Method, device and application for measuring heat and moisture exchange capacity of upward spray heat exchange unit

Abstract

The present invention relates to a method, device, and application for determining the heat and moisture exchange capacity of an upward-spraying heat exchange unit, and relates to the field of underground ventilation and air conditioning technology. The aforementioned method includes the following steps: constructing a flow model for the entire migration process of a spray droplet group within the heat exchange unit; calculating the drag coefficient based on the force of the droplet group; calculating the maximum vertical migration distance and migration time of the spray droplet group; constructing a heat and moisture energy transfer model between air and the spray droplet group; calculating the number of mass transfer units; and calculating the total heat and moisture exchange capacity within the upward-spraying heat exchange unit. The present invention can more accurately determine the heat and moisture exchange capacity of an upward-spraying heat exchange unit, provide support and assistance for the efficient extraction and utilization of heat and moisture energy from mine exhaust, and meet the needs of guiding the efficient extraction and utilization of energy in the device.

Description

Technical Field

[0001] The present invention relates to the technical field of underground ventilation and air conditioning, and in particular to a method, device and application for measuring the heat and moisture exchange capacity of an upward spraying type spray heat exchange unit. Background Art

[0002] Currently, spraying is widely used in exhaust heat recovery and wet dust removal. The direct contact heat exchange between the exhaust air and the droplet cluster fully extracts the sensible and latent heat from the exhaust airflow, while also scrubbing dust particles from the exhaust air. After absorbing the heat, the droplets fall back into the heat pump unit, extracting heat and supplying hot water to industrial production areas, thereby achieving waste heat recovery.

[0003] Existing mine exhaust heat recovery technologies often utilize multiple nozzles to achieve sufficient water flow for optimal cooling. The jets from each nozzle group exhibit significant crossover. The wake and hydrodynamic interactions between the droplet spheres affect the drag, further impacting the flow characteristics of the spray droplet swarm and its heat exchange with the airflow. Furthermore, due to the high moisture content of exhaust air, latent heat transfer within the system is primarily through moisture exchange. However, fundamental research on the interaction between droplet swarm migration and heat and moisture transfer is significantly lagging, hindering the development of efficient energy extraction and utilization systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for measuring the heat and moisture exchange capacity of an upward spraying heat exchange unit to meet the need of guiding the efficient extraction and utilization of energy of the device.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The method for measuring the heat and moisture exchange capacity of an upward spray heat exchange unit comprises the following steps:

[0007] S1. Construct a flow model for the entire process of spray droplet migration in the heat exchange unit;

[0008] S2. Calculate the drag coefficient C based on the force of the droplet group d ;

[0009] S3. Calculate the maximum vertical migration distance and migration time of the spray droplet group;

[0010] S4. Construct a heat and moisture energy transfer model between air and spray droplet groups;

[0011] S5. Calculate the number of mass transfer units NTU m ;

[0012] S6. Calculate the total heat and moisture exchange capacity in the upward spray heat exchange unit based on the air temperature difference and moisture content difference before and after the heat exchange.

[0013] In step S1, a flow model of the entire process of spray droplet migration in the heat exchange unit is constructed. The specific operations are as follows:

[0014] Assuming that the droplets can be regarded as rigid spheres, the airflow velocity is the same at all locations on the same cross section, and the cone angle of the atomizing nozzle is very small, the droplets will move vertically after being ejected from the nozzle. Therefore, the main factors affecting the droplets during movement include gravity, buoyancy, and resistance. The entire process of the spray droplet group migration includes: ① Ascending stage, the droplets move at u d0 The liquid droplets are ejected vertically upward from the nozzle at a speed of 1000 m / s. Due to the resistance of the wind flow, the speed gradually decreases. After the speed drops to 0 m / s, the droplets fall; ② In the falling stage, the falling droplets are in the same direction as the wind flow, and the falling speed gradually increases until they fall into the collection pool.

[0015] The gravitational force on the droplet is:

[0016]

[0017] Where, F g is the gravity acting on the droplet, N; ρ d is the droplet density, kg / m 3 ; g is the acceleration due to gravity, m / s 2 ; D is the droplet diameter, m.

[0018] The buoyancy force on the droplet is:

[0019]

[0020] Where, F b is the buoyancy of the droplet, N; ρ a is the air density, kg / m 3 .

