Download or read book A Universal Mass Flowrate Correlation for Refrigerants and Refrigerant oil Mixtures Flowing Through Short Tube Orifices written by William Vance Payne and published by . This book was released on 1997 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1997 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two phase Flow of Two HFC Refrigerant Mixtures Through Short tube Orifices written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1996 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boiling and Condensation Heat transfer correlations for Flows of Refrigerant oil Mixtures Inside Augmented Tubes written by Ghayyurul Iman Usmani and published by . This book was released on 1995 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two phase Pressure Drop and Flow Regime of Refrigerants and Refrigerant oil Mixtures in Small Channels written by Brandon S. Field and published by ProQuest. This book was released on 2007 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: As microchannel heat exchangers have become more sophisticated in their design, more exact understanding of the flow inside them is necessary. A decrease in diameter enhances the heat transfer (which takes place at the inner walls of the tubes), but also increases the pressure drop (as the diameter decreases, it becomes like drinking a milkshake through a coffee stirrer). The inclusion of even small amounts of oil in circulation can have a significant effect as well. Historical correlations and studies of two-phase flow have been shown to be insufficient for predicting pressure drops in the smaller channels, due to the different fluid physics that are relevant in flows of small diameter. This study is aimed at understanding the fluid property effects that contribute to pressure drop and flow regime. Two-phase pressure drop data for four refrigerants (R134a, R410A, R290 and R717) were measured in a channel with hydraulic diameter of 148 mum. These data were combined with previous two-phase data of R134a in small channels (hydraulic diameters ranging from 70 to 300 mum) to generate a separated flow model that spans a wide variety of fluid properties. Refrigerant was then mixed with two different viscosities of oil at concentrations ranging from 0.5 to 5% oil, and two-phase pressure drop measurements were taken of those mixtures. Flow visualizations of three of these refrigerants (R134a, R290 and R717) and several concentrations of a R134a-oil mixture were made in a channel with 500 mum hydraulic diameter, and flow regime classifications and comparisons with previous flow maps were made. Finally, a mechanistic description of the two-phase flow that occurs in small channels is put forth, based on the pressure drop measurements and the flow visualizations.

Download or read book Flow Boiling of Pure Refrigerants and Binary Refrigerant Mixtures in a Horizontal Tube written by Ali A. Rabah and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Analytical Investigation of Refrigerant and Lubricant Migration written by Steffen Peuker and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The off-cycle refrigerant mass migration has a direct influence on the on-cycle performance since compressor energy is necessary to redistribute the refrigerant mass. No studies, as of today, are available in the open literature which experimentally measured the lubricant migration within a refrigeration system during cycling or stop/start transients. Therefore, experimental procedures measuring the refrigerant and lubricant migration through the major components of a refrigeration system during stop/start transients were developed and implemented. Results identifying the underlying physics are presented. The refrigerant and lubricant migration of an R134a automotive A/C system-utilizing a fixed orifice tube, minichannel condenser, plate and fin evaporator, U-tube type accumulator and fixed displacement compressor-was measured across five sections divided by ball valves. Using the Quick-Closing Valve Technique (QCVT) combined with the Remove and Weigh Technique (RWT) using liquid nitrogen as the condensing agent resulted in a measurement uncertainty of 0.4 percent regarding the total refrigerant mass in the system. The determination of the lubricant mass distribution was achieved by employing three different techniques-Remove and Weigh, Mix and Sample, and Flushing. To employ the Mix and Sample Technique a device-called the Mix and Sample Device-was built. A method to separate the refrigerant and lubricant was developed with an accuracy-after separation-of 0.04 grams of refrigerant left in the lubricant. When applying the three techniques, the total amount of lubricant mass in the system was determined to within two percent. The combination of measurement results-infrared photography and high speed and real time videography-provide unprecedented insight into the mechanisms of refrigerant and lubricant migration during stop-start operation. During the compressor stop period, the primary refrigerant mass migration is caused by, and follows, the diminishing pressure difference across the expansion device. The secondary refrigerant migration is caused by a pressure gradient as a result of thermal nonequilibrium within the system and causes only vapor phase refrigerant migration. Lubricant migration is proportional to the refrigerant mass during the primary refrigerant mass migration. During the secondary refrigerant mass migration lubricant is not migrating. The start-up refrigerant mass migration is caused by an imbalance of the refrigerant mass flow rates across the compressor and expansion device. The higher compressor refrigerant mass flow rate was a result of the entrainment of foam into the U-tube of the accumulator. The lubricant mass migration during the start-up was not proportional to the refrigerant mass migration. The presence of water condensate on the evaporator affected the refrigerant mass migration during the compressor stop period. Caused by an evaporative cooling effect the evaporator held 56 percent of the total refrigerant mass in the system after three minutes of compressor stop time-compared to 25 percent when no water condensate was present on the evaporator coil. Foam entrainment led to a faster lubricant and refrigerant mass migration out of the accumulator than liquid entrainment through the hole at the bottom of the U-tube. The latter was observed for when water condensate was present on the evaporator coil because-as a result of the higher amount of refrigerant mass in the evaporator before start-up-the entrainment of foam into the U-tube of the accumulator ceased before the steady state refrigerant mass distribution was reached.

Download or read book A Study of Metastability Effects for Refrigerant 12 Flowing in Small Bore Tubes written by Jon A. Hoffmann and published by . This book was released on 1966 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaporation and Condensation of Refrigerant oil Mixtures in a Low fin Tube written by L. M. Schlager and published by . This book was released on 1988 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of Two phase Mass Flow Rate in Refrigerant R 134a Pipe Flow written by Jianwei Wang and published by . This book was released on 1993 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Measurement of Heat Transfer Coefficients for Mixed Gas Working Fluids in Joule Thompson Systems written by Cory B. Hughes and published by . This book was released on 2004 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Predictive Method to Describe the Boiling Behavior of Refrigerant oil Mixtures written by John R. Lloyd and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for efficient and environmentally safe refrigerants is of great concern to the Navy, and is driving them to explore the performance of alternate refrigerants for use in shipboard evaporators. Each time a new refrigerant is considered, one must also consider how oil contamination will affect its performance. The present study surveys the literature for a predictive technique to calculate the nucleate boiling heat transfer behavior of refrigerant-oil mixtures that is fundamental to the operation of refrigerant systems. There were three expressions found that could be considered for use. These expressions for the nucleate boiling heat transfer were empirically based formulations, which means that a new series of experiments must be conducted every time a different refrigerant-oil combination is considered for use. An expression that is currently under development for mixtures in general was found that is based only upon the thermophysical properties of the fluids and their mixtures. No empirical constants are necessary. The mass diffusion coefficient of the oil in the refrigerant is found to be the key property to be measured in order to evaluate the predictive capability of this expression. Experiments are proposed to obtain this key property and then to this expression will be developed as the experiments indicate are necessary.

Download or read book Flashing Flow of Refrigerant HFC 134a Through a Diabatic Capillary Tube written by De-Kang Chen and published by . This book was released on 1997 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Zero gravitry Venting of Three Refrigerants written by Thomas L. Labus and published by . This book was released on 1974 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Investigation and Modelling of the Flow Rate of Refrigerant 22 Through the Short Tube Restrictor written by David A. Aaron and published by . This book was released on 1989 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Refrigerant 22 flow through short tube restrictors was investigated. The analysis pertained to initially subcooled refrigerant flowing through short tubes with 5