Open-loop direct surface water cooling and surface water heat pump systems—A review

Direct surface water cooling systems utilize lake or seawater to provide cooling for buildings or district cooling systems, without using a heat pump to lower the temperature further. Surface water heat pump systems can provide heating and/or cooling for buildings and district heating/cooling systems, using lake or seawater as their heat source/sink. These systems have been used from the 1940s, yet neither design guidelines nor energy calculation procedures have been developed. Under the right circumstances, direct surface water cooling systems can have remarkably high seasonal system coefficients of performanceas high as 25. Surface water heat pump systems can also have high seasonal system coefficients of performance; values as high as 4.2 for cooling and 4.0 for heating have been reported. The performance of both system types will depend heavily on the pumping/piping system design. This article reviews the available literature describing previously installed systems and the necessary componentsintake devices, piping, pumps, heat exchangers, heat pumps and/or chillers, and outfall devices.