CN110639367B - Method and device for measuring permeation quantity of non-contact hollow fiber membrane - Google Patents
Method and device for measuring permeation quantity of non-contact hollow fiber membrane Download PDFInfo
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- CN110639367B CN110639367B CN201911025120.6A CN201911025120A CN110639367B CN 110639367 B CN110639367 B CN 110639367B CN 201911025120 A CN201911025120 A CN 201911025120A CN 110639367 B CN110639367 B CN 110639367B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/10—Testing of membranes or membrane apparatus; Detecting or repairing leaks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/364—Membrane distillation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
- B01D63/02—Hollow fibre modules
Abstract
The invention relates to a method for measuring the permeation quantity of a non-contact hollow fiber membrane, which comprises the following steps that a fan is turned off, hot water is added into a first container, after the temperature of the hollow fiber membrane is stable, a second container is emptied and timing is started, after a time period delta t passes, the hot water in the second container is measured, and the quality parameter of the windless permeation hot water is obtained; starting a fan, and measuring the hollow fiber membrane after the temperature of the hollow fiber membrane is stable to obtain the temperature parameter of the hollow fiber membrane; the total heat loss Q and the convection heat transfer Q of the hot water in the process of starting the fan measurement are obtained by utilizing the windless osmotic hot water quality parameter and the temperature parameter of the hollow fiber membrane For a pair of The method comprises the steps of carrying out a first treatment on the surface of the By Q Diving device ＝Q‑Q For a pair of Andthe permeation quantity W' of the hollow fiber membrane was obtained. The method can measure the permeation quantity of a single hollow fiber membrane, and can better explore the amplification effect of the hollow fiber membrane contactor in the air-swept membrane distillation process. The invention also relates to a device for measuring the permeation quantity of the non-contact hollow fiber membrane.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a method and a device for measuring the permeation quantity of a non-contact hollow fiber membrane.
Background
Membrane distillation has received increasing attention due to its potential commercial value. The permeate is the water production per unit area of membrane per unit time. In studying membrane distillation, permeate is a critical parameter that must be measured, often requiring the permeate to be measured for different membranes under different standards and conditions.
In the prior art, the method for measuring the permeation quantity of the hollow fiber membrane comprises the steps of firstly manufacturing a membrane assembly consisting of hundreds of thousands of hollow fiber membranes, wherein one end of the membrane assembly is communicated with a first container, the other end of the membrane assembly is communicated with a second container, and the membrane assembly is horizontally arranged. The second container is first emptied and then hot water is filled in the first container, and the hot water in the first container enters the second container after penetrating through the membrane assembly.
According to the method, temperature sensors are arranged on a first container and a second container to measure the temperature, a flowmeter and a humidity meter are used to measure parameters such as air flow and relative humidity around a membrane module respectively, and finally the measured parameters are calculated through a mass transfer formula to obtain the permeation quantity of the membrane module.
The prior art has the following technical problems:
1. the membrane component consisting of hundreds of thousands of hollow fiber membranes needs to be manufactured, and the preparation process is complicated;
2. the method can only measure the hollow fiber membrane bundles consisting of a plurality of measurement hollow fiber membranes, can not accurately measure the permeation quantity of a single hollow fiber membrane, can not well explore the amplification effect of the hollow fiber membrane contactor in the air-swept membrane distillation process, and can not directly compare different experimental results.
Disclosure of Invention
Aiming at the technical problems existing in the prior art, one of the purposes of the invention is as follows: the method for measuring the permeation quantity of the non-contact hollow fiber membrane is capable of measuring the permeation quantity of a single hollow fiber membrane, does not need to manufacture a complex membrane assembly, is simple in preparation process, can better explore the amplification effect of the hollow fiber membrane contactor in the air-sweeping type membrane distillation process, and can directly compare different experimental results.
Aiming at the technical problems in the prior art, the second purpose of the invention is as follows: the device can measure the permeation quantity of a single hollow fiber membrane, does not need to manufacture a complex membrane component, has simple preparation process, can better explore the amplification effect of the hollow fiber membrane contactor in the air-sweeping type membrane distillation process, and can directly compare different experimental results.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for measuring the permeation quantity of non-contact hollow fiber membrane includes such steps as,
the distance between the first container and the second container is regulated to enable the hollow fiber membrane to be in a horizontal straightening state, and the middle part of the hollow fiber membrane is opposite to the fan;
turning off the fan, adding hot water into the first container, and starting the hot water to permeate from the first container into the second container; after the temperature of the hollow fiber membrane is stable, emptying the second container and starting timing, and measuring hot water in the second container after a time period delta t to obtain a windless osmotic hot water quality parameter;
starting a fan, and measuring the hollow fiber membrane after the temperature of the hollow fiber membrane is stable to obtain the temperature parameter of the hollow fiber membrane;
the total heat loss Q and the convection heat transfer Q of the hot water in the process of starting the fan measurement are obtained by utilizing the windless osmotic hot water quality parameter and the temperature parameter of the hollow fiber membrane For a pair of ；
By Q Diving device ＝Q-Q For a pair of Obtaining the latent heat Q Diving device ；
By means ofThe permeation quantity W' of the hollow fiber membrane was obtained, wherein H is the enthalpy change of changing water into water vapor per unit mass.
