An energy efficient integration of vapour compression refrigeration with LNG-regasification for freeze desalination applications

Abstract

In freeze desalination systems, there are challenges associated with freezing-thawing separation, thermal instability, and low performance of vapour compression systems. In the current work, an integrated system for freshwater production is introduced using a reverse-vapour compression refrigeration (rVCR) in combination with liquefied natural gas cold energy. In the combined system, the rVCR subsystem performs simultaneous freezing–thawing heat exchange, while LNG regasification subsystem ensures thermal stability of the cycle using cold thermal energy. The computational analysis of the proposed integrated cycle is carried out using environment friendly R1234ze(E). The effect of evaporator temperature on the proposed cycle performance is evaluated. The results show that 15%–20% of the refrigerant mass fraction is condensed at the LNG regasification step. The energy performance of the integrated system is increased by 10% to 16%, compared to conventional two stage systems. Refrigerant R1234ze(E) is found to be a good eco-friendly alternative to current ones. Thermodynamic analysis shows that the modified rVCR-LNG system is an energy-efficient solution for freeze desalination applications.