A novel triangular pulsating heat pipe with enhanced heat transfer performance for building energy efficiency

Utilizing renewable energy in buildings is promising for alleviating the energy crisis and environmental pollution problems. Pulsating heat pipes (PHPs) are considered as a good alternative to achieve it due to their simple structure and efficient heat transfer performance. However, recently developed PHPs having a non-vertical orientation require a certain number of turns to initiate operation, which greatly limits its application. To solve this starting-up issue in a single-loop PHP, this study proposes a novel triangular pulsating heat pipe (TPHP). A validated volume of fluid (VOF) model is developed to investigate three important factors on the heat transfer performance including the model structure of the TPHP, the heating temperature and the liquid filling ratio. The results show that the TPHP can achieve heating start-up in non-vertical direction and the heat flow resistance can be reduced by up to 38.04% through a rationalized model structure. The filling ratio influences the heat flow resistance by affecting the flow pattern within the TPHP while the optimum liquid filling ratio is about 50%. This study is critical to broaden the application of single-loop PHP in buildings.