Performance of stationary and vibrated thermosyphon working with water and R134a

An experimental apparatus of a two-phase closed thermosyphon has been designed and constructed to predict its performance characteristics under stationary and vibrated conditions. Water and R134a are used as working fluids. Experiments are carried out over wide ranges of liquid fill ratio (0.4, 0.5, 0.6 and 0.8), length of adiabatic section (275, 325 and 350 mm), vibration frequency (0.0–4.33 Hz) and input heat flux (160–2800 kW/m2). The results showed that adiabatic length of 350 mm and liquid fill ratio of 0.5 provide the highest output heat flux. The effect of vibration is to deteriorate the water-copper thermosyphon performance below the boiling limit by 5–20% and enhance it at the onset of boiling limit by almost the same ratio over the examined range of input heat flux. Minor or no effect is experienced with R134a below the boiling limit and enhancement up to 250% existed above the boiling limit.