Calorimeter method

The standard procedure is illustrated in ASTM C201-98. This method is useful for materials having a conductivity of up to 20 W/mK. A calorimeter is fitted at the cold face of the sample. The calorimeter obtains the mass, specific heat, and temperature rise of the heat flux. 

Oder Inner Center Inner Outer Guard Guard Guard Guard 

Two thermocouples separated by distance L are imbedded in the test specimen, one directly above the other, whereby the temperature drop T2 — T between them is measured. A differential thermocouple measures the temperature rise ATw of the exit water of the calorimeter as compared to its entrance temperature. The mass flow rate of water F into the calorimeter is monitored, so that over a specific time interval At, the total heat absorbed by the calorimeter may be calculated, knowing the specific heat cp of water. Dividing by the time interval will give the rate of heat flow into the calorimeter under steady state conditions  

the thermal conductivity may be determined by a rearrangement of Fourier s equation (section 8.1.2)  

The back-up insulation between the base of the test specimen and the calorimeter is optional. Under conditions of steady state heat flow, introduction of back-up insulation diminishes the heat flow to the calorimeter as well as the temperature drop across the specimen the thermal conductivity, as 

The calorimeter method is considered highly accurate. However, many hours (days) are required at a specific furnace temperature in order to establish steady state conditions, hence, establishing a k versus T relationship may take weeks to complete. 

---

Endothermic peak temperature according to the differential scanning calorimeter method. (Speed of temperature rise 20 C/min.) he figures apply to 2-mm-thick sheet injection molded with cylinder temperature of 150°C and mold temperature 20 C. 

A variation, which results in a more simple apparatus, is the drop calorimeter. The test piece is heated (or cooled) externally, dropped into the calorimeter and the resultant change in temperature monitored. For the simplest measurements, the calorimeter need not be surrounded by an adiabatic jacket but in that case, corrections for the heat exchange with the surroundings must be applied. A procedure using a drop calorimeter has been standardized for thermal insulation in ASTM C35l". It is possible to combine the adiabatic and drop calorimeter methods by dropping a heated sample into an adiabatic chamber and this has been used for plastics12. 

ISO 5660-1 Reaction-to-Fire Tests—I leal Release, Smoke Production and Mass Loss Rate—Part 1 Heat Release Rate (Cone Calorimeter Method). International Organization for Standardization, Geneva, Switzerland. ISO 5660-2 Reaction-to-Fire Tests—I Ieat Release, Smoke Production and Mass Loss Rate—Part 2 Smoke Production Rate (Dynamic Measurement). International Organization for Standardization, Geneva, Switzerland. ISO 9705 Fire Tests—Reaction-to-Fire—Room Fire Test. International Organization for Standardization, Geneva, Switzerland. 

ISO 5660 Reaction-To-Fire Tests—Heat Release, Smoke Production And Mass Loss Rate—Part 1 Heat Release Rate (Cone Calorimeter Method), ISO, Geneva, Switzerland, 2002. 

The calorimeter method is an older technique which is a direct measurement of Fourier s law. It is one of the ASTM [2] standard tests for thermal conductivity, designation C201. The experimental configuration is shown in Figure 9.3. A SiC slab... 

Figure 9.3 Schematic of the calorimeter method of measuring thermal conductivity [2]. Specimen sizes are approximately three bricks of dimensions 23 x 11.4 x 6.4 cm3.

Consider the flow-calorimeter method for measurement of heats of combustion of fuel gases. The fuel is mixed with air at room temperature and ignited. Combustion takes place in a chamber surrounded by a cooling jacket through which water flows. In addition there is a long water-jacketed section in which the products of combustion are cooled to the temperature of the reactants. Whatever the details of this steady-flow process, the overall energy balance [Eq. (2.10)] reduces to... 

ISO 5660-1 (1993), Fire test—Reaction to fire—Part 1, Rate of heat release from building products (cone calorimeter method),... 

ASTM E1354-04 (standard test method for heat and visible smoke release rates for materials and products using an oxygen consumption calorimeter) and ISO 5660-1 2002 (reaction-to-fire tests-heat release, smoke production, and mass loss rate - part 1 heat release rate, cone calorimeter method) for heat release and oxygen consumption. 

The investigation on the phase transition in U-Zr alloy has been conducted. According to the characteristics of the transformation in the U-Zr alloy, the transition temperature were determined by the Differential Scanning Calorimeter method (DSC) analysis as following the peritectoid reaction UZra- — -aU+ya, the eutectoid reaction / U- — aU+yz and... 

The Cone Calorimeter. The cone calorimeter is standardized in North America as ASTM E1354, Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter, and internationally as ISO 5660-1, Fire Tests—Reaction to Fire—Part 1 Rate of Heat Release from Building Products (Cone Calorimeter Method). A photograph of a commercial version of the cone calorimeter is shown in Figure 28. 

Classification of calorimeters Methods of determination of heat effects... 

The heat associated with a specific polymerization reaction depends on the temperatures of both the monomers and polymer. A standard basis that is consistent for treating polymerization heat effects results when the products of polymerization and the monomers are all at the same temperature. Consider a calorimeter method of measurements of heat of polymerization of monomers. The initiator is mixed with the monomer, and the system is a continuous flow CSTR. The polymerization reactions take place in the CSTR. The polymerization products enter a devolatilizer where the monomers are vaporized and removed from the product mix and recycled back to the reactors. The CSTR is water cooled to bring the monomers/polymer to the reactor temperature. There is no shaft work performed by the process. The CSTR is built, so that changes in potential and kinetic energy are negligible. The first law of thermodynamics for open systems can be written for the system as... 

Later work with various binary liquid mixtures and different types of solids indicated that the flow calorimeter methods of specific surface determination can also be applied to homogenous surfaces represented by graphitised carbon blacks. In this case strong preferential adsorption of long-chain paraffins from n—heptane was used to produce a monolayer and the corresponding heat of adsorption measured the total graphitic basal plane in such carbons [11]. 

At the Institute of Thermodynamics, University of Karlsruhe, two series of Cp measurements with the following adiabatic calorimeter method were carried out [3.36, 3.40]. The total error in the measured values of Cp, according to the researchers, is about 0.1%. Their experimental data agree very well with each other, and the discrepancy in Cp values on the isotherms 333 and 353 K at p = 0.1-1.4 MPa does not exceed 0.2-0.3%. 

For determination of enthalpies of fusion and transition, the isothermal calorimeter is, in most cases, used as the calorimeter for receiving the dropped sample in the drop calorimeter method. 

Rectangular shape samples with typical sizes of 10 mm x 4 mm x 1.5 mm were employed to simultaneously measure electrical conductivity o and Seebeck coefficient S by the standard four-probe methods in a He atmosphere (ULVAC-RIKO ZEM-3). Thermal conductivity k was calculated using the equation k = apC from the thermal diflfusivity a obtained by a flash diflusivity method (LFA 457, Netzsch) on a round disk sample with diameter of about 13 mm and thickness of 2 mm, and specific heat Cp was determined by a differential scanning calorimeter method (DSC Q2000, Netzsch). 

Calorimeter method—This method can be used for measurements on low-conductivity insulating materials, but measurements of conductivities up to around 20 W/mK are also possible with this equipment The results from the British Standard (BS 1902.5.5 1991) and ASTM method (C201) are often compared. The position of the calorimeter has the greatest influence on the conductivity values measured. Apparatus in which the calorimeter is positioned underneath the test sample, as in the ASTM method, yields lower conductivity values than when positioned above the test sample such as in the British Standard Method. 

---