管外换热系数h<Sub>fac</Sub>的计算与校核；步骤四,判断翅片表面积A<Sub>f</Sub>是否满足换热性能要求：如求得真实的管外换热系数h<Sub>fact</Sub>,不低于之前所求的所需空气侧所需的换热系数h<Sub>air</Sub>,即视为满足换热性能的要求；否则,修改翅片表面积A<Sub>f,</Sub>再次经步骤二至三校验,直至满足条件；步骤五,根据计算的翅片表面积A<Sub>f</Sub>,若简单波纹面积足够的话,则直接压制简单波纹；若简单波纹面积不足的话,则另外方向同样压制波纹或者使波纹略微弯曲以形成复杂波纹,以进一步增大翅片的表面积来达到计算值。(The invention discloses a kind of check methods of heat exchange fin area in air heat exchanger, comprising the following steps: step 1, the calculating of heat exchanger mean temperature difference △ T；Step 2, theoretical coefficient of heat transfer h needed for air side air Accounting；Step 3, practical heat transfer outside a tube coefficient h fac Calculating and check；Step 4 judges fin surface product A f Whether meet heat exchange property requirement: such as acquiring true heat transfer outside a tube coefficient h fact , not less than coefficient of heat transfer h needed for required air side required before air , that is, it is considered as the requirement for meeting heat exchange property；Otherwise, modification fin surface product A F, Again through step 2 to three verifications, until meeting condition；Step 5, according to the fin surface of calculating product A f If if simple ripple area is enough, the simple ripple of direct pressing；If if simple ripple area is insufficient, in addition the same corrugating in direction or keeping ripple slight curving to form complicated ripple, reaching calculated value to further increase the surface area of fin.)

1. the check method of heat exchange fin area in air heat exchanger, comprising the following steps:

Step 1, the calculating of heat exchanger mean temperature difference △ T:

The calculating of shell-side inlet temperature is based on following formula:

In formula, T_airinIt is the inlet temperature of air, unit DEG C；T_airoutIt is the outlet temperature of air, is given value, unit DEG C；Q It is total heat exchange amount, is given value, unit W；M_airIt is the mass flow of air, according to pressure and temperature, seeks the close of hot end Degree, multiplied by hot end volume flow to obtain the final product, units/kg/s；Cp_airIt is the specific heat at constant pressure in hot end, is looked into and taken according to pressure and temperature, J/kg- DEG C of unit；

Correction factor R, nondimensional FACTOR P, NTU and K are calculated:

K=1-e^-R·NTU；

Then nondimensional mean temperature difference correction factor F is calculated:

To obtain final mean temperature difference △ T；

In formula, T is temperature, unit: DEG C；" air " and " water " in subscript respectively represents air and water, " in " and " out " point It Biao Shi not inlet and outlet；

Step 2, theoretical coefficient of heat transfer h needed for air side_airAccounting:

Water Reynolds number first in computer tube；

Re is Reynolds number, dimensionless；ρ is the density of fluid, units/kg/m³；V is fluid flow rate, unit m/s；D_iIt is in heat exchanger tube Diameter, unit m；μ is the viscosity of fluid, units/kg/m-s；

The water coefficient of heat transfer in managing,

The scope of application: 0.5≤Pr≤2000,2300≤Re≤5 × 10⁶；

In formula, Nu is nusselt number, dimensionless；Pr is Prandtl number, and dimensionless can be looked by physical property and be taken；f_wIt is coefficient of friction, nothing Dimension: f_w=(1.58ln (Re) -3.28)^-2；

According to Nu number, using following formula, the coefficient of heat transfer in computer tube is calculated unified to water in the pipe at heat exchange pipe external surface Coefficient of heat transfer h_water, unit W/m²-℃；

λ_waterIt is the thermal coefficient of water, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is heat exchange bore, unit m；

Calculate the coefficient of heat transfer h of pipe wall of heat exchange pipe_tube: unit W/m²-℃；

λ_tubeIt is the thermal coefficient of tube wall metal, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is heat exchange bore, it is single Position m；

Calculate the unified pipe side dirtiness resistance RF to heat exchange pipe external surface_water,

