Thermal properties latent

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

Effect of physical properties Physical properties of liquid metals that have significant effects on CHF values are thermal conductivity, latent heat of vaporization, and surf ace tension. 

W-3 CHF correlation. The insight into CHF mechanism obtained from visual observations and from macroscopic analyses of the individual effect of p, G, and X revealed that the local p-G-X effects are coupled in affecting the flow pattern and thence the CHF. The system pressure determines the saturation temperature and its associated thermal properties. Coupled with local enthalpy, it provides the local subcooling for bubble condensation or the latent heat (Hfg) for bubble formation. The saturation properties (viscosity and surface tension) affect the bubble size, bubble buoyancy, and the local void fraction distribution in a flow pattern. The local enthalpy couples with mass flux at a certain pressure determines the void slip ratio and coolant mixing. They, in turn, affect the bubble-layer thickness in a low-enthalpy bubbly flow or the liquid droplet entrainment in a high-enthalpy annular flow. 

Next, the thermal properties of the dye must be such that absorption of the laser energy will result in dye diffusion but not in decomposition. The melting temperature Tm, the latent heat of fusion, AH, and the specific heat for these dyes were determined by differential scanning calorimetry using a DuPont 990 Thermal Analyzer. The data are given in Table II. No thermal decomposition products for these dyes were detected upon heating to 600 °C for 20 msec. 

The last database of the eight key data items promised is enthalpy. I have broadly used the term enthalpy to signify all thermal properties that include specific heat, latent heat, and an absolute enthalpy value, expressed as Btu/lb. This section presents a table which, by interpolation, may be applied to any single component or component mixtures, or to any petroleum characterized component groupings. This enthalpy source table (Table 1.10) may be used conveniently and quickly to derive energy or heat values of both liquids and gases. It is compiled from data in Maxwell (pp. 98 to 127) [5]. 

CONDENSATION OF SUPERHEATED VAPORS. If the vapor entering a condenser is superheated, both the sensible heat of superheat and the latent heat of condensation must be transferred through the cooling surface. For steam, because of the low specific heat of the superheated vapor and the large latent heat of condensation, the heat of superheat is usually small in comparison with the latent heat. For example, 50°C of superheat represents only 100 J/g, as compared with approximately 2300 J/g for latent heat. In the condensation of organic vapors, such as petroleum fractions, the superheat may be appreciable in comparison with the latent heat, When the heat of superheat is important, either it can be calculated from the degrees of superheat and the specific heat of the vapor and added to the latent heat, or if tables of thermal properties are available, the total heat transferred per pound of vapor can be calculated by subtracting the enthalpy of the condensate from that of the superheated vapor. 

In this study, the thermal properties of the rock mass were modified to take the effect of groundwater and latent heat of freezing into account. The result of the analysis with these modified thermal properties shows good agreement with the measured temperature distribution. 

Therefore, we conducted the analysis to predict the temperature distribution using modified thermal properties that is calculated by considering the effect of groundwater and latent heat of freezing. Initial thermal properties were estimated considering 20% of volume fraction of groundwater. 

During the numerical calculation, thermal properties were changed into modified values considering the latent heat of freezing when temperature of rock mass is reached 0°C. The modification was made by using the numerical formula (1) and (2). And latent heat term is considered to evaluate the energy need to freezing the water in unit volume of rock mass. 

Cai, Y Wei, Q. Huang, R Lin, S. Chen, F. Gao, W. Thermal stability, latent heat and flame retardant properties of the thermal energy storage phase change materials based on paraffin/high density polyethylene composites. Renew Energ 34 (2009) 2117-2123. 

Par Park, S.-J., Heo, G.-Y., Suh, D.-H. Thermal properties and fracture toughness of epoxy resins cured by phosphonium and pyrazinium salts as latent cationic initiators. J. Polym. Sci. Part B -Polym. Chem. 41 (2003) 2393-2403. 

THERMAL PROPERTIES OF PROPANE. HEAT CAPACITY, JOULE-THOMSON COEFFICIENT, ISOTHERMAL THROTTLING COEFFICIENT, AND LATENT HEAT OF VAPORIZATION. FROM PROCEEDINGS OF THE 4TH SYMPOSIUM ON THERMOPHYSICAL PROPERTIES, UNIV. MARYLAND COLLEGE PARK, MD. 

In an extension of these studies, investigations were conducted into the use of thermally activated latent reactive chain ends [11], as well as chain-end/chain internally crossHnked polycarbosilane and polycarbosiloxanes lacking the polyether soft phase [10]. Although these methods proved successful, there were no significant improvement in the materials properties when compared to previous examples. 

