A gas supply system for eliminating thermal and acoustic vibrations of combustion in gas water heaters

Abstract

The present invention discloses an air supply system for eliminating the thermal-acoustic vibration of combustion in a gas water heater. The system is provided with air and gas supply pipes of variable length, and the blower and the gas supply pipe are arranged outside the gas water heater and integrated in a closed box, so as to facilitate the maintenance of the gas supply system. During design and installation, the air and gas flow path that can avoid combustion vibration is preset in the gas supply system controller. When the vibration sensor detects the vibration signal of the gas water heater, it transmits it to the gas supply system controller, which issues an instruction to control the air and gas flow valves to switch to the corresponding path. The present invention can flexibly and effectively solve the problem of combustion vibration of the gas water heater caused by changes in operating parameters, and the method does not change the water outlet parameters and does not affect the use effect. The gas supply system improves the user experience and improves the economy and safety of the gas water heater operation. It is applicable to both full premixed and partially premixed gas water heaters.

Description

Technical Field

[0001] The invention belongs to the field of gas water heaters, and in particular relates to a gas supply system for eliminating thermal and acoustic vibrations caused by combustion in gas water heaters. Background Art

[0002] As water heater power has increased in recent years, combustion chambers have become smaller and smaller. The resulting vibrations, caused by the large volumetric heat load, have become increasingly common and severe. Thermoacoustic vibrations associated with water heater combustion have long been a problem for both manufacturers and users. This not only significantly reduces the combustion performance of gas water heaters but also causes damage to key combustion components within the combustion chamber, creating safety hazards and significantly impacting the economic efficiency, safety, and user experience of gas water heaters.

[0003] Numerous researchers have extensively studied the problem of combustion vibration in water heaters. However, due to the extremely complex thermal-acoustic coupling process during combustion, which is influenced by numerous factors, its mechanisms remain largely unresolved. Generally, increasing burner power leads to increased vibration. This is caused by a sudden increase in gas flow, which increases heat release, dramatically raising the temperature within the combustion chamber, and increasing the frequency of the acoustic standing wave, which in turn decreases the wavelength of the acoustic waves within the gas supply pipe. The coupling between the fluctuations in combustion heat release and acoustic pressure can then promote combustion vibration. Furthermore, unpredictable factors such as sudden changes in ambient temperature and water flow can alter the coupling between these fluctuations, which can also contribute to combustion vibration. Currently, major water heater manufacturers address combustion vibration by installing silencers within the combustion chamber casing or exhaust duct to increase system acoustic loss. However, this approach allows system vibration to occur without fundamentally eliminating it. Other researchers have also attempted to improve combustion vibration by modifying the burner structure, but this approach lacks universal applicability and requires the development of specialized, tailored modification technologies for different combustion chamber structures. Our team conducted experimental research on the key technology of passive vibration control of combustion system with flexible and adjustable gas supply pipe length. The results showed that when the length of air and gas supply pipes increases by half the wavelength of sound wave, the change of system vibration state will repeat a cycle, such as Figure 3 and Figure 4 Therefore, by simply making the longest path longer than the shortest path by half a wavelength, the system can be switched between an unstable state and a stable state by switching the paths. Summary of the Invention

[0004] The purpose of the present invention is to provide an air supply system that eliminates the thermal and acoustic vibrations of gas water heater combustion. By setting a variable length air supply pipe and arranging the fan and the air supply pipe outside the gas water heater, it is convenient to inspect and repair the air supply system, effectively controlling the occurrence of gas water heater combustion vibrations, improving the economy and safety of the gas water heater operation, and improving the user experience.

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

[0006] An air supply system for eliminating thermal and acoustic vibrations caused by combustion in a gas water heater, comprising an air supply system and a gas supply system with variable air supply pipe length;

[0007] The air supply system includes a blower, an air flow channel valve, an air flow channel, a burner, and an air supply system controller. The blower's air outlet is connected to the air flow channel, which in turn is connected to the burner's air inlet. The air flow channel is equipped with four bypasses, and the air supply system controller controls the opening and closing of the air flow channel valve in the air flow channel to change the length of the air pipeline.

[0008] The gas supply system includes a gas flow channel valve, a gas flow channel, a burner, and a gas supply system controller. The gas inlet is connected to the gas flow channel, which is in turn connected to the gas inlet of the burner. The gas flow channel is provided with four bypasses. The gas supply system controller controls the opening and closing of the gas flow channel valve in the gas flow channel to change the length of the gas pipeline.

[0009] The vibration sensor is connected to the gas water heater burner to measure the vibration frequency of the gas water heater combustion chamber.

