Methanol, properties thermal conductivity

Passive types of leak detection such as observation wells and collection sumps where product is collected and analyzed directly should work effectively with methanol. Active leak detection systems that rely on thermal conductivity and electrical resistivity sensors will not work with methanol because its properties are so different from gasoline. Another type of active leak detection system that will work with methanol or any other type of fuel relies on changes in impedance in a sensor wire as it becomes wetted with the fuel [4.5]. These leak detection systems also have the advantage that they can pinpoint the location of the leak along the length of the sensor wire. 

The values in these tables were generated from the NIST REFPROP software (Lemmon, E. W., McLinden, M. O., and Huber, M. L., NIST Standard Reference Database 23 Reference Fluid Thermodynamic and Transport Properties—fePPROP, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, Md., 2002, Version 7.1). The primary source for the thermodynamic properties is de Reuck, K. M., and Craven, R. J. B., Methanol, International Thermodynamic Tables of the Fluid State—12, lUPAC, Blackwell Scientific Publications, London, 1993. Validated equations for the viscosity and thermal conductivity are not currently available for this fluid. 

A lot of works reported that multiblock cojwlymer showed higher water uptake, proton conductivity, proton/methanol selectivity, thermal stability, etc. than a similar random copolymer [61-63]. Liang et al. [64] have shown recently the morphology differences between random and multiblock copolymers (Scheme 4.11, Table 4.6) and the effects of the membrane morphology on the properties of the membranes. 

Many new polymers have been synthesized and tested for their proton conductivity, methanol permeability, thermal as well as mechanical stability, electrode-manbrane interface connectivity, etc., aiming at improvanent in m brane performance for fuel cell applications. These efforts seem to continue with insightfirl vision and strong commitment in the fnture. However, only a handful of polymers are currently being used as the materials for commercial apphcations, and they are not necessarily the polymers of the best performance properties. This is mainly due to the cost factor that governs the present membrane rrrarket. The fuel cell performance of membranes is, on the other hand, known primarily ruled by the various factors, mainly, membrane fuel permeability, electrode-membrane adhesion (or compatibility), thermal and mechanical stabilities. The knowledge of the effects of these factors on... 

The temperature dependence of many properties of methanol has been described in figures, tables, and equations. Plots of vapor pressure, liquid density, liquid heat capacity, vapor heat capacity, heat of vaporization, surface tension, liquid thermal conductivity, vapor thermal conductivity, liquid viscosity, and vapor viscosity against temperature have been given by Yaws [13] and by Flick [14]. Tables of vapor pressure [3,1517], liquid density [3,15,17], liquid volume [16], vapor density [15,17], vapor volume [16], liquid viscosity [15,18], vapor viscosity [15], surface tension [15,19], liquid heat capacity [15,17,20], vapor heat capacity [3,15,17], solid heat capacity [11], liquid thermal conductivity [15,17], vapor thermal conductivity [15], second viral coefficient [16], dielectric constant [21], refractive index [3], and heat of vaporization [16] have also been published. Thermodynamic properties of methanol in the condensed phases have been tabulated by Wilhoit et al. [11], and those in the gas phase have been given by Chao et aL [9]. 

Properties including freezing point, boiling point, and flash point of methanol-water solutions of different methanol contents have been given by Flick [14]. Data for density [14,29], viscosity [14], vapor pressure [14,29], thermal conductivity [14], specific heat [14,29], surface tension [30], and refractive index [31] at selected temperatures have also been tabulated. Heat of mixing can be found in Reference 32. Diffusion coefficients of methanol and water in methanol-water solutions have been evaluated in detail by Derlacki et al. [33]. 

The crosslinked membranes show less water uptake, a lower level of methanol permeability, and good thermal and mechanical properties in comparison to pristine membranes while maintaining a reasonable level of proton conductivity [120]. 

The properties of the copolymers depend on the sulfonic acid group content in the copolymers. The copolymers show a good thermal stability, low liquid uptake, and low methanol crossover, however, they exhibit a lower proton conductivity than Nafion or sulfonated PEEK. 

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