Capillary Jet Loop performance in parabolic flight

In this study, a prototype Capillary Jet Loop Heat Pipe partially filled with R1233zd(E) has been tested to investigate its thermal behaviour on board of parabolic flights where gravity condition changes in the range from 0 to 1.8 g level with a 22 s window of microgravity. The device has been tested both in horizontal and vertical orientations, varying the thermal load provided to the evaporator from 40 W to 180 W. With power higher than 100 W, the device operated in stationary conditions during hypergravity and normal gravity periods. During the microgravity periods, the device has always shown a sharp increase in pressure and temperatures, reducing temporarily the transport capability of the CJL and fast recovery when gravity increases again. Each series of power level results is presented and discussed in terms of temperature, pressure, and temperature difference from the saturation temperature. The thermal power dissipated by the condenser and an estimation of the condensing flow rate have been calculated from the condenser cooling water inlet and outlet to highlight the Capillary Jet Loop operating phenomena. The temperature of the ejector's primary, secondary, and mixing flows (vapour jet pump) are compared for both configurations.