JP2002115504A - Rankine cycle device - Google Patents

Abstract

(57) [Problem] To improve the heat exchange efficiency of a condenser of a Rankine cycle device, and to prevent supercooling of a liquid phase working medium, thereby saving energy consumption of an evaporator. The Rankine cycle device includes an evaporator (3) for generating steam, an expander (4) for converting heat energy of the steam into mechanical energy, and a condenser (5) for cooling the steam discharged by the expander (4) and returning it to water. And a supply pump 6 that pressurizes the water from the condenser 5 and supplies the pressurized water to the evaporator 3. Condenser 5
Is divided into an upstream gas phase portion 24 (portion containing steam and water) and a downstream liquid phase portion 25 (portion containing substantially only water), and the cooling efficiency of the gas phase portion 24 is Set higher than the cooling efficiency. Thereby, the latent heat released when the saturated vapor is liquefied in the gas phase portion 24 can be effectively absorbed to enhance the condensation performance, and the water is supercooled in the liquid phase portion 25 where the release of the latent heat is not expected. Can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Rankine cycle device for converting thermal energy such as exhaust gas of an internal combustion engine into mechanical energy.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 59-174308 discloses that
An evaporator that heats the liquid-phase working medium with exhaust gas of the internal combustion engine to generate steam, an expander driven by the steam generated by the evaporator, and a liquid-phase working medium that cools the steam that has passed through the expander A Rankine cycle apparatus is described which includes a condenser for returning to the evaporator and a supply pump for pressurizing the liquid-phase working medium from the condenser and supplying the pressurized liquid-phase working medium to the evaporator.

[0003]

Generally, the steam supplied from the expander to the condenser is a saturated steam containing a small amount of water,
The saturated vapor liquefies while releasing latent heat while flowing inside the condenser, and the proportion of the vapor gradually decreases, and when leaving the condenser, becomes water containing no vapor. Therefore, when heat is exchanged with steam by applying cooling air to the condenser, the heat exchange efficiency is increased in the gas phase portion on the upstream side of the condenser, that is, in a region where steam and water are mixed. The heat exchange efficiency is low in the liquid phase portion on the downstream side of, that is, in the region where only water exists. Therefore, if cooling air is applied uniformly to the entire condenser by the cooling fan, the water is supercooled in the liquid phase where no latent heat can be released, and the water is supplied to the evaporator and heated again. In this case, there is a problem that extra heat energy is consumed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enhances the heat exchange efficiency of a condenser of a Rankine cycle device and prevents the liquid-phase working medium from being supercooled, thereby saving energy consumption of an evaporator. The purpose is to:

[0005]

According to the first aspect of the present invention, there is provided an evaporator for heating a liquid-phase working medium to generate steam, and the evaporator discharges the evaporator. An expander that converts the heat energy of the steam into mechanical energy, a condenser that cools the steam discharged by the expander and returns it to the liquid-phase working medium, and pressurizes the liquid-phase working medium discharged by the condenser to the evaporator. In a Rankine cycle device provided with a supply pump for supplying, a Rankine cycle device has been proposed, wherein the cooling efficiency of the gas phase portion on the upstream side of the condenser is higher than the cooling efficiency of the liquid phase portion on the downstream side. You.

According to the above configuration, since the cooling efficiency of the gas phase on the upstream side of the condenser is higher than the cooling efficiency of the liquid phase on the downstream side, the saturated vapor is discharged when liquefied in the gas phase. Not only can it effectively absorb the latent heat that occurs and improve the condensation performance, but also prevent the liquid-phase working medium from being supercooled in the liquid-phase part where the release of latent heat is not expected, and connect it to the downstream side of the condenser In the evaporator used, energy consumption can be reduced.

According to the second aspect of the present invention,
In addition to the configuration of claim 1, heat exchange is performed between steam flowing in the condenser mounted on the vehicle and the cooling wind, and the cooling wind, which has passed through the gas phase portion of the condenser and has been heated, is cooled in the vehicle compartment. A Rankine cycle device characterized by being used for heating is proposed.

According to the above configuration, the cooling air heated by the latent heat of the saturated steam released from the gaseous phase portion of the condenser and raised in temperature is used for heating the vehicle interior, so that the waste heat of the internal combustion engine mounted on the vehicle is used. Even when the vehicle cannot be used for heating, the passenger compartment can be heated without any trouble.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 3 show an embodiment of the present invention. FIG. 1 is a view showing the overall configuration of a Rankine cycle device.
FIG. 2 is a partial side view of a vehicle equipped with a Rankine cycle device, and FIG. 3 is an enlarged view taken along line 3-3 of FIG.

As shown in FIG. 1, a Rankine cycle device 2 which recovers thermal energy of exhaust gas of an internal combustion engine 1 and outputs mechanical energy is provided by heating water using the exhaust gas of the internal combustion engine 1 as a heat source to thereby increase the temperature. An evaporator 3 for generating high-pressure steam, an expander 4 for outputting an axial torque by expansion of the high-temperature and high-pressure steam, a condenser 5 for cooling and liquefying the cooled down-pressure steam discharged from the expander 4, Vessel 5
And a supply pump 6 for pressurizing the water discharged from the evaporator 3 and supplying the pressurized water to the evaporator 3 again.

