Glow plug Integrated Solar Heater for Reducing Initial Waiting Period of Evaporation Lag and Improve Thermal Efficiency in Solar Still Desalination

The current solar desalination process is facing a challenge of longer time for the brine temperature to reach the evaporation threshold during the winter with cooler ambient temperature, cloudy, and the initial hours of the day. This study aims to address the challenge by reducing initial waiting period of evaporation lag through integrating a glow plug enabled solar powered water heater (SPWH), operates at low resistance (0.48 – 0.81 Ω) and high power (12 V, 25 A, 300 W). Prior to implementation, mathematical modelling is employed to determine the appropriate sizing of the PV system, battery, cable, and maximum power point tracking (MPPT) controller. The results demonstrate a significant increase in the temperature of the brine, reaching 79.2°C within 45 minutes at a rate of 0.96°C/min. The temperature profile demonstrates that the brine water, reaching a steady peak with minimal fluctuations of ± 2°C, retains heat more effectively than the chamber temperature due to its higher specific heat capacity. Throughout the experiment, the average brine temperature is maintained at 70.58°C, even on a day with heavy cloud cover (average irradiance 418 W/m²). Another noteworthy finding is that the system can produce more than 3.35 kg/m² of freshwater per day with the highest thermal efficiency of 68.18% under cloudy ambient conditions. The electrical performance of the system proves to be highly stable, with the voltages of both the PV system and battery experiencing minimal fluctuations not more than 0.9%. In addition, the system has achieved a cost-effective production rate of $0.09/kg. By employing this technique, challenges related to limited access to clean drinking water, scarcity of freshwater sources, and water quality issues in remote Malaysian islands can be effectively overcome.