Combined heat and power system and operating method of combined heat and power system
A combined heat and power system is provided with a Rankine cycle passage, a heat medium passage, an evaporator, an expander, a condenser, a pump, a temperature sensor, a sensor, and a controller. The evaporator receives the heat from the heat medium to heat a working fluid. The temperature sensor detects the temperature of the heat medium after radiating heat for heating the working fluid. The sensor detects the pressure of the working fluid flowing between the outlet of the evaporator and the inlet of the expander. The controller adjusts the rotation speed of the pump based on the temperature detected by the temperature sensor, and in addition, adjusts the rotation speed of the expander based on the pressure detected by the sensor.
1. A combined heat and power system comprising:
a Rankine cycle passage in which a working fluid flows;
a heat medium passage in which a heat medium supplied from a heat source flows;
an evaporator that is disposed in the Rankine cycle passage and that directly or indirectly receives heat from the heat medium to heat the working fluid;
an expander that is disposed in the Rankine cycle passage and that expands the working fluid flowing from the evaporator to generate rotational power;
a condenser that is disposed in the Rankine cycle passage and that cools the working fluid flowing from the expander;
a pump that is disposed in the Rankine cycle passage and that pumps the working fluid flowing from the condenser to the evaporator;
a temperature sensor that detects a temperature of the heat medium after radiating heat for heating the working fluid; and
a controller that controls a rotation speed of the pump based on (1) the temperature detected by the temperature sensor and (2) a temperature required for an external fixture configured to utilize heat energy of the heat medium after heating the working fluid.
2. The combined heat and power system according to claim 1 , further comprising:
a fan that is controlled by the controller and that causes air to cool the condenser, wherein
the condenser cools the working fluid by heat exchange between the working fluid and the air.
3. The combined heat and power system according to claim 2 , wherein the controller
increases the rotation speed of the fan in a case in which the temperature detected by the temperature sensor is higher than an upper limit value of a predetermined temperature range, and
decreases the rotation speed of the fan in a case in which the temperature detected by the temperature sensor is lower than a lower limit value of the predetermined temperature range.
4. The combined heat and power system according to claim 1 further comprising a sensor for determining a pressure of the working fluid flowing between an outlet of the expander and an inlet of the expander in the Rankine cycle passage, wherein
the controller controls a rotation speed of the expander based on the pressure determined based on a result of a detection by the sensor.
5. The combined heat and power system according to claim 4 , wherein the controller
adjusts the rotation speed of the pump to keep the temperature detected by the temperature sensor inside a predetermined temperature range, and
adjusts the rotation speed of the expander to keep the pressure determined according to the result of the detection by the sensor inside a predetermined pressure range.
6. The combined heat and power system according to claim 5 , wherein the controller
increases the rotation speed of the pump in a case in which the temperature detected by the temperature sensor is higher than an upper limit value of the predetermined temperature range, and
decreases the rotation speed of the pump in a case in which the temperature detected by the temperature sensor is lower than a lower limit value of the predetermined temperature range.
7. The combined heat and power system according to claim 5 , wherein the controller
increases the rotation speed of the expander in a case in which the pressure determined according to the result of the detection by the sensor is higher than an upper limit value of the predetermined pressure range, and
decreases the rotation speed of the expander in a case in which the pressure determined according to the result of the detection by the sensor is lower than a lower limit value of the predetermined pressure range.
8. An operating method of the combined heat and power system according to claim 4 , the operating method comprising:
determining whether or not the temperature detected by the temperature sensor is inside a predetermined temperature range;
changing a rotation speed of the pump in a case in which the temperature is not inside the predetermined temperature range;
determining whether or not a pressure determined according to the result of the detection by the sensor after changing the rotation speed of the pump is inside a predetermined pressure range; and
changing the rotation speed of the expander in a case in which the pressure is not inside the predetermined pressure range.
9. The combined heat and power system according to claim 1 , wherein the external fixture is a heating radiator.
10. The combined heat and power system according to claim 1 , wherein the external fixture is a hot water supply.
11. The combined heat and power system according to claim 1 , wherein the heat medium is a water.
12. The combined heat and power system according to claim 1 , wherein the controller controls the rotation speed of the pump based on a value obtained by subtracting the temperature required for the external fixture from the temperature detected by the temperature sensor.
13. The combined heat and power system according to claim 12 , wherein the controller
increases the rotation speed of the pump in a case in which the value is positive and the value is higher than a allowed value, and
decreases the rotation speed of the pump in a case in which the value is negative and an absolute value of the value is higher than the allowed value.