Further, the airless penetrating hot water quality parameter includes the hot water quality m in the second container 1 The obtaining steps are as follows,
closing a fan, adding hot water into the first container, emptying the second container after the temperature of the hollow fiber membrane is stable, starting timing, and weighing the hot water mass in the second container after the time period delta t passes to obtain the hot water mass m in the second container 1 。
Further, the temperature parameters of the hollow fiber membrane include the inlet water temperature T fin2 Outlet water temperature T fout2 Inlet wall temperature T min2 And outlet wall temperature T mout2 The obtaining steps are as follows,
starting a fan, and measuring the contact position of the outer wall of the hollow fiber membrane and the first container to obtain the inlet water temperature T after the temperature of the hollow fiber membrane is stable fin2 Measuring the contact position of the outer wall of the hollow fiber membrane and the second container to obtain the outlet water temperature T fout2 Measuring the front end of the outer wall of the hollow fiber membrane to obtain the inlet wall temperature T of the hollow fiber membrane min2 Measuring the tail part of the outer wall of the hollow fiber membrane to obtain the outlet wall temperature T mout2 。
Further, the total heat loss Q of the hot water during the start-up fan measurement is obtained as follows,
by m 1 ’＝m 1 Obtaining the windless mass flow rate m by delta t 1 ’；
Setting the qualitative temperature of the hot water asChecking the specific heat capacity C of the current hot water by the qualitative temperature;
with q=cm 1 ’(T fin2 -T fout2 ) The total heat loss Q is determined.
Further, the convection heat transfer quantity Q during the start-up fan measurement For a pair of The steps of the obtaining of (a) are as follows,
measuring the current ambient temperature t 1 From the current ambient temperature t 1 Checking the density ρ of the current air p Viscosity mu p Planck number Pr p The method comprises the steps of carrying out a first treatment on the surface of the Setting the qualitative temperature of the hot water asFrom the qualitative temperature, the density ρ of the current hot water is checked f Viscosity mu f ；
By Re p ＝DU p ρ p /μ p Obtaining Reynolds number Re of air around hollow fiber membrane p Wherein D is the outer diameter of the hollow fiber membrane, U p Is the wind speed of the fan;
by means ofObtaining the Nu number of the air around the hollow fiber membrane p ；
By means ofObtaining the convection heat transfer coefficient h of the air around the hollow fiber membrane p Wherein lambda is p The heat conductivity coefficient of the air around the hollow fiber membrane;
by means ofObtaining A, wherein A is the cross-sectional area of the hollow fiber membrane, and d is the inner diameter of the hollow fiber membrane;
by means ofObtaining the flow velocity u of hot water in the hollow fiber membrane f ；
By means ofObtaining Reynolds number Re of hot water in hollow fiber membrane f ；
By means ofObtaining the Nu number of the hot water in the hollow fiber membrane f Wherein Pr is f The Planck number of the hot water is the length of the hollow fiber membrane;
by means ofObtaining the convection heat transfer coefficient h of hot water in the hollow fiber membrane f Wherein lambda is f Is the heat conductivity coefficient of the hot water in the hollow fiber membrane;
by means ofObtaining the convection heat transfer coefficient h of the hollow fiber membrane m Wherein lambda is m Is the heat conductivity coefficient delta of the hollow fiber membrane m The thickness of the hollow fiber membrane is;
by means ofObtaining a total convection heat transfer coefficient h;
by means ofObtaining a logarithmic average temperature difference delta T;
by Q For a pair of =haΔT to obtain the convective heat transfer quantity Q For a pair of 。
Further, adjusting the distance between the first container and the second container includes the steps of detachably connecting the movable end of the stretching machine to the first container, detachably connecting the fixed end of the stretching machine to the second container, and moving the movable end of the stretching machine in a direction away from the fixed end to straighten the hollow fiber membrane.
The device comprises a first container, a hollow fiber membrane, a second container, a distance adjusting device, a fan, an infrared thermometer and a weighing device, wherein the first container is communicated with one end of the hollow fiber membrane, the other end of the hollow fiber membrane is communicated with the second container, the distance between the first container and the second container is adjusted by the distance adjusting device, and the hollow fiber membrane is horizontally arranged; the fan is located hollow fiber membrane one side and towards hollow fiber membrane middle part, and infrared thermoscope corresponds the setting with hollow fiber membrane, and weighing device is arranged in weighing from the hot water quality of first container infiltration to the second container.
Further, the distance adjusting device comprises a pulling machine, the pulling machine is provided with a movable end and a fixed end, the movable end is detachably connected to the first container, and the fixed end is detachably connected to the second container.
Further, when the moving end of the pulling machine stops moving, the reading of the pulling machine is 0.2-0.4N.
Further, the air passage of the fan toward the hollow fiber membranes is perpendicular to the extending direction of the hollow fiber membranes.
