CRDS-based gas analysis device

Abstract

The invention discloses a CRDS-based gas analysis device which comprises a case, the case is provided with an air inlet and an air outlet, a laser module, a structure module and an optical cavity module which are sequentially connected through optical fibers are arranged in the case, the optical cavity module is arranged below the laser module, and a circuit board is arranged in the vertical direction of the optical cavity module. A first air channel is formed in the direction of the air inlet, the circuit board and the air outlet, the structural module is arranged on the other side opposite to the laser module, a ventilation interval is arranged between the structural module and the optical cavity module, and a second air channel is formed in the direction of the air inlet, the laser module, the ventilation interval and the air outlet. The gas analysis device can quickly take away heat generated by each component in the instrument, and can enable each module in the instrument to be in a temperature stable state.

Description

[0001] The patent application number of the parent case of this case is: 202411365018.1 Technical Field

[0002] The present invention relates to the field of gas analysis, and in particular to a gas analysis device based on cavity ring-down spectroscopy technology. Background Art

[0003] Products using CRDS (Cavity ring-down spectroscopy) technology have ultra-high sensitivity and resolution, and are lightweight, stable, and easy to operate. They are used in a variety of atmospheric composition and isotope observation studies. At pressures below atmospheric pressure, it consists of some narrow, well-resolved sharp lines, each with a specific wavelength, and the concentration of a substance can be determined based on the height of a specific absorption peak.

[0004] CRDS technology has the advantages of not being affected by laser intensity fluctuations, long path for laser-medium interaction, high detection accuracy, no calibration, simple device, and convenient operation. CRDS technology has been applied to atmospheric detection in field and aerial surveys, promoting the development of trace greenhouse gas research and making climate prediction more accurate. However, the measurement accuracy of this product is greatly affected by temperature changes, and the existing CRDS gas analysis device has an unreasonable air duct design, resulting in poor heat dissipation and affecting the measurement accuracy. Summary of the invention

[0005] The object of the present invention is to provide a CRDS gas analysis device with a simple structure, a reasonable air duct, and sufficient temperature reduction of each component.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: a gas analysis device based on CRDS, comprising a chassis, wherein the chassis is provided with an air inlet and an air outlet, the air inlet and / or the air outlet is provided with a fan, a laser module and an optical cavity module connected in sequence by optical fibers are provided in the chassis, the laser module is provided on a side close to the air inlet, the optical cavity module is provided horizontally below the laser module, a circuit board is fixed vertically above the optical cavity module, the air inlet, the circuit board and the air outlet form a first air duct, a structural module is provided on the other side opposite to the laser module, a ventilation interval is provided between the structural module and the optical cavity module, the air inlet, the laser module, the ventilation interval and the air outlet form a second air duct, and the optical cavity module is provided with an air inlet duct and an air outlet duct of a sample to be tested.

[0007] Preferably, a first radiator is disposed on the outer side of the optical cavity module, and a second radiator is disposed on the inner side of the optical cavity module. The second radiator is connected to the first radiator via a refrigeration device, and a ventilation device is also disposed on the second radiator.

[0008] Preferably, the first radiator is located in the ventilation space, and the first radiator is arranged on a side of the optical cavity module close to the air outlet.

[0009] Preferably, the width of the second air duct located at the laser module is greater than the width of the air duct located at the ventilation interval.

[0010] Preferably, the structural module includes at least one AC / DC power supply and a power supply interface, and the AC / DC power supply is arranged on a side close to the air outlet.

[0011] Preferably, the structural module comprises a measuring module, an optical switch is provided in the measuring module, and the optical switch is respectively connected to the laser module and the optical cavity module through optical fibers.

[0012] Preferably, an optical module is connected between the structural module and the optical cavity module for adjusting the laser signal.

[0013] Preferably, the distance between the optical cavity module and the rear cover of the chassis is less than 25 mm.

[0014] Preferably, the height of the first air duct at the circuit board is 36-64 mm.

[0015] Preferably, the width of the second air duct located in the ventilation interval is 24-45 mm.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] 1. The layout design of the first air duct and the second air duct can quickly take away the heat generated by various components in the instrument, and can keep the temperature of each module inside the instrument stable.