[0021] The resistance force on the droplet is:

[0022]

[0023] Where R is the resistance of the droplet, N; u s is the relative velocity between the droplet and the wind flow, u s =u a -u d , m / s; u d is the droplet velocity, m / s; u a is the wind speed, m / s; C d is the drag coefficient, dimensionless; A is the projected area of ​​the droplet, A=πD 2 / 4,m 2 .

[0024] Considering the direction of the droplet movement as positive, according to Newton's law of motion:

[0025]

[0026] Therefore, the flow model of the spray droplet group is:

[0027]

[0028] Where t is the migration time, s.

[0029] In step S2, the drag coefficient C based on the force of the droplet group is calculated. d , the specific operations are as follows:

[0030] In actual heat and moisture exchange equipment, in order to achieve sufficient water volume to maintain a good cooling effect, multiple groups of nozzles are often arranged, and there is a clear intersection between the jets of each group of nozzles. On the other hand, the individual droplets in the droplet group affect each other, and the wake and hydrodynamic interactions between the droplet balls affect the resistance they experience. Therefore, when the spatial distribution of the droplet group changes, the drag coefficient also changes. The drag coefficient is not only related to the Reynolds number, but also to the distribution of the droplet group in space. Therefore, the dispersed phase fraction is introduced into the calculation of the droplet resistance coefficient in two-phase flow under general working conditions. The dispersed phase fraction is the volume ratio of the droplet volume to the total space, which characterizes the density of the droplets in the light column space. The unit is PPM, that is, 10 -6 Affected by the liquid breakup mechanism, the smaller the characteristic droplet size, the larger the dispersed phase fraction. After introducing the dispersed phase fraction, the resistance coefficient can be expressed as:

[0031]

[0032] Where μ* is the dynamic viscosity ratio, μ*=μ d / μ a , dimensionless; μ d is the droplet dynamic viscosity, N·s / m 2 ;μ a is the air dynamic viscosity, N·s / m 2 ; ε is the dispersed phase fraction, 10 -6 ; P1, P2, P3, P4 are correlation coefficients, P1=4+6ε 5 / 3 , P2=6-6ε 5 / 3 , P3=4+6ε 1 / 3 +6ε 2 / 3 +ε, P4=4+3ε 1 / 3 -3ε 2 / 3 -4ε; Re is the relative Reynolds number of the two-phase flow, Re=ρ a |u s |D / μ a ;Re c is the critical Reynolds number, Re c=33+8600ε 2 / 3 , dimensionless.

[0033] In step S3, the maximum vertical migration distance and migration time of the spray droplet group are calculated. The specific operation is as follows:

[0034]

[0035] In step S4, a heat and moisture energy transfer model between air and spray droplet group is constructed, and the specific operations are as follows:

[0036] In order to facilitate the calculation and analysis, the heat and moisture transfer process between the unsaturated air and the droplet group in the gas-liquid two-phase flow heat exchange unit is reasonably simplified and a mathematical model is established. A microelement in the air flow direction is taken, and the following assumptions are made: ① The confined space is an isolated system, that is, the unsaturated air and the droplet group have no energy and mass exchange with the outside world, the heat loss of the air is equal to the heat gain of the droplet group, and the physical parameters are constants; ② On the vertical section along the air flow direction, the temperature of the unsaturated air and the temperature of the droplet group remain uniform; ③ The unsaturated air and the droplet group are in full contact, that is, the heat and mass transfer areas are equal; ④ The temperature of the saturated air layer on the droplet surface mainly depends on the temperature inside the droplet, and the heat transfer between the droplets is ignored; ⑤ In the air flow direction, the air mass flow rate and the droplet group mass flow rate remain uniform and unchanged.