In general, the invention has the following advantages:
the prior art hollow fiber membrane permeation quantity measuring method and device need to manufacture complex membrane components in advance, the preparation process is complex, a thermometer and a hygrometer need to be used for measuring the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane components in the measuring process, a plurality of measuring devices need to be prepared, and the steps are complex. If the component only comprises a single hollow fiber membrane, the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane is not obvious enough, so that the final measurement accuracy is not high, therefore, the measurement method in the prior art cannot accurately measure the permeation quantity of the single hollow fiber membrane, cannot well explore the amplification effect of the hollow fiber membrane contactor in the air sweeping type membrane distillation process, and cannot directly compare different experimental results. According to the invention, a complex membrane component is not required to be manufactured, the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane component is not required to be measured, a hygrometer is not required to be used, the preparation process and the measurement process are simple, the windless osmotic hot water quality parameter and the temperature parameter of the hollow fiber membrane are only required to be respectively measured under the conditions of closing the fan and starting the fan, the osmotic quantity of the hollow fiber membrane can be obtained by calculating through a formula based on the principle of conservation of heat by utilizing the parameters, the osmotic quantity of a single hollow fiber membrane or a small quantity of hollow fiber membranes can be measured, and the amplification effect of the hollow fiber membrane contactor in the air-swept membrane distillation process can be better explored.
Drawings
Fig. 1 is a schematic perspective view of an embodiment of the present invention.
Fig. 2 is a schematic view of the air inlet side and the air outlet side of the hollow fiber membrane side.
Fig. 3 is a schematic representation of energy transfer across a hollow fiber membrane.
FIG. 4 is a schematic diagram showing the temperature definition of the test method according to the embodiment of the invention.
Reference numerals illustrate:
1-a pulling machine, 11-a first support, 12-a first vice, 13-a second support, 14-a second vice; 2—a first container; 3-a second container; 4-hollow fiber membranes; 5-a water storage cup; 6, a fan; 7-infrared thermometer.
Detailed Description
The present invention will be described in further detail below.
As shown in fig. 1, a method for measuring the permeation quantity of a non-contact hollow fiber membrane comprises the following steps,
the distance between the first container 2 and the second container 3 is regulated to enable the hollow fiber membrane 4 to be in a horizontal straightening state, and the middle part of the hollow fiber membrane 4 is opposite to the fan 6;
the fan 6 is turned off, hot water is added to the first container 2, and the hot water starts to permeate from the first container 2 into the second container 3; after the temperature of the hollow fiber membrane 4 is stable, emptying the second container 3 and starting timing, and measuring hot water in the second container 3 after the time period delta t passes to obtain the quality parameter of the windless osmotic hot water;
starting a fan 6, and measuring the hollow fiber membrane 4 after the temperature of the hollow fiber membrane 4 is stable to obtain the temperature parameter of the hollow fiber membrane 4;
by using the quality parameters of the windless osmotic hot water and the temperature parameters of the hollow fiber membrane 4, the total heat loss Q and the convection heat transfer Q of the hot water in the process of starting the fan 6 for measurement are obtained For a pair of ；
By Q Diving device ＝Q-Q For a pair of Obtaining the latent heat Q Diving device ；
By means ofThe permeation quantity W' of the hollow fiber membrane 4 was obtained, where H is the enthalpy change from water to steam per unit mass.
Specifically, the first container 2 is connected to one end of the hollow fiber membrane 4, the other end of the hollow fiber membrane 4 is connected to the second container 3, and the distance between the first container 2 and the second container 3 can be adjusted. By adjusting the distance between the first vessel 2 and the second vessel 3, the first vessel 2 and the second vessel 3 straighten the hollow fiber membranes 4 and put the hollow fiber membranes 4 in a horizontal state. The contact parts of the outer walls of the two ends of the hollow fiber membrane 4 with the first container 2 and the second container 3 are sealed by epoxy resin, so that hot water passes through the inner cavity of the hollow fiber membrane 4 and only contacts with the inner surface of the hollow fiber membrane 4.
Before measurement, the fan 6 was turned off, hot water was added to the first vessel 2, and the temperature of the outer wall of the hollow fiber membrane 4 was gradually increased. When the temperature of the outer wall of the hollow fiber membrane 4 reaches a set value, the second vessel 3 is emptied and the time is started, and measurement is started after the lapse of the time period Δt. Measuring the hot water in the second container 3 results in a windless permeated hot water quality parameter permeated from the first container 2 into the second container 3. The time period deltat is recorded so that the same time period is used when measuring the quality parameter of the hot water of the wind penetration during the verification process, so that the measurements have the same time basis.
