Integration of reverse osmosis and refrigeration systems for energy efficient seawater desalination

Reverse osmosis (RO) systems have minimum energy consumption compared to other desalination
methods and their energy consumption is only in the form of electric power. However, in addition to
fresh water, many buildings and even many factories and industries also need air conditioning, which
requires large amounts of energy. The aim of this study was to introduce a new method for combined
cold and fresh water (CCW) generation by integration of a RO and a refrigeration system. In this new
integrated system, the electrical power consumption of the pumps in the RO system was conserved by
preheating the seawater through the waste heat recovery in the condenser of the refrigeration cycle. A
further reduction in the electrical power demand of these pumps can be made by replacement of the
expansion valve in the refrigeration cycle with a turbo expander Related coding in energy efficient
seawater (EES) software was used to study the feasibility study of the integration of the RO and
refrigeration systems to co-generate 10 M3/day fresh water and 3 refrigeration tons of cooling as an
illustrative example and the best state for this combined system was determined. The results confirmed
that the proposed method provides a reduction of about 7.6% of the power consumption used in the
separate production of fresh water and cooling.