[0010] A further improvement of the present invention is that the intervals A and G between two adjacent bypasses in the air flow channel and the gas flow channel are 1 / 16 of the wavelength of the sound wave in the air pipe and the gas pipe, respectively. Each longer path will be 1 / 8 wavelength longer than the shorter path, and the longest path will be 1 / 2 wavelength longer than the shortest path.

[0011] A further improvement of the present invention is that the wavelength of the sound waves in the air and gas pipes can be estimated based on the frequency of the water heater's vibration and the speed of sound in the air and gas pipes. First, the speed of sound in the air and gas pipes is estimated using the formula: = _ ...

[0012]

[0013] Where: γ is the adiabatic index of the mixed gas; R: gas universal constant 8.314 J·K -1 ·mol -1 ; T is the temperature of the mixed gas, K; M is the molar mass, g·mol -1 .

[0014] A further improvement of the present invention is that γ is selected as 1.3 according to the composition of local household gas.

[0015] A further improvement of the present invention is that the air flow channel valve includes air flow channel valve a, air flow channel valve b, air flow channel valve c, and air flow channel valve d, respectively provided on the four bypass channels of the air flow channel; and the gas flow channel valve includes gas flow channel valve a, gas flow channel valve b, gas flow channel valve c, and gas flow channel valve d, respectively provided on the four bypass channels of the gas flow channel;

[0016] In the working state, the air flow channel valve a and the gas flow channel valve a are opened and closed at the same time, the air flow channel valve b and the gas flow channel valve b are opened and closed at the same time, the air flow channel valve c and the gas flow channel valve c are opened and closed at the same time, and the air flow channel valve d and the gas flow channel valve d are opened and closed at the same time, so that four different lengths of air pipes and gas supply pipes can be obtained.

[0017] A further improvement of the present invention is that, during design and installation, the air and gas flow path that can avoid combustion vibration when the gas water heater vibrates due to factors such as power increase, sudden change in ambient temperature and water volume fluctuation is tested in advance and preset in the gas supply system controller. After the vibration sensor detects the vibration signal, it is transmitted to the gas supply system controller, which controls the opening and closing of the air flow valve and the gas flow valve to switch to the corresponding flow path.

[0018] A further improvement of the present invention is that the gas supply system is connected to the gas water heater with threads; and the gas supply system and the fan are integrated in a closed box, and the position corresponding to the fan air inlet is hollowed out to facilitate air intake.

[0019] A further improvement of the present invention is that the air flow channel adopts stainless steel 304 or 316 light pipe, which is covered with a flame-retardant PVC protective layer.

[0020] A further improvement of the present invention is that the gas flow channels all use stainless steel 304 or 316 smooth tubes, which are covered with a flame-retardant PVC protective layer.

[0021] The present invention has at least the following beneficial technical effects:

[0022] The present invention provides an air supply system for eliminating the thermoacoustic vibrations of combustion in a gas water heater, comprising an air supply system and a gas supply system with a variable gas supply pipe length. Furthermore, the fan and gas supply pipe are arranged outside the gas water heater, facilitating maintenance of the gas supply system. During the design and installation of this system, air and gas flow paths that can avoid combustion vibrations caused by power increases, sudden changes in ambient temperature, and water volume fluctuations are pre-tested and pre-set in the gas supply system controller. A vibration sensor detects the vibration signal and transmits it to the gas supply system controller, which controls the opening and closing of the air and gas flow valves, switching to the corresponding flow paths. Compared to existing technologies, the air supply system disclosed in the present invention for eliminating the thermoacoustic vibrations of combustion in gas water heaters is flexible and controllable, suitable for both fully premixed and partially premixed gas water heaters, and greatly improving the economic efficiency, safety, and user experience of gas water heater operation. After the initial design is completed, no further modification is required; simply controlling the air and gas flow valves to switch the flow paths can address the recurrence of combustion vibrations in the gas water heater caused by changes in operating parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural principle diagram of the present invention.

[0024] Figure 2 This is a structural diagram of the air flow channel and the gas flow channel.

[0025] Figure 3 This is a diagram showing the relationship between the system vibration state and the ratio of the air supply pipe length to the sound wave wavelength when the equivalence ratio is 0.7.

[0026] Figure 4 This is a diagram showing the relationship between the system vibration state and the ratio of the air supply pipe length to the sound wave wavelength when the equivalence ratio is 0.9.