And starting the fan 6, gradually reducing the temperature of the outer wall of the hollow fiber membrane 4, and measuring the hollow fiber membrane 4 to obtain the temperature parameter of the hollow fiber membrane 4 after the temperature of the outer wall of the hollow fiber membrane 4 is stable. The fan 6 is used for providing the incoming wind at the side of the hollow fiber membrane 4 and taking away the evaporation amount of the hollow fiber membrane 4 in time. As shown in fig. 2, the side of the arrow directed to the hollow fiber membranes 4 is the position of the fan 6, i.e., the side of the hollow fiber membranes 4 that is the air inlet side, and the side of the arrow away from the hollow fiber membranes 4 is the air outlet side. Wherein W is fin 、T fin Indicating the flow and temperature of the hot water inlet; w (W) fout 、T fout Indicating the flow and temperature of the hot water outlet.
The infiltration amount of the hollow fiber membrane 4 can be obtained by formula conversion by using the airless infiltration hot water quality parameter and the temperature parameter of the hollow fiber membrane 4.
In the prior art, the permeation quantity measuring device needs to manufacture a complex membrane assembly in advance, the preparation process is complex, a thermometer and a hygrometer are needed to be used for measuring the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 assembly in the measuring method, a plurality of measuring devices need to be prepared, and the steps are complex. If the membrane module only comprises a single hollow fiber membrane 4, the final measurement accuracy is not high because the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 is not obvious enough, so that the measurement method in the prior art cannot accurately measure the permeation quantity of the single hollow fiber membrane 4, and the amplification effect of the hollow fiber membrane 4 contactor in the air-swept membrane distillation process cannot be well explored. According to the invention, a complex membrane assembly is not required to be manufactured, the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 assembly is not required to be measured, a hygrometer is not required to be used, the preparation process and the measurement process are simple, the windless osmotic hot water quality parameter and the temperature parameter of the hollow fiber membrane 4 are only required to be respectively measured under the conditions of closing the fan 6 and starting the fan 6, the osmotic quantity of the hollow fiber membrane 4 can be obtained by calculating through a formula based on the principle of conservation of heat by using the parameters, the osmotic quantity of a single hollow fiber membrane 4 or a small quantity of hollow fiber membranes 4 can be measured, and the amplification effect of a hollow fiber membrane 4 contactor in the air-swept membrane distillation process can be better explored.
Windless penetrating hot waterThe quality parameter comprises the quality m of the hot water in the second container 3 1 The obtaining steps are as follows,
the fan 6 is turned off, hot water is added to the first container 2, and the membrane wall temperature of the hollow fiber membranes 4 is gradually increased. When the temperature of the outer wall of the hollow fiber membrane 4 reaches the set value, the second container 3 is emptied and the timing is started, and after the time period deltat elapses, the hot water in the second container 3 is weighed to obtain the hot water mass m in the second container 3 1 . In this embodiment, the hot water in the second container 3 is poured out and weighed by a balance.
The temperature parameters of the hollow fiber membranes 4 include the inlet water temperature T fin2 Outlet water temperature T fout2 Inlet wall temperature T min2 And outlet wall temperature T mout2 The obtaining steps are as follows,
starting a fan 6, gradually reducing the temperature of the outer wall of the hollow fiber membrane 4, and measuring the contact position of the outer wall of the hollow fiber membrane 4 and the first container 2 to obtain the inlet water temperature T after the temperature of the outer wall of the hollow fiber membrane 4 is stable fin2 Measuring the contact position of the outer wall of the hollow fiber membrane 4 and the second container 3 to obtain the outlet water temperature T fout2 Measuring the front end of the outer wall of the hollow fiber membrane 4 to obtain the inlet wall temperature T of the hollow fiber membrane 4 min2 Measuring the tail part of the outer wall of the hollow fiber membrane 4 to obtain the outlet wall temperature T mout2 。
The reference temperature of many researches in the prior art is not defined clearly, and some of the reference temperatures are measured by inserting a thermometer or a temperature sensor into the first container 2 and the second container 3, the temperature is measured by only measuring the hot water temperature at a certain point in the first container 2 or the second container 3, the hot water temperature at the certain point is taken as the whole hot water temperature in the first container 2 or the second container 3, the whole hot water temperature is taken as the temperature of hot water entering the hollow fiber membrane 4 or the temperature of hot water flowing out of the hollow fiber membrane 4, and in fact, the hot water temperature at the certain point and the temperature of the hot water entering and exiting the hollow fiber membrane 4 have certain difference, so that a relatively large error exists in the final measurement result; meanwhile, the first container 2 and the second container 3 need to be accessed for measurement, interference to the measurement process is easy to occur, and the measurement accuracy is affected.
The present inventors have uniquely found that, because the membrane walls of the hollow fiber membranes 4 are very thin, after a certain time of hot water entering the hollow fiber membranes 4, the temperature at which the outer wall of the hollow fiber membranes 4 contacts the first vessel 2 and the temperature at which the hot water enters the inlet of the hollow fiber membranes 4 are approximately equal; the temperature at the contact position of the outer wall of the hollow fiber membrane 4 and the second container 3 is approximately equal to the temperature at the outlet of the hot water flowing out of the hollow fiber membrane 4, so that the temperature at the contact position of the outer wall of the hollow fiber membrane 4 and the first container 2 is taken as the inlet water temperature, the temperature at the contact position of the outer wall of the hollow fiber membrane 4 and the second container 3 is taken as the outlet water temperature, the temperature is more accurate than the reference temperature in the prior art, the measurement error is smaller, the infrared thermometer 7 can be used for measuring the temperature of the outer wall of the hollow fiber membrane 4, the contact or the measurement of the hot water flowing into the first container 2 and the second container 3 is not needed, the interference to the measurement process is avoided, and more accurate measurement results are facilitated.
