TY - JOUR
TI - Phase angle effect on heat transfer and indicated power of free piston Stirling engine
AU - Munir Umair
AU - Syed Murawat Abbas
AU - Javaid Muhammad Yasar
AU - Waqas Muhammad
AU - Waqas Hafiz Muhammad
JN - Thermal Science
PY - 2024
VL - 28
IS - 6
SP - 4473
EP - 4481
PT - Article
AB - In this work, a transient CFD analysis is performed to analyze the effects posed by changing the phase angle between the displacer and power piston in a free piston Stirling engine. The numerical model that is used for analysis is axisymmetric which contains live engine spaces (expansion and compression space) and dead spaces (heater, regenerator, and cooler). The displacer and power piston movements are defined by a user defined function. The results showed that the com¬pression ratio and pressure wave amplitude are strong function of phase angle and peaked at 120° phase angle. The optimum phase angle is also changing with operating frequency. The suitable phase angle at 80 Hz is the range of 60-70°, but at a lower frequency around 50 Hz, its range is 80-100°. The results also showed that the heat transfer rate at the heater and cooler channels are influenced by the change of phase angle. The heat exchange at the heater and cooler is peaked at 90° and 100° phase angle, respectively. The flow losses from the heater, regenerator and cooler showed a rising trend with phase angle increase. The optimum phase angle was obtained by making a balance between phase angle effects and found the optimum range to be between 60°- 80° for peak power and efficiency.