JP2511176B2 - Steam prime mover - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a steam engine with improved thermal efficiency,
In particular, the present invention relates to a steam engine mounted on a vehicle that uses exhaust heat of an automobile engine that requires high efficiency and high specific output, or a stationary steam engine that uses industrial exhaust heat.

(Prior Art) A steam engine based on a Rankine cycle is a process of adiabatic compression of a condensate by a pump (water supply pump) and sending it to an evaporator (boiler), isobaric superheating in the evaporator, and working gas (superheated steam). ), A step of adiabatically expanding it with an expander (turbine) to obtain work, and a step of isothermally cooling the exhaust gas with a condenser (condenser) and condensing, and repeating this step in sequence. Is getting the mechanical output.

The respective devices for performing these steps are combined as shown in FIG. The expander 110 has an expansion chamber 114 defined by an actuator rotor 115, and the expansion chamber 114 includes an evaporator.
Receive working gas from 113, expand this working gas,
Further, it works to send the working gas after the completion of the expansion process to the condenser 111. The condenser 111, the pump 112 and the evaporator 113 are connected in series as shown.

A heat source for heating the compressed condensate at a constant pressure in the evaporator 113 to obtain a working gas (superheated steam) is required for industrial waste heat or waste heat of an automobile engine.

The theoretical thermal efficiency of this type of steam engine can be obtained by increasing the initial pressure and temperature of the working gas to the expansion chamber and lowering the exhaust pressure to the condenser.

(Problems to be solved by the present invention) Although the pressure and temperature of the working gas supplied to the expander are constantly changed due to changes in the amount of waste heat to the evaporator, etc. The pressure ratio before and after was constant. Therefore, the pressure of the working gas returned from the expansion chamber to the condenser cannot be freely changed after the expansion process, and the pressure of the working gas discharged from the expander does not match the pressure in the condenser. In other words, for example, even though the outside air temperature is lowered and the saturated vapor pressure corresponding to the outside air temperature is also lowered, the working gas having the saturated vapor pressure or higher is sucked into the condenser from the expander to operate. Since the gas is discharged from the expander before performing sufficient expansion work, the amount of expansion work per unit flow rate is reduced, and the efficiency of the entire system is reduced.

On the contrary, when the outside air temperature rises and the saturated vapor pressure corresponding to this outside temperature rises, when the working gas below this saturated vapor pressure is discharged by the expander, Negative torque is generated and the work of expansion that can be taken out is reduced, reducing the efficiency of the entire steam engine.

Therefore, an object of the present invention is to solve the above-mentioned disadvantages of the related art.

[Configuration of the present invention]

(Means for Solving the Problem) In order to solve the above-mentioned problems, the present invention sets the state of the working gas from the expander after the expansion process to the state of the working gas in the condenser determined by the outside temperature. To be almost the same,
The basic idea is to adjust the start timing of adiabatic expansion of the working gas in the expansion chamber by the valve mechanism according to the actual temperature and pressure state of the working gas from the evaporator and the outside air temperature.

The technical means according to the present invention taken to achieve the above-mentioned technical problem is as follows. First, a valve mechanism for opening and closing the passage is provided in a passage for guiding a working gas from the evaporator to the expansion chamber of the expander, Controlling the timing at which the working gas starts adiabatic expansion, and further providing a sensor for detecting the working gas pressure in the condenser (or the working gas pressure in the passage between the expansion chamber and the condenser), Working gas pressure at the end of the expansion process in the expansion chamber (or converted from the working gas pressure in the passage between the vaporizer and expansion chamber) and working gas pressure in the condenser (or pressure converted from temperature) To control the supply of the working gas to the expansion chamber by the valve mechanism so as to achieve a highly efficient expansion operation or to increase the supply amount of the working gas to increase the specific output.

