Field experiment on flow stabilization of working fluid in a top-heat-type thermosyphon

Abstract

Abstract To address the problem of global warming, increasing efforts are being made to use renewable sources of energy, such as solar energy, wind energy, and geothermal energy. However, the effective use remains a major challenge for its sustainable development. In this study, we used a top-heat-type thermosyphon to heat water using solar energy and transport the low-density hot water from the source to the sink (high to low elevation) without an external power source. The transported hot water can be used for cooking, bathing, underfloor heating, and heating homes and buildings, and warming cold springs. However, a disadvantage of top-heat-type thermosyphon is the intermittent flow of the circulating working fluid under low solar radiation. To address this issue, the authors proposed and developed a control system to stabilize the intermittent flow and prevent equipment damage and failure due to the sudden boiling of water. Field experiments were conducted to assess the practicability of the developed controller. The results showed that the controller efficiently converted the intermittent flow of working fluid to continuous flow by reducing the pressure in the buffer chamber and thus lowering the boiling point of the working fluid in the header of the solar collector.