A water supply pipeline microbial reaction simulation device and design method thereof

Abstract

The invention discloses a water supply pipeline microbial reaction simulation device and a design method thereof, which comprises a rectangular tube, wherein two ends of the rectangular tube are respectively connected with a water inlet pipe and a water outlet pipe, and a pressurized water pump and a valve group are arranged on the water inlet pipe; a plurality of grooves connected with the interior of the rectangular tube are arranged on the upper wall in the middle part, and a detachable glass slide for attaching a microbial community is arranged in each groove; the rectangular tube is designed by simulation software and a computational fluid dynamics model, and the water flow in the rectangular tube is a non-circulating flow state, which can truly simulate the water flow state in the pipeline; after a reaction time, a microbial community will be formed on the glass slide, and the microbial community that can be used for experimental analysis can be obtained by directly removing the glass slide.

Description

Technical Field

[0001] The invention relates to the fields of computational fluid dynamics and environmental microbiology, and in particular to a water supply pipeline microbial reaction simulation device and a design method thereof. Background Art

[0002] At present, most of the microbial community growth simulation devices in the prior art maintain a certain water flow condition, and place fillers in the simulation device to increase the attachment area of ​​microorganisms, so that more microorganisms in the water are retained on the sampling device. However, such simulation devices fail to take into account the shape and hydraulic conditions of the actual water supply network. In addition, the placed fillers will inevitably affect the water flow state in the device. Studies have shown that hydraulic conditions such as the water flow velocity in the water supply pipe, the shear stress of the water flow near the pipe wall, and the static pressure will affect the microbial community growing on the pipe wall. Since most of the reported simulation devices fail to simulate the hydraulic conditions in the actual pipe network, it is difficult to ensure that the water body in the simulation device and the types and quantities of the collected microorganisms are close to the actual situation. Summary of the invention

[0003] In view of the above-mentioned problems in the prior art, the present invention aims to provide a water supply pipe microbial reaction simulation device and a design method thereof, which solves the problem that the microbial community growth simulation device cannot accurately simulate the types and quantities of microbial communities in actual water pipes because of its built-in fillers that affect the water flow state.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0005] A water supply pipeline microbial reaction simulation device is provided, which comprises a rectangular tube, wherein the two ends of the rectangular tube are respectively connected with a water inlet pipe and a water outlet pipe, and a pressurized water pump and a valve group are arranged on the water inlet pipe; a plurality of grooves connected with the interior of the rectangular tube are arranged on the upper wall in the middle part, and a detachable glass slide for attaching a microbial community is arranged in each groove.

[0006] The basic principle of the water supply pipeline microbial reaction simulation device in this scheme is: open the valve group, water enters the rectangular tube through the water inlet pipe at a certain initial velocity under the action of the pressure water pump, and after a period of time, the tube is full, and water flows out of the rectangular tube from the water outlet pipe. After a period of reaction time, a microbial community will be formed on the glass slide, and the glass slide can be directly removed to obtain a microbial community that can be used for experimental analysis. At the same time, the glass slide is directly sterilized in a 120℃ high-temperature sterilizer before use, which can ensure that the collected microbial community microorganisms are generated during the water flow of the simulation device, and sterilized again after use, and can be reused.

[0007] Furthermore, the size of the rectangular tube is 15000×40×30mm. Due to the difference in the cross-sectional shape of the rectangular tube, there are inevitably differences in the hydraulic conditions between the rectangular tube and the circular tube. In order to simulate the hydraulic conditions in the real pipe network, the design size of the rectangular tube is simulated. The size of the rectangular tube is determined to be 15000×40×30mm through CFD calculation, so that the water flow in the rectangular tube is a non-circulating flow state, which can truly simulate the water flow state in the pipeline.

