Enhancing desalination efficiency using waste heat from household air conditioning: A heat pipe-assisted HDH system performance analysis.

[Display omitted] • Investigate HDH for freshwater from saltwater using heat pipes, employing waste heat from residential ACs. • Innovate with recovered AC waste heat to enhance efficiency in freshwater production. • Experimentally assess system performance across varied AC temperatures (19 °C, 20 °C, 21 °C). • Highlight superior freshwater production of R32 heat pipe compared to R134a and R600a. • Contribute to a holistic understanding of HDH system performance, emphasizing efficiency benefits. This study presents an experimental exploration of a desalination system that produces freshwater from saltwater using a novel heat pipe-assisted humidification-dehumidification (HDH) process. The system utilizes waste heat recovered from residential air conditioners that use vapour compression refrigeration systems. The study focuses on the mass and heat transfer within the system's components, with performance evaluations conducted at three different air conditioning temperatures (19 °C, 20 °C, and 21 °C). The experiments highlight the freshwater production of the R32 heat pipe over the R134a and R600a heat pipes. The study estimates the system's cost-effectiveness at $0.0085/L, emphasizing its economic viability. Preheating resulted in significant improvements in freshwater yield, ranging from 43.33 % to 51.5 %, at temperatures of 21 °C and 20 °C, respectively. The Gain Output Ratio (GOR) doubled from 0.75 to 1.52, indicating a more energy-efficient process with significant improvements in the effectiveness of humidification and dehumidification. The pH levels improved from 8.32 to 7.07, representing a 15 % reduction and falling within the WHO-recommended range of 6.5–8.5. Electrical Conductivity (EC) shows a notable reduction from 62,720 to 826.1 micromhos/cm, representing a 98.68 % reduction, and well below the permissible limit of 1500 micromhos/cm. Total Dissolved Solids (TDS) also experienced a drop from 31,777 to 413.1 ppm, representing a 98.7 % reduction, and falls under the WHO guideline of <600 ppm for drinking water. The experiments prove that the use of waste heat from household air conditioners for sustainable freshwater production through the HDH desalination method, with the added efficiency benefits of heat pipe. [ABSTRACT FROM AUTHOR]