As shown in FIG. 2, a crankshaft 11 is arranged in the engine room of the vehicle V in a lateral direction of the vehicle body.
The internal combustion engine 1 is mounted with the cylinder axis L inclined forward. An evaporator 3 is disposed between an exhaust port 13 and an exhaust pipe 14 opening to the front of a cylinder head 12 of the internal combustion engine 1, and an inlet port of a positive displacement expander 4 provided integrally with the internal combustion engine 1. 4a and outlet port 3 of evaporator 3
a is connected by a high-pressure steam pipe 15. The condenser 5 arranged at the front of the engine room is provided with a steam introduction chamber 16 at the upper end.
And a water collecting chamber 17 at the lower end, and the outlet port 4b of the expander 4 and the steam introducing chamber 16 of the condenser 5 are connected by a low-pressure steam pipe 18. The supply pump 6 connected to the water collecting chamber 17 of the condenser 5 is connected to the inlet port 3b of the evaporator 3 via the high-pressure water pipe 19.

Referring to FIG. 3 together, it is apparent that
The condenser 5 is provided with a number of cooling pipes 20 connecting the steam introduction chamber 16 and the water collecting chamber 17 in a vertical direction, and the plurality of cooling pipes 20 are provided with a number of cooling fins 21 arranged in a horizontal direction. ... penetrates. Each of the cooling pipes 20 and the cooling fins 21 is made of a metal having excellent heat conductivity. Box-shaped shroud 2 arranged on the rear surface of condenser 5
2 is vertically partitioned by a partition plate 23 extending in the horizontal direction, and the upper space of the partition plate 23 faces the gas phase portion 24 on the upstream side of the condenser 5 in the vapor flow direction.
Is opposed to the liquid phase part 25 on the downstream side in the condenser 5 in the vapor flow direction. In the gas phase section 24, the steam introduction chamber 1
Most of the working medium introduced into the cooling pipes 20 from 6 is in a gas phase (vapor) state, and in the liquid phase section 25, most of the working medium flowing through the cooling pipes 20 is in a liquid phase (condensed water) state. It is in.

Behind the gas phase section 24, the shroud 22
Further, two fan motors 27 are supported on the partition plate 23 via stays 26, and the cooling fans 28 are driven by the respective fan motors 27. One fan motor 30 is supported by the shroud 22 and the partition plate 23 via stays 29 behind the liquid phase section 25, and the cooling motor 31 is driven by the fan motor 30.

A hot air duct 32 and an exhaust air duct 33 are branched from the upper half and the lower half of the shroud 22, respectively. The hot air duct 32 communicates with a vehicle interior 34, and the exhaust air duct 33 is At the outside of the vehicle compartment 34. A variable partition plate 35 actuated by an actuator 38 is pivotally supported on a branch portion of the hot air duct 32 and the exhaust air duct 33 located behind the partition plate 23 so as to be vertically swingable. Dampers 36 and 37 for changing the blowing direction of the warm air are pivotally supported at a portion communicating with the inside.

An electronic control unit (not shown) controls the operation of one fan motor 30 corresponding to the liquid phase section 25 on the basis of the water temperature at the outlet of the condenser 5, and varies based on the temperature of the vehicle compartment 34. The operation of the actuator 38 of the partition plate 35 is controlled.

A relatively low temperature (for example, 8 mm) discharged from the expander 4 with the operation of the Rankine cycle device 2
The steam at 0 ° C.) is introduced into the steam introduction chamber 16 of the condenser 5 through the low-pressure steam pipe 18, branches off there, and flows into the plurality of cooling pipes 20. In addition to the traveling wind of the vehicle V, the cooling wind sucked by the three cooling fans 28, 28; 31 is supplied to the condenser 5.
4, that is, the strong cooling air acts on the portion where steam and water are mixed in the cooling pipes 20 by the two cooling fans 28, 28, so that the latent heat released when the steam is liquefied is cooled by the cooling air. Can be collected effectively. On the other hand, a weak cooling wind is applied by a single cooling fan 31 to the liquid phase portion 25 on the downstream side of the condenser 5, that is, a portion where substantially only water exists in the cooling pipes 20.
It is possible to prevent the already liquefied water from being excessively cooled and becoming supercooled. The water condensed in the cooling pipes 20 of the condenser 5 is collected in the water collecting chamber 17, from which the water is pressurized by the supply pump 6 and supplied to the evaporator 3.

When the water temperature at the outlet of the condenser 5 is higher than the target water temperature, one cooling fan 3
The number of rotations of 1 is increased by a command from the electronic control unit,
The cooling effect in the liquid phase section 25 is enhanced so that the water temperature at the outlet of the condenser 5 matches the target water temperature. Conversely, when the water temperature at the outlet of the condenser 5 is lower than the target water temperature, the rotation speed of one cooling fan 31 corresponding to the liquid phase portion 25 is reduced, or the cooling fan 31 is stopped. In addition, the cooling effect in the liquid phase section 25 is weakened so that the water temperature at the outlet of the condenser 5 matches the target water temperature, and the supercooling of the condensed water is reliably prevented. By controlling the condensed water to the target temperature by preventing the supercooled condensed water in this way, the efficiency of the evaporator 3 that heats the condensed water with the exhaust gas and converts the condensed water into high-temperature high-pressure steam can be increased.