[0037] On the basis of the above assumptions being valid, take air as the research object, the air flow rate as the unit mass flow rate, i.e. 1kg / s, the uniformly distributed droplet group and air in the microelement area dA d The air temperature changes to dT a , the moisture content changes to dω a , the sensible heat exchange capacity on the air side can be expressed as:

[0038] dQ x =G a c p,a dT a =α(T a -T d,b )dA d (8)

[0039] The moisture exchange capacity on the air side is:

[0040] dW=G a dω a =α m (ω a -ω d,b )dA d (9)

[0041] in:

[0042] dA d =A d / ZdZ (10)

[0043] Where Q x is the sensible heat exchange capacity, kJ / s; G a is the air mass flow rate, kg / s; c p,a is the specific heat capacity of air at constant pressure, kJ / (kg·℃); α is the heat transfer coefficient, kW / (m 2 ℃); T d,b is the saturated air layer temperature on the surface of the droplet group, ℃; W is the moisture exchange rate between air and droplet group, kg / s; ω a is the humidity content of air, kg / kg; α m is the mass transfer coefficient, kg / (m 2 ·s);ω d,b is the moisture content of the saturated air layer on the surface of the droplet group, kg / kg; A d is the total heat transfer area composed of the surface of the droplet group in the heat exchange device, m 2 ; Z is the total heat exchange length, m.

[0044] Combining equations (8), (9) and (10), we can obtain:

[0045]

[0046]

[0047] Among them, in step S5, the number of mass transfer units NTU is calculated m , the specific operations are as follows:

[0048] Due to the high humidity in the air, the latent heat transfer in the system is mainly due to the moisture exchange. In order to measure the moisture exchange capacity of the heat exchange device, the number of mass transfer units (NTU) is introduced. m With Lewis Number Le.

[0049] The number of mass transfer units, derived from the number of heat transfer units (NTU), is a parameter that reflects the ease of moisture transfer between cold and hot fluids. Therefore, the number of mass transfer units of heat transfer medium per unit mass flow rate is:

[0050] NTU m =α m A d (13)

[0051]

[0052] where Sc is the Schmidt number, a dimensionless measure of the relative effectiveness of diffusion-induced momentum and mass transport in velocity and concentration boundary layers; D m is the mass diffusion coefficient, m 2 / s.

[0053] Lewis number, which characterizes the relationship between heat exchange and moisture exchange during direct contact heat exchange between air and water:

[0054]

[0055] Substitute equations (7), (13), and (15) into equations (11) and (12):

[0056]

[0057]

[0058] In step S6, the total heat and moisture exchange capacity in the upper spray type spray heat exchange unit is calculated, and the specific operation is as follows:

[0059] According to the difference in air temperature and humidity before and after heat exchange, the total heat and moisture exchange in the system can be calculated:

[0060] Q=c p,a ΔT a +γΔω a (18)

[0061] Where c p,a is the specific heat capacity of air at constant pressure, kJ / (kg·℃); ΔT a is the air temperature difference before and after heat exchange, ℃; Δω a is the difference in air moisture content before and after heat exchange, kg / kg; γ is the latent heat of vaporization, kJ / kg.

[0062] Another object of the present invention is to provide a device for measuring the heat and moisture exchange capacity of an upward spray type spray heat exchange unit, comprising:

[0063] The migration flow model construction unit is used to construct the flow model of the entire migration process of the spray droplet group in the heat exchange unit;

[0064] A drag coefficient calculation unit, used to calculate the drag coefficient based on the force of the droplet group;

[0065] Distance and time calculation unit, used to calculate the maximum vertical migration distance and migration time of the spray droplet group;

[0066] Heat and moisture energy transfer model construction unit, used to construct the heat and moisture energy transfer model between air and spray droplet group;

[0067] Mass transfer unit number calculation unit, used to calculate the number of mass transfer units;

[0068] The heat and moisture exchange calculation unit is used to calculate the total heat and moisture exchange in the upward spray heat exchange unit based on the air temperature difference and moisture content difference before and after heat exchange.

[0069] In addition, the above-mentioned method for measuring the heat and moisture exchange capacity of the upward spraying heat exchange unit can also be applied in mine exhaust heat recovery.

[0070] The present invention includes the main influencing factors (including gravity, buoyancy and resistance) on the droplets during their movement in the flow model of the whole process of spray droplet group migration in the constructed heat exchange unit, introduces the dispersed phase fraction in the calculation of the resistance coefficient based on the droplet group force, constructs the heat and moisture energy transfer model between air and spray droplet group, and introduces the mass transfer unit number NTU m The Lewis number Le is used to measure the moisture exchange capacity of the heat exchange device. Finally, the total heat and moisture exchange capacity in the system is calculated based on the air temperature difference and moisture content difference before and after the heat exchange. This can more accurately determine the heat and moisture exchange capacity of the upward spray heat exchange unit, provide support and assistance for the efficient extraction and utilization of heat and moisture energy in mine exhaust, and meet the needs of guiding the efficient extraction and utilization of energy in the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 Schematic diagram of droplet migration process and force analysis;

[0072] Figure 2 Schematic diagram of the change of droplet migration speed;

[0073] Figure 3 Schematic diagram of the change in droplet migration distance;

[0074] Figure 4 Schematic diagram of the changes in air state and spray droplet state. DETAILED DESCRIPTION

[0075] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention.

