Mipro2012 Proceedings
Sound of boiling as a disturbing noise and as a functional signal Albin Smrke*, Jurij Prezelj**, Peter Šteblaj ***, Iva Smrke**** * MSX d.o.o., Ljubljanska 108,1230 Domžale, Slovenija [email protected] ** Fakulteta za strojništvo, Aškerčeva 6, 1000 Ljubljana, Slovenija [email protected] *** Fakulteta za strojništvo, Aškerčeva 6, 1000 Ljubljana, Slovenija [email protected] **** Smrkearhitekti, Dunajska 43, 1000 Ljubljana, Slovenija [email protected] Abstract Hot or even boiling water is often used in the household. During the process of heating the water, molecules become more and more active. Intensity of their movement depends on the temperature. Moving molecules are bumping into the container and causing audible noise. This audible noise can be regarded as a useful and functional signal on one hand, but some people find it as a disturbing noise. A MSX technology was developed. MSX technology is presented in this article, together with some results of applied active noise control. MSX technology uses a sound sensor for determination of temperature of the water and even more important, the state of boiling itself. Microphone is placed in the base of the kettle and is recording sound. A microcontroller regulates the power of kettle according to calculated algorithm, which is based on the sound signal. The boiling point of the water is the main regulation point and by monitoring the sound, we can detect it much better then by monitoring the thermal sensor, which is commonly used in digital kettles. A new step forward in MSX technology is integration of Active Noise Control algorithm. Such algorithm enables the use of generated noise for control purposes and it attenuates the very same signal with additional loudspeaker. Audible noise is attenuated and almost silent performance of the kettle is achieved.
is with electronic in the kettles body. In the first case the connector is different and also base is complicated with user interface. The second case is made with electronic in the kettle. All these kettles are very expensive. The MSX regulation is simple and very efficient. Only single microphone is placed in the base of the kettle the sound is used in simple electronic to obtain the temperature / sound connected algorithm. On top of MSX base each regular kettle can be used Figure 1. The regulation has also an important possibility to regulate the process on different level of boiling.
I.INTRODUCTION The acronym MSX, which stands for Multi Sensor Approach, is trademark, and the method used is patented. MSX technology uses a sound sensor for determination of temperature of the water and even more important, the state of boiling itself. Regular kettle on the market have only 360 grad connector and bimetal switch for disconnecting electricity from the heater. Vapor from water surface produce steam that travels true the pipes to the bimetal switch and after it reaches the temperature it disconnect the power. The experiments show that the time of disconnecting power is not precise and the result is unnecessary use of energy after water boils. These kettles are not energy efficient because on heating bimetal switch needs time after boiling point is reached. There are two different types of digital kettle on the market. First system is with electronic in the base and Thermometer sensor is in the kettle and second system
MIPRO 2012/CIS
Figure 1: Regular kettle on MSX base
A microcontroller regulates the power of kettle according to calculated algorithm, which is based on the sound signal. The boiling point of the water is the main regulation point and by monitoring the sound, the regulation of boiling is much better than by monitoring the thermal sensor commonly used in digital kettles. The kettle electronic is ready for market and the price of electronic is lower the today PCB in kettles. We achieve
1229
the goal to produce the technology that can be build in all kettles bringing minimum 10% energy saving.
II. BOILLING PROCESS
The boiling phase is monitored. The boiling phase starts when individually isolated bubbles start to appear, denoted with nucleate boiling in Figure 2. During the boiling phase, bubbles appear in jets creating the effect commonly referred to as simmering. Finally, in the fully developed boiling phase (denoted with film boiling in Figure 2), the bubbling of the liquid is generalized, resulting in the familiar turbulence of a boiling liquid. Transition from nucleate boiling to film boiling is not discrete, but uniform as depicted in Figure 2.
Figure 3: Sound pressure signal of cooking process
The formation and collapse of the bubbles during the phases create an acoustic signature, which changes with the size and number of the bubbles, the rate of their formation, their collapse, and the temperature gradient in the liquid. The response includes an audible component, which can be easily observed when cooking, and it has distinctive frequency band 1.[2]
Sound pressure signal [Arbitrary Unit]
Figure 4: Waterfall diagram of cooking process
Time [sec]
Figure 5: Sound signature of kettle is very good for regulating boiling Figure 2: Boiling phases of water
3. MEASUREMENT RESULTS AND DISCUSION A microphone with an integrated preamplifier is fitted to the base of the kettle. Typical Sound produced by heat is depicted in Figure 3 and Figure 4. In Figure 3 the sound pressure signal is presented. Increasing sound pressure amplitude at 75 seconds can be easily observed. Frequency analysis is presented in Figure 4. This frequency range was also found in all our experiments and they are correlated with the formation of end implosions of bubbles. Sound signature of kettle is very good for regulating boiling in shown on Figure 5.
