Numerical study to recover low-grade waste heat using pulsating heat pipes and a comparative study on performance of conventional pulsating heat pipe and additional branch pulsating heat pipe

Abstract

To understand the low-grade waste heat recovery ability of a pulsating heat pipes (PHPs) with water as working fluid. A two-dimensional conventional pulsating heat pipe (C-PHP) and an additional branch pulsating heat pipe (AB-PHP) were simulated using computational fluid dynamics and the volume of fluid method. Results revealed that based on the wall heat flux at condenser walls the waste heat recovery capability of the AB-PHP is 11% more than that of the C-PHP. Current work also presented the outcomes of a numerical simulation that compared the performance of AB-PHP with C-PHP. The comparison is made based on the flow and thermal performance by maintaining constant wall temperature at various filling ratios (FR) and tilt angles (TA). To understand the flow performance of PHP’s mean fluid flow velocity is used. Owing to the additional driving force provided by the additional branch the maximum mean flow velocity of AB-PHP is 1.16 times that of C-PHP. To understand the thermal performance of PHP’s temperature gradient of working fluid is used. In AB-PHP, the minimum fluid temperature gradient is observed at 50% FR and 90^° TA. AB-PHP had a 21.6%, 11.5%, 9.3%, and 6% lower temperature gradient than C-PHP at 90^°, 60^°, 45^°, and 30^° TA, respectively.

Keywords:

• Filling ratios and tilt angles
• fluid temperature gradient
• low-grade waste heat recovery
• mean flow velocity
• pulsating heat pipe