[0027] Description of reference numerals:

[0028] 1 is a fan, 2 is an air flow channel valve, 3 is an air flow channel, 4 is a gas flow channel valve, 5 is a gas flow channel, 6 is a burner, and 7 is a gas water heater; in addition, 2-1 is an air flow channel valve a, 2-2 is an air flow channel valve b, 2-3 is an air flow channel valve c, 2-4 is an air flow channel valve d, 4-1 is a gas flow channel valve a, 4-2 is a gas flow channel valve b, 4-3 is a gas flow channel valve c, 4-4 is a gas flow channel valve d, 8 is a vibration sensor, and 9 is a gas supply system controller. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] like Figure 1 and Figure 2As shown, the present invention provides an air supply system for eliminating thermal and acoustic vibrations of combustion in a gas water heater, comprising an air supply system and a gas supply system.

[0031] The air supply system includes a fan 1, an air flow channel valve 2, an air flow channel 3 and a burner 6; wherein, the air outlet of the fan 1 is connected to the air flow channel 3, and the air outlet of the air flow channel 3 is connected to the air inlet of the burner 6; the air flow channel 3 is provided with 4 bypasses, and the opening and closing state of the air flow channel valve 2 in the air supply system is controlled by the air supply system controller 9 to thereby change the length of the air pipeline.

[0032] The gas supply system includes a gas flow channel valve 4, a gas flow channel 5 and a burner 6; the gas inlet is connected to the gas flow channel 5, and the gas flow channel 5 is connected to the gas inlet of the burner 6; the gas flow channel 5 is provided with 4 bypasses, and the gas supply system controller 9 controls the opening and closing state of the gas flow channel valve 4 in the gas supply system to change the length of the gas pipeline.

[0033] The vibration sensor 8 is connected to the burner of the gas water heater to measure the vibration frequency of the combustion chamber of the gas water heater.

[0034] The air supply system utilizes 304 or 316 stainless steel tubes, which are easily shaped and resist deformation, and are covered with a flame-retardant PVC protective layer. These tubes are threaded into the combustion chamber 7, allowing for easy disassembly and maintenance. Furthermore, the air supply system and fan 1 are integrated into a closed enclosure. The enclosure surface corresponding to the fan 1's air inlet is hollowed out to facilitate air intake.

[0035] The intervals A and G between two adjacent bypasses in the air flow channel 3 and the gas flow channel 5 are 1 / 16 of the wavelength of the sound wave in the air pipe and the wavelength of the sound wave in the gas pipe, respectively. Each longer path will be 1 / 8 of a wavelength longer than a shorter path, and the longest path will be 1 / 2 of a wavelength longer than the shortest path. The wavelength of the sound wave in the air and gas pipes can be estimated based on the frequency of the system vibration and the speed of sound in the air and gas pipes. First, the speed of sound in the air and gas pipes can be calculated using formula (1-1). Second, for a given gas water heater, it often vibrates strongly at a certain frequency f. After the water heater is designed, the vibration frequency f is measured by the vibration sensor 8. Finally, after the gas supply system is designed and manufactured according to the above method, it is equipped on the gas water heater 7 for use.

[0036]

[0037] Where: γ: adiabatic index of the mixed gas; R: gas universal constant 8.314 J·K -1 ·mol -1 ; T: temperature of the mixed gas, K.

[0038] When the system is in use, air flow valve a2-1 and gas flow valve a4-1 are opened and closed simultaneously; air flow valve b2-2 and gas flow valve b4-2 are opened and closed simultaneously; air flow valve c2-3 and gas flow valve c4-3 are opened and closed simultaneously; and air flow valve d2-4 and gas flow valve d4-4 are opened and closed simultaneously. This allows for four different air and gas supply pipe lengths. Engineers pre-tested and determined the air and gas flow paths that can avoid combustion vibrations caused by factors such as power increases, sudden changes in ambient temperature, and water volume fluctuations in the gas water heater, and pre-set these paths into the gas supply system controller 9. Vibration sensor 8 detects vibration signals and transmits them to the gas supply system controller 9, which then controls the opening and closing of air flow valve 2 and gas flow valve 4, switching to the corresponding flow paths.

[0039] In summary, the disclosed gas supply system for eliminating thermoacoustic vibrations associated with combustion in gas water heaters is flexible and controllable, applicable to both fully premixed and partially premixed gas water heaters. After the initial design is complete, no further modifications are required; simply switching the air and gas flow path valves can address recurring combustion vibrations caused by changes in operating parameters.