[0018] 2. The optical cavity module is set on the same side of the laser module, and the structural module is set on the other side of the laser module, which can reduce the length of the optical fiber, reduce the risk of optical fiber damage, and thus improve the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of Example 1 of the present invention.

[0020] Figure 2 It is a schematic diagram of the first air duct and the second air duct of the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of Example 2 of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of Example 3 of the present invention.

[0023] Figure 5This is the relationship diagram between the first air duct height and the comprehensive heat dissipation performance.

[0024] Figure 6 This is a relationship diagram between the second air duct width and the comprehensive heat dissipation performance.

[0025] Figure 7 It is a schematic diagram of the first air duct height and the second air duct width.

[0026] 1-button switch, 2-USB interface, 3-display screen, 4-chassis, 5-structural module, 6-insulation material, 7-optical switch, 8-wavelength meter, 9-AC / DC power supply, 10-first radiator, 11-power interface, 12-optical cavity module, 13-driving board, 14-shielding cover, 15-mainboard, 16-optical module, 17-laser module, 18-fan, 19-inlet duct, 20-outlet duct, 21-first air duct, 22-second air duct, 23-ventilation device, 24-second radiator, 25-refrigeration device. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0028] Embodiment 1, as Figure 1 and Figure 2 As shown, the gas analysis device based on CRDS includes a chassis 4, a button switch 1, a USB interface 2 and a display screen 3 are arranged on the front panel of the chassis, and the button switch and the USB interface are arranged on the right side of the front panel for easy operation. The chassis is provided with an air inlet and an air outlet, and the air inlet and / or the air outlet are provided with a fan 18, the air inlet is arranged on a side of the chassis side cover close to the front panel, and the air outlet is arranged on the rear panel of the chassis.

[0029] The chassis is provided with a laser module 17, a structural module 5 and an optical cavity module 12 which are sequentially connected by optical fibers. An optical module 16 is also provided between the structural module and the optical cavity module for adjusting the laser signal.

[0030] The laser module includes at least one laser for emitting a laser of a specific wavelength. The laser can be a multi-quantum well-type laser (for example, a 14PIN butterfly package DFB laser produced by EM4, USA), with a wavelength of 1500-1650nm. The structural module includes a first shell, on which joints corresponding to the laser are provided, and the number of joints is greater than or equal to the number of lasers. A wavelength meter 8 is provided in the first shell, and the wavelength meter and the optical cavity module are connected by optical fiber. An optical switch 7 can also be provided in the first shell, and the optical switch is respectively connected to the wavelength meter and the optical cavity module by optical fiber. The wavelength meter is used to measure the wavelength of light, and the optical switch is used to control the opening and closing of the laser. The inner side of the structural module is also filled with a heat-insulating material 6.

[0031] A circuit board is arranged vertically above the optical cavity module, and the circuit board includes a driving board 13 and a main board 15. A shielding cover 14 is fixed to the periphery of the circuit board, which can prevent electromagnetic signals from interfering with the circuit board and protect the circuit board. A first radiator 10 is arranged on the outside of the optical cavity module, and a second radiator 24 is arranged on the inside of the optical cavity module. The second radiator is connected to the first radiator through a refrigeration device 25, wherein the refrigeration device is a refrigeration structure such as a TEC (Thermoelectric cooler, semiconductor refrigerator). In order to improve the temperature stability in the cavity and improve the heat dissipation efficiency, the first radiator is arranged on the side close to the air outlet on the optical cavity module, and a ventilation device 23 such as a fan is also provided on the second radiator. The optical cavity module is provided with an air inlet pipe 19 and an air outlet pipe 20 of the sample to be tested near the rear side of the chassis for measuring the concentration of the gas to be tested. In order to improve the sampling efficiency and prevent the formation of condensed water in the air pipe, the length of the air inlet pipe and the air outlet pipe in the chassis is less than 25mm, and 3-8mm is more effective. At one end of the structural module near the air outlet, horizontally below the measuring module, at least one AC / DC power supply 9 is also provided, and the power supply and the power interface 11 on the rear cover of the chassis are used to power the analyzer, which facilitates the internal wiring of the instrument and reduces the distribution range of the high-voltage line inside the instrument. In another embodiment, in order to reduce the weight of the chassis, no AC / DC power supply is provided in the chassis, and the instrument is connected to an external power supply when in use.