The front end part of the outer wall of the hollow fiber membrane 4 refers to the part of the outer wall of the hollow fiber membrane 4 close to the first container 2; the tail part of the outer wall of the hollow fiber membrane 4 refers to the part of the outer wall of the hollow fiber membrane 4 close to the second container 3. In this embodiment, as shown in FIG. 4, the inlet water temperature T fin Outlet water temperature T represented by the surface temperature at the contact of the outer wall of the hollow fiber membrane 4 with the first vessel 2 fout Represented by the surface temperature at which the outer wall of the hollow fiber membrane 4 contacts the second vessel 3.
The inlet wall temperature measuring point is located at the outer wall of the hollow fiber membrane 4 10mm from the rear of the first vessel 2, and the outlet wall temperature measuring point is located at the outer wall of the hollow fiber membrane 4 10mm from the front of the second vessel 3.
The invention does not need to measure the temperature and humidity of the air at the two sides of the hollow fiber membrane 4, the main data of the measurement is the water temperature entering and exiting the hollow fiber membrane 4 and calculates the difference value, and the difference value is caused by the heat loss of the hot water. The heat loss of the hot water includes convective heat transfer within the hollow fiber membranes 4, heat conduction of the hollow fiber membranes 4, evaporation of the hot water and radiation of the hollow fiber membranes 4, and convective heat transfer of the sides of the hollow fiber membranes 4. The radiative heat transfer is negligible due to the lower temperature of the hollow fiber membranes 4. As shown in FIG. 3, the heat loss at the inlet and outlet of the hollow fiber membrane 4 is mainly due to the vapor evaporation ΔQ COV And the air convection of the outer surface of the hollow fiber membrane 4 takes away heat DeltaQ Lat As a result, heat loss due to the latent heat of vaporization can be obtained by the heat conservation calculation, thereby calculating the permeation quantity.
The total heat loss Q of the hot water during the measurement of the start-up of the fan 6 is obtained as follows,
by m 1 ’＝m 1 Obtaining the windless mass flow rate m by delta t 1 ’；
Setting the qualitative temperature of the hot water asChecking the specific heat capacity C of the current hot water by the qualitative temperature;
with q=cm 1 ’(T fin2 -T fout2 ) The total heat loss Q is determined.
The convection heat transfer quantity Q during the measurement of the start-up fan 6 For a pair of The steps of the obtaining of (a) are as follows,
measuring the current ambient temperature t 1 From the current ambient temperature t 1 Checking the density ρ of the current air p Viscosity mu p Planck number Pr p The method comprises the steps of carrying out a first treatment on the surface of the Setting the qualitative temperature of the hot water asFrom the qualitative temperature, the density ρ of the current hot water is checked f Viscosity mu f ；
By Re p ＝DU p ρ p /μ p Obtaining Reynolds number Re of air around hollow fiber membrane 4 p Wherein D is the outer diameter of the hollow fiber membrane 4, U p Wind speed for the fan 6;
by means ofObtaining the Nu number of the air around the hollow fiber membrane 4 p ；
By means ofObtaining the convection heat transfer coefficient h of the air around the hollow fiber membrane 4 p Wherein lambda is p Is hollow fiberThe thermal conductivity of the air surrounding the vitamin membrane 4;
by means ofObtaining A, wherein A is the cross-sectional area of the hollow fiber membrane 4, and d is the inner diameter of the hollow fiber membrane 4;
by means ofObtaining the flow velocity u of hot water in the hollow fiber membrane 4 f ；
By means ofDetermination of Reynolds number Re of Hot Water in hollow fiber Membrane 4 f ；
By means ofObtaining the Nu number of the hot water in the hollow fiber membrane 4 f Wherein Pr is f The planckian number of the hot water, i is the length of the hollow fiber membrane 4;
by means ofObtaining the convection heat transfer coefficient h of the hot water in the hollow fiber membrane 4 f Wherein lambda is f Is the thermal conductivity coefficient of the hot water in the hollow fiber membrane 4;
by means ofObtaining the convective heat transfer coefficient h of the hollow fiber membrane 4 m Wherein lambda is m Is the heat conductivity coefficient delta of the hollow fiber membrane 4 m The thickness of the hollow fiber membrane 4 is;
by means ofObtaining a total convection heat transfer coefficient h;
by means ofObtaining a logarithmic average temperature difference delta T;
by Q For a pair of =haΔT to obtain the convective heat transfer quantity Q For a pair of 。
Adjusting the distance between the first container 2 and the second container 3 comprises the following steps that the movable end of the tension machine 1 is detachably connected with the first container 2, the fixed end of the tension machine 1 is detachably connected with the second container 3, and the movable end of the tension machine 1 moves away from the fixed end to straighten the hollow fiber membrane 4.
