University of Twente Student Theses

Login

Characterization of the Onset of Boiling for Ammonia in Minichannels

Luten, T. (2022) Characterization of the Onset of Boiling for Ammonia in Minichannels.

[img] PDF
21MB
Abstract:The temperature of an aircraft or spacecraft heat load can be controlled by a two-phase mechanically pumped loop (MPL) thermal management system. A two-phase MPL thermal management system is an emerging cooling technique for the aerospace industry, for instance for hydrogen fuel cells or power electronics. The boiling process plays a critical role in the heat transfer from the heat load to fluid in a two-phase MPL. However, the onset of the boiling process in the evaporator is not yet fully understood and superheated liquid may show up at the beginning of the evaporator. In this research, it is investigated whether it is possible to reduce the superheated liquid temperature and to improve the onset of boiling by adding non-condensable gases (NCGs) to a two-phase system. Experiments verified that superheated liquid is exhibited at relatively low heat fluxes on the evaporator in combination with a low saturation temperature. The tests presented here were carried out with ammonia as a refrigerant at saturation temperatures of 40, 60 and 80 ◦C. The heat flux range was from 1 to 20 W/cm2 and a laminar mass flow of 0.1 g/s is used. The hypothesis that dissolved gasses affect the boiling process has neither been confirmed nor disproved by the carried-out experiments.
Item Type:Essay (Master)
Clients:
Royal Netherlands Aerospace Centre, Marknesse, The Netherlands
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Link to this item:https://purl.utwente.nl/essays/93859
Export this item as:BibTeX
EndNote
HTML Citation
Reference Manager

 

Repository Staff Only: item control page