[0076] The method for measuring the heat and moisture exchange capacity of an upward spray heat exchange unit comprises the following steps:

[0077] S1. Construct a flow model for the entire process of spray droplet migration in the heat exchange unit;

[0078] S2. Calculate the drag coefficient C based on the force of the droplet group d ;

[0079] S3. Calculate the maximum vertical migration distance and migration time of the spray droplet group;

[0080] S4. Construct a heat and moisture energy transfer model between air and spray droplet groups;

[0081] S5. Calculate the number of mass transfer units NTU m;

[0082] S6. Calculate the total heat and moisture exchange in the upward spray heat exchange unit.

[0083] The details are as follows.

[0084] (1) Construct a flow model for the entire process of spray droplet migration in the heat exchange unit. The specific operations are as follows:

[0085] Assuming that the droplets can be regarded as rigid spheres, the airflow velocity is the same at all locations on the same cross section, the cone angle of the atomizing nozzle is very small, and the droplets will move vertically after being ejected from the nozzle. Therefore, the main factors affecting the droplet group during movement include gravity, buoyancy, and resistance. Figure 1 As shown in the figure, the entire process of spray droplet migration includes: ① the rising phase, in which droplets are ejected vertically upward from the nozzle at an initial velocity of 16 m / s. The velocity gradually decreases due to wind resistance, and after the velocity drops to 0 m / s, the droplets fall; ② the falling phase, in which the falling droplets move in the same direction as the wind flow, and the falling velocity gradually increases until they fall into the collection tank. The collection tank is installed 3 m below the nozzle.

[0086] The gravitational force on the droplet is:

[0087]

[0088] Where, F g is the gravity acting on the droplet, N; ρ d is the droplet density, kg / m 3 ; g is the acceleration due to gravity, m / s 2 , take 9.8m / s 2 ; D is the droplet diameter, m, which is 500 μm.

[0089] The buoyancy force on the droplet is:

[0090]

[0091] Where, F b is the buoyancy of the droplet, N; ρ a is the air density, kg / m 3 .

[0092] The resistance force on the droplet is:

[0093]

[0094] Where R is the resistance of the droplet, N; u s is the relative velocity between the droplet and the wind flow, u s =u a -u d , m / s; u dis the droplet velocity, m / s; u a is the wind speed, m / s, and is -4m / s. The negative sign indicates that the wind speed is in the opposite direction to the initial velocity of the droplet. C d is the drag coefficient, dimensionless; A is the projected area of ​​the droplet, A=πD 2 / 4,m 2 .

[0095] Considering the direction of the droplet movement as positive, according to Newton's law of motion:

[0096]

[0097] Therefore, the flow model of the spray droplet group is:

[0098]

[0099] Where t is the migration time, s.

[0100] (2) Calculation of the drag coefficient C based on the force of the droplet group d , the specific operations are as follows:

[0101] In actual heat and moisture exchange equipment, in order to achieve sufficient water volume to maintain a good cooling effect, multiple groups of nozzles are often arranged, and there is a clear intersection between the jets of each group of nozzles. On the other hand, the individual droplets in the droplet group affect each other, and the wake and hydrodynamic interactions between the droplet balls affect the resistance they experience. Therefore, when the spatial distribution of the droplet group changes, the drag coefficient also changes. The drag coefficient is not only related to the Reynolds number, but also to the distribution of the droplet group in space. Therefore, the dispersed phase fraction is introduced into the calculation of the droplet resistance coefficient in two-phase flow under general working conditions. The dispersed phase fraction is the volume ratio of the droplet volume to the total space, which characterizes the density of the droplets in the light column space. The unit is PPM, that is, 10 -6 Affected by the liquid breakup mechanism, the smaller the characteristic droplet size, the larger the dispersed phase fraction. After introducing the dispersed phase fraction, the resistance coefficient can be expressed as:

