Recovery of power from low level heat sources

Claim 1

A method for converting low grade heat into useful work, said method comprising connecting a set of three pressure vessels to a common high pressure feed manifold and a common low pressure return manifold, connecting a fluid pressure driven motor across said manifolds, said vessels, said manifolds and said motor forming a sealed system, charging said system with a volatile refrigerant, providing fluid flow controlling valves between said pressure vessels and said manifolds, and sequentially heating and cooling selected vessels with concomitant valve operation to maintain a continuous pressure differential across said fluid pressure driven motor and further providing a high and low liquid level control for each pressure vessel and wiring said liquid level controls and said fluid control valves into a central process controller to automatically maintain said pressure differential.

Claim 2

A method for converting low grade heat into useful work, said method comprising connecting a set of three pressure vessels to a common high pressure feed manifold and a common low pressure return manifold, connecting a fluid pressure driven motor across said manifolds, said vessels, said manifolds and said motor forming a sealed system, charging said system with a volatile refrigerant, providing fluid flow controlling valves between said pressure vessels and said manifolds, and sequentially heating and cooling selected vessels with concomitant valve operation to maintain a continuous pressure differential across said fluid pressure driven motor and further providing a high and low liquid level control for each pressure vessel and wiring said liquid level controls and said fluid control valves into a central process controller to automatically maintain said pressure differential.

Claim 4

A system for generating power from a source of low grade heat comprising a plurality of pressure vessels, said vessels connected to a common high pressure manifold and a common low pressure manifold, valve means in fluid control relationship between each vessel and said manifolds, a fluid pressure driven motor connected across said manifolds, said vessels, manifolds and motor forming a closed refrigeration system, a volatile refrigerant charged into said system, said refrigerant existing in the liquid and vapor phases, means to sequentially heat and cool the pressure vessels to maintain a pressure differential across said manifolds; and said means to sequentially heat and cool the pressure vessels including a refrigerant liquid level sensor to sense the refrigerant level in each vessel.

Claim 5

A system for generating power from a source of low grade heat comprising a plurality of pressure vessels, said vessels connected to a common high pressure manifold and a common low pressure manifold, valve means in fluid control relationship between each vessel and said manifolds, a fluid pressure driven motor connected across said manifolds, said vessels, manifolds and motor forming a closed refrigeration system, a volatile refrigerant charged into said system, said refrigerant existing in the liquid and vapor phases, means to sequentially heat and cool the pressure vessels to maintain a pressure differential across said manifolds; and said means to sequentially heat and cool the pressure vessels including a refrigerant liquid level sensor to sense the refrigerant level in each vessel.

Claim 9

A system to recover low grade heat comprising at least three pressure vessels, each vessel being connected to a common high pressure feed manifold and a common low pressure return manifold, a fluid pressure driven motor connected across said manifolds, said vessels, manifolds and motor forming a closed refrigeration system, a volatile refrigerant including a liquid and vapor phase charged into said refrigeration system, each pressure vessel being equipped with a low level and high level refrigerant liquid sensor to sense the refrigerant liquid in each vessel, a heat exchanger isolated from but conductively associated with each pressure vessel to supply each vessel with heating or cooling fluid so that the vessels sequentially serve as a source or sink for the refrigerant, valve means in fluid control relationship with said pressure manifolds and heat exchangers for effecting said sequential operation of said pressure vessels; and wherein said valve means includes a valve pair connected to a heating manifold to supply heating fluid and a cooling manifold to supply cooling fluid to said pressure vessels.

Claim 10

A system to recover low grade heat comprising at least three pressure vessels, each vessel being connected to a common high pressure feed manifold and a common low pressure return manifold, a fluid pressure driven motor connected across said manifolds, said vessels, manifolds and motor forming a closed refrigeration system, a volatile refrigerant including a liquid and vapor phase charged into said refrigeration system, each pressure vessel being equipped with a low level and high level refrigerant liquid sensor to sense the refrigerant liquid in each vessel, a heat exchanger isolated from but conductively associated with each pressure vessel to supply each vessel with heating or cooling fluid so that the vessels sequentially serve as a source or sink for the refrigerant, valve means in fluid control relationship with said pressure manifolds and heat exchangers for effecting said sequential operation of said pressure vessels; and wherein said valve means includes a valve pair connected to a heating manifold to supply heating fluid and a cooling manifold to supply cooling fluid to said pressure vessels.