Hybrid paper membranes incorporated with carbon and phase change materials for improved thermal performance

Energy recovery ventilators (ERVs) are essential for improving indoor air quality (IAQ) and reducing energy consumption. However, conventional membranes often lack thermal storage capability and long-term durability. This study developed a composite paper membrane by impregnating a pulp-derived corrugated substrate with n-octadecane-based phase change material (PCM) and carbon additives, including carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnP), graphene, and activated carbon (AC), to enhance thermal regulation and moisture permeability. Thermal conductivity measurements, differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and dynamic thermal tests were conducted for performance evaluation. The results show that PCM integration significantly improved the composite paper membranes, which exhibited a latent heat storage equivalent to 68 % of the latent heat value of pure PCM. Carbon additives improved heat transfer efficiency and increased thermal conductivity, promoting uniform temperature distribution during heating and cooling cycles. Moisture permeability was maintained, with S_d values below 1 m, meeting ISO 12572 standards for breathable membranes. Durability evaluation through 1,000 thermal cycles, equivalent to approximately three years of ERV operation, confirmed consistent latent heat capacity and structural integrity. Dynamic testing also demonstrated a slower cooling rate and reduced heat dissipation, indicating the potential of these membranes to buffer indoor environments under variable outdoor conditions. The PCM–carbon composite paper membrane provides a cost-effective and environmentally sustainable alternative to polymer-based ERV membranes, offering dual functionality—moisture control and thermal energy storage—while improving ventilation performance and contributing to low-emission building technologies.