Heat, Q, however, can also be exchanged without affecting the temperature of a sample. This occurs during chemical or physical transitions of the material. The heat involved is generally called a latent heat, L (at constant pressure in J mol ). From heat capacity and latent heats measured from the zero of temperature to the value of interest, it is possible to establish the integral thermal properties ... 

With these three simple equations, all equilibrium calorimetry can be described, so that measurement of heat capacity and latent heat allows a full thermal characterisation. Figure 4.2 illustrates a typical diagram of the thermal properties of crystalline polyethylene and its melt. The data were obtained by extrapolation of measurements of heat capacities on... 

The performance of an extruder is determined as much by the characteristics of the feedstock as it is by the machine. Feedstock properties that affect the extrusion process inciude buik properties, meit flow properties, and thermal properties. Important buik flow properties are the buik density, compressibility, particle size, particle shape, external and internal coefficient of friction, and agglomeration tendency. Important melt flow properties are the shear and eiongational viscosity as a function of strain rate and temperature. The commonly used melt indexer provides only limited information on the meit viscosity. Important thermal properties include the specific heat, the glass transition temperature, the crystalline melting point, the latent heat of fusion, the thermal conductivity, the density, the degradation temperature, and the induction time as a function of temperature. 

The general designation (i.e., chemical name, CAS registry number, UN number), the relative atomic and molar mass, the physical properties (i.e., density, viscosity), thermal properties (i.e., molar heat capacities, latent enthalpies, and thermal conductivity), optical properties (e.g., refractive index), along with properties important for health and safety (i.e., flammability limits, ignition temperature, toxicity) of some important gases are reported in Tables 19.15-19.17. 

Phase transitions in a material can be classified as first order and continuous (second order). At a first-order phase transition, we observe a discontinuity of some physical property representative of the degree of order in the system. For example, this could be material density or a calculated measure of order in the material (i.e., an order parameter). If we measure this parameter across the phase boundary, there will be a step, or discontinuity, at the transition point. An example of a typical first-order phase transition is ice melting. At the transition point, the density of the material abruptly changes as we go from ice to liquid water. First-order transitions also have a measureable latent heat. Some phase transitions can be described as weakly first order. In this case, the enthalpy change associated with that transition is very small. This is often true of phase transitions in soft matter systems. As a result, the enthalpy change may be difficult to measure, thus making the phase change difficult to detect by thermal properties alone. 

Meanwhile, Chen and co-workers also investigated the effect of PCM content on the thermal properties of the electrospun PCM/polymer fibers [14]. Figure 9.6 showed the DSC curves of LA powder and electrospun LA/PET composite fibers with different LA/PET mass ratios and the corresponding data of thermal properties. Clearly, the latent heats (A//f and Alfc) of the four LA/PET composite fibers were lower than that of LA powder (169.41 J/g and 165.12 J/g, respectively) because PET in the composite fibers has few contribution to the latent heat at this temperature range, and the latent heats of the fibers increased with the increase of LA/PET mass ratio. However, the phase transition temperatures (Tm and Tc) of all the electrospun LA/PET composite fibers have no obvious variations compared with those of LA (less than 1 °C). It indicated that the PCM/polymer mass ratio plays an important role on the latent heat of the form-stable PCM/polymer composite fibers but has less effect on their phase-change temperature. 

In summary, the thermal properties of the electrospun form-stable PCM/polymer composite fibers can be affected dramatically according to different types of PCMs [14, 31, 38, 43, 48] and various PCM/polymer mass ratios or PCM contents [14, 33, 37-39, 41, 43, 48, 49]. The former factor is in charge of the intrinsic thermal properties of the novel thermal-storage materials, because it fixes the phase transition temperatures and limits the maximum value of the latent heats of the composite fibers. The latter one plays a key role in the latent heats of the form-stable PCM/polymer composite fibers but has less effect on their phase transition temperatures. All those novel composite fibers showed good thermal stability and reliability no matter what electrospinning methods were applied. 

The cross-sectional area of the wick is deterrnined by the required Hquid flow rate and the specific properties of capillary pressure and viscous drag. The mass flow rate is equal to the desired heat-transfer rate divided by the latent heat of vaporization of the fluid. Thus the transfer of 2260 W requires a Hquid (H2O) flow of 1 cm /s at 100°C. Because of porous character, wicks are relatively poor thermal conductors. Radial heat flow through the wick is often the dominant source of temperature loss in a heat pipe therefore, the wick thickness tends to be constrained and rarely exceeds 3 mm. 

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