[0032] The laser module is arranged on a side close to the air inlet, and the optical cavity module is arranged on the same side as the laser module and directly below it, so that the air entering through the air inlet will pass through the circuit board in the process of flowing toward the air outlet, forming an arc-shaped first air duct 21 (i.e., an arc-shaped air flow path of air inlet-circuit board-air outlet). The structural module is arranged on the other side opposite to the laser module, and a ventilation interval is arranged between the structural module and the optical cavity module, so that the air entering through the air inlet will pass through the laser module at the same time in the process of flowing toward the air outlet, and pass through the ventilation interval to form a second air duct 22 (i.e., an air flow path of air inlet-laser module-ventilation interval-air outlet), and because the structural module and the laser module are arranged relative to each other, the second air duct is an L-shaped air duct. In order to increase the heat dissipation efficiency, the width of the second air duct formed at the laser module (i.e., the distance between the top of the optical cavity module and the top plate of the chassis) is greater than the width of the second air duct formed at the ventilation interval (i.e., the distance between the structural module and the optical cavity module), so that the second air duct forms a funnel-shaped air duct at the laser module. When a power supply is provided horizontally below the structural module in the chassis, the distance between the power supply and the optical cavity module can be extended to extend the distance of the second air duct, thereby improving the heat dissipation efficiency.

[0033] Because the sizes of the optical cavity module and the structural module are fixed, the height of the first air duct flowing through the circuit board can be adjusted by adjusting the height of the circuit board, and the width of the second air duct can be adjusted by adjusting the spacing between the structural module and the optical cavity module (i.e., the width of the ventilation interval) to achieve the best cooling effect of the analyzer air duct.

[0034] Embodiment 2, as Figure 3 As shown, the gas analysis device based on CRDS includes a chassis 4, a button switch 1, a USB interface 2 and a display screen 3 are arranged on the front panel of the chassis, and the button switch and the USB interface are arranged on the right side of the front panel for easy operation. The chassis is provided with an air inlet and an air outlet, and the air inlet and / or the air outlet are provided with a fan 18, the air inlet is arranged on a side of the chassis side cover close to the front panel, and the air outlet is arranged on the rear panel of the chassis.

[0035] The chassis is provided with a laser module 17 and an optical cavity module 12 which are connected in sequence through optical fibers. An optical module 16 is also provided between the laser module and the optical cavity module for adjusting the laser signal. In another embodiment, Figure 4 As shown, no optical module is provided between the structure module and the optical cavity module according to the on-site working conditions. The laser module includes at least one laser for emitting laser of a specific wavelength, and the laser is a multi-quantum well type laser with a wavelength of 1500-1650nm.

[0036] A circuit board is arranged in the vertical direction of the optical cavity module, and the circuit board includes a driving board 13 and a main board 15. A shielding cover 14 is fixed to the periphery of the circuit board, which can prevent electromagnetic signals from interfering with the circuit board and protect the circuit board. A first radiator 10 is arranged on the outside of the optical cavity module, and a second radiator 24 is arranged on the inside of the optical cavity module. The second radiator is connected to the first radiator through a refrigeration device 25, wherein the refrigeration device is a refrigeration structure such as TEC. In order to improve the temperature stability in the cavity and improve the heat dissipation efficiency, the first radiator is arranged on the side close to the air outlet on the optical cavity module, and a ventilation device 23 such as a fan is also provided on the second radiator. The optical cavity module is provided with an air inlet pipe 19 and an air outlet pipe 20 of the sample to be tested near the rear side of the chassis for measuring the concentration of the gas to be tested. In order to improve the sampling efficiency and prevent the formation of condensed water in the air pipe, the length of the air inlet pipe and the air outlet pipe in the chassis is less than 25mm, and 3-8mm is more effective.