When the temperature in the passenger compartment 34 is high and heating is not necessary, the actuator 38 is actuated by a command from the electronic control unit to raise the variable partition plate 35 to the position shown in FIG. This suppresses the supply of the heated hot air to the vehicle compartment 34 via the hot air duct 32, and guides the hot air to the exhaust air duct 33 to discharge the hot air to the outside of the vehicle. Conversely, when the temperature in the passenger compartment 34 is low and heating is necessary, the actuator 38 is controlled by a command from the electronic control unit.
Is operated to lower the variable partition plate 35, and the hot air that has passed through the condenser 5 is introduced into the vehicle interior 34 through the hot air duct 32. The angle of the variable partition plate 35 is arbitrarily controlled according to the temperature in the vehicle interior 34, and the ratio between the hot air supplied into the vehicle interior 34 and the hot air discharged outside the vehicle can be arbitrarily set. .

By the way, when the Rankine cycle device 2 is mounted on the vehicle V and the evaporator 3 is operated by the thermal energy of the exhaust gas, the thermal energy taken by the cooling water circulating in the cylinder head 2 and the cylinder block from the exhaust gas is reduced. Because of the decrease, there is a problem that the capacity is insufficient in the conventional heating device using the cooling water. However, according to the present embodiment, by using the heat energy recovered by the condenser 5 of the Rankine cycle device 2 for heating, it is possible to heat the passenger compartment 34 without providing a special heat source.

Although the embodiments of the present invention have been described in detail above, various design changes can be made in the present invention without departing from the gist thereof.

In the embodiment, a gas phase portion 24 upstream of the condenser 5 is provided.
As means for increasing the cooling efficiency of the liquid phase part 25 on the downstream side, two cooling fans 28, 28 are provided corresponding to the gas phase part 24, and one cooling fan 28 is provided for the liquid phase part 25. Although the cooling fans 31 are provided, other means can be employed. For example, the same number of cooling fans may be provided corresponding to the gas phase portion 24 and the liquid phase portion 25, and the cooling fan on the gas phase portion 24 may be rotated at high speed and the cooling fan on the liquid phase portion 25 may be rotated at low speed. good. The cooling fins 21 of the gas phase part 24 are arranged at a fine pitch,
May be arranged at a coarse pitch. Further, a shutter may be provided in front of the liquid phase section 25, and the shutter may be closed as necessary.

In the embodiment, water is used as the working medium of the Rankine cycle device 2. However, any working medium other than water can be used.

[0024]

As described above, according to the first aspect of the invention, the cooling efficiency of the gas phase on the upstream side of the condenser is made higher than that of the liquid phase on the downstream side. In addition to effectively absorbing the latent heat released when the saturated vapor liquefies in the gas phase, the condensation performance can be improved, and the liquid phase working medium is supercooled in the liquid phase where the release of latent heat is not expected. Energy consumption can be saved in the evaporator connected downstream of the condenser.

According to the second aspect of the present invention,
Cooling air that has been heated by the latent heat released in the gas phase of the condenser and used to heat the passenger compartment is used for heating the passenger compartment, so even if the waste heat of the internal combustion engine mounted on the vehicle cannot be used for heating, The room can be heated without any trouble.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a Rankine cycle device.

FIG. 2 is a partial side view of a vehicle equipped with a Rankine cycle device.

FIG. 3 is an enlarged view taken on line 3-3 of FIG. 2;

[Explanation of symbols]

 Reference Signs List 3 evaporator 4 expander 5 condenser 6 supply pump 24 gas phase section 25 liquid phase section 34 cabin V vehicle

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Makoto Uda 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G081 BA01 BA20 BB00 BC07 BD03

Claims (2)

[Claims] An evaporator (3) for heating a liquid-phase working medium to generate steam, an expander (4) for converting heat energy of the steam discharged from the evaporator (3) into mechanical energy,
A condenser (5) for cooling the steam discharged by the expander (4) and returning it to the liquid-phase working medium, and pressurizing the liquid-phase working medium discharged by the condenser (5) and supplying it to the evaporator (3). In the Rankine cycle device provided with the supply pump (6), the cooling efficiency of the gas phase part (24) on the upstream side of the condenser (5) is made higher than the cooling efficiency of the liquid phase part (25) on the downstream side. Rankine cycle device characterized by the above-mentioned. 2. A heat exchange is performed between steam flowing in a condenser (5) mounted on a vehicle (V) and cooling air, and passes through a gas phase portion (24) of the condenser (5) to obtain a temperature. The Rankine cycle device according to claim 1, wherein the raised cooling air is used for heating a vehicle compartment (34).