Method to characterize a thermal diode in saturated steam atmosphere

• Published in: Review of scientific instruments 2020-06, Vol.91 (6), p.065104-065104
• Main Authors: Maier, L. M., Hess, T., Kaube, A., Corhan, P., Fitger, A., Bachmann, N., Schäfer-Welsen, O., Wöllenstein, J., Bartholomé, K.
• Format: Article
• Language: English
• Subjects: Diameters; Ethanol; Heat; Heat pumps; Heat transfer; Heat transmission; Mathematical models; Methanol; Orifices; Pressure sensors; Scientific apparatus & instruments; Temperature gradients; Thermodynamic properties
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/5.0006602

We present a novel measurement method for the characterization of thermal diodes in a saturated steam atmosphere. A measuring setup has been developed in which two pressure sensors are integrated. Using a developed analytical model, the heat flow, the volume flow, and the cracking pressure are determined from the measured absolute pressures and the pressure difference. The analytical model was verified using a flow through an orifice. We first calculated the volume flow through the orifice, with a diameter of 3 mm, using the Reader-Harris equation and then compared it to experimentally determined values. The experimentally determined values showed a discrepancy of 9%. With the measurement setup, we have characterized a check valve developed for magnetocaloric heat pumps, which has a thermally rectifying behavior. The developed check valve consists of three spring arms, which are radially attached to a valve disk. The heat flow through the check valve in the forward direction is 166 W for water, 239 W for ethanol, and 547 W for methanol at a temperature difference of 1 K. In the reverse direction, the heat flow is −0.03 W at a temperature difference of −1 K. For methanol, this corresponds to a rectification coefficient of more than 18 000.