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EXPERIMENTAL APPARATUS FOR MEASUREMENT OF DENSITY OF SUPERCOOLED WATER AT HIGH PRESSURE
Hrubý, Jan ; Hykl, Jiří ; Peukert, Pavel ; Šmíd, Bohuslav
Thermodynamic behavior of supercooled water (metastable fluid water existing transiently below the equilibrium freezing point) at high pressures was subject to many recent theoretical studies. Some of them assume that a second critical point of water exists, related to two liquid phases of supercooled water: the low-density liquid and the high-density liquid. To test these theories, an original experimental cryogenic apparatus is being developed. The volume changes are measured optically in custom-treated fused-silica capillary tubes. The capillaries are placed in a metal vessel designed for pressures up to 200 MPa. The vessel is connected to a circulation thermostat enabling a rapid change of temperature to prevent freezing. A new high-vacuum device was developed for degassing of the ultrapure water sample and filling it into the measuring capillaries. The experiments will contribute to fundamental understanding of the anomalous behavior of water and to applications in meteorology, aerospace engineering, cryobiology etc.
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Measurement of heat transfer on an experimental exchanger with a specially-shaped capillary tube
Peukert, Pavel ; Hrubý, Jan
First results were evaluated from tests with a new experimental condensation heat exchanger with a corrugated capillary tube. Several measurements were performed at different inlett steam pressure levels (from 2.3 to 7.4 bar) and different flow velocities on the cooling side of the tube. One of the goals is to observe the effective length of the corrugated tube. The second objective is determining the dependence on the flow velocity of the cooling water. Klíčová slova: condensation heat exchanger, minichanel tube heat
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Nová laboratorní parní zkušební trať
Peukert, Pavel ; Hrubý, Jan
A novel laboratory steam test rig is being developed. It is intended primarily for the following purposes: i. development and testing of probes for sampling dry steam to determine heterogeneous nuclei in the steam, ii. study of liquid-vapor transport of admixtures in boiling, iii. study of heat transport in boiling and condensation processes, especially methods of heat transfer enhancement. The test rig allows accurate adjustment of the mass flow up to 0.25 kg per minute and adjustment of pressure up to 34 MPa and temperature up to 400°C. In the present stage, the pressure is limited to 4 MPa.
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