The permeation amount of the hollow fiber membranes 4 may be affected by the degree of tension of the hollow fiber membranes 4. When the hollow fiber membranes 4 are not straightened, the oscillation of the hollow fiber membranes 4 increases the flow resistance of the liquid in the hollow fiber membranes 4 and the air at the sides of the hollow fiber membranes 4, resulting in a smaller measured permeation quantity, and a relatively accurate permeation quantity cannot be obtained. If applied to actual production, the permeation quantity of the hollow fiber membrane 4 component is reduced, and the distillation efficiency is affected.
The tension machine 1 is provided with a fixed end and a movable end. The hollow fiber membrane 4 is straightened and not stretched by the fixed end and the movable end of the tension machine 1, the tension of the hollow fiber membrane 4 can be accurately controlled, the length of the hollow fiber membrane 4 can be kept to be a fixed value, the hollow fiber membrane 4 is in a straightened and not stretched state, accurate measurement results are favorably obtained, the tensioning state of the hollow fiber membrane 4 under different tests is ensured to be equivalent, and different experimental results can be directly compared.
The measuring method can verify the accuracy by a mass conservation method. Mass conservation method, i.e. measuring the windless mass flow rate m of the second container 3 when the fan 6 is turned off, respectively 1 ' and the windy mass flow rate m of the second container 3 when the fan 6 is turned on 2 ’，m 1 ' subtracting m 2 The "obtained difference value" is the permeation quantity of the hollow fiber membrane 4.
Wherein there is a wind mass flow rate m 2 The' acquisition step is as follows,
starting the fan 6, gradually reducing the temperature of the outer wall of the hollow fiber membrane 4, emptying the second container 3 after the temperature of the outer wall of the hollow fiber membrane 4 is stable, starting timing, and after the time period delta t passesMeasuring the hot water in the second container 3 to obtain the quality parameter m of the hot water permeated by the wind 2 . In this embodiment, the hot water in the second container 3 is poured out and weighed by a balance.
By m 2 ’＝m 2 Obtaining the windy mass flow rate m by delta t 2 ’。
Experiments show that the difference between the permeation quantity of the hollow fiber membrane 4 obtained by the measuring method of the invention and the permeation quantity measured based on mass conservation is within the allowable range of error.
The device for measuring the permeation quantity of the non-contact type hollow fiber membrane comprises a first container 2, a hollow fiber membrane 4, a second container 3, a distance adjusting device, a fan 6, an infrared thermometer 7 and a weighing device, wherein the first container 2 is communicated with one end of the hollow fiber membrane 4, the other end of the hollow fiber membrane 4 is communicated with the second container 3, the distance between the first container 2 and the second container 3 is adjusted by the distance adjusting device, and the hollow fiber membrane 4 is horizontally arranged; the fan 6 is located hollow fiber membrane 4 one side and towards hollow fiber membrane 4 middle part, and infrared thermoscope 7 corresponds the hollow fiber membrane 4 setting, and weighing device is used for weighing from the hot water quality of first container 2 infiltration to in the second container 3.
Specifically, the fan 6 is turned off, hot water is added to the first container 2, and the membrane wall temperature of the hollow fiber membranes 4 gradually increases. When the temperature of the outer wall of the hollow fiber membrane 4 reaches a set value, the second container 3 is emptied, timing is started, and the quality of the hot water in the second container 3 is weighed by a weighing device after a time period deltat, so that the airless osmotic hot water quality parameter which permeates into the second container 3 from the first container 2 is obtained. And starting the fan 6, gradually reducing the temperature of the outer wall of the hollow fiber membrane 4, and after the temperature of the outer wall of the hollow fiber membrane 4 is stable, measuring the temperature of the hollow fiber membrane 4 to obtain the temperature parameter of the hollow fiber membrane 4. The infiltration amount of the hollow fiber membrane 4 can be obtained by formula conversion by using the airless infiltration hot water quality parameter and the temperature parameter of the hollow fiber membrane 4. In this embodiment, the weighing device is a balance.
The prior art permeation quantity measuring device comprises a membrane component with complex manufacturing process, the preparation process is complex, a thermometer and a hygrometer are needed to be used for measuring the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 component in the measuring process, the number of measuring devices is needed to be prepared, and the steps are complex. If the assembly only comprises a single hollow fiber membrane 4, the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 is not obvious enough, so that the final measurement accuracy is not high, therefore, the measuring device in the prior art cannot accurately measure the permeation quantity of the single hollow fiber membrane 4, cannot well explore the amplification effect of the hollow fiber membrane 4 contactor in the air-swept membrane distillation process, and cannot directly compare different experimental results.
The device does not need to manufacture a complex membrane assembly, does not need to measure the temperature and humidity difference value of air passing through two sides of the hollow fiber membrane 4 assembly, does not need to use a hygrometer, has simple preparation process and measurement process, can obtain the permeation quantity of the hollow fiber membrane 4 by calculation according to a formula based on the principle of conservation of heat only by measuring a small quantity of parameters under the conditions of closing the fan 6 and starting the fan 6, can measure the permeation quantity of a single hollow fiber membrane 4 or a small quantity of hollow fiber membranes 4, and can better explore the amplification effect of the hollow fiber membrane 4 contactor in the air-swept membrane distillation process.
