A refrigerator of the present invention includes a Rankine cycle heat engine and a refrigeration cycle heat engine which share a condenser, and drives a compressor of the refrigeration cycle by an expander of the Rankine cycle. A screw expander and a screw compressor are set up within a common casing, and the exhaust side of a rotating shaft of the screw expander is connected to the discharge side of a rotating shaft of the screw compressor. Preferably, an intermediate space in which an exhaust passage of the screw expander and a discharge passage of the screw compressor are merged together and connected to a condenser, and a coupling which connects the rotating shaft of the screw expander to the rotating shaft of the screw compressor is housed is formed within the casing.
1. A refrigerator comprising:
a high-temperature evaporator thermally communicating with a high temperature heat source for vaporizing a heat medium;
a screw expander comprising male and female rotors for converting the expansion force of the heat medium vaporized in said high-temperature evaporator to rotational force;
a condenser to which the heat medium exhausted from said screw expander is introduced;
a circulation pump for supplying at least a portion of the heat medium liquefied in said condenser to said high-temperature evaporator;
an expansion valve for decompressing the remaining portion of the heat medium liquefied in said condenser;
a low-temperature evaporator thermally communicating with a low temperature heat source having a temperature lower than a temperature of the high temperature heat source, for vaporizing the heat medium decompressed by said expansion valve for heat absorption;
a screw compressor comprising male and female rotors for compressing the heat medium vaporized by said low-temperature evaporator; and
a casing for housing said screw expander and said screw compressor, wherein said casing comprises a screw expander rotor chamber housing said male and female rotors of the screw expander, and a screw compressor rotor chamber housing said male and female rotors of the screw compressor, and wherein said screw expander and said screw compressor are arranged such that an exhaust side of the rotating shaft of said screw expander and a discharge side of the rotating shaft of said screw compressor face an intermediate space in said casing, the intermediate space being provided between said screw expander and said screw compressor, and an exhaust passage of said screw expander and a discharge passage of said screw compressor are merged together in the intermediate space of said casing,
wherein the refrigerator is configured to introduce the heat medium discharged from said screw compressor to said condenser while the heat medium merges with the heat medium exhausted from said screw expander, and
wherein the exhaust side of the rotating shaft of said screw expander is connected within said intermediate space of said casing to the discharge side of the rotating shaft of said screw compressor.
2. The refrigerator according to claim 1 , wherein the merged exhaust passage of said screw expander and the discharge passage of said screw compressor are connected to said condenser, and wherein the intermediate space houses a coupling which connects the exhaust side of said rotating shaft of said screw expander to the discharge side of said rotating shaft of said screw compressor.
3. The refrigerator according to claim 2 , wherein a generator is provided within said intermediate space to generate electricity by the rotational force of said screw expander.
4. The refrigerator according to claim 3 , wherein said coupling includes a clutch capable of separating said rotating shaft of said screw expander from said rotating shaft of said screw compressor.