Cost-effective carbon foam/paraffin composites for enhanced multifunctional energy conversion and storage

Abstract

Phase change material (PCM) composites have been introduced in various application fields to optimize the balance between energy supply and consumption using renewable energy sources. However, intrinsic weaknesses of PCMs hinder their applications in industrial and residential applications. Herein, the high-strength, lightweight, highly thermally conductive, and cost-effective carbon foam (CF) was utilized as an encapsulation framework for a commercial PCM, paraffin wax (PW), via vacuum infiltration to overcome the limitations of PCMs. The prepared high-performance, shape-stabilized PCM composite is suitable for utilization in multiple applications, including solar thermoelectric power generators (TEGs), resistant heaters, and solar-to-heat converters. The prepared composite was installed on a water-cooled TEG to convert the light to electrical energy. When the proposed thermoelectric conversion system was irradiated with light intensities of 1700, 1800, and 1900 W m⁻², the output voltages were 0.63, 0.83, and 1 V, respectively. The capability of the PCM composite as a resistance heater in energy management of residential buildings at energy peak time was investigated by applying a voltage in the test room. After seven heating/cooling cycles between 55 and 60 °C by turning on/off the voltage under a constant power of 6 W, the temperature of the test room reached comfort conditions. After completely turning off the electrical heater, the release of latent heat energy contributed to maintaining the indoor temperature under convenient conditions. Such excellent performance revealed that the prepared low-cost CF possesses high potential for application in residential heating systems. Furthermore, the high light absorption capacity of commercial CF/PW enables efficient performance in the solar to thermal conversion process.