6Kaygusuz K. Experimental and theoretical investigation of a solar heating system with heat pump [ J 1. Renewable Energy, 2000, 21: 79-102.
7Baek N C, Shin U C, YoonJ H. A study on the design and analysis of a heat pump heating system using wastewater as a heat source[J]. Solar Energy, 2005, 78: 427440.
8Aye L. Charters W W, Chaiehana C. Solar heat pump systems for domestic hot water[ J]. Solar Energy, 2002, 73 (3) :169-175.