[0037] The laser module is arranged on a side close to the air inlet, and the optical cavity module is arranged on the same side as the laser module and directly below it, so that the air entering through the air inlet will pass through the circuit board in the process of flowing toward the air outlet, forming an arc-shaped first air duct 21 (i.e., an arc-shaped air flow path of air inlet-circuit board-air outlet). The structural module is arranged on the other side opposite to the laser module, and a ventilation interval is arranged between the structural module and the optical cavity module, so that the air entering through the air inlet will pass through the laser module at the same time in the process of flowing toward the air outlet, and pass through the ventilation interval to form a second air duct 22 (i.e., an air flow path of air inlet-laser module-ventilation interval-air outlet), and because the structural module and the laser module are arranged relative to each other, the second air duct is an L-shaped air duct. In order to increase the heat dissipation efficiency, the width of the second air duct formed at the laser module (i.e., the distance between the top of the optical cavity module and the top plate of the chassis) is greater than the width of the second air duct formed at the ventilation gap (i.e., the distance between the structural module and the optical cavity module), so that the second air duct forms a funnel-shaped air duct at the laser module.

[0038] At one end of the structural module near the air outlet, at least one AC / DC power supply 9 and a power interface 11 are provided to power the analyzer, which facilitates the internal wiring of the instrument and reduces the distribution range of the high-voltage line inside the instrument. In another embodiment, the power supply can be externally installed, and the power supply is not provided in the structural module. The structural module is composed of a baffle that is convenient for forming a second air duct, and the baffle can be an external baffle or a side cover of the chassis.

[0039] Because the sizes of the optical cavity module and the structural module are fixed, the height of the first air duct flowing through the circuit board can be adjusted by adjusting the height of the circuit board (i.e., the distance from the top of the optical cavity module to the top of the circuit board), and the width of the second air duct can be adjusted by adjusting the spacing between the structural module and the optical cavity module (i.e., the width of the ventilation interval) to achieve the best cooling effect of the analyzer air duct.

[0040] In order to improve the heat dissipation efficiency, the present invention also discloses a duct design method for a gas analysis device based on CRDS, and the specific steps are as follows:

[0041] Step 1: Calculate the total air volume required to maintain a constant temperature in the device Where Q is the total heat dissipation of each module in the device, ΔT is the change in air temperature in the device, and a fan with an air volume greater than q' and a wind pressure of P is selected;

[0042] Step 2: Calculate based on the working condition analysis of the device:

[0043]

[0044] Where ΔP A1 is the wind resistance of the components inside the first air duct, ΔPB1 is the wind resistance of the components inside the second air duct, L 1 is the height of the first air duct (i.e., the distance from the top of the optical cavity module to the top of the circuit board), L 2 is the first air duct width (i.e., the width of the optical cavity module), L 3 is the height of the second air duct (i.e., the height of the structural module), L 4 is the second air duct width (i.e., the distance between the optical cavity module and the structural module), λ A is the friction resistance coefficient of the first air duct, λ B is the friction coefficient of the second air duct, ρ is the air density, v is the air kinematic viscosity, l A is the length of the first air duct, l B is the length of the second air duct, ζ A is the local resistance coefficient in the first air duct, ζ B is the local resistance coefficient in the second air duct, ΔP A is the wind resistance of the first wind duct, ΔP B is the wind resistance of the second wind duct.

[0045] Step 3: Obtain the total wind resistance in the device based on the fitting

[0046]

[0047] Step 4: Because the heat dissipation effect is better when the fan wind pressure is greater than 1.5 times the total wind resistance in the device, the preferred first air duct height and second air duct width are obtained according to calculation.

[0048] like Figure 5 , Figure 6 and Figure 7 As shown, in one embodiment, the peak value Q of the total heat dissipation of each module inside the device is about 41.9W, and the circuit board accounts for about 23% of the total heat dissipation power. The fan can be selected according to the air volume q', and the fan outlet diameter d=76mm and the air pressure P are selected.

