Polyurethane macro-encapsulation for CH3COONa•3H2O-Na2S2O3•5H2O/Melamine sponge to fabricate form-stable composite phase change material

Using nano-sized porous supporting materials as carriers to shape-stabilize phase change materials (PCMs) is leading currently. However, the high carrier proportion and the existence of nonfreezing liquid layer in the composite significantly reduce the phase change enthalpy of composite. In this work, macroporous Melamine sponge (MS) as lightweight semi-adsorbed supporting material and the eutectic hydrated salt of Na2S2O3 center dot 5H(2)O-CH3COONa center dot 3H(2)O as PCM were introduced, and the enthalpy reduction of the PCM@MS composite was much smaller (within 5%). Subsequently, the solid polyurethane (PU) thin-layer was adapted to macro-encapsulate PCM@MS , by which PCM operated stably in a closed system, solving the leakage problem and eliminating salt corrosion. With the addition of 2% SrCl2 center dot 6H(2)O as nucleating agent, the eutectic hydrated salt PCM with the mass ratio of 72%Na2S2O3 center dot 5H(2)O-28%CH3COONa center dot 3H(2)O processed a suitable melting point (41.45 degrees C), high enthalpy (186.6 J/g) and low supercooling (0.462 degrees C). The morphology of MS and the distribution of PCM in MS were investigated in detail. Leakage and thermal stability tests for PCM@MS @PU indicated that 2.5 mm PU thinlayer owned a prominent cladding effect on PCM@MS. Heat conductivity determination manifested that PCM@MS @PU presented a brilliant thermal insulation property. Moreover, its thermal performance difference was small after 150 thermal cycles. All these enable the application of PCM@MS @PU in radiant floor heating system and provide a new routine for shape-stabilizing PCMs with polymer-based macroporous supporting material and thin-coating material.

Automated summary

This study utilized lightweight semi-adsorbed supporting material Melamine sponge and a eutectic salt as PCM, with solid polyurethane thin-layer encapsulation to stabilize PCM operation. The addition of nucleating agent and detailed investigations on morphology and distribution led to suitable melting point, high enthalpy, low supercooling, and excellent thermal insulation properties. The PCM@MS @PU composite showed promising results for radiant floor heating systems and provides a new approach for shape-stabilizing PCMs.