[0008] Furthermore, the number of glass slides is 4, and the 4 glass slides are evenly spaced and arranged at the upper wall position of 0.4m to 1.2m in the length direction of the rectangular tube. There is an unfilled area above the rectangular tube near the entrance due to the structure, so not all the wall areas of the rectangular tube are suitable for the placement of glass slides, and the wall shear stress and water flow state at the position of 0.4m to 1.2m in the rectangular tube tend to be stable, and setting the glass slide at the position of 0.4m to 1.2m in the rectangular tube can reduce the influence of the wall shear stress on the microbial community on the glass slide, ensuring that the microbial community generated by the entire microbial reaction simulation device is consistent with the actual water supply network.

[0009] Furthermore, the inner end surface of each glass slide is flush with the top inner wall of the rectangular tube, which can avoid the influence of the glass slide on the hydraulic conditions in the entire microbial reaction simulation device and avoid interfering with the distribution and growth of the microbial community.

[0010] Furthermore, as for the specific design size of the glass slide and how to achieve the connection with the rectangular tube, the size of each glass slide is 760×260×1mm, and a plurality of connecting screws are provided on the upper surface of each glass slide, and each glass slide is fixedly connected to the rectangular tube through a connecting screw.

[0011] Furthermore, it was used to simulate the growth of microbial communities in a DN40 circular pipe, with a water flow velocity of 0.6 m / s in the inlet pipe.

[0012] The scheme also provides a design method for a water supply pipeline microbial reaction simulation device, which includes:

[0013] Step 1: Select the actual water supply pipe section and determine the size and flow rate of the actual water supply pipe section;

[0014] Step 2: Establish the actual water supply pipe CFD model according to the size and flow rate parameters of the actual water supply pipe section through modeling software;

[0015] Step 3: Determine the hydraulic conditions that affect the microbial community in the actual water supply pipe based on the actual water supply pipe CFD model;

[0016] Step 4: Establish a rectangular tube CFD model through modeling software, and determine the initial hydraulic conditions that affect the microbial community based on the rectangular tube CFD model:

[0017] Step 5: Compare the hydraulic conditions affecting the microbial community in the actual water supply pipe with the initial hydraulic conditions affecting the microbial community in the rectangular pipe CFD model to see if they are consistent. If the comparison results are consistent, proceed to step 6, otherwise proceed to step 7;

[0018] Step 6: Obtain a rectangular tube capable of simulating the hydraulic conditions in an actual water supply pipe, and set a water inlet pipe and a water outlet pipe at both ends of the rectangular tube and install a glass slide on the rectangular tube to obtain a microbial reaction simulation device capable of simulating the hydraulic conditions in an actual water supply pipe;

[0019] Step 7: Change the size, shape and flow state parameters of the rectangular tube CFD model through the modeling software, and determine the hydraulic conditions of the changed rectangular tube CFD model affecting the microbial community, replace the hydraulic conditions of the changed rectangular tube CFD model affecting the microbial community with the initial hydraulic conditions of the microbial reaction simulation device affecting the microbial community, and proceed to step 6.

[0020] Furthermore, the modeling software in steps 3, 4 and 7 is Fluent 18.0. In the modeling process, the actual water supply pipe CFD model, the microbial reaction simulation device CFD model and the changed microbial reaction simulation device CFD model are meshed, and the number of mesh divisions is 150,000-370,000, the minimum orthogonal quality value range of the mesh is 0-1, and the maximum aspect ratio value range of the mesh is ≥1. The minimum orthogonal quality and maximum aspect ratio are used as Fluent mesh quality evaluation indicators. The minimum orthogonal quality value range of the mesh is 0-1, preferably 1; the maximum aspect ratio value range of the mesh is ≥1, preferably 1. The mesh quality of all models ensures the accuracy of the simulation results.

[0021] The beneficial effects of the present invention are as follows: 1. In this solution, a rectangular tube is designed by simulation software and a computational fluid dynamics model, and the water flow in the rectangular tube is a non-circulating flow state, which can truly simulate the water flow state in the pipeline.

[0022] 2. The water flow state and hydraulic conditions inside the real pipe section were investigated through simulation software and computational fluid dynamics models. The size of the microbial reaction simulation device was optimized by comparing the actual water supply pipe model and the microbial reaction simulation device model, so that the microbial reaction simulation device can more realistically simulate the flow rate, pipe wall shear stress, static pressure and other hydraulic conditions in the real pipe section, ensuring that the microbial community generated on the wall of the simulation device is consistent with the actual water supply network.