The permeation amount of the hollow fiber membranes 4 may be affected by the degree of tension of the hollow fiber membranes 4. When the hollow fiber membranes 4 are not straightened, the oscillation of the hollow fiber membranes 4 increases the flow resistance of the liquid in the hollow fiber membranes 4 and the air at the sides of the hollow fiber membranes 4, resulting in a smaller measured permeation quantity, and a relatively accurate permeation quantity cannot be obtained. If applied to actual production, the permeation quantity of the hollow fiber membrane 4 component is reduced, and the distillation efficiency is affected. The invention uses the distance adjusting device to straighten the hollow fiber membrane 4 without stretching, can accurately control the tension of the hollow fiber membrane 4, can keep the length of the hollow fiber membrane 4 to be a constant value, is beneficial to obtaining accurate measurement results, ensures that the tension state of the hollow fiber membrane 4 is equivalent under different experiments, and can directly compare different experimental results.
The distance adjusting device comprises a pulling machine 1, wherein the pulling machine 1 is provided with a movable end and a fixed end, the movable end is detachably connected with a first container 2, and the fixed end is detachably connected with a second container 3.
Specifically, the tension machine 1 is provided with a base, the moving end of the tension machine 1 is provided with a first support 11, the first support 11 can slide on the base, and a first vice 12 is fixedly connected on the first support 11; the fixed end of the tension machine 1 is a second support 13, a second vice 14 is fixedly connected to the second support 13, and the second support 13 is fixed on the base. The distance between the first container 2 and the second container 3 can be accurately adjusted by using the tension machine 1, the hollow fiber membrane 4 can be ensured to be in a straightened and non-stretched state, and the measured permeation quantity result is accurate.
The first container 2 is an inlet box and is held by a first vice 12; the second container 3 is an outlet box and is held by a second vice 14. When the first support 11 slides on the base in a direction away from the second support 13, the hollow fiber membranes 4 are straightened by the inlet box and the outlet box and are not stretched.
In this embodiment, the outlet box is connected with the water storage cup 5, and hot water in the outlet box can flow into the water storage cup 5. The water storage cup 5 can be taken down to pour out the hot water therein for weighing. The outlet box serves to support the hollow fiber membranes 4.
When the moving end of the tension machine 1 stops moving, the reading of the tension machine 1 is 0.2-0.4N. I.e., the hollow fiber membrane 4 has a tension of 0.2 to 0.4N. Within this numerical range, the hollow fiber membranes 4 are in a straightened and unstretched state, and the measured permeation quantity results are relatively accurate.
The air passage of the fan 6 toward the hollow fiber membranes 4 is perpendicular to the extending direction of the hollow fiber membranes 4. The wind blows to the middle part of the hollow fiber membrane 4 in the direction, so that the incoming wind at the side part of the hollow fiber membrane 4 can be provided, the evaporation capacity of the middle part of the hollow fiber membrane 4 can be taken away in time, the temperature at the two ends of the hollow fiber membrane 4 cannot be greatly influenced, and accurate measurement results are facilitated.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (4)
1. A method for measuring the permeation quantity of a non-contact hollow fiber membrane is characterized by comprising the following steps: comprises the steps of,
the distance between the first container and the second container is regulated to enable the hollow fiber membrane to be in a horizontal straightening state, and the middle part of the hollow fiber membrane is opposite to the fan;
closing a fan, adding hot water into the first container, emptying the second container after the temperature of the hollow fiber membrane is stable, starting timing, and measuring the hot water in the second container after a time period delta t to obtain a windless infiltration hot water quality parameter;
starting a fan, and measuring the hollow fiber membrane after the temperature of the hollow fiber membrane is stable to obtain the temperature parameter of the hollow fiber membrane;
the total heat loss Q and the convection heat transfer Q of the hot water in the process of starting the fan measurement are obtained by utilizing the windless osmotic hot water quality parameter and the temperature parameter of the hollow fiber membrane For a pair of ；
By Q Diving device ＝Q-Q For a pair of Obtaining the latent heat Q Diving device ；
By means ofObtaining the permeation quantity W' of the hollow fiber membrane, wherein H is the enthalpy change of changing water into water vapor in unit mass;
the airless penetrating hot water quality parameter includes the hot water quality m in the second container 1 The obtaining steps are as follows,
closing a fan, adding hot water into the first container, emptying the second container after the temperature of the hollow fiber membrane is stable, starting timing, and weighing the hot water mass in the second container after the time period delta t passes to obtain the hot water mass m in the second container 1 ；
The temperature parameter of the hollow fiber membrane comprises the inlet water temperature T fin2 Outlet water temperature T fout2 Inlet wall temperature T min2 And outlet wall temperature T mout2 The obtaining steps are as follows,
