Thermodynamic Properties Of Nitrogen Research Articles

Theoretical prediction of thermodynamic properties of N2 and CO using pseudo harmonic and Mie-type potentials

In this work, thermodynamic properties of nitrogen (N2) and carbon monoxide (CO) were theoretically predicted by using two potential models, pseudo harmonic and Mie-type. We have solved the Schrödinger equation for the potential models and obtained the analytical expressions for energy eigenvalues. Using the energy spectra, partition function and thermodynamic properties of N2 and CO were calculated. Examples of the thermodynamic properties are specific heat at constant pressure, entropy and enthalpy. According to the obtained results, it is found that there is good agreement between our theoretical results and experimental data.

A simplified model for a diesel spray

This paper describes a computer simulation and measurements of the liquid phase of Diesel spray formation.The spray is divided into small elementary volumes in which the amounts of liquid and gaseous fuel, air, mean, maximum and minimum fuel droplet diameter are calculated, as well as their number. The total air–fuel and air–fuel vapour ratios are calculated for each elementary volume. The mathematical model of the Diesel spray is based on continuity and momentum equations in Eulerian-Lagrangian formulation.The measurements of the sprays were carried out in the combustion chamber at the LTT, which is equipped with a high pressure 250 MPa fuel injection system. During the experiments, ambient pressure varied from 3 MPa to 7 MPa, temperature from 673 K to 973 K, injection pressure from 40 MPa to 200 MPa and nozzle temperature from 243 K to 363 K. The injection quantity was 13.5 mm3 per cycle in all cases. The combustion chamber was filled with pure nitrogen instead of air. Thermodynamic properties of nitrogen are similar to those of air. That way, self-ignition was prevented. We measured only the liquid phase of the fuel in the spray, and to this end, Mie scattering measuring technique was applied.The comparison between the simulated and actual liquid spray penetration depth and spray cone angle showed good matching.

Adsorption Behaviors of Nitrogen on Ti Doped SBA-15

Thermodynamic properties of nitrogen on Ti doped santa barbara amorphous No. 15 samples having large pore sizes in an order of a few micrometers were studied by analyzing the adsorption isotherm data obtained near the triple point (63.15 K). A series of adsorption data as a function of the normalized pressure revealed that nitrogen forms two distinctive isotherm steps. The first step represents the adsorption behavior on surface while the second step is believed to be responsible for the interaction of gas molecules in a capillary, so called a 'capillary condensation.' The existence of a hysteresis measured between adsorption and desorption isotherms at 77.3 K evidenced that gas molecules fill the pores in the sample. Plots of 2-dimensional compressibility values that were calculated in terms of change of adsorbed molecules with respect to the change of measured pressure exhibit a prominent peak near the second isotherm step supporting that the pores are filled with adsorbed molecules. A careful examination of the second isotherm step revealed that the amount of adsorbed molecules increased at temperatures below the triple point while it decreased above the triple point, and such a phenomenon is responsible for the geometrical confinement of gas molecules in porous materials.

The thermodynamic properties of nitrogen, argon, oxygen, and their mixtures in the region of the liquid-gas phase transition

A procedure for constructing the equation of state for metastable and labile regions in the liquid-gas phase transition is suggested. A consistent description of p, ρ, T, and caloric properties was obtained. The spinodals of both pure fluids and their mixtures were located.

A Reference Quality Equation of State for Nitrogen

A new formulation describing the thermodynamic properties of nitrogen has been developed. New data sets which have been used to improve the representation of the p–ρ–T surface of gaseous, liquid and supercritical nitrogen, including the saturated states are now available. New measurements on the speed of sound from spherical resonators have been used to improve the accuracy of caloric properties in gaseous and supercritical nitrogen. State-of-the-art algorithms for the optimization of the mathematical structure of the equation and special functional forms for an improved description of the critical region were used to represent even the most accurate data within their experimental uncertainty. The uncertainty in density of the new reference equation of state ranges from ±0.01% between 270 and 350 K at pressures less than 12MPa, within ±0.02% over all other temperatures less than 550 K and pressures less than 12 MPa, and up to a maximum of ±0.6% at the highest pressures. The equation is valid from the triple point to temperatures of 1000 K and pressures up to 2200 MPa. The new formulation yields a reasonable extrapolation up to the limits of chemical stability of nitrogen as indicated by comparison to experimental shock tube data. Constraints regarding the structure of the equation ensure reasonable extrapolated properties up to temperatures and pressures of 5000 K and 25 GPa. For typical calibration applications, the new reference equation is supplemented by a simple but also highly accurate formulation, valid only for supercritical nitrogen between 270 and 350 K at pressures up to 30 MPa.

Thermodynamic properties of nitrogen molecules at high temperatures

Calculations of the second virial coefficients and their derivatives for the Hulburt-Hirschfelder (HH) and other accurate interaction potentials are used to determine the thermodynamic properties of nitrogen at high temperatures. Unlike the usual methods employing partition functions, which are most accurate at low temperatures where the energy levels are precisely known, the virial coefficient method depends on integrating over potential energy functions which provide a useful description of energies even near the top of the potential well, a region where the vibrational-rotational energy levels are not readily accessible. This makes this method particularly useful for predicting high-temperature properties outside the range of laboratory measurements and beyond the useful limits of the partition function approach. In the present work, we use the virial coefficient method to predict the heat capacities and enthalpies of nitrogen up to 25,000 K.

