A comparative investigation of heat transfer capacity limits of heat pipes

Küçük, Sinan
Heat pipe is a passive two phase device capable of transferring large rates of heat with a minimal temperature drop. It is a sealed tube with a wick structure lined in it and with a working fluid inside the tube. It consists of three parts: an evaporator, a condenser and an adiabatic section. The heat pipes are widely used in electronics cooling and spacecraft applications. Although they can transfer large rate of heat in a short range, they have operating limits, namely: the capillary limit, the viscous limit, the entrainment limit, the sonic limit and the boiling limit. These limits determine the heat transfer capacity of the heat pipe. The properties of the working fluid, the structure of the wick, the orientation of the pipe, the length and the diameter of the tube etc. are the parameters that affect the limits. In this study, an analytical 1-D heat pipe model is formed and a computer code is prepared in order to analyze the effects of the parameters on the heat transfer capacity of a heat pipe. Water, Ammonia and Mercury are investigated as working fluids for different operating temperature ranges. The software is tested for a typical application for each working fluid.


Tijsseling, Arris S.; Hou, Qingzhi; Bozkuş, Zafer (2014-07-24)
An improved one-dimensional (1D) model - compared to previous work by the authors - is proposed which is able to predict the acceleration and shortening of a single liquid slug propagating in a straight pipe with a downstream bend. The model includes holdup at the slug's tail and flow separation at the bend. The obtained analytical and numerical results are validated against experimental data. The effects of the improvement and of holdup are examined in a parameter variation study.
ÇAĞLAR, AHMET; Yamali, Cemil (Begell House, 2019-01-01)
Heat transfer enhancement inside the adsorbent bed of a thermal wave adsorption cooling cycle is investigated both experimentally and theoretically. Various adsorbent materials are tested using a finned tube adsorbent bed for the thermal wave cycle. The mathematical model is well defined, including a 2-D coupled heat and mass transfer analysis. This study presents the effects of heat transfer fluid velocity, regeneration temperature, condenser pressure, and particle diameter on the heat transfer enhancement...
Analysis of single phase convective heat transfer in microtubes and microchannels
Çetin, Barbaros; Yüncü, Hafit; Department of Mechanical Engineering (2005)
Heat transfer analysis of two-dimensional, incompressible, constant property, hydrodynamically developed, thermally developing, single phase laminar flow in microtubes and microchannels between parallel plates with negligible axial conduction is performed for constant wall temperature and constant wall heat flux thermal boundary conditions for slip flow regime. Fully developed velocity profile is determined analytically, and energy equation is solved by using finite difference method for both of the geometr...
A new approach to thin film evaporation modeling
Akkuş, Yigit; Dursunkaya, Zafer (2016-10-01)
Heat pipes which use phase change heat transfer mechanism and can carry large amounts of heat, are preferred in the cooling of high heat dissipating electronic components due to the fact that they are self-operating devices with ease of manufacturing for different geometries and ability of performance in micro-gravity applications. Heat pipes having rectangular micro channels as wick structure are used in many studies because of the relative ease of developing analytical and numerical solutions to problems ...
A novel approach to condensation modeling at the fin top of a grooved heat pipe
Akdağ, Osman; Dursunkaya, Zafer; Department of Mechanical Engineering (2019)
Phase-change passive heat spreaders have the capability of carrying large amounts of heat from a heat source to a heat sink creating a small temperature difference. One common type of the passive heat spreaders is the heat pipes. The liquid flow inside a heat pipe is driven by the capillary pressure gradient created by a wick structure on the inner wall, which may be in the form of grooves, sintered grains or wire meshes. In the literature, grooved heat pipes are the most studied ones for modeling and exper...
Citation Formats
S. Küçük, “A comparative investigation of heat transfer capacity limits of heat pipes,” M.S. - Master of Science, Middle East Technical University, 2007.