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Experimentally, it was determined that various phases of boiling have distinctive acoustic signatures and that the acoustic signatures are repeatable and robust to many commonly occurring disturbances. Microphone in the base is taking sound samples and microcontroller is regulating the power of kettle according to calculated algorithm settings. The boiling point of the water is the main regulation point. One Example of Heating water in kettle 0,7 lit is depicted on Figure 6.
MIPRO 2012/CIS
MSX software algorithm for definition of temperature derived from sound signature uses for different temperature settings different parameter. Boiling point is defined with P1 and P2. In regular kettle BM is time where bimetal switch turn OFF the electricity.
Figure 7 MSX PCB
P1 P2 BM
The base is modified with holder and white plate on the bottom to cover the bottom of the base and to prevent possible touch with electricity. Single magnet on the housing of the kettles and reed relees in the base make it possible. Figure 8. The level of boiling can be defined from industries. We choose possibility to set up different levels of boiling. LOW .. MIN ..MED.. HIGH ..MAX. Saving of energy is minimum 10%. [4]
Figure 6: measured and calculated data – x axis is time y axis is temperature [1]
Time: P1 = 146 s P2 = 162 s BM = 170 s In case if we choose to regulate on P1 we have 24 s saving what is 14%. The percentage depends on BM switch that is not repeatable defined. On the marked and standard of kettles there is no definition of level of boiling [3]. This makes the presentation of MSX kettle on the market more difficult because boiling is determined under big influence of user’s habits.
For the producer of kettles MSX offers:
Special constructions on interactive interface
For demonstrating technology to companies that produce kettles we built MSX technology in different kettles. MSX have his own hardware profile based on MSX algorithms. The PCB Figure 7 Printed electronic board is placed in the base of kettle. The price power performance is all the time present so we have not expensive electronic board.
MIPRO 2012/CIS
Figure 8 MSX base with LED user interface
MSX kettle development kit
For easy application of MSX technology in the industry we prepare development kit. MSX development kit is based on measuring data, analyzing data, defining parameter, producing software for microprocessor, programming hardware MSX kettle. Included is all hardware for developing, samples of hardware for kettle, programming tools and software for PC. A new step forward in MSX technology is integration of Active Noise Control algorithm. Such algorithm enables the use of generated noise for control purposes and it attenuates the very same signal with additional loudspeaker. Audible noise is attenuated and almost silent performance of the kettle is achieved.
4. ACTIVE NOISE CONTROL SYSTEM IN KETTLES
Figure 9 indicates changes in noise amplitude during different phases of heating the water. Higher frequency noise above 1000 Hz is correlated to formation of small bubbles, which can be correlated to formation of isolated bubbles, which are composed of dissolved gasses in the water.
1231
Sound of water heating with frequencies above 2000 Hz has god signal to noise ratio and can be used as for controlling the cooking process. Sound signal in this frequency range can be directly correlated to the temperature of water during the heating process Lowest frequency range around 125 Hz increases with temperature. Lower frequency noise is associated film boiling, and with big bubbles dynamics.
Impulse response of the control system is relatively very long, and it clearly indicates towards a resonant frequency. This is because the microphone was attached directly on the metal housing. Simulation results of feedback active noise control system in the kettle are presented in Figure 12.
Sound pressure [micro pascal]
Minimum of noise level wit 250 Hz, at 110 sec indicates start of film boiling. High values after 110 sec indicate to strong bubbling in the liquid with big bubbles.
7000 250 Hz
6000 5000 4000
1000 Hz
125 Hz
3000 2000 Hz
2000
500 Hz
1000
145
136
127
118
109
91
100
82
73
64
55
46
37
28
19
1
10
0 Time [sec]
Figure 9: Time chart of different frequency ranges
Figure 10. Frequency response of the kettle as a controlled noise source in comparison to noise spectra generated during the heating and boiling process.
Noise of water heating is around 5000 mPa (70 dBA) at a distance 4 cm away from the kettle. Majority of noise after 80 sec can be assigned to frequency range around 250 Hz. This frequency range can be controlled with active systems. For this purpose a shaker was attached to the bottom of the kettle. In such a way the kettle itself become a sound-generating device. With signal processing, kettle can produce anti noise. Anti noise is noise with the same form as noise, only its phase is inverted. In order to analyze if the idea of integrating the active noise control in the kettle is feasible simulations were performed. Simulations are based on the measured impulse response of the kettle with attached shaker as a sound source. Frequency response of the kettle working as a soundgenerating device is presented in Figure 10.
