Analysis of the Thermal Performance of Isothermal Composite Heat Accumulators Containing Organic Phase-Change Material

Abstract

This paper presents the results of material tests, experimental tests and statistical analysis of the thermal performance of three types of heat accumulators containing an organic phase-change material and two materials of a higher thermal conductivity: a copper mesh and porous coke recyclate. The aim of the research was to empirically and statistically compare the increase in the PCM heat distribution through a copper conductor and coke recyclate. The research was conducted in accordance with an incomplete central compositional experimental design and using the Statistica software. The studies of the structure and chemical composition of the coke recyclate used and the empirical testing of the finished heat accumulators confirmed an improvement in the distribution and storage of heat by the accumulator with the phase-change material and coke recyclate compared to the pure phase-change material and copper-conductor accumulators, as the holding time of a temperature of 20°C was extended by seven minutes and nine minutes, respectively. Moreover, the results of the statistical analysis provided answers as to which of the assumed input quantities—initial temperature, battery geometry, and heating temperature— were statistically significant for each of the three battery types considered. The determined approximating functions were verified in terms of the statistical validity of their use for all three types of heat accumulators tested. The results obtained are important answers to the current problems in the design and modification of phase-change heat accumulators applied in the construction industry to reduce the emissivity of structures and increase their energy efficiency.

Multi-Faceted Analysis of Phase-Change Composite Intended for Autonomous Buildings

“…To find an answer as to what effect the content of the individual components has on the efficiency of heat distribution and the strength of the newly designed composite, it was necessary to carry out an experimental plan. Because the individual plan input quantities (concentrations of the three mixture components) are dependent on each other, it was not possible to use incomplete experimental plans, such as the central or rotational compositional plan described in [ 53 , 54 , 55 ]. In this case, it was necessary to use a full, symplectic–centroid plan, which imposes limits on the values of the input parameters [ 56 , 57 , 58 ].…”

Structure and Operation Optimization of a Form-Stable Carbonate/Ceramic-Based Electric Thermal Storage Device for Space Heating

“…They used expanded graphite (EG) to improve thermal conductivity and stability. Musial et al [13] combined pure organic PCM or composite materials with PCM and high conductive material to achieve more uniform temperature distribution. Zhou et al [14] analyzed the thermal performance of the composite phase-change material embedded in a porous ceramic skeleton, based on the lattice Boltzmann method.…”

Modern Thermal Energy Storage Systems Dedicated to Autonomous Buildings

“…The majority of scientific studies use finite element methods to model the prediction of the thermal functioning of phase change materials or buildings and composites containing PCMs [78][79][80][81]; some use the finite differences method [82][83][84][85] and, more rarely, the finite volumes method [86,87].…”

“…The above equations are dedicated to pure phase change materials or their isotropic composites. On the other hand, the approach described by Musiał et al [87] allows the determination of the heat flux flowing through an anisotropic composite using Formula (6).…”