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igem news – yppc

TABLE 1 COMPARISON OF DIFFERENT SENSORS
performance

type of sensor sensitivity accuracy (non- power size cost total
interrupted) consumption

reed flow switch 1 3 2 1 3 10
hall flow sensor 1 3 1 1 3 9
different pressure sensor 2 2 3 2 1 10
mems pressure sensor 3 1 3 3 2 12
mems flow sensor 3 3 3 3 1 13

sensor selection. This is to ensure TABLE 2 EFFECT ON APPLIANCE RATING AFTER INSTALLATION OF SMART CONTROL DEVICE
the stove ON/OFF status can be
correctly distinguished and avoids any type of gas used Hong Kong town gas Natural gas
interference from other gas appliances.
type of appliance Hotplate Built-in hob Built-in hob

Three per cent of fire pressure supply 1.5 kPa 1 kPa 2 kPa
accidents are related to
cooking appliances, many actual rating 13.89 kW 13.02 9.7 kW
caused by users leaving their actual rating w/ 13.1 kW 12.18 9.42 kW
appliances unattended smart control device

Appliance rating
Drawback of typical sensors within ± 10 per cent Satisfactory –
The stove ON/OFF signal is normally of rated value
monitored by a pressure sensor, in
which the static pressure drops when Appliance Rating ≥85
the stove turns on. However, the static per cent of sum of – Satisfactory
pressure is interrupted if another gas individual burners
appliance such as the water heater
is turned on, which produces a false
signal for the stove status. A flow switch between two points. different sensors based on multiple
was therefore chosen to eliminate this Thanks to this feature, the sensor factors. Score 1 to 3 represents
problem, however the gas flow at low can detect the stove’s ON/OFF status the worst and best performance
flame is not sufficient to trigger the via the temperature difference and accordingly.
switch, meaning sensitivity is limited. prevent any false signals with the help Overall, MEMS flow sensor most suits
of flow directions. the application regardless of cost, even
Features of the MEMS flow sensor Table 1 scores the performance of though it is the most expensive.
The MEMS flow sensor was therefore
adopted, not only because of its compact
size but also due to its high sensitivity. FIGURE 4 GAS VELOCITY IN SMART CONTROL DEVICE WITH FLOW ACCESSORY AT 0.25KW
Normally, a MEMS flow sensor
consists of two thermopiles and a
heater in between. As the gas flows
in either direction, it creates uneven
heat distribution on the surface, thus
the temperature difference is detected

FIGURE 3 CROSS SECTION OF VALVE

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27/01/2022 14:24
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