1 / 4

An OHP consists of a capillary sized tube and a refrigerant.

Oscillating (Pulsating) Heat Pipes. An OHP consists of a capillary sized tube and a refrigerant. Most OHPs are formed in closed serpentine loops with multiple turns, but OHPs can operate in other configurations Closed End (serpentine but not looped) Open End

hisa
Download Presentation

An OHP consists of a capillary sized tube and a refrigerant.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Oscillating (Pulsating) Heat Pipes • An OHP consists of a capillary sized tube and a refrigerant. • Most OHPs are formed in closed serpentine loops with multiple turns, but OHPs can operate in other configurations • Closed End (serpentine but not looped) • Open End • The tube is evacuated then partially filled with the working fluid • Capillary forces create a natural separation of liquid slugs and vapor plugs. Khandekar ‘04

  2. Operating Regimes Static Slug/Plug distribution, generation of small bubbles at high temps. similar to nucleate boiling Critical Heat Flux Oscillatory slug/plug flow develops in individual loops Heat flux ‘Stable’ oscillations develop, amplitudes increase with increasing heat flux, and oscillations in multiple tubes come into phase with one another -direction is arbitrary and periodically changes (more so with lower heat flux) -local oscillations superimposed on system oscillation Annular flow develops in fluid traveling from the evaporator to condenser • References • Khandekar, S., 2004, “Thermo-hydrodynamics of Closed Loop Pulsating Heat Pipes,” Institut fur Kernenergetik und EnergiesystemederUniversitat Stuttgart. • Ma., H. B., Borgmeyer, B., Cheng, P., Zhang, Y., 2008, “Heat Transport Capability in an Oscillating Heat Pipe,” Journal of Heat Transfer, 130(8), pp. 81501-1-7. • Borgmeyer, B., 2005, “Theoretical Analysis and Experimental Investigation of A Pulsating Heat Pipe for Electronics Cooling,” Master’s Thesis, University of Missouri-Columbia.

  3. Modeling • OHP modeling has focused on the “simpler” slug/plug flow regime • Multiple modeling approaches have been tried • Chaos • Continuity, Momentum & Energy • Spring-Mass-Damper • Non-Dimensional Analysis • Artificial Neural Networks • Our model has its roots in the spring-mass-damper models presented by Ma, Borgmeyer, et al.2,3 • EES/MATLAB based thermo-hydrodynamic model of an OHP operating in slug-plug flow. Evaporator Adiabatic Region Condenser . Q Tc Vapor Plug Liquid Slug

  4. The OHP Advantage and Project Goals • Advantages • OHPs are simpler/lighter than other two-phase heat transfer devices • No wick • No additional fluid reservoir • OHPs may be more robust? • Dry-out problems, while not extensively studied, do not appear to be a major problem…OHPs may be able to handle higher heat fluxes (convective heat transfer vs. phase change) • May be used as a thermal switch • Disadvantages • Lower effective conductance than Capillary Pumped Loops and Loop Heat Pipes Project Objective: Further the development of the technology/understanding required for successful implementation of an OHP in spacecraft thermal control applications. Approach: theoretical and experimental Deliverable: OHP design guidelines and a physics-based, but semi-empirical, model suitable for design

More Related