Anti-dry burning strategy of thick film heater of purifying machine

Stainless steel thick film heating tube as the core parts of instant desktop drinking machine, with the electronic control board to achieve the functions of 3 seconds of instant heat, accurate temperature regulation, at the same time, its anti-dry burning control is also very key, the following share several common anti-dry burning control strategies for reference.

1. prevent dry burning without water

1.1 Flowmeter: there is a flowmeter in the electronic control system. When the water flow is detected, it is allowed to turn on the heating. The cost is slightly higher, suitable for special requirements of the models, now most of the hot models are no longer used.

1.2 according to the water temperature response time determine whether dry: electronic control system with cold water and hot water temperature probe temperature probe, such as when set the water temperature 95 ℃, the cold water temperature is 25 ℃, open for 5 seconds after heating test did not reach the actual water temperature 60 ℃, anhydrous dry can be judged, while to control board to cut off the thick film heating tube power supply. The corresponding protection value of each outlet water temperature is also different, which should be adjusted according to the different power, response speed and electric control algorithm of thick film heating tube.

2.Prevent water dry burning

According to the water outlet temperature to judge whether there is water drying boiling. Generally, the maximum outlet water temperature set by the instant drinking machine does not exceed 95℃. If the outlet water temperature detected by the hot water temperature probe is greater than 103℃ or 105℃, the power supply of the heater should be cut off. This protection value should also be set by considering the accuracy of the hot water temperature probe, the distance between the hot water temperature probe and the outlet of the heating pipe and other factors.

3. Pipe wall patch thermistor

Some electronic control engineers like to use welding or pressing thermistor on the surface of the heating tube to monitor the temperature of the heating tube surface or indirectly calculate the temperature of hot water, it can also be used to do dry burning control. The cost is slightly higher, and the high temperature resistance of solder is limited. There is a certain probability of failure of this scheme, which will lead to the alarm of the whole machine and affect the customer experience.