Nitrogen binding to deoxyhemoglobin at high pressures and its relation to changes in hemoglobin-oxygen affinity.

The stoichiometric and thermodynamic properties of nitrogen (N2) binding to human deoxyhemoglobin (Hb) at N2 saturation pressures up to 400 atm were derived from measured N2 solubilities in protein-free buffers (pH 7.1) and in corresponding buffer + Hb (6.5% w/w) solutions at 20.0, 25.0, and 37.0 degrees C. At each temperature, approximately 3 N2 molecules bind per Hb tetramer at N2 pressures of 100 atm, while about 7 N2 molecules bind per tetramer at 400 atm N2 pressure, where available binding sites are still not fully saturated. Calculated N2-Hb binding isotherms are well described by a simple binding model with 12 independent and equivalent binding sites/Hb tetramer. N2 binding at each of the sites is hydrophobic, exhibiting the typical increase of the dissociation enthalpy with temperature. Enthalpies of dissociation are slightly more negative, while corresponding unitary entropies are somewhat less negative than those for the transfer of N2 from olive oil to water. Calculated partial molar volumes of N2 in Hb are positive but less than the corresponding partial molar volumes of N2 in buffer. Results indicate that N2 binding to Hb is accompanied by only small protein conformational changes which entail slight structural destabilization and loss of free volume in the protein that partially accommodates the volume of the N2 ligand. Results are related to previously reported effects of high pressure and high-pressure N2 on HbO2 affinity, illuminating essential features of the molecular mechanisms for these effects.

Theoretical study of the thermodynamic properties of nitrogen at high temperatures and pressures

A theoretical analytical equation of state is derived and used to compute new thermodynamic data for nitrogen at high tempratures and pressures.

Thermodynamic properties of nitrogen from a perturbation theory for ISM fluids

A first-order Barker-Henderson perturbation theory for interaction-site model (ISM) fluids has been applied to calculate the Helmholtz free energy, entropy and internal energy of liquid nitrogen. Comparison with experiment reinforces the idea that the theory is accurate over a wide range of temperatures and densities corresponding to the liquid state, except for the critical region.

Experimental pVT data and thermodynamic properties of nitrogen up to 1000°C and 5000 bar

The values of the density of nitrogen measured with an accuracy of 0.3% in the high-temperature high-pressure range of 1000°C–5000 bar are presented and a comparison with data of other workers is discussed. Although this comparison is limited due to lack of data beyond 400°C, the good agreement is an interesting test of the validity of the experimental method used. Then the results of computation of the main thermodynamic functions which can be derived from these experimental values are given in the same range of temperature and pressure; in addition, the principle and the accuracy of this computation are analysed.

Thermodynamic properties of nitrogen at high pressures

Thermodynamic properties of nitrogen at high pressures

Thermodynamic properties of nitrogen up to 1300?K and 1000 bars

Thermodynamic properties of nitrogen up to 1300?K and 1000 bars

Partition Functions and Thermodynamic Properties of Nitrogen and Oxygen Plasmas

The equilibrium chemical composition and thermodynamic properties of nitrogen and oxygen plasmas have been calculated for six pressures (0.01, 0.1, 0.5, 1.0, 2.0, and 5.0 atm) at 100° K increments for the temperature range 2000–35 000° K. The plasma is assumed to be a perfect gas complex consisting of seven components for nitrogen (i.e., molecules, singly ionized molecules, atoms, electrons, and the first three atomic ions) and eight components for oxygen (same as for nitrogen plus the first negative atomic ion). The internal partition functions for nitrogen molecular species were calculated by an approximate technique proposed by Mayer and Mayer using the most recent spectroscopic data available. For oxygen molecular species, the method of Stupochenko et al. was employed to determine the intermolecular potential curves, and the internal partition function was computed by direct summation over the energy states so determined. The electronic partition functions for atoms and atomic ions were computed using published data for observed electronic energy levels plus estimated energies for electronic states which are predicted but not spectroscopically observed. These electronic partition function series were terminated by application of the Debye cutoff criterion, and a corresponding lowering of the ionization potential was included. The two methods of computing the molecular internal partition function are compared and evaluated. Typical calculated data are presented in graphical and tabular form.

The equation of state and thermodynamic properties of molecular nitrogen

An equation of state has been obtained for nitrogen in the pressure range (1–1,000)·105 n/m2 for temperatures up to 1,000°K. This equation shows good agreement with the experimental data. A detailed table of thermodynamic properties of nitrogen, based on the new equation, is presented.

Intermolecular-force effects on the thermodynamic properties of nitrogen

Intermolecular-force effects on the thermodynamic properties of nitrogen

Thermodynamic properties of nitrogen and oxygen adsorbed on rutile

Thermodynamic properties of nitrogen and oxygen adsorbed on rutile

Thermodynamic properties of nitrogen as functions of pressure and temperature between 0 and 6000 atmospheres and −125° and +150°C

Thermodynamic properties of nitrogen as functions of pressure and temperature between 0 and 6000 atmospheres and −125° and +150°C

Thermodynamic Properties of Nitrogen at High Pressures as Analytic Functions of Temperature and Pressure

Thermodynamic Properties of Nitrogen at High Pressures as Analytic Functions of Temperature and Pressure