Results indicate that kettle can produce anti noise levels, which are comparable to noise levels produced by the heating and boiling process. From this point of view it can be used as a controlled noise source. However, its impulse response should be suitable as well. Impulse response of the active noise cancellation system in the kettle is presented in Figure 11.
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Figure 11: Impulse response of the active noise cancellation system in the kettle
Sound cancelation ON
Figure 12: Simulation results of feedback active noise control system in the kettle
MIPRO 2012/CIS
Frequency range noise, after the noise cancellation system is switched on, is presented in figure 12. We can see, that even with a very long impulse response of control element and with distinguished resonant frequency of the control element, some positive effect was achieved in desired frequency range. In order to improve the performance of the ANC system in the kettle some additional work has to be done. First of all, the impulse response of the control element should be improved by using some vibration absorbing material. Efficiency of the kettle, as sound generating device in low frequency range should be improved by using stronger shaker.
5. CONCLUSION Energy conservation achieved by new designs of kettle will have an effect on global energy consumption. Preliminary data shows that decreasing the consumption of energy is possible in the design of cooking consumer appliances. The quality of energy regulation can be improved if the boiling states are identified. Audible sound is a parameter, which has proven to be very helpful in obtaining exact data in identifying the different boiling states. The pattern signature in the sound signal can be easily detected and analyzed to find the algorithm for identifying boiling states. With application of the new proposed methods, we expect savings higher then 20%. Regular kettle becomes all the benefits off the best digital kettle on the market and the production price is only little part of the temperature regulated digital kettle with following Advantages:
MSX can be located in base without connection to the kettle and the production cost is much cheaper
MSX regulation is the only technology in world concentrated on boiling process and only technology that can bring so high savings in comparison with bimetal switch.
MSX technology can be used for simple regulation of “normal” kettle where it replace the bimetal switch and also for most sophisticated definition of different temperature levels and MSX is market ready
MSX kettle with active noise system is the most quite kettle REFERENCES
[1] Bejan, A., et.all, Thermal Design and Optimization; John Wiley & Sons, New York, 1995. [2] Čudina, M., Tehnična akustika.; FS Ljubljana, 2001. [3] Kuščer, I.,: Termodinamika; Društvo mat, fizikov in astronomov, Ljubljana, 1974 Allyn and Bacon, Inc, Boston, 1986 [4] Prelec, Z., Energetika u procesnoj industriji; Školska knjiga, Zagreb,1994. [5] Smrke, A., US Patent 5,951,900, EP 0820573, RUS 97118228, JPN504701, SLO 9600097, SLO 9500106 , Kitajska HM 971678, 1995-2002
MSX technology uses sound sensor for determination of temperature of the water and state of boiling.
MIPRO 2012/CIS
1233
is with electronic in the kettles body. In the first case the connector is different and also base is complicated with user interface. The second case is made with electronic in the kettle. All these kettles are very expensive. The MSX regulation is simple and very efficient. Only single microphone is placed in the base of the kettle the sound is used in simple electronic to obtain the temperature / sound connected algorithm. On top of MSX base each regular kettle can be used Figure 1. The regulation has also an important possibility to regulate the process on different level of boiling.
I.INTRODUCTION The acronym MSX, which stands for Multi Sensor Approach, is trademark, and the method used is patented. MSX technology uses a sound sensor for determination of temperature of the water and even more important, the state of boiling itself. Regular kettle on the market have only 360 grad connector and bimetal switch for disconnecting electricity from the heater. Vapor from water surface produce steam that travels true the pipes to the bimetal switch and after it reaches the temperature it disconnect the power. The experiments show that the time of disconnecting power is not precise and the result is unnecessary use of energy after water boils. These kettles are not energy efficient because on heating bimetal switch needs time after boiling point is reached. There are two different types of digital kettle on the market. First system is with electronic in the base and Thermometer sensor is in the kettle and second system
MIPRO 2012/CIS
Figure 1: Regular kettle on MSX base
A microcontroller regulates the power of kettle according to calculated algorithm, which is based on the sound signal. The boiling point of the water is the main regulation point and by monitoring the sound, the regulation of boiling is much better than by monitoring the thermal sensor commonly used in digital kettles. The kettle electronic is ready for market and the price of electronic is lower the today PCB in kettles. We achieve
1229
the goal to produce the technology that can be build in all kettles bringing minimum 10% energy saving.
