To improve the exhaust heat recovery efficiency, a compressor includes a heat exchanger for cooling a gas, coolant, water, or oil heated by the compressor during compressor operation by heat exchange with a working fluid, for circulating the working fluid of a Rankine cycle. The Rankine cycle is implemented by the heat exchanger, an expander, a condenser, and a circulating pump to circulate the working fluid through the cycle.
1. An air compressor, comprising:
a compressor body for compressing air in a state in which oil or water is supplied into a compression chamber, wherein a coolant flow path formed in a casing of the compressor body allows a coolant to circulate therethrough;
a first heat exchanger for cooling and supplying the coolant to the coolant flow path to heat exchange with a working fluid, for circulating the working fluid;
a second heat exchanger for cooling the air compressed and heated by the compressor body during compressor operation by heat exchange with a working fluid, for circulating the working fluid;
a separator for separating oil or water included in the compressed air discharged from the compressor body;
an expander for expanding the working fluid heated and vaporized by the second heat exchanger to generate a driving force;
a condenser for cooling and liquefying the working fluid supplied from the expander to supply the liquefied working fluid to the second heat exchanger; and
a circulating pump for circulating the working fluid among the first and second heat exchangers, the expander, and the condenser, wherein:
the first heat exchanger, the second heat exchanger, the expander, the condenser, and the circulating pump implement a Rankine cycle,
the second heat exchanger includes:
a compressed air heat exchanger for cooling compressed air discharged from the compressor body, by heat exchange with the working fluid.
2. The air compressor according to claim 1 , further comprising:
a motor for generating power for the compressor body; and
a gear system connected between the motor and the compressor body,
wherein the second heat exchanger further includes a lubricating oil heat exchanger for cooling lubricating oil, heated by the gear system, by heat exchange with the working fluid.
3. The air compressor according to claim 1 , wherein:
first and second heat exchangers are series-connected in such a manner that the working fluid circulates in increasing order of exchange heat quantity.
4. The air compressor according to claim 2 , wherein the first and second heat exchangers are series-connected in such a manner that the working fluid circulates in increasing order of exchange heat quantity.
5. The air compressor according to claim 1 , further comprising:
a temperature detector for detecting, upstream of the separator, temperature of the compressed air including oil or water; and
a flow rate controller for controlling circulating flow rate of the Rankine cycle depending on a detection result of the temperature detector.
6. The air compressor according to claim 1 , further comprising a generator connected to the expander.
7. The air compressor according to claim 6 , wherein:
the motor comprises an electric motor,
the compressor further comprises an inverter for varying rotational speed of the electric motor, and
the inverter is connected to the generator.
8. The air compressor according to claim 1 , wherein the working fluid flows in a direction from the oil or water heat exchanger to the compressed air heat exchanger.
9. The air compressor according to claim 1 , wherein the second heat exchanger further includes:
an oil or water heat exchanger for cooling the oil or water separated by the separator, by heat exchange with the working fluid.