[0102]

[0103] Where μ* is the dynamic viscosity ratio, μ*=μ d / μ a , dimensionless; μ d is the droplet dynamic viscosity, N·s / m 2 ;μ a is the air dynamic viscosity, N·s / m 2 ; ρ* is the density ratio, ρ*=ρ d / ρ a , dimensionless; ε is the dispersed phase fraction, 10 -6; P1, P2, P3, P4 are correlation coefficients, P1=4+6ε 5 / 3 , P2=6-6ε 5 / 3 , P3=4+6ε 1 / 3 +6ε 2 / 3 +ε, P4=4+3ε 1 / 3 -3ε 2 / 3 -4ε;Re c is the critical Reynolds number, Re c =33+8600ε 2 / 3 , dimensionless; ε is the dispersed phase fraction, 10 -6 , take 500×10 -6 .

[0104] Substituting equation (6) into equation (5), we can calculate the change in droplet migration velocity, as follows: Figure 2 As shown in the figure, during the rising phase, the velocity of the droplet group decays to 0 at 0.214s. After the droplet's rising velocity decays to 0, its motion direction changes to the same direction as the airflow and gradually increases until the droplets are subjected to balanced forces in the motion field and the acceleration is 0. The droplet group's velocity remains at around -6.212m / s, and it moves at a constant speed until the heat exchange is completed.

[0105] (3) Calculate the maximum vertical migration distance and migration time of the spray droplet group. The specific operation is as follows:

[0106]

[0107] Substituting Equation (7) into Equation (5) and performing iterative calculation, we can obtain the change in droplet migration distance, as follows: Figure 3 The vertical axis takes the nozzle installation position as point 0. The nozzle is installed 3 meters above the water collection tank. The total migration time of the droplet from the nozzle to the droplet falling into the water collection tank is 1.104s, and the maximum migration distance in the rising stage is 1.212m.

[0108] (4) Construct a heat and moisture energy transfer model between air and spray droplet groups. The specific operations are as follows:

[0109] In order to facilitate the calculation and analysis, the heat and moisture transfer process between the unsaturated air and the droplet group in the gas-liquid two-phase flow heat exchange unit is reasonably simplified and a mathematical model is established. A microelement in the air flow direction is taken, and the following assumptions are made: ① The confined space is an isolated system, that is, the unsaturated air and the droplet group have no energy and mass exchange with the outside world, the heat loss of the air is equal to the heat gain of the droplet group, and the physical parameters are constants; ② On the vertical section along the air flow direction, the temperature of the unsaturated air and the temperature of the droplet group remain uniform; ③ The unsaturated air and the droplet group are in full contact, that is, the heat and mass transfer areas are equal; ④ The temperature of the saturated air layer on the droplet surface mainly depends on the temperature inside the droplet, and the heat transfer between the droplets is ignored; ⑤ In the air flow direction, the air mass flow rate and the droplet group mass flow rate remain uniform and unchanged.

[0110] On the basis of the above assumptions being valid, take air as the research object, the air flow rate as the unit mass flow rate, i.e. 1kg / s, the uniformly distributed droplet group and air in the microelement area dA d The air temperature changes to dT a , the moisture content changes to dω a , the sensible heat exchange capacity on the air side can be expressed as:

[0111] dQ x =G a c p,a dT a =α(T a -T d,b )dA d (8)

[0112] The moisture exchange capacity on the air side is:

[0113] dW=G a dω a =α m (ω a -ω d,b )dA d (9)

[0114] in:

[0115] dA d =A d / ZdZ (10)

[0116] Where Q x is the sensible heat exchange capacity, kJ / s; G a is the air mass flow rate, kg / s, take 1kg / s; c p,a is the specific heat capacity of air at constant pressure, kJ / (kg·℃), which is taken as 1.0046kJ / (kg·℃); α is the heat transfer coefficient, kW / (m 2 ℃); Td,b is the saturated air layer temperature on the surface of the droplet group, ℃; W is the moisture exchange rate between the air and the droplet group, kg / s, taken as 1kg / s; ω a is the humidity content of air, kg / kg; α m is the mass transfer coefficient, kg / (m 2 ·s);ω d,b is the moisture content of the saturated air layer on the surface of the droplet group, kg / kg; A d is the total heat transfer area composed of the surface of the droplet group in the heat exchange device, m 2 ; Z is the total heat exchange length, m.

