Specific heat standard method

The rea.son for this choice of low pressure ratio is illustrated by an approximate analysis [12], which extends the graphical method of calculating gas turbine pierformance described in Chapter 3. If the gas turbine higher plant is assumed to ojjerate on an air standard cycle (i.e. the working fluid is a perfect gas with a constant ratio of specific heats, y), then the compressor work, the turbine work, the net work output and the heat supplied may be written as... 

The need for entropy values is bypassed when the van t Hoff equation (d In K/dT) =AH/RT2 is used. This can be integrated, either assuming AH is temperature-independent, or by incorporating a specific heat-temperature variation. This is the so-called second law method which contrasts with the third law method. In the latter method, the standard enthalpy is obtained from each equilibrium constant using free-energy functions of all the species present, for example... 

An industrial standard method has been developed to test the lightfastness of polymers in accelerated test equipment [103]. The apparatus consists of a quartz-xenon tube with a special optical filter between the light source and the specimen to produce light that resembles window glass-filtered daylight [104], Samples are mounted at a specific distance from the arc and are supported on a frame which revolves around the arc 1 to 5 times per minute for uniform exposure. A blower unit in the base provides a flow of air which makes it possible to maintain a black panel temperature of 45°C, measured by a black panel thermometer which is positioned at level with the samples. A black panel unit consists of a bimetallic thermometer mounted on a steel frame. Both faces of the frame plate and also the stem of the thermometer are coated with a heat-resistant glossy black enamel. The relative humidity level in the exposure cabinet is closely controlled. 

This is another example of the application of thermogravimetry for determination of equilibrium temperatures in dissociation studies. This also enables one to calculate the heat of dissociation from the linear relation between log of dissociation pressure and 1/T. Determination of the specific heat by means of DTA was used afterwards for conversion of the heat of dissociation into the standard values of formation at 298 °K. Ba02 was chosen for these investigation56 because it has been investigated in the past by calorimetric methods and therefore gives a possibility for comparing those values obtained from static methods with those obtained from values from dynamic methods. 

ASTM C351, 1999. Standard test method for the mean specific heat of thermal insulation. 

ASTM E1269, 2004. Standard test method for determining specific heat capacity by differential scanning calorimetry. 

The heat capacity of coal can be measured by standard calorimetric methods that have been developed for other materials (e.g., ASTM C-351). The units for heat capacity are Btu per pound per degree Fahrenheit (Btu/lb-0F) or calories per gram per degree Celsius (cal/g °C), but the specific heat is the ratio of two heat capacities and is therefore dimensionless. 

ASTM C-351. Standard Test Method for Mean Specific Heat of Thermal Insulation. 

Similarly, if a quantity such as the volume exhibits an abrupt change in slope, which occurs at the T, then there is a discontinuity in quantities associated with first derivatives of this parameter, or second derivatives of the free energy (with respect to appropriate thermodynamic variables), such as the specific heat (Figure 10-19). Accordingly, the Tg may be related to a second-order phase transition, but this remains in dispute. The experimentally observed transition is clearly governed by kinetics and the standard method of measuring this transition is by differential scanning calorimetry (DSC), which measures the specific heat. 

The determination of the specific heat of water at various temperatures (that at 15°C. being the standard or unit of heat, 1 g.cal., 1,12.11) is equivalent to the determination of the mechanical equivalent of heat, and the methods have been mentioned ( 12,14.11). Its variation with temperature was first established by Rowland (1879-80). 

Electrical resistivity measurement adopted conventional four probes method. Seebeck coefficient was measured by the standard DC method. Thermal conductivity k was calculated from density, specific heat, and thermal diffiisivity. Specific heat measurement was carried out by use of a differential scanning calorimeter (DSC model 8230, Rigaku, Japan) compared with a standard material of a -AI2O3. The values of thermal diffiisivity obtained from a differential phase analysis of photo-pyroelectric signal (AL- A 0 analysis) [9]. All measiu ements were done at room temperature. 

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