Calculate the dirtiness resistance RF of the unified shell-side to heat exchange pipe external surface_air,

According to coefficient of heat transfer h, unit W/m needed for the totality that design surface area and mean temperature difference, heat exchange amount acquire outside heat exchanger tube²- DEG C: Q=hArea Δ T；

In formula, Q is overall heat exchange amount, W；H is the overall coefficient of heat transfer, unit W/m²-℃；Area is design heat exchange area, unit m²；△ T is mean temperature difference, unit DEG C；

Coefficient of heat transfer h needed for calculating air side according to the following formula_air, unit W/m²DEG C:

Step 3, practical heat transfer outside a tube coefficient h_facCalculating and check:

Firstly, the Numerical heat transfer j factor, dimensionless；

In formula, Re_DcIt is the Reynolds number based on sleeve outer, dimensionless, Dc=Do+2 δ, the i.e. fin thickness of outer diameter+twice；σ It is area of section shrinkage ratio, equal to the minimum flow area at casing, divided by the maximum flow area of the entrance of fin；Casing Reynolds number at outer diameter, based at sleeve outer maximum flow rate and sleeve outer calculate:

In formula, ρ_airIt is the density of air, units/kg/m³；V_maxIndicate the air velocity at casing, unit unit m/s；D_cIt is set Pipe outside diameter, m；μ_airIt is the viscosity of air, units/kg/m-s；

Coefficient of heat transfer h when the outer air side fin area of computer tube does not extend_initial；Unit W/m²-K；

In formula, Pr is Prandtl number, dimensionless；K is thermal coefficient, unit W/m-K；Subscript " air " represents air；

Then, the coefficient of heat transfer h of the outer air side of pipe after transformed area extension is carried out by following step_fac:

A: fin efficiency η is calculated:

Firstly, being calculate by the following formula the balance equivalent radius R of Round fin_eq:

Balance equivalent radius R_eq, unit m；R is the inside radius of heat exchanger tube, unit m, r=D in formula_i/2；X_MAnd X_LWith heat exchanger tube Arrange related, unit m is calculated as follows:

In formula, P_tIt is the pitch of heat exchanger tube, perpendicular to flow direction, unit m；P_lIt is the pitch of heat exchanger tube, is parallel to flowing side To, unit m, equilateral triangle arrangement, P_l=P_t×sin(60°)；

Then, variable is calculatedDimensionless；

Then, the equivalent parameter m of fin is calculated_f,Unit 1/m；

In formula, k_fIt is the thermal coefficient of fin material, unit W/m-K；T is the thickness of fin, unit m；

In this way, fin efficiency η, dimensionless can be acquired；

Tanh (x)=(e^x-e^-x)/(e^x+e^-x)；

B: a nondimensional Area modificatory coefficient η is calculated_so,

In formula, A_fIt is the setting surface area of fin, is calculated by single side, do not include fin sleeve portion external surface area A_b, unit m²； Fin total surface area A comprising sleeve portion_o=A_f+A_b, unit m²；

C: it calculates unified to the practical coefficient of heat transfer h of air side at heat exchanger tube light tube outer surface after fin extends_fact, unit W/m²-K；

In formula, A_tIt is the external surface area of heat exchanger tube light pipe, unit m²；

Step 4 judges fin surface product A_fWhether meet heat exchange property requirement: such as acquiring true heat transfer outside a tube coefficient h_fact, Not less than coefficient of heat transfer h needed for required air side required before_air, that is, it is considered as the requirement for meeting heat exchange property；Otherwise, it repairs Change fin surface product A_F,, again through step 2 to three verifications, until meeting condition；

Step 5, according to the fin surface of calculating product A_f, the surface shape of heat exchange fin is determined, if simple ripple area is enough It talks about, then the simple ripple of direct pressing；If if simple ripple area is insufficient, in addition the same corrugating in direction or making ripple It is slight curving to form complicated ripple, reach calculated value to further increase the surface area of fin.

2. the check method of heat exchange fin area in air heat exchanger as described in claim 1, it is characterised in that: the heat dissipation Fin is aluminum radiating fin.

