Influence of ultrasound to convectional heat transfer with fouling of cooling water

• A double-tube heat exchanger and an ultrasonic device were precisely combined.
• Effects of properties of cooling water to fouling were investigated with ultrasound.
• The parameters of ultrasound were studied to convective heat transfer and fouling.
• The cavitational effect to antifouling was analyzed for present results.

Experimental study was conducted to investigate antifouling effect of ultrasound to convective heat transfer process with cooling water as working fluid in different hardness and temperature. An ultrasonic treatment device was preinstalled before a double-tube heat exchanger. The ultrasound was applied and controlled in the range of 28–40 kHz in frequency and 25–50 W in power. A remarkable effect of antifouling was observed from experimental results of heat transfer process with ultrasonic treatment. There was lower fouling resistance which means better antifouling effect in lower frequency of 20 kHz than that in higher frequency of 40 kHz. But a contrary result was observed for ultrasonic power, i.e. a higher antifouling rate was reached with the high power of 50 W ultrasound.