[0040] It should be understood that this embodiment is only used to illustrate the present invention and is not used to limit the scope of the present invention. In addition, it should also be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, yet, these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A gas supply system for eliminating thermal and acoustic vibrations caused by combustion in a gas water heater, characterized in that: Including an air supply system and a gas supply system with variable gas supply pipe length; The air supply system comprises a fan (1), an air flow channel valve (2), an air flow channel (3), a burner (6) and an air supply system controller (9); wherein the air outlet of the fan (1) is connected to the air flow channel (3), and the air outlet of the air flow channel (3) is connected to the air inlet of the burner (6); the air flow channel (3) is provided with four bypasses, and the air supply system controller (9) controls the opening and closing state of the air flow channel valve (2) in the air flow channel (3) to thereby change the length of the air pipeline; The gas supply system comprises a gas flow channel valve (4), a gas flow channel (5), a burner (6) and a gas supply system controller (9); a gas inlet is connected to the gas flow channel (5), and the gas flow channel (5) is connected to the gas inlet of the burner (6); the gas flow channel (5) is provided with four bypasses, and the gas supply system controller (9) controls the opening and closing state of the gas flow channel valve (4) in the gas flow channel (5) to thereby change the length of the gas pipeline; The vibration sensor (8) is connected to the burner of the gas water heater and measures the vibration frequency of the combustion chamber of the gas water heater.

2. The gas supply system for eliminating thermal acoustic vibration of gas water heater combustion according to claim 1, characterized in that: The intervals A and G between two adjacent bypasses in the air flow channel (3) and the gas flow channel (5) are 1 / 16 of the wavelength of the sound wave in the air pipe and the wavelength of the sound wave in the gas pipe respectively. Each longer path will be 1 / 8 wavelength longer than the shorter path, and the longest path will be 1 / 2 wavelength longer than the shortest path.

3. The gas supply system for eliminating thermal acoustic vibrations of gas water heater combustion according to claim 2, characterized in that: The wavelength of the sound waves in the air and gas pipes can be estimated based on the frequency of the water heater's vibration and the speed of sound in the air and gas pipes. First, the speed of sound in the air and gas pipes is estimated using formula (1-1). Second, for a given gas water heater, it vibrates strongly at a certain frequency f. After the water heater is designed, the vibration frequency f is measured by a vibration sensor (8). Finally, the gas supply system is designed and manufactured according to the above method and then installed on the gas water heater (7). Where: γ is the adiabatic index of the mixed gas; R: gas universal constant 8.314 J·K -1 ·mol -1 ; T is the temperature of the mixed gas, K; M is the molar mass, g·mol -1 .

4. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 3, characterized in that: γ is selected as 1.3 based on the local household gas composition.

5. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 1, characterized in that: The air flow channel valve (2) includes an air flow channel valve a (2-1), an air flow channel valve b (2-2), an air flow channel valve c (2-3), and an air flow channel valve d (2-4) respectively arranged on four bypass channels of the air flow channel (3); the gas flow channel valve (4) includes a gas flow channel valve a (4-1), a gas flow channel valve b (4-2), a gas flow channel valve c (4-3), and a gas flow channel valve d (4-4) respectively arranged on four bypass channels of the gas flow channel (5); In the working state, the air flow channel valve a (2-1) and the gas flow channel valve a (4-1) are opened and closed at the same time, the air flow channel valve b (2-2) and the gas flow channel valve b (4-2) are opened and closed at the same time, the air flow channel valve c (2-3) and the gas flow channel valve c (4-3) are opened and closed at the same time, and the air flow channel valve d (2-4) and the gas flow channel valve d (4-4) are opened and closed at the same time, so that four different lengths of air pipes and gas supply pipes can be obtained.

6. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 1, characterized in that: During design and installation, an air and gas flow path that can avoid combustion vibration when the gas water heater vibrates due to power increase, sudden change in ambient temperature, and water volume fluctuation is tested in advance, and the air and gas flow path is preset in advance in the gas supply system controller (9). After the vibration sensor (8) detects the vibration signal, it is transmitted to the gas supply system controller (9), which controls the opening and closing of the air flow path valve (2) and the gas flow path valve (4) to switch to the corresponding flow path.

7. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 1, characterized in that: The gas supply system is connected to the gas water heater (7) by means of threads; the gas supply system and the fan (1) are integrated into a closed box, and the position corresponding to the air inlet of the fan (1) is hollowed out to facilitate air intake.

8. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 1, characterized in that: The air flow channel (3) is made of stainless steel 304 or 316 light pipe, which is covered with a flame retardant PVC protective layer.

9. The gas supply system for eliminating thermal acoustic vibrations of combustion in a gas water heater according to claim 1, characterized in that: The gas flow passages (5) are made of stainless steel 304 or 316 light pipes, covered with a flame retardant PVC protective layer.

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