Phase Change Temperature Range Sample Clauses

Phase Change Temperature Range. Figure 3-1 Operating Temperature Range of LHTES With the defined operating temperature (46-72°C) where the charge is performed with inlet warm HTF at 72°C and the discharge is performed with inlet cold HTF at 46°C as shown in Figure 3-1, a number of commercial PCM candidates with a melting temperature of around 60°C have been tested with T-history methods. The properties of these PCMs as provided by the suppliers are presented in Table 1. The datasheets are provided in appendices3. Table 1 Performance Characteristics of PCMs per Suppliers 3 Datasheets of these materials are provided in the appendix 1. The values provided by the suppliers were mainly obtained with Differential Scanning Calorimetry (DSC), with which only a small sample size can be tested (<50 mL). T-history method with a larger sample size is deemed to provide more realistic application behaviour. All these shortlisted PCMs were heated and cooled for five cycles in the ACS Hygross 1200 climate chamber4. The resulting enthalpy versus temperature graph was obtained as shown in Figure 3-2 . Figure 3-2 Enthalpy vs Temperature from T-History; (a) Heating cycle and (b) Cooling cycle Both Axiotherm-58 and SunAmp-58 show instability and uncertainty during different heating and cooling cycles. RT-64HC phase change temperature range is slightly higher than required and it seems to be non- homogeneous because of two sets of phase changes that are undesirable for the current application. Comparing RT-62HC and Crodatherm-60, Crodatherm-60 has higher enthalpy change and there is no significant super- cooling in case of Crodatherm-60. Moreover, heat conductivity and specific heat capacity of Crodatherm-60 are slightly higher (0.29 W/m.K, 2.3 kJ/(kg∙K)) as compared to RT-62HC (0.2 W/m.K, 2 kJ/(kg∙K)). Crodatherm-60 has thus been selected as the heat storage material in the validation-site LHTES unit for its better thermo-physical properties. The properties are shown in Table 2. Table 2 Thermal Properties of Crodatherm-60 Thermal Parameters Value Peak melting/solidification temperature [°C] 60 Density: solid (55 °C) [kg/m3] 922 Density: liquid (65 °C) [kg/m3] 824 Enthalpy change from 45 to 72 °C [kJ/kg] (T-History) 310 Thermal conductivity: solid [W/(m·K)] 0.29 Thermal conductivity: liquid [W/(m·K)] 0.17 CrodaTherm 60 is a water insoluble organic phase change material derived from plant-based feedstock (100% biobased). It is expected to be readily biodegradable and received the (U.S. Department of Agricultur...