3. the check method of heat exchange fin area in air heat exchanger as claimed in claim 2, it is characterised in that: the heat dissipation Fin uses herringbone rippled fin, and under the premise of guaranteeing heat exchange area, guarantees bending angle θ >=120 °.

Technical field

The present invention relates to a kind of check methods of heat exchange fin area in air heat exchanger.

Background technique

When cooler for motor is cooling using cooling air mode, what is flowed in heat exchanger tube is the component cooling water of low temperature, It is the air of high temperature outside cooling tube.The heat that motor distributes is ultimately transferred to component cooling water by air, to guarantee electricity Machine is not in excessively high temperature.

The coefficient of heat transfer of water in managing manages outer air part, passes through wave much higher than air outside pipe to save arrangement space Line type aluminum fin carries out area extension, the Lai Tigao coefficient of heat transfer.How the heat exchange fin of suitable area is made, to guarantee to exchange heat The heat exchange amount of device is particularly significant.

Summary of the invention

The technical problems to be solved by the present invention are: providing a kind of check side of heat exchange fin area in air heat exchanger Method.

In order to solve the above technical problems, the technical scheme adopted by the invention is as follows: heat exchange fin area in air heat exchanger Check method, comprising the following steps:

Step 1, the calculating of mean temperature difference △ T:

The calculating of shell-side inlet temperature is based on following formula:

In formula, T_airinIt is the inlet temperature of air, unit DEG C；T_airoutIt is the outlet temperature of air, is given value, unit ℃；Q is total heat exchange amount, is given value, unit W；M_airIt is that the mass flow of air according to pressure and temperature seeks hot end Density, multiplied by hot end volume flow to obtain the final product, units/kg/s；Cp_airIt is the specific heat at constant pressure in hot end, is looked into according to pressure and temperature It takes, J/kg- DEG C of unit；

Correction factor R, nondimensional FACTOR P, NTU and K are calculated:

K=1-e^-R·NTU；

Then nondimensional mean temperature difference correction factor F is calculated:

To obtain final mean temperature difference △ T；

In formula, T is temperature, unit: DEG C；" air " and " water " in subscript respectively represents air and water, " in " and " out " respectively indicates inlet and outlet；

Step 2, theoretical coefficient of heat transfer h needed for air side_airAccounting:

Water Reynolds number first in computer tube；

Re is Reynolds number, dimensionless；ρ is the density of fluid, units/kg/m³；V is fluid flow rate, unit m/s；D_iIt is heat exchange Bore, unit m；μ is the viscosity of fluid, units/kg/m-s；

Water in managing, is substantially turbulent flow, the coefficient of heat transfer,

The scope of application: 0.5≤Pr≤2000,2300≤Re≤5 × 10⁶；

In formula, Nu is nusselt number, dimensionless；Pr is Prandtl number, and dimensionless can be looked by physical property and be taken；f_wIt is friction system Number, dimensionless: f_w=(1.58ln (Re) -3.28)²；

According to Nu number, using following formula, the coefficient of heat transfer in computer tube is calculated unified to the pipe at heat exchange pipe external surface The coefficient of heat transfer h of interior water_water, unit W/m²-℃；

λ_waterIt is the thermal coefficient of water, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is heat exchange bore, it is single Position m；

Calculate the coefficient of heat transfer h of pipe wall of heat exchange pipe_tube: unit W/m²-℃；

λ_tubeIt is the thermal coefficient of tube wall metal, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is in heat exchanger tube Diameter, unit m；

The unified pipe side dirtiness resistance RFwater to heat exchange pipe external surface is calculated,

The dirtiness resistance RFair of the unified shell-side to heat exchange pipe external surface is calculated,

According to coefficient of heat transfer h, unit W/ needed for the totality that design surface area and mean temperature difference, heat exchange amount acquire outside heat exchanger tube m²DEG C: Q=hArea Δ T；

In formula, Q is overall heat exchange amount, W；H is the overall coefficient of heat transfer, unit W/m²-℃；Area is design heat exchange area, Unit m²；△ T is mean temperature difference, unit DEG C；

