Indoor heating systems currently used are highly dependent on fossil fuels; hence, it is urgent to develop a new heating system to achieve carbon zero-emission. A solar air heater is eco-friendly because it generates nearly zero greenhouse gases. In this study, a parametric study was conducted for optimizing solar air heater design applicable to indoor heating. Installing the internal structure in the solar heater changes the interior flow characteristic, resulting in the air temperature increased by about 14.2 K on average compared to the heater without the internal structure. An additional case study was carried out to optimize the ideal quantity of phase change materials (PCM) in terms of mass fraction and heat capacity for various operating conditions. An excessive amount of PCM (e.g., 66% of the storage space filled with PCM) deteriorates the performance of the air heater unless the entire PCM could be melted during the daytime. After heating, the air temperature was maintained the longest when only 33% of the internal space was filled with PCM. The solar air heater can fully replace or partly assist a conventional heater for indoor heating, and it could reduce approximately 0.6 tCO2 per year.

Summary This study presents the evaluation of the heat transfer characteristics and mechanical deformation of new composite material heat sinks using experimental and computational approaches. First, we synthesized a composite material composed of copper (Cu) and graphite (C) with 60 wt% Cu, with higher thermal conductivity and a lower thermal expansion coefficient than pure Cu and aluminum. The composite material was used to fabricate a heat sink integrated with an insulated‐gate bipolar mode transistor (IGBT) module for enhanced heat dissipation from the IGBT. Compared with the pure Cu heat sink, the composite heat sink decreases the average temperature of the IGBT module by approximately 22 K. It also decreases the total deformation of the heat sink caused by thermal expansion of the material by 78% and the equivalent stress by 25.2%. This study introduces a way to use Cu‐C composite materials in many potential applications, such as heat sinks integrated with IGBT inverters.

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