30 May 2005

APPLICATION OF LAKE-WATER HEAT-PUMP SYSTEM FOR DISTRICT HEATING AND COOLING IN SOUTH CHINA


In recent years, many ground water heat pump systems have been constructed in China, but
surface water heat pump (SWHP) systems are very rare. In south China, surface water resources are
very ample. Water temperature at the depth of 3 m from the surface of many lakes and rivers changes
less than air temperature does during heating and cooling seasons. SWHP systems at these situations
thus are suitable to be developed in south China.
A district heating and cooling (DHC) system which utilizes lake water as heat sources and sinks
of heat pump has been constructed in Xiangtan, a city in Hunan province in south China. Mengze Lake,
which is 82,000 m2 in area and 3 m in average depth, is located among several buildings. An open-loop
system with relatively low initial cost was proposed in 2002. After one year investigation of the key
technical problems, the central plant was designed, constructed and has been operating since summer
2003. This paper introduces the basic scheme of the system, and it also presents the performance and
operating experience of the system. The possibility of improving its efficiency and reliability is also
discussed.