Simulation Study On Heat Transfer Performance Of Two-phase Closed Thermosyphon For Geothermal Extraction

The planet earth has large geothermal energy reserves,however,the geothermal utilization is poor,and the existing model has certain disadvantages.The study about two-phase closed thermosyphon for geothermal extraction is of great significance.Experimental study on the performance of two-phase closed thermosyphon between R1234 ze and R245 fa.Transient simulation model of 3 meters long two-phase closed thermosyphon has been established by Sinda/Fluint software with R245 fa as working fluid,and the simulation results were compared with the experimental results.Base on this model,the effects of relevant factors,including heat source temperature,cooling water flow rate and temperature,condenser and adiabatic length,filling rate,pipe diameter,have been investigated on heat transfer performances of two-phase closed thermosyphon in the range of 30-100?.The running performance of long thermosyphon has also been predicted.In order to further explore the efficient thermosyphon,a new type of two-phase closed thermosyphon model has been built.To R1234 ze,the experimental results show that the heat transfer coefficient is higher than R245 fa,but both heat load are nearly the same.The simulation results have been compared with the experimental results,and good correspondence confirms that the model is accurate and reliable.Rely on the Sinda/Fluint simulation model,3m,60 m,100m and 150 m,the operational parameters of thermosyphon under different working condition obtained,then the performance prediction and optimization can be completed.Under the same conditions of heat pipe size and operating parameters,the new type of two-phase closed thermosyphon is superior to common two-phase closed thermosyphon in heat efficiency,which is worth further exploring.