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A flow mixing unit using a SETARAM C-80 calorimeter, developed for measuring the enthalpy of solution of two fluids, has been used to measure enthalpies of absorption of carbon dioxide in a 30 wt.% aqueous solution of methyldiethanolamine (MDEA) at three temperatures 313.15, 353.15, 393.15 K and three pressures 2.0, 5.0, 10.0 MPa. We have established that the effect measured by calorimetry corresponds not only to the absorption of CO2 in the aqueous solution but also to the vaporisation of water into the carbon dioxide depending on the temperature and the pressure of the experiment. The enthalpies measured by calorimetry were compared with those calculated from solubility measurements and a reasonable agreement within the accuracy of measurement and calculation was found. 相似文献
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A flow mixing unit (calorimetric cell and auxiliary devices) has been designed for measuring the enthalpy of mixing or reaction of two fluids (gas+liquid or liquid+liquid). The indicator of the heat effect is a differential heat flux calorimeter, SETARAM C-80, allowing measurements at temperatures up to 300°C. The mixing cell is made of a stainless-steel capillary (o.d 1.6 mm, length 2.4m) which is coiled in a cylindrical form and tightly fitted in the thermopile well of the calorimeter. The fluids are delivered from the high pressure piston pumps and circulated through the system at controlled flow rates ranging from 100 to 1500 L-min–1. The tests were carried out at pressures up to 20 MPa. Special care was taken to allow good thermostatting of fluids entering the mixing cell. Check measurements were made with one liquid-liquid system (C2H5OH+H2O) and one gas-liquid system (CO2+C6H5CH3); our enthalpies of mixing agreed with the literature values in most cases to 2%. For the system ethanol+water the experiments have been also performed at temperature of 250°C and pressures of 15 and 20 MPa. The endothermal mixing effect was higher than expected indicating an increase in the excess heat capacity. 相似文献
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Le Parlouër P. Dalmazzone Christine Herzhaft B. Rousseau L. Mathonat C. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):165-172
Gas hydrates are solid structures formed from water and gas under low temperature and high pressure conditions. Differential
scanning calorimeter, operating under high pressure, is a very useful technique for the determination of the thermodynamic
properties and the kinetics of gas hydrate formation. Specific gas tight controlled pressure vessels have to be used to obtain
the hydrate formation in complex fluids. Based on the MicroDSC technology, a new High Pressure MicroDSC with a vessel (0.7
cm3) operating up to 400 bars between -45 and 120°C is introduced for this type of research. An example of the use of the HP
MicroDSC is given with the formation of gas hydrates in drilling muds. With the increasing number of deep offshore drilling
operations, operators and service companies have to solve more and more complex technical challenges. Extreme conditions encountered
at these depths require an adaptation of the drilling muds. The range of temperature (down to -1°C) and pressure (up to 400
bars) are favorable conditions to the formation of hydrates. HP MicroDSC is used to determine the thermodynamic properties
and kinetics of hydrate formation in mud formulations, particularly in the presence of large amounts of minerals. The technique
allows the detection of phase transitions vs. time, temperature and pressure. Using such a technique, dangerous areas of hydrate formation in drilling muds formulations
(water-base and oil-base) can be predicted.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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