Academic literature on the topic 'Aluminium-ammonia heat pipes'

A novel heat pipe (HP) manufacturing method has been developed based on an additive layer manufacturing technique called “selective laser melting” or SLM. This innovation is expected to benefit current applications of aluminium/ammonia heat pipes in space and terrestrial projects as well as many new HP applications. The project was jointly sponsored by the Northumbria University and Thermacore, a world leading heat pipe manufacturing company in the UK, and formed the feasibility stage of a much larger program in Thermacore aiming to develop the next generation of HPs for space applications. In this project, sinter-style aluminium SLM HPs have been produced and tested to prove their functionality and to provide an overall image of the new production process with regard to the major involved parameters. During the project several properties of the new heat pipes e.g. wick porosity, permeability and pore size; wall density, hardness, vibration resistance and optimum SLM build parameters have also been determined by the existing or especially developed rigs in Thermacore or Northumbria University laboratories including scanning electronic microscope (SEM), vibration table, permeability measurement rig, etc. Converting the SLM products into functional heat pipes involves many other steps which have also been completed and explained. At the end of the project two successful functional samples were obtained and clear and precise answers were found to the project questions. SLM process was proved to be capable of producing functional heat pipes. Functional sinter-style heat pipes are proved to be producible by SLM. A numerical design tool is now available to evaluate SLM produced heat pipes and major challenges of this new HP production process including the density of the solid structures and possible contamination of the materials have been identified. Also a reasonably good overall image of this new HP production process and the new HPs has been provided in this project through the conducted measurements and experiments. The contribution of this project to knowledge is supported by two papers published in prestigious heat pipe journals and one paper presented in the 16th international heat pipe conference.

Abstract Heat dissipation in space applications is very much necessary. For example, a satellite works under an extreme temperature environment depending on the satellite’s position in the orbit. Apart from thermal energy from the sun, the electronic component in the satellite itself generates heat as well. To maintain the temperature of the components within their operational range, a grooved heat pipe (GHP) is one of the best solutions. Within GHP, capillary action plays a major role to transfer the liquid from the condenser side to the evaporator side under a near-zero gravitational environment. This paper focuses on the numerical simulation of heat and mass transfer in GHP for space application. The Computational Fluid Dynamics (CFD) simulation is performed using Ansys Fluent software. The omega-shaped axial micro-channelled GHP made from aluminium is considered for this study. The working fluid in the heat pipe is ammonia. The volume-of-fluid (VOF) multiphase model along with the Lee model equation is used to perform the mass transfer prediction. The effects of different heat load for a 25% filling ratio (FR) are studied. This paper mainly focuses on the fluid flow development in the initial 40s of the GHP operation for a specified percentage of FR and heat load. The CFD simulations give much more insights of the heat and mass transfer phenomena, which would not possible to obtain by experimentation. The results like pressure, velocity, temperature, and volume fraction profiles inside the GHP along the length were studied.