II. BOILLING PROCESS
The boiling phase is monitored. The boiling phase starts when individually isolated bubbles start to appear, denoted with nucleate boiling in Figure 2. During the boiling phase, bubbles appear in jets creating the effect commonly referred to as simmering. Finally, in the fully developed boiling phase (denoted with film boiling in Figure 2), the bubbling of the liquid is generalized, resulting in the familiar turbulence of a boiling liquid. Transition from nucleate boiling to film boiling is not discrete, but uniform as depicted in Figure 2.
Figure 3: Sound pressure signal of cooking process
The formation and collapse of the bubbles during the phases create an acoustic signature, which changes with the size and number of the bubbles, the rate of their formation, their collapse, and the temperature gradient in the liquid. The response includes an audible component, which can be easily observed when cooking, and it has distinctive frequency band 1.[2]
Sound pressure signal [Arbitrary Unit]
Figure 4: Waterfall diagram of cooking process
Time [sec]
Figure 5: Sound signature of kettle is very good for regulating boiling Figure 2: Boiling phases of water
3. MEASUREMENT RESULTS AND DISCUSION A microphone with an integrated preamplifier is fitted to the base of the kettle. Typical Sound produced by heat is depicted in Figure 3 and Figure 4. In Figure 3 the sound pressure signal is presented. Increasing sound pressure amplitude at 75 seconds can be easily observed. Frequency analysis is presented in Figure 4. This frequency range was also found in all our experiments and they are correlated with the formation of end implosions of bubbles. Sound signature of kettle is very good for regulating boiling in shown on Figure 5.
1230
Experimentally, it was determined that various phases of boiling have distinctive acoustic signatures and that the acoustic signatures are repeatable and robust to many commonly occurring disturbances. Microphone in the base is taking sound samples and microcontroller is regulating the power of kettle according to calculated algorithm settings. The boiling point of the water is the main regulation point. One Example of Heating water in kettle 0,7 lit is depicted on Figure 6.
MIPRO 2012/CIS
MSX software algorithm for definition of temperature derived from sound signature uses for different temperature settings different parameter. Boiling point is defined with P1 and P2. In regular kettle BM is time where bimetal switch turn OFF the electricity.
Figure 7 MSX PCB
P1 P2 BM
The base is modified with holder and white plate on the bottom to cover the bottom of the base and to prevent possible touch with electricity. Single magnet on the housing of the kettles and reed relees in the base make it possible. Figure 8. The level of boiling can be defined from industries. We choose possibility to set up different levels of boiling. LOW .. MIN ..MED.. HIGH ..MAX. Saving of energy is minimum 10%. [4]
Figure 6: measured and calculated data – x axis is time y axis is temperature [1]
Time: P1 = 146 s P2 = 162 s BM = 170 s In case if we choose to regulate on P1 we have 24 s saving what is 14%. The percentage depends on BM switch that is not repeatable defined. On the marked and standard of kettles there is no definition of level of boiling [3]. This makes the presentation of MSX kettle on the market more difficult because boiling is determined under big influence of user’s habits.
For the producer of kettles MSX offers:
Special constructions on interactive interface
For demonstrating technology to companies that produce kettles we built MSX technology in different kettles. MSX have his own hardware profile based on MSX algorithms. The PCB Figure 7 Printed electronic board is placed in the base of kettle. The price power performance is all the time present so we have not expensive electronic board.
MIPRO 2012/CIS
Figure 8 MSX base with LED user interface
MSX kettle development kit
For easy application of MSX technology in the industry we prepare development kit. MSX development kit is based on measuring data, analyzing data, defining parameter, producing software for microprocessor, programming hardware MSX kettle. Included is all hardware for developing, samples of hardware for kettle, programming tools and software for PC. A new step forward in MSX technology is integration of Active Noise Control algorithm. Such algorithm enables the use of generated noise for control purposes and it attenuates the very same signal with additional loudspeaker. Audible noise is attenuated and almost silent performance of the kettle is achieved.
4. ACTIVE NOISE CONTROL SYSTEM IN KETTLES
Figure 9 indicates changes in noise amplitude during different phases of heating the water. Higher frequency noise above 1000 Hz is correlated to formation of small bubbles, which can be correlated to formation of isolated bubbles, which are composed of dissolved gasses in the water.