More specifically, the present invention relates to an expander 10 that adiabatically expands a working gas to obtain mechanical work, a condenser 11 that cools the working gas discharged from the expander to an isobaric pressure and condenses it, and a condenser from a condenser. A pump 12 for adiabatically compressing the condensate, and an evaporator that heats the condensate from the pump isobarically and uses it as working gas that is superheated steam.
13, the evaporator and the expansion chamber 14 of the expander the first valve mechanism 1
6, 16 ', and passages 34, 34 for connecting the expansion chamber of the expander and the condenser via the second valve mechanism. (EN) Provided is a steam engine which adjusts the start time of adiabatic expansion of a working gas in an expansion chamber.

(Operation) In summary, the above technical means operates as follows.

In the present invention, the adiabatic expansion period of the working gas flowing into the expander is adjusted by changing the timing of closing the working gas supply stop valve (first valve mechanism), and the pressure of the working gas after expansion is adjusted to the outside air temperature. Equalize the pressure inside the condenser determined by. Further, in the present invention, when the heat input to the evaporator is high, that is, when the heat energy amount of the energy source is increased, the timing of closing the working gas supply stop valve is delayed, and the expansion chamber is set to a high pressure for a correspondingly long time, thereby the rotor in the expander The torque that can be taken out from the (rotor) can be increased. In other words, the prime mover of the present invention efficiently takes out a large output from the limited energy source when the heat amount as the energy source is not sufficiently supplied, and when the heat amount as the energy source is sufficiently supplied, the required torque is obtained. It acts to generate from a smaller prime mover.

 The operation of the present invention will be described in more detail.

A sensor detects the working gas pressure or temperature in the condenser. This information is read directly into the control unit as P _min after conversion into pressure using the known operating gas saturation vapor pressure curve for temperature and directly for temperature. That is, changes in the pressure and temperature of the working gas due to changes in atmospheric temperature and the like are also recorded in the control unit.

On the other hand, the pressure P _L ⁰ immediately after the end of the expansion process in the expander is directly read by the pressure sensor. By the way, this pressure P _L ⁰ is determined by the expansion chamber inlet pressure P _max and the operating gas supply closing angle θ ₀ to the expansion chamber, and satisfies the relationship of the following equation. The operating gas supply closing angle θ ₀ is the angle of the rotor center O ′ to the center O of the expander housing (based on when the circuit is at the top dead center). One side will have a θ circuit of 1080 ° until it returns to its original position.

P _L ⁰ = P _max × _{[{V M + V H (1} -cos (2θ 0/3)) / 2} / {V M + V H} ] ^K ... (1) where V _M: dead volume of the expansion chamber V _H : Variable volume of expansion chamber K: Both specific heat ratio of working gas, that is, P _L ⁰ can be controlled by changing working gas supply closing angle θ ₀ . When P _L ⁰ is larger than P _{min, the} control unit advances the valve closing timing to decrease θ _0, and when P _L ⁰ is smaller than P _min , the valve closing timing is set to increase θ _0. Be delayed.

In this way, the supply of the working gas to the expansion chamber is controlled by the valve mechanism so that P _min = P _L ^0, and power with maximum efficiency is obtained.

By the way, the efficiency η can be controlled by changing θ ₀ ,
Further, it is shown below that the power of maximum efficiency can be obtained at P _min = P _L ⁰ .

In Fig. 3, when the high temperature heat source is 100 ℃ and the condensing temperature is 50 ℃
When θ ₀ is changed, the efficiency η (θ ₀ ) changes as shown by the I-η (θ ₀ ) curve. By the way, θ ₀ that gives the maximum efficiency at this time is 122 (° C.), and the pressure P _L ⁰ immediately after the end of the expansion process is calculated to be about 2.5 (bar) from the equation (1). On the other hand, the critical pressure (that is, the condenser pressure P obtained from the saturated vapor pressure curve of this working gas corresponding to the condensation temperature 50 (° C))
_min ) is still 2.5 (bar), which agrees with P _L ⁰ described above. Similarly, as the outside air temperature drops, the condensation temperature rises to 25
At (° C), the efficiency changes as shown by II-η (θ ₀ ). At this time, θ ₀ that gives the maximum efficiency is 82 (° C)
Thus, the pressure P _L ⁰ immediately after the expansion process is about 1.3 (bar). This is a critical pressure of about 1.
It is almost the same as 2 (bar).