starting a fan, and measuring the connection between the outer wall of the hollow fiber membrane and the first container after the temperature of the hollow fiber membrane is stableThe contact position obtains the inlet water temperature T fin2 Measuring the contact position of the outer wall of the hollow fiber membrane and the second container to obtain the outlet water temperature T fout2 Measuring the front end of the outer wall of the hollow fiber membrane to obtain the inlet wall temperature T of the hollow fiber membrane min2 Measuring the tail part of the outer wall of the hollow fiber membrane to obtain the outlet wall temperature T mout2 ；
The total heat loss Q of the hot water during the start-up fan measurement is obtained as follows,
by m 1 ’＝m 1 Obtaining the windless mass flow rate m by delta t 1 ’；
Setting the qualitative temperature of the hot water asChecking the specific heat capacity C of the current hot water by the qualitative temperature;
with q=cm 1 ’(T fin2 -T fout2 ) Obtaining total heat loss Q;
convection heat transfer quantity Q during start-up fan measurement For a pair of The steps of the obtaining of (a) are as follows,
measuring the current ambient temperature t 1 From the current ambient temperature t 1 Checking the density ρ of the current air p Viscosity mu p Planck number Pr p The method comprises the steps of carrying out a first treatment on the surface of the Setting the qualitative temperature of the hot water asFrom the qualitative temperature, the density ρ of the current hot water is checked f Viscosity mu f ；
By Re p ＝DU p ρ p /μ p Obtaining Reynolds number Re of air around hollow fiber membrane p Wherein D is the outer diameter of the hollow fiber membrane, U p Is the wind speed of the fan;
by means ofObtaining the Nu number of the air around the hollow fiber membrane p ；
By means ofObtaining the convection heat transfer coefficient h of the air around the hollow fiber membrane p Wherein lambda is p The heat conductivity coefficient of the air around the hollow fiber membrane;
by means ofObtaining A, wherein A is the cross-sectional area of the hollow fiber membrane, and d is the inner diameter of the hollow fiber membrane;
by means ofObtaining the flow velocity u of hot water in the hollow fiber membrane f ；
By means ofObtaining Reynolds number Re of hot water in hollow fiber membrane f ；
By means ofObtaining the Nu number of the hot water in the hollow fiber membrane f Wherein Pr is f The Planck number of the hot water is the length of the hollow fiber membrane;
by means ofObtaining the convection heat transfer coefficient h of hot water in the hollow fiber membrane f Wherein lambda is f Is the heat conductivity coefficient of the hot water in the hollow fiber membrane;
by means ofObtaining the convection heat transfer coefficient h of the hollow fiber membrane m Wherein lambda is m Is the heat conductivity coefficient delta of the hollow fiber membrane m The thickness of the hollow fiber membrane is;
by means ofObtaining a total convection heat transfer coefficient h;
by means ofObtaining a logarithmic average temperature difference delta T;
by Q For a pair of =haΔT to obtain the convective heat transfer quantity Q For a pair of 。
2. A method for measuring the permeation quantity of a non-contact hollow fiber membrane according to claim 1, characterized by: adjusting the distance between the first container and the second container comprises the following steps that the movable end of the pulling machine is detachably connected with the first container, the fixed end of the pulling machine is detachably connected with the second container, and the movable end of the pulling machine moves away from the fixed end to straighten the hollow fiber membrane.
3. A non-contact hollow fiber membrane permeation quantity measuring device used in the measuring method according to claim 1 or 2, characterized in that: the device comprises a first container, a hollow fiber membrane, a second container, a distance adjusting device, a fan, an infrared thermometer and a weighing device, wherein the first container is communicated with one end of the hollow fiber membrane; the fan is positioned at one side of the hollow fiber membrane and faces the middle part of the hollow fiber membrane, the infrared thermometer is arranged corresponding to the hollow fiber membrane, and the weighing device is used for weighing the mass of hot water permeated into the second container from the first container;
the distance adjusting device comprises a tension machine, the tension machine is provided with a movable end and a fixed end, the movable end is detachably connected with the first container, and the fixed end is detachably connected with the second container;
the air passage of the fan blowing to the hollow fiber membranes is perpendicular to the extending direction of the hollow fiber membranes.
4. A non-contact hollow fiber membrane permeation quantity measuring device according to claim 3, characterized in that: when the moving end of the pulling machine stops moving, the reading number of the pulling machine is 0.2-0.4N.
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| CN211274240U (en) * | 2019-10-25 | 2020-08-18 | 华南理工大学 | Non-contact hollow fiber membrane permeation quantity measuring device |
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| JP2000107575A (en) * | 1998-10-05 | 2000-04-18 | Toyobo Co Ltd | Leak inspection method for permselective membrane module |
| CN102407078A (en) * | 2011-10-13 | 2012-04-11 | 天津工业大学 | Hollow fiber membrane filter performance testing device |
| CN109890485A (en) * | 2016-10-24 | 2019-06-14 | 费森尤斯医疗护理德国有限责任公司 | Method for determining the permeance property of hollow fiber membrane bundle |
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