Subcooling

About: Subcooling is a research topic. Over the lifetime, 6150 publications have been published within this topic receiving 99125 citations.

Apparatus having refrigeration cycle

Abstract: In an apparatus having a refrigeration cycle, the refrigeration cycle is formed by annularly connecting a compressor, a condenser, an expansion device and an evaporator with one another, the apparatus uses propane, isobutane or ethane as a refrigerant, and uses refrigerating machine oil having less mutual solubility with the refrigerant, and a dryer is provided in the refrigeration cycle for absorbing water. In stead of the dryer, an additive which reacts with water may be included in said refrigerating machine oil. With this arrangement, the amount of the refrigerant can be reduced, and the long term reliability of the apparatus can be obtained.

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity

Abstract: The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83% by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/sq m). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 C, respectively. The boiling process during the entire heating period, as well as the jet-induced mixing process for the first 2 min of the mixing period, was also recorded on video. The unique features of the experimental results are the sustainability of high liquid superheats for long periods and the occurrence of explosive boiling at low heat fluxes (0.86 to 1.1 kW/sq m). For a heat flux of 0.97 kW/sq m, a wall superheat of 17.9 C was attained in 10 min of heating. This superheat was followed by an explosive boiling accompanied by a pressure spike of about 38% of the tank pressure at the inception of boiling. However, at this heat flux the vapor blanketing the heating surface could not be sustained. Steady nucleate boiling continued after the explosive boiling. The jet-induced fluid mixing results were obtained for jet Reynolds numbers of 1900 to 8000 and Weber numbers of 0.2 to 6.5. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number.

Energy analysis of dedicated and integrated mechanical subcooled CO2 boosters for supermarket applications

Abstract: Energy improvements offered by dedicated and integrated mechanical subcooling systems in CO2 booster systems for supermarket applications are analyzed here through the use of thermodynamic models close to reality. Using a reference supermarket with 41 kW and 140 kW thermal loads at low and medium temperature, respectively, and considering as state-of-the-art system the CO2 booster with parallel compressor and flash gas by-pass, it has been concluded that both systems allow to reduce energy consumption. However, its operation is highly dependent on environmental conditions. The dedicated mechanical subcooling system offers annual energy reductions for tempered places from 1.5% to 2.9%, for warm between 2.9% and 3.4% and for hot from 3.0% to 5.1%. The integrated subcooling system obtains reductions between 3.1% and 4.0% for cold regions, from 1.4% to 2.9% for tempered, from 2.9% to 3.4% for warm and from 1.3% to 2.4% for hot regions.