Experimental study of vapor-dynamic thermosyphon for thermal regulation of accumulators and thermal transformers thermal control

Аuthors

Tsitovich A. P.^*, Kanonchik L. E.^*

A. V. Luikov Heat and Mass Transfer Institute of NAS of Belarus, 15 P. Brovka Str., Minsk, 220072, Belarus

*e-mail: atsitovich@hmti.ac.by

Abstract

The paper describes a new vapor-dynamic thermosyphon with a long condenser and miniature U-shaped heat exchanger. The thermosyphon serves to thermal control of gas accumulators and heat transformers sorbers (heat pumps, refrigerators etc.). Sorbers’ thermal control allows obtaining large amounts of retained gas in gas accumulators and fast cycles in heat transformers with higher heat fluxes.

The total length of the setup is 1060 mm, with the height of 190 mm and width of 50 mm. The outer diameter of the thermosyphon condenser is 16 mm. The U-tube outer diameter is 4 mm. The setup material is stainless steel, and the coolant is water.

The article describes the processes occurring in the system while the setup’s operation.

At the phase of heating, the system operates like a conventional vapor-dynamic thermosyphon. Fr om the evaporator the vapor enters the condenser wh ere it releases heat to the sorbent material at the condenser wall. Then the condensed liquid returns to the condenser due to the gravity force. The design of the vapor-dynamic thermosyphon allows low temperature difference along the surface of the condenser wall.

At the phase of cooling, the heat passes from the condenser wall to the U-shaped tube in radial direction. Then the U-shaped tube draws the heat off the system in the longitudinal direction. If the initial temperature of the cooling phase is high, then the short-term coolant blocking may occur at the beginning of this phase.

The experiments reveal that the thermosyphon operates successfully at thermal loadings up to 500 W and temperatures up to 260ºC. The effectiveness of the U-tube heat exchanger is 0.85. Thermal resistance of the thermosyphon is within the range of 0.05–0.2 K/W. The sorber heating time is 2000 s, and cooling time is 1000 s.

Based on the data obtained, conclusions were made on the advantages of a new thermosyphon over conventional systems. A U-shaped tube inclusion into the condenser of vapor-dynamic thermosyphon allows heat transfer not only in one direction as in conventional thermosyphon. A high heat transfer allows also employ short cycles in gas accumulators charging, and higher heat transformers effectiveness with short operation cycles.

Keywords:

sorbent, vapor-dynamic thermosyphon, thermosyphon, heat exchanger, heat transformers, gas accumulator

References

1. Vasil’ev L.L., Kanonchik L.E. Organizaciya aktivnogo sorbcionnogo ob"ema termoreguliruemoj sistemy hraneniya vodorodsoderzhashchego gaza [Organization of an active sorption volume of temperature-controlled storage system of hydrogenous gas]. Teplovye processy v tekhnike – Thermal processes in engineering, 2013, vol. 5, no. 3, pp. 124–130. In Russ.

2. Alyousef Y., Antukh A.A., Tsitovich A.P., Vasiliev L.L. Three adsorbers solar cooler with composite sorbent bed and heat pipe thermal control. Applied Thermal Engineering, 2012, vol. 38, pp. 124–130.
   

3. Vasiliev L. L. , Vasiliev L. L. Jr. Heat transfer enhancement using heat pipes and thermosyphons with nanotechnologies. Proceedings of 11 International Heat Pipe Symposium. June 9–12, 2013. Beijing, China, 2013, pp. 37–47.

4. Vasiliev L.L., Grakovich L.P., Rabetsky M.I., Vassiliev L.L. Jr., Zhuravlyov A.S. Thermosyphons with innovative technologies. Applied Thermal Engineering, 2017, vol. 111, pp. 1647–1654.