[0049] The wind pressure of the fan under rated working conditions should be greater than the total wind resistance inside the air duct. Where ΔP A =ΔP A1 +ΔP A2 , ΔP B =ΔP B1 +ΔP B2 . ΔP A Wind resistance of the first wind duct, ΔP B is the wind resistance of the second wind duct, ΔP A1 and ΔP B1 is a constant, which can be found in the component manual. A2 =P AM +PAN , ΔP B2 =P BM +P BN , where P AM and P BM are the friction resistance of air flowing in the first and second air ducts, λ A and λ B is the friction coefficient in the first and second air ducts, v A and v B is the average air velocity in the first and second air ducts, ρ is the air density, l A and l B is the length of the first and second air ducts, D A and D B is the cross-sectional area of ​​the first and second air ducts, where P AN and P BN are the local resistances of the air when the air turns and the cross section is reduced in the first and second air ducts, respectively. Calculated:

[0050]

[0051] The fan pressure P should be greater than 1.5ΔP to achieve the best heat dissipation effect. 4 When L is 40 mm, 1 Set them to 15, 30, 45, 60, and 75 mm respectively, and measure the temperature of each module of the device during operation:

[0052]

[0053] Other conditions remain unchanged and L 1 For 30mm, change L 4 Set them to 15, 20, 35, 45, and 55 mm respectively, and measure the temperature of each module of the device during operation:

[0054]

[0055] When the peak value Q of the total heat dissipation of each module inside the device is about 41.9W, L 1 The best heat dissipation effect is 32-64mm. 4 The best heat dissipation effect is 24-45mm.

[0056] The above description is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A gas analysis device based on CRDS, comprising a chassis (4), wherein the chassis (4) is provided with an air inlet and an air outlet, and is characterized in that: The chassis (4) comprises a side cover, a front plate and a rear plate, the air inlet being arranged on the side cover of the chassis (4), and the air outlet being arranged on the rear plate of the chassis (4); a laser module (17), a structural module (5) and an optical cavity module (12) which are sequentially connected via optical fibers are arranged in the chassis (4), the laser module (17) being arranged on a side close to the air inlet, the optical cavity module (12) being arranged on the same side as the laser module (17) and directly below the laser module (17), and the optical cavity module (12) being arranged along the A circuit board is arranged in a vertical direction, and a first air duct (21) is formed along the direction of the air inlet, the circuit board and the air outlet; the structural module (5) and the laser module (17) are arranged opposite to each other, and a ventilation interval is provided between the structural module (5) and the optical cavity module (12); a second air duct (22) is formed along the direction of the air inlet, the laser module (17), the ventilation interval and the air outlet; and the optical cavity module (12) is provided with an air inlet duct (19) and an air outlet duct (20) of a sample to be tested.

2. The CRDS-based gas analysis device according to claim 1, characterized in that: The air inlet and / or the air outlet is provided with a fan (18).

3. The CRDS-based gas analysis device according to claim 1 or 2, characterized in that: The air inlet is arranged on a side of the side cover of the chassis (4) close to the front plate.

4. The CRDS-based gas analysis device according to claim 1, characterized in that: A first heat sink (10) is arranged outside the optical cavity module (12), and a second heat sink (24) is arranged inside the optical cavity module (12); the second heat sink (24) is connected to the first heat sink (10) via a refrigeration device (25).

5. The CRDS-based gas analysis device according to claim 4, characterized in that: The first heat sink (10) is arranged on the optical cavity module (12) at a side close to the air outlet, and the second heat sink (24) is also provided with a ventilation device (23).

6. The CRDS-based gas analysis device according to claim 5, characterized in that: The first heat sink (10) is located in the ventilation space, and the first heat sink (10) is arranged on a side of the optical cavity module (12) close to the air outlet.

7. The CRDS-based gas analysis device according to claim 1, characterized in that: The width of the second air duct (22) formed at the laser module (17) is greater than the width of the second air duct (22) formed at the ventilation interval, so that the second air duct (22) forms a funnel-shaped air duct at the laser module (17).

8. The CRDS-based gas analysis device according to claim 1, characterized in that: The distance between the optical cavity module (12) and the rear cover of the chassis (4) is less than 25 mm.

9. The CRDS-based gas analysis device according to claim 1, characterized in that: The height of the circuit board in the chassis is 32-64 mm.

10. The CRDS-based gas analysis device according to claim 1, characterized in that: The distance between the structural module (5) and the optical cavity module (12) is 24-45 mm.

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