[0023] 3. When sampling the water supply pipe microbial reaction simulation device in this scheme, it is only necessary to directly remove the glass slide fixed to the upper pipe wall. The sampling process does not affect the microbial environment in the simulation device. The size of the glass slide can be directly used for direct analysis by laboratory microscopes and point spray desorption ionization instruments. There is no need for additional transfer, which avoids possible interference during the transfer of microbial communities and ensures the quality of microbial samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a water supply pipeline microbial reaction simulation device.

[0025] Figure 2 This is the shear stress distribution diagram on the upper wall of the rectangular tube model.

[0026] Figure 3 Shear stress distribution on the wall of the circular tube model.

[0027] Figure 4 This is the velocity distribution diagram of the square tube model.

[0028] Figure 5 This is the velocity distribution diagram of the circular tube model.

[0029] Figure 6 This is the water volume ratio diagram of the square tube model.

[0030] Figure 7 This is a table of parameters for the pipeline microbial community growth simulation device.

[0031] Among them, 1. rectangular tube; 2. water inlet pipe; 3. water outlet pipe; 4. pressure water pump; 5. valve group; 6. glass slide. DETAILED DESCRIPTION

[0032] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0033] Example 1

[0034] like Figure 1 As shown, the present invention provides a water supply pipeline microbial reaction simulation device, including a rectangular tube 1, with a water inlet pipe 2 and a water outlet pipe 3 connected to both ends of the rectangular tube 1 respectively, and a pressurized water pump 4 and a valve group 5 are arranged on the water inlet pipe 2.

[0035] A plurality of grooves communicating with the interior of the rectangular tube 1 are arranged on the upper wall in the middle part, and a detachable glass slide 6 for attaching microbial communities is arranged in each groove. As for the specific design size of the glass slide 6 and how to realize the connection with the rectangular tube 1, the size of each glass slide 6 is 760×260×1mm, and a plurality of connecting screws are arranged on the upper surface of each glass slide 6, and each glass slide 6 is fixedly connected with the rectangular tube 1 through a connecting screw.

[0036] When the water supply pipeline microbial reaction simulation device is conducting a simulation experiment, first, the glass slide 6 is directly sterilized in a 120°C high-temperature sterilizer before use, which can ensure that the collected microbial community microorganisms are generated during the water flow of the simulation device, and then the valve group 5 is opened. Under the action of the pressure water pump 4, water enters the rectangular tube 1 through the water inlet pipe 2 at a certain initial velocity. After a period of time, the tube is full, and the water flows out of the rectangular tube 1 from the water outlet pipe 3. The glass slide 6 will form a microbial community after a period of reaction time. The microbial community that can be used for experimental analysis can be obtained by directly removing the glass slide 6; when sampling, it is only necessary to directly remove the glass slide 6 fixed to the upper tube wall. The sampling process does not affect the microbial environment in the simulation device. The size of the glass slide 6 can be directly used for direct analysis by a laboratory microscope or a point spray desorption ionization instrument, and no additional transfer is required, thereby avoiding possible interference during the transfer of the microbial community and ensuring the quality of the microbial sample.

[0037] Example 2

[0038] This embodiment is further limited on the basis of Embodiment 1. The size of the rectangular tube 1 is 15000×40×30mm. The size of the rectangular tube 1 is 15000×40×30mm. Due to the difference in the cross-sectional shape of the rectangular tube 1, there are inevitably differences in the hydraulic conditions between the rectangular tube 1 and the circular tube. In order to simulate the hydraulic conditions in the real pipe network, the design size of the rectangular tube 1 is simulated. The size of the rectangular tube 1 is determined to be 15000×40×30mm through CFD calculation, so that the water flow in the rectangular tube 1 is a non-circulating flow state, which can truly simulate the water flow state in the pipeline.