When it is difficult to measure the pressure inside the expansion chamber as in the Wankel type rotary rotor expander, the formula (1) can also be used to estimate P _L ⁰ from the expander inlet pressure P _max and the operating gas supply closing angle θ ₀ , and the valve The control is similar to that described above.

(Examples) Hereinafter, the present invention will be described based on examples.

In FIG. 1, the condenser 11, the pump 12, the evaporator 13, and the expander 10 are connected by passages 31, 32, 33, and 34. A rotor 15, which is a moving element, is arranged in the expander 10, and the expansion chamber 14
To form. The rotor 15 is connected to the output shaft. Evaporator 13
Passage 33 from the expander 10 to the condenser 11
In the passage 34 leading to the first valve mechanism 16, 16 'and the second valve mechanism 16,
The valve mechanisms 17 and 17 'are provided to open and close the passages 33 and 34. The control unit 20 is a valve mechanism described above.
From the function of opening and closing 16, 16 ', 17, 17', the sensor 21 for detecting the gas pressure or temperature in the condenser 11, and the sensor 23 for detecting the gas pressure in the expansion chamber 14 provided in the expander 10. From the sensor 22 'which detects the gas pressure flowing into the expansion chamber 14 provided in the passage 33 leading from the evaporator 13 to the expander 10 and the sensor 23' which detects the position state of the rotor 15. It has a function of receiving signals and a function of comprehensively controlling these functions.

With the above configuration, when the atmospheric temperature changes and the working gas pressure or temperature in the condenser 11 changes, the pressure or temperature signal sensed by the sensor 21 is sent to the control circuit 20. On the other hand, the operating gas pressure signal in the expansion chamber 14 sensed by the sensor 23 provided in the expander 10 is also sent to the control unit 20. Further, in some cases, the signal indicating the rotational position of the rotor 15 is detected by the sensor 23 'and the expansion detected by the sensor 22 provided in the passage 33 connecting the evaporator 13 and the expansion chamber 14 of the expander 10. The machine inlet working gas pressure signal is also sent into the control unit 20 by the sensor 22. From the above signals, an opening / closing adjustment signal is sent to each valve mechanism 16, 16'17, 17 'so that the pressure at the end of expansion of the working gas in the expansion chamber 14 becomes equal to the working gas pressure in the condenser 11, and the supply gas amount is supplied. Adjust. As a result, the expander 10 performs expansion operation with maximum efficiency.

The second valve mechanisms 17 and 17 ′ periodically send the working gas adiabatically expanded in the expansion chamber 14 to the condenser 11. That is, the second valve mechanism opens when the expansion chamber 14 reaches the maximum volume (when θ = 270 °), and the expansion chamber 14 reaches the minimum volume (θ
= 540 °), the second valve mechanism closes.

The working gas or working medium used in this example is water,
Freon or the like is used.

The present invention further includes a sensor 24, which measures the heat input supplied to the evaporator 13, in the evaporator 13, receives a heat input signal from the sensor 24, and expands the expander together with the control function described above. It is also possible to control 10. That is, when the heat input is low, the control unit 20 controls the valve mechanisms 16, 16 ', so as to perform the expansion operation with the maximum efficiency as described above.
The control unit 20 controls the valve mechanism 16, 16 ', 17, so that the valve is closed later, that is, in order to supply a larger amount of working gas into the expansion chamber 14, at the time of high heat input. Adjust 17 '. This allows the expander
The maximum efficiency of 10 is not obtained, but a large amount of power can be taken out.

FIG. 4 is an example showing changes in the efficiency η and the power output P with respect to the operating gas supply closing angle θ ₀ . When θ ₀ is delayed to about 180 °, the efficiency η drops to over 7%, but the output P
It is shown to increase to 4.2KW (2.6KW at θ ₀ = 110 °).

As the expander 10, a rotary type is used in the embodiment, but a reciprocating piston type (moving element is a piston) can also be used.