Coefficient of heat transfer h needed for calculating air side according to the following formula_air, unit W/m²DEG C:

Step 3, practical heat transfer outside a tube coefficient h_facCalculating and check:

Firstly, the Numerical heat transfer j factor, dimensionless；

In formula, Re_DcIt is the Reynolds number based on sleeve outer, dimensionless, Dc=Do+2 δ, the i.e. fin of outer diameter+twice are thick Degree；σ is area of section shrinkage ratio, equal to the minimum flow area at casing, divided by the maximum flow area of the entrance of fin； Reynolds number at sleeve outer, based at sleeve outer maximum flow rate and sleeve outer calculate:

In formula, ρ_airIt is the density of air, units/kg/m³；V_maxIndicate the air velocity at casing, unit unit m/s；D_c It is sleeve outer, m；μ_airIt is the viscosity of air, units/kg/m-s；

Coefficient of heat transfer h when the outer air side fin area of computer tube does not extend_initial；Unit W/m²-K；

In formula, Pr is Prandtl number, dimensionless；K is thermal coefficient, unit W/m-K；Subscript " air " represents air；

Then, the coefficient of heat transfer h of the outer air side of pipe after transformed area extension is carried out by following step_fac:

A: fin efficiency η is calculated:

Firstly, being calculate by the following formula the balance equivalent radius R of Round fin_eq:

Balance equivalent radius R_eq, unit m；R is the inside radius of heat exchanger tube, unit m, r=D in formula_i/2；

X_MAnd X_LRelated with the arrangement of heat exchanger tube, unit m is calculated as follows:

In formula, P_tIt is the pitch of heat exchanger tube, perpendicular to flow direction, unit m；P_lIt is the pitch of heat exchanger tube, is parallel to flowing Direction, unit m, equilateral triangle arrangement, P_l=P_t×sin(60°)；

Then, variable is calculatedDimensionless；

Then, the equivalent parameter m of fin is calculated_f, unit 1/m；

In formula, k_fIt is the thermal coefficient of fin material, unit W/m-K；T is the thickness of fin, unit m；

In this way, fin efficiency η, dimensionless can be acquired；

Tanh (x)=(e^x-e^-x)/(e^x+e^-x)；

B: a nondimensional Area modificatory coefficient η is calculated_so,

In formula, A_fIt is the setting surface area of fin, is calculated by single side, do not include fin sleeve portion external surface area A_b, unit m²；Fin total surface area A comprising sleeve portion_o=A_f+A_b, unit m²；

C: it calculates unified to the practical coefficient of heat transfer h of air side at heat exchanger tube light tube outer surface after fin extends_fact, Unit W/m²-K；

In formula, A_tIt is the external surface area of heat exchanger tube light pipe, unit m²；

Step 4 judges fin surface product A_fWhether meet heat exchange property requirement: such as acquiring true heat transfer outside a tube coefficient h_fact, not less than coefficient of heat transfer h needed for required air side required before_air, that is, it is considered as the requirement for meeting heat exchange property；It is no Then, modification fin surface product A_f, again through step 2 to three verifications, until meeting condition；

Step 5, according to the fin surface of calculating product A_f, the surface shape of heat exchange fin is determined, if simple ripple area foot If enough, then the simple ripple of direct pressing；If if simple ripple area is insufficient, in addition the same corrugating in direction or making Ripple is slight curving to form complicated ripple, reaches calculated value to further increase the surface area of fin.

As a preferred solution, the radiating fin is aluminum radiating fin.

As a preferred solution, the radiating fin uses herringbone rippled fin, and is guaranteeing heat exchange area Under the premise of, guarantee bending angle θ >=120 °.

The beneficial effects of the present invention are: this method can accurately and effectively calculate cooling fin area, it is ensured that cooler Effectively operation.

Detailed description of the invention

Fig. 1 is the connection signal of rippled fin and heat exchanger tube.

Specific embodiment

Specific embodiments of the present invention are described below in detail.