[0039] There are 4 glass slides 6, and the 4 glass slides 6 are evenly spaced on the upper wall of the rectangular tube 10.4m to 1.2m. There is an unfilled area above the rectangular tube 1 near the entrance due to the structure, so not all wall areas of the rectangular tube 1 are suitable for the placement of glass slides 6. At the position of 10.4m to 1.2m in the rectangular tube, the shear stress of the tube wall and the water flow state tend to be stable. Placing the glass slide 6 at the position of 10.4m to 1.2m in the rectangular tube can reduce the impact of the shear stress of the tube wall on the microbial community on the glass slide 6, ensuring that the microbial community generated by the entire microbial reaction simulation device is consistent with the actual water supply network.

[0040] Taking the water supply pipe microbial reaction simulation device to simulate the growth of microbial communities under hydraulic conditions in a DN40 water supply pipe in a water supply network of a university in Guangzhou as an example, the reasons for the design of the size parameters of the rectangular tube 1 and the placement of the glass slide 6 are explained.

[0041] A DN40 circular pipe model was established, and according to the "Code for Design of Building Water Supply and Drainage" and related architectural drawings, two inlet flow rate conditions of 0.6m / s and 1m / s were considered. Under the two flow rates, the DN40 circular pipe model only takes 7s and 3s to fill the pipe and enter a stable state. In contrast, the design of the microbial reaction simulation device model takes a longer time to reach a full pipe due to its smaller inlet and outlet. Taking into account the size of the sampling slide 6 and the simultaneous collection of multiple microbial communities, 0.5m and 1.5m were preliminarily considered as the length of the rectangular tube 1, and 0.04m and 0.03m were considered as the width and height of the rectangular tube 1. And the following was established: Figure 7 The microbial community simulation device and DN40 circular tube model shown in the table.

[0042] The model numbered as tube 2.15 only takes 8 seconds to fill the pipe and enter a stable flow process due to its short length of 0.5m. Other device models require about 60-160 seconds to fill the pipe due to the 1.5m long structural dimension. Therefore, the water supply pipeline microbial reaction simulation device requires more than 3 minutes of pre-operation time to ensure the stability of the water flow in the rectangular tube 1. ICEM CFD is used to mesh the three-dimensional model of the flow field in the rectangular tube 1. The mesh is divided into tetrahedrons. The inlet pipe 2 and the outlet pipe 3 are both circular pipes. The O-grid (circular grid) division scheme is adopted to reduce the impact between the inlet pipe 2 and the outlet pipe 3 and the wall interface of the rectangular tube 1.

[0043] like Figure 6 As shown, an unfilled area is left above the near entrance of the rectangular tube 1 due to the structure, so not all the wall areas of the device are suitable for placing the sterile glass slide 6. Figure 2 and Figure 3 The shear stress distribution on the upper wall of rectangular tube 1 and DN40 tube is given. First, the increase in inlet flow rate obviously causes higher wall shear stress. According to Newton's viscosity law, the shear stress τ is:

[0044] τ=μdu / dy (1)

[0045] Where μ is the dynamic viscosity of the fluid (Pa·s), and du / dy is the normal velocity gradient (1 / s). When the flow velocity in the pipe increases, the velocity gradient near the wall increases, and the shear stress of the pipe wall increases. The shear stress of the DN40 pipe model tends to be stable after 0.4m, while the shear stress of the rectangular pipe 1 tends to be stable at the upper wall of about 0.4m-1.2m due to the different structural parameters and the backflow caused by the smaller outlet.

[0046] The flow rates at the inlet and outlet of the DN40 pipe model are as follows: Figure 5 As shown, the flow rates of the water inlet and outlet of the rectangular tube 1 are as follows: Figure 4 As shown in , the central flow field near the outlet has backflow, which causes the velocity gradient near the wall to change, thus increasing the shear stress of the tube wall near the outlet. Figure 7 As shown, by comparing the tubes numbered 2.15 and 1.15, it can be seen that the tube length does not greatly affect the distribution of the shear stress on the tube wall, and the microbial community sampling area is difficult to determine due to the mutual influence of the inlet inflow and the outlet reflux for a tube length of 0.5m. Therefore, the tube length of rectangular tube 1 is 1.5m, which is the best choice. In summary, considering the distribution law of the flow velocity and shear stress on the tube wall, the microbial community sampling area where the sterile slide 6 is placed should be at 0.4m-1.2m on the tube wall to ensure that the microbial community generated on the slide 6 of the simulation device is consistent with the actual water supply network.