[Effect] The present invention sets the opening degree of the passage to be short when exhaust heat energy is small when the available heat energy fluctuates depending on operating conditions such as automobile engine exhaust gas heat energy (e.g. By increasing the efficiency, the maximum power can be taken out from the limited thermal energy, and when the exhaust heat energy is large, the opening state of the passage is set long (for example, top dead center). After 180
(The passage is closed at °) A large amount of power can be taken out at a limited engine speed.

[Brief description of drawings]

1 is a schematic diagram of a steam engine system according to the present invention, FIG. 2 is a schematic diagram of a conventional technology, FIG. 3 is a characteristic diagram of efficiency-operating gas supply closing angle of a steam engine system according to the present invention, FIG. FIG. 4 is a characteristic diagram of output and efficiency-operating gas supply closing angle of the steam engine system according to the present invention. In the figure, 10 ... expander, 11 ... condenser, 12 ... pump, 13 ... evaporator, 14 ... expansion chamber, 15 ... rotor (mover), 16,16 ', 17,1
7 '... Valve mechanism, 20 ... Control unit, 21 ... Gas pressure or temperature sensor, 22,23 ... Gas pressure sensor, 23'
… Position sensor, 24… Heat input sensor, 31, 32, 33, 34…
aisle.

Continuation of the front page (56) Reference JP-A-58-48706 (JP, A) JP-A-61-123704 (JP, A) JP-A-55-17655 (JP, A)

Claims (3)

(57) [Claims] 1. An expander 10 for adiabatically expanding a working gas to obtain mechanical work, a condenser 11 for isostatically cooling a working gas discharged from the expander to condense it, and an adiabatic compression of a condensate from the condenser. Pump 12, an evaporator 13 that heats the condensate from the pump to the working gas that is superheated steam by isobaric heating, and the evaporator and the expansion chamber 14 of the expander are connected via the first valve mechanism 16 and 16 '. Passages 33, 33 for connecting the expansion chamber of the expander and the condenser via the second valve mechanism 17, 17 '
34, and adjusts the adiabatic expansion start timing of the working gas in the expansion chamber by the first valve mechanism so that the working gas pressure in the condenser and the working gas pressure at the end of the expansion process in the expander are almost A steam engine that controls the opening and closing of the first valve mechanism so that they are equal. 2. An expander 10 for adiabatically expanding a working gas to obtain mechanical work, a condenser 11 for isostatically cooling and condensing the working gas discharged from the expander, and an adiabatic compression of a condensate from the condenser. Pump 12, an evaporator 13 that heats the condensate from the pump to the working gas that is superheated steam by isobaric heating, and the evaporator and the expansion chamber 14 of the expander are connected via the first valve mechanism 16 and 16 '. Passages 33, 33 for connecting the expansion chamber of the expander and the condenser via the second valve mechanism 17, 17 '
34, which adjusts the adiabatic expansion start timing of the working gas in the expansion chamber by the first valve mechanism, and further detects the working gas pressure or temperature in the condenser 11 and the inside of the expansion chamber 14. The control unit has a sensor 22 for detecting the working gas pressure or the working gas pressure in the passage 33, and a control unit is provided to make the working gas pressure in the condenser approximately equal to the working gas pressure at the end of the expansion process in the expander. By controlling the opening and closing of the valve mechanism of No. 1, the working gas pressure at the end of the expansion process converted from the working gas pressure in the expansion chamber 14 or the passage 33 and the working gas pressure in the condenser 11 or the pressure converted from the temperature. The control unit controls the supply of the working gas to the expansion chamber 14 with the valve mechanisms 16 and 16 'so that the expansion operation becomes highly efficient and the control unit outputs a signal according to the heat input to the evaporator. When the heat input to the evaporator is low, the high-efficiency expansion operation is performed, and when the heat input to the evaporator is high, the high-efficiency expansion operation is ignored and the closing timing of the first valve mechanism is delayed. A steam engine that controls opening and closing of the first valve mechanism so as to increase the amount of working gas supplied to the expansion chamber. 3. The steam engine according to claim 2, further comprising a sensor 24 for measuring a heat input supplied to the evaporator 13.