1231
Sound of water heating with frequencies above 2000 Hz has god signal to noise ratio and can be used as for controlling the cooking process. Sound signal in this frequency range can be directly correlated to the temperature of water during the heating process Lowest frequency range around 125 Hz increases with temperature. Lower frequency noise is associated film boiling, and with big bubbles dynamics.
Impulse response of the control system is relatively very long, and it clearly indicates towards a resonant frequency. This is because the microphone was attached directly on the metal housing. Simulation results of feedback active noise control system in the kettle are presented in Figure 12.
Sound pressure [micro pascal]
Minimum of noise level wit 250 Hz, at 110 sec indicates start of film boiling. High values after 110 sec indicate to strong bubbling in the liquid with big bubbles.
7000 250 Hz
6000 5000 4000
1000 Hz
125 Hz
3000 2000 Hz
2000
500 Hz
1000
145
136
127
118
109
91
100
82
73
64
55
46
37
28
19
1
10
0 Time [sec]
Figure 9: Time chart of different frequency ranges
Figure 10. Frequency response of the kettle as a controlled noise source in comparison to noise spectra generated during the heating and boiling process.
Noise of water heating is around 5000 mPa (70 dBA) at a distance 4 cm away from the kettle. Majority of noise after 80 sec can be assigned to frequency range around 250 Hz. This frequency range can be controlled with active systems. For this purpose a shaker was attached to the bottom of the kettle. In such a way the kettle itself become a sound-generating device. With signal processing, kettle can produce anti noise. Anti noise is noise with the same form as noise, only its phase is inverted. In order to analyze if the idea of integrating the active noise control in the kettle is feasible simulations were performed. Simulations are based on the measured impulse response of the kettle with attached shaker as a sound source. Frequency response of the kettle working as a soundgenerating device is presented in Figure 10.
Results indicate that kettle can produce anti noise levels, which are comparable to noise levels produced by the heating and boiling process. From this point of view it can be used as a controlled noise source. However, its impulse response should be suitable as well. Impulse response of the active noise cancellation system in the kettle is presented in Figure 11.
1232
Figure 11: Impulse response of the active noise cancellation system in the kettle
Sound cancelation ON
Figure 12: Simulation results of feedback active noise control system in the kettle
MIPRO 2012/CIS
Frequency range noise, after the noise cancellation system is switched on, is presented in figure 12. We can see, that even with a very long impulse response of control element and with distinguished resonant frequency of the control element, some positive effect was achieved in desired frequency range. In order to improve the performance of the ANC system in the kettle some additional work has to be done. First of all, the impulse response of the control element should be improved by using some vibration absorbing material. Efficiency of the kettle, as sound generating device in low frequency range should be improved by using stronger shaker.
5. CONCLUSION Energy conservation achieved by new designs of kettle will have an effect on global energy consumption. Preliminary data shows that decreasing the consumption of energy is possible in the design of cooking consumer appliances. The quality of energy regulation can be improved if the boiling states are identified. Audible sound is a parameter, which has proven to be very helpful in obtaining exact data in identifying the different boiling states. The pattern signature in the sound signal can be easily detected and analyzed to find the algorithm for identifying boiling states. With application of the new proposed methods, we expect savings higher then 20%. Regular kettle becomes all the benefits off the best digital kettle on the market and the production price is only little part of the temperature regulated digital kettle with following Advantages:
MSX can be located in base without connection to the kettle and the production cost is much cheaper
MSX regulation is the only technology in world concentrated on boiling process and only technology that can bring so high savings in comparison with bimetal switch.
MSX technology can be used for simple regulation of “normal” kettle where it replace the bimetal switch and also for most sophisticated definition of different temperature levels and MSX is market ready
MSX kettle with active noise system is the most quite kettle REFERENCES
[1] Bejan, A., et.all, Thermal Design and Optimization; John Wiley & Sons, New York, 1995. [2] Čudina, M., Tehnična akustika.; FS Ljubljana, 2001. [3] Kuščer, I.,: Termodinamika; Društvo mat, fizikov in astronomov, Ljubljana, 1974 Allyn and Bacon, Inc, Boston, 1986 [4] Prelec, Z., Energetika u procesnoj industriji; Školska knjiga, Zagreb,1994. [5] Smrke, A., US Patent 5,951,900, EP 0820573, RUS 97118228, JPN504701, SLO 9600097, SLO 9500106 , Kitajska HM 971678, 1995-2002
MSX technology uses sound sensor for determination of temperature of the water and state of boiling.
MIPRO 2012/CIS
1233
