Impact of microchannel wall temperature distribution on the flow and transmission behaviors in hydrogen Knudsen pumps

Uneven heat flux and non-uniform microchannels result in varying temperature distributions within the microchannel, affecting flow and transmission behaviors. Therefore, investigating flow and transmission behaviors under different temperature distributions is essential. This study establishes a three-dimensional numerical model of the Knudsen pump with non-uniform temperature distribution along the wall. The effects of temperature distributions on flow behavior and transmission performance are analyzed. Results show that temperature variations lead to opposite pressure distributions in the microchannel. For conditions with a large outlet temperature gradient, a negative pressure of −25 Pa is generated, whereas a positive pressure of 30 Pa forms with a larger inlet temperature gradient. Negative pressure promotes hydrogen flow, improving transmission performance by 5.4%. Additionally, when a temperature lower than the low-temperature container exists in the microchannel, a low pressure of −93 Pa is generated, enhancing transmission capacity by 9.6% compared to uniform temperature gradient conditions. This study provides theoretical support for regulating the flow and transmission of hydrogen in Knudsen pumps through temperature control.