Experimental analysis of gravitational heat pipe using R507 as a working fluid

The paper presents possibility of using R507 as a working fluid in gravitational heat pipe. The outcome of experimental analysis are compared to the results obtained with mathematical model. The simulations allow to calculate fluid and wall temperatures in the thermosyphon. The model equations contain the formulas for boiling and condensing heat transfer coefficients. Proposed new model is in good agreement with real operation of the device, especially at the steady state. There are discrepancies during the start-up process, but the differences between the results obtained by the model and experiments do not exceed 5% at the steady state. The thermal efficiency of the thermosyphon is also determined as 0.63.