[0117] Combining equations (8), (9) and (10), we can obtain:

[0118]

[0119]

[0120] (5) Calculate the number of mass transfer units NTU m , the specific operations are as follows:

[0121] Due to the high humidity in the air, the latent heat transfer in the system is mainly due to the moisture exchange. In order to measure the moisture exchange capacity of the heat exchange device, the number of mass transfer units (NTU) is introduced. m With Lewis Number Le.

[0122] The number of mass transfer units, derived from the number of heat transfer units (NTU), is a parameter that reflects the ease of moisture transfer between cold and hot fluids. Therefore, the number of mass transfer units of heat transfer medium per unit mass flow rate is:

[0123] NTU m =α m A d (13)

[0124]

[0125] where Sc is the Schmidt number, a dimensionless measure of the relative effectiveness of diffusion-induced momentum and mass transport in velocity and concentration boundary layers; D m is the mass diffusion coefficient, m 2 / s.

[0126] Lewis number, which characterizes the relationship between heat exchange and moisture exchange during direct contact heat exchange between air and water:

[0127]

[0128] Substitute equations (7), (13), and (15) into equations (11) and (12):

[0129]

[0130]

[0131] Couple equations (16) and (17) with equation (5) and perform iterative calculations using numerical calculation software. The changes in the state of air and the state of spray droplets are as follows: Figure 4 As shown in the figure, high-humidity air at 25°C and 80% relative humidity directly contacts low-temperature spray water at 8°C for heat and moisture transfer. After the heat exchange is completed, the air temperature drops to 20.31°C, the moisture content decreases from 0.0159kg / kg to 0.0138kg / kg, and the spray water temperature rises by 2.38°C.

[0132] (6) Calculate the total heat and moisture exchange capacity in the upward spray heat exchange unit. The specific operation is as follows:

[0133] According to the air temperature of 20.31℃ and the moisture content of 0.0138kg / kg after heat exchange, the total heat and moisture exchange in the system can be calculated as:

[0134] Q=1.0046×(25-20.31)+2500×(0.0159-0.0138)

[0135] Q=9.96kJ / kg

[0136] This embodiment practically proposes a method for calculating the heat and moisture energy of an upward spray heat exchange unit (i.e., a method for measuring the heat and moisture exchange capacity of an upward spray heat exchange unit), which is of great significance for the efficient extraction and utilization of heat and moisture energy of mine exhaust.

[0137] In addition, this embodiment also provides a device for measuring the heat and moisture exchange capacity of an upward spray type spray heat exchange unit, which includes:

[0138] The migration flow model construction unit is used to construct the flow model of the entire migration process of the spray droplet group in the heat exchange unit;

[0139] A drag coefficient calculation unit, used to calculate the drag coefficient based on the force of the droplet group;

[0140] Distance and time calculation unit, used to calculate the maximum vertical migration distance and migration time of the spray droplet group;

[0141] Heat and moisture energy transfer model construction unit, used to construct the heat and moisture energy transfer model between air and spray droplet group;

[0142] Mass transfer unit number calculation unit, used to calculate the number of mass transfer units;

[0143] The heat and moisture exchange calculation unit is used to calculate the total heat and moisture exchange in the upward spray heat exchange unit.

[0144] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has disclosed the preferred embodiments as above, it is not intended to limit the product form and style of the present invention. Any technician familiar with this profession can make some changes or modifications to the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, all contents that do not depart from the technical solution of the present invention still fall within the patent scope of the technical solution of the present invention.

Claims

1. A method for determining the heat and moisture exchange capacity of an upward spray heat exchange unit, characterized in that: The steps include: S1. Construct a flow model for the entire process of spray droplet migration in the heat exchange unit; S2. Calculate the drag coefficient based on the force of the droplet group; S3. Calculate the maximum vertical migration distance and migration time of the spray droplet group; S4. Construct a heat and moisture energy transfer model between air and spray droplet groups: Where, T a is the air temperature, ℃; T d,b is the saturated air layer temperature on the droplet surface, °C; ω a is the humidity content of air, kg / kg; ω d,b is the moisture content of the saturated air layer on the droplet surface, kg / kg; Z is the total heat exchange length, m; NTU m is the number of mass transfer units, dimensionless; Le is the Lewis number, dimensionless; S5. Calculate the number of mass transfer units; S6. Calculate the total heat and moisture exchange in the upward spray heat exchange unit.

