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Project - March 2006.

"Liquid Piston" air compressor with concentric double-acting pneumatic intensifier. The intensifier cylinder is 1m in diameter.

Designed to drive a heat pump for domestic heating and hot water supply, using the spent drive water as the source of low-grade heat. A water source with a head of 30m or more alternately fills and empties the two main compressor drums. As it is the surface of the water that acts as the seal there is no wear or leakage - the loose-fitting wood and foam "false pistons" shown prevent thermal exchange between the drive water and the air above, reduce splashing and actuate the change-over mechanism (not shown) at the end of each stroke. Two conical traps remove condensation from the compessed air. Unless a very large head of water is available, the pressure generated is insufficient to drive an efficient heat pump. Here a pneumatic intensifier increases the primary pressure to over 30bar, permitting the use of carbon dioxide as the high pressure refrigerant medium.
Designed to run continually, with a minimum of maintenance, the installation is intended for domestic or small community use. A cold store or small freezer can easily be adapted as part of the heat source.