Heat pipe is a device with several applications in various industries such as electronics cooling, nuclear and renewable technologies. This apparatus transfers heat from a hot source to a cold one. Thermosyphon is a special type of heat pipe that transmits heat using gravitational forces. Although scholars have performed many experiments on thermosyphon, mostly they were about the thermal characteristics of thermosyphon and rarely the hydraulic specifications of thermosyphon have been investigated. But it is clear that these two specifications (thermal, hydraulic) relate to each other closely and detailed study about their interaction may bring out better results. In this thesis, initially a...