2. The method for measuring the heat and moisture exchange capacity of the upward spray heat exchange unit according to claim 1, characterized in that: In step S1, the entire process of the migration of the spray droplet group in the heat exchange unit includes: ① In the rising stage, the droplet moves at u d0 The liquid is ejected vertically upward from the nozzle at a speed of 1000 m / s. The speed gradually decreases due to the wind resistance. When the speed drops to 0 m / s, the droplets fall. ② In the falling section, the falling droplets move in the same direction as the wind flow, and the falling speed gradually increases until they fall into the collection pool; The constructed flow model of the entire process of spray droplet migration in the heat exchange unit is: Where u d is the droplet velocity, m / s; t is the migration time, s; g is the gravitational acceleration, m / s 2 ; D is the droplet diameter, m; ρ d is the droplet density, kg / m 3 ρ a is the air density, kg / m 3 ;u s is the relative velocity between the droplet and the wind flow, u s =u a -u d , m / s; u a is the wind speed, m / s; C d is the drag coefficient, dimensionless; A is the projected area of ​​the droplet, A=πD 2 / 4,m 2 .

3. The method for measuring the heat and moisture exchange capacity of the upward spray heat exchange unit according to claim 1, characterized in that: In step S2, the resistance coefficient C based on the force of the droplet group d for: Where μ* is the dynamic viscosity ratio, μ*=μ d / μ a , dimensionless; μ d is the droplet dynamic viscosity, N·s / m 2 ;μ a is the air dynamic viscosity, N·s / m 2 ; ε is the dispersed phase fraction, 10 -6 ; P1, P2, P3, P4 are correlation coefficients, P1=4+6ε 5 / 3 , P2=6-6ε 5 / 3 , P3=4+6ε 1 / 3 +6ε 2 / 3 +ε, P4=4+3ε 1 / 3 -3ε 2 / 3 -4ε; Re is the relative Reynolds number of the two-phase flow, Re=ρ a |u s |D / μ a ;Re c is the critical Reynolds number, Re c =33+8600ε 2 / 3 , dimensionless.

4. The method for measuring the heat and moisture exchange capacity of the upward spray heat exchange unit according to claim 1, characterized in that: In step S6, the total heat and moisture exchange capacity Q in the upper spray type spray heat exchange unit is calculated as follows: Q=c p,a ΔT a +gDọ a Where c p,a is the specific heat capacity of air at constant pressure, kJ / (kg·℃); ΔT a is the air temperature difference before and after heat exchange, ℃; Δω a is the difference in air moisture content before and after heat exchange, kg / kg; γ is the latent heat of vaporization, kJ / kg.

5. A device for measuring the heat and moisture exchange capacity of an upward spray heat exchange unit, characterized in that: include: The migration flow model construction unit is used to construct the flow model of the entire migration process of the spray droplet group in the heat exchange unit; A drag coefficient calculation unit, used to calculate the drag coefficient based on the force of the droplet group; Distance and time calculation unit, used to calculate the maximum vertical migration distance and migration time of the spray droplet group; Heat and moisture energy transfer model construction unit, used to build the heat and moisture energy transfer model between air and spray droplet group: Where, T a is the air temperature, ℃; T d,b is the saturated air layer temperature on the droplet surface, °C; ω a is the humidity content of air, kg / kg; ω d,b is the moisture content of the saturated air layer on the droplet surface, kg / kg; Z is the total heat exchange length, m; NTU m is the number of mass transfer units, dimensionless; Le is the Lewis number, dimensionless; Mass transfer unit number calculation unit, used to calculate the number of mass transfer units; The heat and moisture exchange calculation unit is used to calculate the total heat and moisture exchange in the upward spray heat exchange unit.

6. Application of the method for measuring the heat and moisture exchange capacity of the upward spray heat exchange unit according to any one of claims 1 to 4 in mine exhaust heat recovery.

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