6MARTIN M A, DURFEE D J, HUGHES P J. Comparing maintenance costs of geothermal heat pmnp systems with other HVAC systems in Lincoln Public Schools: Repair, service, and corrective actions [ J ]. ASHRAE Transactions, 1999, ( 1 ) : 1208 - 1215.
7MARTIN M A, DURFEE D J, HUGHES P J. Comparing maintenance costs of geothermal heat pump systems with other HVAC systems:Preventive maintenance actions and total maintenance costs[J]. ASHRAE Transactions, 2000, ( 1 ) :408 -423.
8MURAYA N K,DENNIS L W,WARREN M W. Thermal interference of adjacent legs in a vertical U-tube heat exchanger for a ground-coupled heat pump[J]. ASHRAE Transactions, 1996,102 ( 2 ) : 12 - 21.