[0047] In addition, if Figure 2 and Figure 3 By comparing the shear stress of the DN40 model and rectangular tube 1, it is found that the shorter structural height parameter, that is, the tube with an inlet flow rate of 1.5m / s, can have a higher upper tube wall shear stress. At the same time, considering the process limitations, the rectangular tube 1 structural parameters of 150cm long, 4cm wide, and 3cm high are the best structural solutions. The shear stress result of rectangular tube 1 is close to the shear stress result of DN40 circular tube, that is, when the rectangular tube 1 size is 15000×40×30mm and the water inlet flow rate is 1.5m / s, it can better simulate the upper tube wall shear stress of the DN40 circular tube with an inlet flow rate of 0.6m / s.

[0048] Preferably, but not limited to, the inner end surface of each glass slide 6 is flush with the top inner wall of the rectangular tube 1, which can avoid the influence of the glass slide 6 on the hydraulic conditions in the entire microbial reaction simulation device and avoid interfering with the distribution and growth of the microbial community.

[0049] Furthermore, the present solution also provides a design method for a water supply pipeline microbial reaction simulation device, which includes step 1: selecting an actual water supply pipeline section and determining the size and flow rate of the actual water supply pipeline section;

[0050] Step 2: Establish the actual water supply pipe CFD model according to the size and flow rate parameters of the actual water supply pipe section through modeling software;

[0051] Step 3: Determine the hydraulic conditions that affect the microbial community in the actual water supply pipe based on the actual water supply pipe CFD model;

[0052] Step 4: Establish a rectangular tube 1CFD model through modeling software, and determine the initial hydraulic conditions that affect the microbial community based on the rectangular tube 1CFD model:

[0053] Step 5: Compare the hydraulic conditions affecting the microbial community in the actual water supply pipe with the initial hydraulic conditions affecting the microbial community in the rectangular pipe 1CFD model to see if they are consistent. If the comparison results are consistent, proceed to step 6, otherwise proceed to step 7;

[0054] Step 6: Obtain a rectangular tube 1 capable of simulating the hydraulic conditions in an actual water supply pipe, and arrange the water inlet pipe 2 and the water outlet pipe 3 at both ends of the rectangular tube 1 and install the glass slide 6 on the rectangular tube 1 to obtain a microbial reaction simulation device capable of simulating the hydraulic conditions in an actual water supply pipe;

[0055] Step 7: Change the size, shape and flow state parameters of the rectangular tube 1 CFD model through the modeling software, and determine the hydraulic conditions of the changed rectangular tube 1 CFD model affecting the microbial community, replace the hydraulic conditions of the changed rectangular tube 1 CFD model affecting the microbial community with the initial hydraulic conditions of the microbial reaction simulation device affecting the microbial community, and proceed to step 6.

[0056] Furthermore, the modeling software in steps 3, 4 and 7 is Fluent 18.0. In the modeling process, the actual water supply pipe CFD model, the rectangular pipe 1 CFD model and the changed rectangular pipe 1 CFD model are meshed, and the number of meshes is 150,000 to 370,000, the minimum orthogonal quality value range of the mesh is 0 to 1, and the maximum aspect ratio value range of the mesh is ≥1. The minimum orthogonal quality and the maximum aspect ratio are used as Fluent mesh quality evaluation indicators. The minimum orthogonal quality value range of the mesh is 0 to 1, preferably 1; the maximum aspect ratio value range of the mesh is ≥1, preferably 1. The mesh quality of all models ensures the accuracy of the simulation results. The water flow state and hydraulic conditions inside the real pipe section were investigated by simulation software and computational fluid dynamics model. The size of the microbial reaction simulation device was optimized by comparing the actual water supply pipe model and the microbial reaction simulation device model, so that the microbial reaction simulation device can more realistically simulate the hydraulic conditions such as flow velocity, pipe wall shear stress, and static pressure in the real pipe section, ensuring that the microbial community generated by the simulation device wall is consistent with the actual water supply network.