Since air-side temperature is 50 DEG C in heat exchanger, much higher than 25 DEG C of room temperature, even if relative air humidity at room temperature It is 100%, after temperature rises, relative humidity declines, and there's almost no water droplet in air, flows through the corrugated plating with centrifugation When, also just go out without elutriation.Therefore, it can not consider the influence of analysis wet environment heat exchanging.

Due to being set with connection between heat exchanger tube and aluminum fin, interference fit almost without gap, can not consider therein Interval station.

Since the thermal coefficient of fine aluminium is very high, aluminum fin is again very thin, therefore aluminium casings part, the coefficient of heat transfer are non- The increased thermal resistance of casing thickness can be ignored in Chang Gao.

The check method of heat exchange fin area in air heat exchanger, comprising the following steps:

Step 1, the calculating of mean temperature difference △ T:

The calculating of shell-side inlet temperature is based on following formula:

In formula, T_airinIt is the inlet temperature of air, unit DEG C；T_airoutIt is the outlet temperature of air, is given value, unit ℃；Q is total heat exchange amount, is given value, unit W；M_airIt is that the mass flow of air according to pressure and temperature seeks hot end Density, multiplied by hot end volume flow (intake of cooler shell-side) to obtain the final product, units/kg/s；Cp_airIt is the specific heat at constant pressure in hot end Hold, is looked into and taken according to pressure and temperature, J/kg- DEG C of unit；

Correction factor R, nondimensional FACTOR P, NTU and K are calculated:

K=1-e^-R·NTU；

Then nondimensional mean temperature difference correction factor F is calculated:

To obtain final mean temperature difference △ T；

In formula, T is temperature, unit: DEG C；" air " and " water " in subscript respectively represents air and water, " in " and " out " respectively indicates inlet and outlet；

Step 2, theoretical coefficient of heat transfer h needed for air side_airAccounting:

Water in managing, first calculating Reynolds number, judge laminar flow or turbulent flow；

Re is Reynolds number, dimensionless；ρ is the density of fluid, units/kg/m³；V is fluid flow rate, unit m/s；D_iIt is heat exchange Bore, unit m；μ is the viscosity of fluid, units/kg/m-s；

Water in managing, is substantially turbulent flow, the coefficient of heat transfer,

The scope of application: 0.5≤Pr≤2000,2300≤Re≤5 × 10⁶；

In formula, Nu is nusselt number, dimensionless；Pr is Prandtl number, and dimensionless can be looked by physical property and be taken；f_wIt is friction system Number, dimensionless: f_w=(1.58ln (Re) -3.28)^-2；

The scope of application: smooth pipe, sufficiently development turbulent flow, 10⁴≤Re≤10⁷；

According to Nu number, using following formula, the coefficient of heat transfer in computer tube is calculated unified to the pipe at heat exchange pipe external surface The coefficient of heat transfer h of interior water_water, unit W/m²-℃；

λ_waterIt is the thermal coefficient of water, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is heat exchange bore, it is single Position m；

Calculate the coefficient of heat transfer h of pipe wall of heat exchange pipe_tube: unit W/m²-℃；

λ_tubeIt is the thermal coefficient of tube wall metal, W/m- DEG C of unit；D_oIt is heat exchange pipe outside diameter, unit m；D_iIt is in heat exchanger tube Diameter, unit m；

The unified pipe side dirtiness resistance RFwater to heat exchange pipe external surface is calculated,

The dirtiness resistance RFair of the unified shell-side to heat exchange pipe external surface is calculated,

According to coefficient of heat transfer h, unit W/ needed for the totality that design surface area and mean temperature difference, heat exchange amount acquire outside heat exchanger tube m²DEG C: Q=hArea Δ T；

In formula, Q is overall heat exchange amount, W；H is the overall coefficient of heat transfer, unit W/m²-℃；Area is design heat exchange area, Unit m²；△ T is mean temperature difference, unit DEG C；

Coefficient of heat transfer h needed for calculating air side according to the following formula_air, unit W/m²DEG C:

In addition, if fin, is sleeved on heat exchanger tube, fin is relatively thin, the tube wall heat conduction of this part, may be regarded as plate biography Heat is unified to heat exchange pipe external surface:

The unified coefficient of heat transfer h to fin metal at heat exchange pipe external surface_Al, unit W/m²-℃；

λ_AlIt is the thermal coefficient of fin metal, W/m- DEG C；D_oIt is heat exchange pipe outside diameter, m；δ is the thickness of fin, m.h_AlUsually It is very big, in totally heat exchange calculates, it can be ignored.

