Waste heat recovery device
View Patent ↗In a waste heat recovery device comprising a Rankine cycle in which working fluid circulates and a cooling circuit in which coolant water of an engine circulates, a heat source of a heater of the Rankine cycle is waste heat of the engine. A condenser of the Rankine cycle is configured to exchange heat between the working fluid and coolant water of a third coolant water circuit configured to circulate coolant water having passed through a radiator without passing through the engine.
1. A waste heat recovery device comprising:
a Rankine cycle including a working fluid circuit, the working fluid circuit including:
a heater configured to heat and evaporate working fluid,
an expander configured to expand the working fluid having passed through the heater to generate power,
a condenser configured to condense the working fluid having passed through the expander, and
a working fluid pump configured to feed, to the heater, the working fluid having passed through the condenser,
wherein the heater, the expander, the condenser and the working fluid pump are sequentially arranged;
a first coolant water circuit configured to circulate coolant water by way of an internal combustion engine and a radiator;
a second coolant water circuit configured to circulate the coolant water by way of the internal combustion engine and a first branched path branched between the internal combustion engine and the radiator; and
a third coolant water circuit configured to circulate the coolant water by way of the radiator and a second branched path branched between the first branched path and the radiator, wherein
a heat source of the heater is waste heat of the internal combustion engine,
the condenser is a heat exchanger configured to exchange heat between the working fluid and the coolant water of the third coolant water circuit, and
a check valve configured to prevent a backflow of the coolant water toward the radiator is provided between the first branched path and the second branched path on a downstream side of the radiator in the first coolant water circuit.
2. The waste heat recovery device according to claim 1 , wherein
a first water pump configured to circulate the coolant water is provided between the internal combustion engine and the first branched path,
a second water pump configured to circulate the coolant water is provided at the second branched path, and
an opening degree adjustment unit configured to adjust a path opening degree of each of the first and second coolant water circuits based on a coolant water temperature after passage through the internal combustion engine is provided at a branching point of the first branched path.
3. The waste heat recovery device according to claim 2 , further comprising:
a waste heat state detection unit configured to detect a waste heat state of the internal combustion engine; and
a control unit configured to control driving of the second water pump and driving of the working fluid pump, wherein
when the waste heat state of the internal combustion engine detected by the waste heat state detection unit exceeds a first predetermined value, the control unit drives the second water pump and the working fluid pump.
4. The waste heat recovery device according to claim 3 , wherein
the control unit includes a Rankine output calculation unit configured to calculate an output of the Rankine cycle, and
when the Rankine output calculated by the Rankine output calculation unit is a negative value, the control unit stops driving of the second water pump and the working fluid pump.
5. The waste heat recovery device according to claim 2 , wherein
the heater is a heat exchanger configured to exchange heat between the working fluid and the coolant water of the second coolant water circuit.
6. The waste heat recovery device according to claim 5 , further comprising:
a coolant water temperature detection unit configured to detect the coolant water temperature after passage through the internal combustion engine; and
a control unit configured to control driving of the second water pump and driving of the working fluid pump, wherein
when the coolant water temperature detected by the coolant water temperature detection unit exceeds a first predetermined temperature, the control unit drives the second water pump and the working fluid pump.
7. The waste heat recovery device according to claim 6 , wherein
the control unit includes a Rankine output calculation unit configured to calculate an output of the Rankine cycle, and
when the coolant water temperature detected by the coolant water temperature detection unit is equal to or lower than the first predetermined temperature or the Rankine output calculated by the Rankine output calculation unit is a negative value, the control unit stops driving of the second water pump and the working fluid pump.
8. The waste heat recovery device according to claim 6 , wherein
the first predetermined temperature is set higher than a minimum coolant water temperature for preventing overcooling of the internal combustion engine and lower than the coolant water temperature after passage through the internal combustion engine when the path opening degree of the first coolant water circuit is changed from a closed state to an open state by the opening degree adjustment unit.