Water desalination and power cogeneration utilizing heat pipe heat exchanger

Abstract

Energy production in Australia is predominantly achieved with non-renewable sources such as coal and natural gas, with up to 86% of national energy being produced by these processes. Further, access to fresh water is fast becoming an issue in the harsh Australian climate. This paper proposes a novel design capable of producing electrical energy and desalinating water using only waste heat from industrial processes. A finned heat pipe heat exchanger plays an integral role in this process, extracting heat from a low-medium temperature waste heat stream and passing it through a thermoelectric generator and evaporative water desalination unit. Preliminary experimentation on this system showed that different desalination loop configurations played a large role in the desalination ability of the system, however had negligible effect on the thermal to electrical conversion efficiency of the system. When a closed loop system was used, the recovery ratio of the desalination unit reached 4% at the highest waste heat temperature. In the open loop configuration, the recovery ratio was below 1% for all tested inputs. The thermal to electrical conversion efficiency of this system was also measured and a value of about 1.2% was determined for most cases. Thus the ability of this novel system to both produce useful electrical energy and desalinate water was proven.