Claims

1. A design method for a water supply pipeline microbial reaction simulation device, characterized in that: The water supply pipeline microbial reaction simulation device comprises a rectangular tube, the two ends of which are respectively connected to a water inlet pipe and a water outlet pipe, and the water inlet pipe is provided with a pressurized water pump and a valve group; a plurality of grooves communicating with the interior of the rectangular tube are provided on the upper wall in the middle part, and a detachable glass slide for attaching a microbial community is provided in each of the grooves; the design method comprises: Step 1: Select the actual water supply pipe section and determine the size and flow rate of the actual water supply pipe section; Step 2: Establish the actual water supply pipe CFD model according to the size and flow rate parameters of the actual water supply pipe section through modeling software; Step 3: Determine the hydraulic conditions that affect the microbial community in the actual water supply pipe based on the actual water supply pipe CFD model; Step 4: Establish a rectangular tube CFD model through modeling software, and determine the initial hydraulic conditions that affect the microbial community based on the rectangular tube CFD model: Step 5: Compare the hydraulic conditions affecting the microbial community in the actual water supply pipe with the initial hydraulic conditions affecting the microbial community in the rectangular pipe CFD model to see if they are consistent. If the comparison results are consistent, proceed to step 6, otherwise proceed to step 7; Step 6: Obtain a rectangular tube capable of simulating the hydraulic conditions in an actual water supply pipe, and set a water inlet pipe and a water outlet pipe at both ends of the rectangular tube and install a glass slide on the rectangular tube to obtain a microbial reaction simulation device capable of simulating the hydraulic conditions in an actual water supply pipe; Step 7: Change the size, shape and flow state parameters of the rectangular tube CFD model through the modeling software, and determine the hydraulic conditions of the changed rectangular tube CFD model affecting the microbial community, replace the hydraulic conditions of the changed rectangular tube CFD model affecting the microbial community with the initial hydraulic conditions of the microbial reaction simulation device affecting the microbial community, and proceed to step 6.

2. The design method of the water supply pipeline microbial reaction simulation device according to claim 1 is characterized in that: The dimensions of the rectangular tube are 15000×40×30 mm.

3. The design method of the water supply pipeline microbial reaction simulation device according to claim 2 is characterized in that: The number of the glass slides is 4, and the 4 glass slides are evenly spaced and arranged at positions on the tube wall at 0.4m to 1.2m in the length direction of the rectangular tube.

4. The design method of the water supply pipeline microbial reaction simulation device according to claim 3 is characterized in that: The inner end surface of each glass slide is flush with the top inner wall of the rectangular tube.

5. The design method of the water supply pipeline microbial reaction simulation device according to claim 3 is characterized in that: The size of each glass slide is 760×260×1 mm, and a plurality of connecting screws are arranged on the upper surface of each glass slide, and each glass slide is fixedly connected to the rectangular tube via a connecting screw.

6. The design method of the water supply pipeline microbial reaction simulation device according to claim 3 is characterized in that: Used to simulate the growth of microbial communities in a DN40 circular pipe, the water flow velocity in the water inlet pipe is 0.6 m / s.

7. The design method of the water supply pipeline microbial reaction simulation device according to claim 1 is characterized in that: The modeling software in step 3, step 4 and step 7 are all Fluent 18.

0. During the modeling process, the actual water supply pipe CFD model, the rectangular pipe CFD model and the changed rectangular pipe CFD model are meshed, and the number of mesh divisions is 150,000 to 370,000, the minimum orthogonal quality value range of the mesh is 0 to 1, and the maximum aspect ratio value range of the mesh is ≥1.

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