Step 3, practical heat transfer outside a tube coefficient h_facCalculating and check:

Firstly, the Numerical heat transfer j factor, dimensionless；

In formula, Re_DcIt is the Reynolds number based on sleeve outer, dimensionless, Dc=Do+2 δ, the i.e. fin of outer diameter+twice are thick Degree；σ is area of section shrinkage ratio, equal to the minimum flow area at casing, divided by the maximum flow area of the entrance of fin； Reynolds number at sleeve outer, based at sleeve outer maximum flow rate and sleeve outer calculate:

In formula, ρ_airIt is the density of air, units/kg/m³；V_maxIndicate the air velocity at casing, unit unit m/s；D_c It is sleeve outer, m；μ_airIt is the viscosity of air, units/kg/m-s；

Coefficient of heat transfer h when the outer air side fin area of computer tube does not extend_initial；Unit W/m²-K；

In formula, Pr is Prandtl number, dimensionless；K is thermal coefficient, unit W/m-K；Subscript " air " represents air；

Then, the coefficient of heat transfer h of the outer air side of pipe after transformed area extension is carried out by following step_fac:

A: fin efficiency η is calculated:

Firstly, being calculate by the following formula the balance equivalent radius R of Round fin_eq:

Balance equivalent radius R_eq, unit m；R is the inside radius of heat exchanger tube, unit m, r=D in formula_i/2；

X_MAnd X_LRelated with the arrangement of heat exchanger tube, unit m is calculated as follows:

In formula, P_tIt is the pitch of heat exchanger tube, perpendicular to flow direction, unit m；P_lIt is the pitch of heat exchanger tube, is parallel to flowing Direction, unit m, equilateral triangle arrangement, P_l=P_t×sin(60°)；

Then, variable is calculatedDimensionless；

Then, the equivalent parameter m of fin is calculated_f, unit 1/m；

In formula, k_fIt is the thermal coefficient of fin material, unit W/m-K；T is the thickness of fin, unit m；

In this way, fin efficiency η, dimensionless can be acquired；

Tanh (x)=(e^x-e^-x)/(e^x+e^-x)；

B: a nondimensional Area modificatory coefficient η is calculated_So,

In formula, A_fIt is the setting surface area of fin, is calculated by single side, do not include fin sleeve portion external surface area A_b, unit m²；Fin total surface area A comprising sleeve portion_o=A_f+A_b, unit m²；

C: it calculates unified to the practical coefficient of heat transfer h of air side at heat exchanger tube light tube outer surface after fin extends_fact, Unit W/m²-K；

In formula, A_tIt is the external surface area of heat exchanger tube light pipe, unit m²；

Step 4 judges fin surface product A_fWhether meet heat exchange property requirement: such as acquiring true heat transfer outside a tube coefficient h_fact, not less than coefficient of heat transfer h needed for required air side required before_air, that is, it is considered as the requirement for meeting heat exchange property；It is no Then, modification fin surface product A_f, again through step 2 to three verifications, until meeting condition；

Step 5, according to the fin surface of calculating product A_f, the surface shape of heat exchange fin is determined, if simple ripple area foot If enough, then the simple ripple of direct pressing；If if simple ripple area is insufficient, in addition the same corrugating in direction or making Ripple is slight curving to form complicated ripple, reaches calculated value to further increase the surface area of fin.For example, such as Fig. 1 institute Showing, the radiating fin uses herringbone rippled fin, and under the premise of guaranteeing heat exchange area, guarantee bending angle θ >= 120°。

The principles and effects of the invention, and the implementation that part uses only is illustrated in the above embodiments Example, and is not intended to limit the present invention；It should be pointed out that for those of ordinary skill in the art, not departing from wound of the present invention Under the premise of making design, various modifications and improvements can be made, and these are all within the scope of protection of the present invention.