Details

Autor(en) / Beteiligte

• Tecchio, C.
• Oliveira, J.L.G.
• Paiva, K.V.
• Mantelli, M.B.H.
• Galdolfi, R.
• Ribeiro, L.G.S.

Titel

Geyser boiling phenomenon in two-phase closed loop-thermosyphons

Ist Teil von

• International journal of heat and mass transfer, 2017-08, Vol.111, p.29-40

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2017

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• •Geyser boiling can eventually yield intense evaporator accelerations in loop-thermosyphons.•Acceleration amplitudes up to 110 and 1100m/s2 were observed for filling ratios of 0.5 and 0.9, respectively.•In thermosyphon unsteady regime, geyser occurs for heat fluxes less than 20kW/m2 and vapor pressures less than 25kPa.•In thermosyphon steady-state regime, geyser occurs for heat fluxes higher than 12.5kW/m2 and vapor pressures below 25kPa. Geyser boiling is experimentally investigated in two-phase closed loop-thermosyphons, consisting of two parallel condensers and a shared evaporator. Heat sink conditions at each condenser vary from forced to natural convection in a multitude of thermal arrangements. A cartridge resistance provides input power ranging from 0.1 to 0.85kW to the evaporator. Water is employed as working fluid with filling ratios of 0.5 and 0.9. The effects of thermal conditions in both condensers, filling ratio, heat flux and vapor pressure on geyser boiling phenomenon are investigated. Geyser boiling eventually yields intense evaporator vibrations inferred by acceleration measurements. The ratio of convective thermal resistances acting at each condenser affects the acceleration. Amplitudes up to 110 and 1100m/s2 were observed for filling ratios of 0.5 and 0.9, respectively. In unsteady regime, geysering occurs for heat fluxes less than 20kW/m2 and vapor pressures less than 25kPa. The vapor pressure is increased with increasing heat flux, suppressing geyser boiling intensity. In steady-state regime geyser boiling occurs for heat fluxes higher than 12.5kW/m2 and vapor pressures below 25kPa.