Abstract An open-cycle thermodynamic engine using a working fluid which is a gas at ambient conditions and which is liquefiable at temperatures below ambient. The engine operates by compressing the working fluid, such as liquid nitrogen, with a pump, convectively heating the nitrogen in a heat exchanger, and isentropically expanding the nitrogen within an expandable chamber to produce shaft work. The cycle is repeated both without compression and with compression of the working fluid. To salvage the remaining energy in the nitrogen or other fluid, an exhaust engine is used. In one embodiment the exhaust engine uses an expandable chamber and piston driven by a plurality of long, small diameter heat responsive wires coupled under tension between the chamber wall and piston. When gases of different temperatures are directed across the chamber, the wires expand and contract thereby reciprocally moving the piston. In another embodiment of the heat engine a manifold is connected to numerous closed tubes in which nitrogen is heated by natural convention. When the pressures within the tubes reach a maximum, the tubes are selectively exhausted against a double acting piston to produce work.
An improved thermodynamic method of producing mechanical energy from a fluid, said method comprising the steps of: a. insulatively storing said fluid at a temperature substantially below ambient; b. isothermally pumping said fluid to a pressure above atmospheric pressure; c. performing at least twice the sequential steps of: i. isobarically heating said fluid by passing said fluid through a heat exchanger having an exterior surface in thermal contact with ambient; and ii. isentropically expanding said fluid in an expansion engine to produce mechanical energy; and d. isentropically compressing said fluid after one of said steps of isentropically expanding said fluid and before the succeeding step of isobarically heating said fluid.
Claim 2
Dependent Claim
110 words
An improved thermodynamic method of producing mechanical energy from a fluid, said method comprising the steps of: a. insulatively storing said fluid at a temperature substantially below ambient; b. isothermally pumping said fluid to a pressure above atmospheric pressure; c. performing at least twice the sequential steps of: i. isobarically heating said fluid by passing said fluid through a heat exchanger having an exterior surface in thermal contact with ambient; and ii. isentropically expanding said fluid in an expansion engine to produce mechanical energy; and d. isentropically compressing said fluid after one of said steps of isentropically expanding said fluid and before the succeeding step of isobarically heating said fluid.
Claim 3
Dependent Claim
32 words
The method of claim 1 further including the step of removing accumulated ice from said exterior surface of at least one of said heat exchangers to maintain the thermal transfer efficiency thereof.
Claim 4
Dependent Claim
52 words
The method of claim 1 further including the steps of: e. converting to mechanical energy the thermal energy remaining in said fluid after the last of said steps of isentropically expanding said fluid; and f. using the mechanical energy obtained by step (e) to perform step (d) of isentropically compressing said fluid.
Claim 5
Dependent Claim
30 words
The method of claim 3 further including the step of using a portion of the mechanical energy obtained by step (e) to perform step (b) of isothermally pumping said fluid.