Assessment of T-History Method Variants to Obtain Enthalpy–Temperature Curves for Phase Change Materials With Significant Subcooling

Abstract

To assess the potential of thermal energy storage systems using phase change materials (PCMs), numerical simulations rely on an enthalpy–temperature curve (or equivalent specific heat curve) to model the PCM thermal storage behavior. The so-called “T-history method” can be used to obtain an enthalpy–temperature curve (H versus T) through conventional laboratory equipment and a simple experimental procedure. Different data processing variants of the T-history method have been proposed yet no systematic comparison between these versions exists in the literature nor is there a consensus as to which should be used to obtain reliable enthalpy–temperature curves. In this paper, an inorganic salt hydrate is tested in both heating and cooling. Four different data processing variants of the T-history method are used to characterize the PCM and produce enthalpy–temperature curves for this original experimental data set. Differences in the results produced by the different methods are discussed, the issues encountered are indicated, and possible approaches to overcome these problems are provided. A specific variant is recommended when using the T-history method to determine enthalpy–temperature curves. For PCMs that exhibit subcooling, an alternative interpretation using an absolute temperature interval is described so that the subcooling phase is taken into account in the enthalpy–temperature curve.

Thermal properties of disodium hydrogen phosphate dodecahydrate coated metal foam/sodium acetate trihydrate composite as phase change material

“…The highest increase was found in the 80 PPI copper samples which showed a 388.15% increase when compared to pure SAT. The thermal conductivity of pure SAT is shown in Table 1 of 0.68 W/(m K) is in line with results of 0.7 W/(m K) found in prior experiments by Mark et al [16]. This supports the validity of the results.…”

“…The T-History method is a very effective way to measure supercooling. A review of several T-History method approaches in D'Avignon et al 2015 [16] concludes that the "time delay" method proposed by Marvin et al 2003 [17] is the most accurate and reputable method for measuring supercooling. Figure 16.…”

“…Figure 16. T-History curve water [16] Figure 15 shows an example cooling curve for a material that experiences supercooling.…”

Alginate–Sodium Sulfate Decahydrate Phase Change Composite with Extended Stability

“…Compared to DSC method, the T-history method has been considered to be more reliable to the real thermal behavior obtained in large scale TES applications and can better represent the general intrinsic thermal properties of PCM as it allows the use of a much larger sample size. − However, the measurements are lengthy. Therefore, T-history measurement was conducted on selected samples with low viscosity, and the results are compared with those obtained using the DSC method.…”