Theoretical analysis of an improved adsorption desalination system under different operating conditions

This paper presents the development of an advanced adsorption desalination system (ADS) with heat and mass recovery. By means of internal heat and mass recovery, this adsorption desalination system (ADS), offers a significantly higher performance ratio compared to the conventional systems. After vapor desorption, the pressure difference in the hot bed is first transmitted to the cold bed using mass recovery. Then, the heat from the hot bed is transferred into the cold bed and, eventually, to the condenser and evaporator, by means of the cold water. Numerical simulations for this system are compared to a verified experimental model, and then developed to study the effect of the operating parameters. The level of SDWP or specific daily water production for this ADS was found to be 13.48 m^3/ton of silica gel/day at a hot water temperature of 92.5 (°C) and a cold water temperature of 30 (°C). Consequently, in these operating conditions, the SDWP of the advanced ADS was found to be 153% more than the conventional ADS. Also, at the same temperature conditions, the performance ratio of the ADS with heat and mass recovery was 35% higher than the ADS without heat and mass recovery.

Exergy Analysis of Advanced Adsorption Cooling Cycles

This study conducted an exergy analysis of advanced adsorption cooling cycles. The possible exergy losses were divided into internal losses and external losses, and the exergy losses of each process in three advanced cycles: a mass recovery cycle, heat recovery cycle and combined heat and mass recovery cycle were calculated. A transient two-dimensional numerical model was used to solve the heat and mass transfer kinetics. The exergy destruction of each component and process in a finned tube type, silica gel/water working paired-adsorption chiller was estimated. The results showed that external loss was significantly reduced at the expense of internal loss. The mass recovery cycle reduced the total loss to 60.95 kJ/kg, which is −2.76% lower than the basic cycle. In the heat recovery cycle, exergy efficiency was significantly enhanced to 23.20%. The optimum value was 0.1248 at a heat recovery time of 60 s. The combined heat and mass recovery cycle resulted in an 11.30% enhancement in exergy efficiency, compared to the heat recovery cycle. The enhancement was much clearer when compared to the basic cycle, with 37.12%. The observed dependency on heat recovery time and heating temperature was similar to that observed for individual mass recovery and heat recovery cycles.