Experimental demonstration of the performance of the novel thermosyphon heat transport device and comparison with CFD predictions

Thermosyphon heat transport device (THTD) is a novel system operating on the principle of single-phase natural circulation driven by density difference and is significantly different from a heat pipe wherein the flow is pressure driven. The present experimental and numerical analyses deliberate the heat transportation capability of THTD and its flow phenomena, which are linked to the operating conditions viz. Power, heating length, and flow rate of coolant. Experiments confirmed the instability for the entire range of parameters tested as a chaotic oscillation of temperature rise across the heater and temperature drop across the cooler is seen. Additionally, the temperature rise across the heater was found to be significantly larger than the temperature drop across the cooler, indicating the flow is not purely unidirectional natural circulation flow, which was further confirmed by CFD simulations. It also revealed that the unstable flow pattern is a unidirectional flow with a recirculation loop in the cooler, which has both downward and upward flows. The extent of downward flow is found to depend on the operating conditions. Further, the unidirectional flow is observed in the entire cold leg, heated section, and near to the inner adiabatic wall along the hot leg and the cooler. The essence of the study is that despite the unstable nature of flow for the entire range of parameters tested, the heat transport capability of THTD is uninterrupted.