This invention provides a refrigerator using a gaseous
working fluid such as air and based upon the well-developed structure of reciprocating compressors or rotating engines. The invention combines the compression functionality of a compressor and the expansion functionality of a
turbine in an
air cycle machine into a single
refrigeration unit having a simple mechanical structure, and provides a significantly increased heat removal time period before the expansion
stroke to reduce the temperature of the
working fluid under a substantially constant volume without increasing the number of strokes per
discharge in a cycle. Moreover, the need of using a man-made chemical as the
working fluid is eliminated. Said refrigerator
system comprises at least a
piston and cylinder
assembly including a
piston reciprocatingly mounted within the cylinder space, and at least two cooling chambers associated with said cylinder. Each said
cooling chamber has therewithin a
heat exchanger unit that facilitates
heat transfer from the working fluid to a
heat sink, a port leading to said cylinder space, and a cooling-chamber valve, said
valve opening or closing said port to establish or block communication between said chamber and cylinder space. Said refrigerator is adapted to operate on a cycle having 4n essential strokes for a refrigerator utilizing intake and
discharge strokes for respective intake and
discharge purposes, or 2n essential strokes for a refrigerator utilizing a
scavenging process for discharge and intake purposes, where n is the number of cooling chambers associated with each cylinder. For a refrigerator having intake and discharge strokes, each said
cooling chamber has an associated compression
stroke, an expansion
stroke, and between said compression and expansion strokes a time period of 4(n-1) strokes available for
heat transfer from the working fluid enclosed within the
cooling chamber to the
heat sink. For a refrigerator utilizing a
scavenging process for discharge and intake, each said cooling chamber has an associated compression stroke, an expansion stroke, and between said compression and expansion strokes a time period of 2(n-1) strokes available for
heat transfer from the working fluid enclosed within the cooling chamber to the
heat sink. In both cases, during the time period of heat transfer between the enclosed working fluid and heat sink, said
piston would provide strokes for the working fluid associated with another cooling chamber. Additionally, the structure of a rotating refrigerator based on the structure of a
rotary engine is disclosed.