Method to characterize a thermal diode in saturated steam atmosphere

Area of Science:

• Thermodynamics
• Fluid Mechanics
• Materials Science

Background:

• Thermal diodes are crucial for efficient heat management.
• Characterizing their performance, especially in demanding environments like saturated steam, is challenging.
• Magnetocaloric heat pumps require advanced components like thermally rectifying check valves.

Purpose of the Study:

• To develop and validate a novel measurement method for thermal diodes in saturated steam.
• To characterize the thermal rectification behavior of a newly designed check valve.
• To determine key parameters like heat flow, volume flow, and cracking pressure.

Main Methods:

• A custom measuring setup with integrated pressure sensors was developed.
• An analytical model was employed to calculate heat flow, volume flow, and cracking pressure.
• The model's accuracy was verified using flow through an orifice, showing a 9% discrepancy.
• The check valve's thermal performance was tested with water, ethanol, and methanol.

Main Results:

• The measurement method successfully characterized a check valve for magnetocaloric heat pumps.
• Forward heat flow values were 166 W (water), 239 W (ethanol), and 547 W (methanol) at a 1 K temperature difference.
• Reverse heat flow was -0.03 W at a -1 K temperature difference.
• Methanol exhibited a rectification coefficient exceeding 18,000.

Conclusions:

• The novel measurement method is effective for characterizing thermal diodes in saturated steam.
• The developed check valve demonstrates excellent thermal rectification, suitable for magnetocaloric heat pumps.
• The findings contribute to the advancement of efficient heat transfer technologies.