JP2730006B2 - Reciprocating external combustion engine operating according to the Carnot cycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application fields] All fields in which it is required to extract mechanical energy with high efficiency from an environment where there is a temperature difference due to combustion heat, exhaust heat, solar heat, cold heat, etc. It can be used in all fields where high energy is required to pump heat from low temperature to high temperature by inputting mechanical energy.

[Prior Art] As an invention devised to carry out a Carnot cycle, there is an engine having a mechanism combining cylinders and pistons having different diameters (JP-A-52-37645). An engine whose theoretical efficiency matches the Carnot efficiency is a Stirling engine.

[Problems to be Solved by the Invention] There is no engine that has been put into practical use and has an efficiency approaching Carnot efficiency. The purpose of this institution is to obtain a highly efficient institution by simulating the Carnot cycle. It is another object of the present invention to provide an engine that can be operated as a Carnot cycle corresponding to any heat source / cooling source temperature by simply replacing and adjusting the engine parts.

[Means for Solving the Problems] This engine is composed of four cylinders, each of which performs each process of the Carnot cycle (isothermal heating expansion, adiabatic expansion, isothermal cooling compression, adiabatic compression). The cylinders are connected to each other in order by a ventilation pipe, and have an annular closed structure. There are valves between the cylinder and the vent pipe, and when these valves and each piston move in conjunction, the fluid automatically circulates in one direction and changes state according to the Carnot diagram.

The inside contains three independent fluids, each of which changes state according to the Carnot cycle while shifting the phase from each other. With respect to one cylinder, each cylinder is always in operation, such that when one fluid is delivered to the next cylinder, the next fluid is immediately delivered from the opposite cylinder.

[Operation] FIG. 1 is a diagram for explaining the operation of the engine.

Operation Of the three independent fluids, let us focus on the fluid with thick diagonal lines as an example. (A) In the state shown in the figure, the fluid is in the cylinder A, and is in the state 1 on the pv diagram and the TS diagram (both valves are closed and the inside of the cylinder is closed).
At this time, a fluid having a pressure and a temperature corresponding to 2 on the diagram remains in the vent pipe a as a result of the previous process. Although not shown in the drawing, a crank mechanism is provided below each piston, and the four cranks are interlocked with each other while being out of phase with each other. The relative relationship between the crank angles is as shown in the figure of the center circle. This phase corresponds to the diagram (a) (for example, the piston of D is at the top dead center).

Due to the rotation of the crank, the fluid in A absorbs heat from a high-temperature heat source that has a large heat capacity and can be regarded as almost isothermal, and expands isothermally. (B) At the position shown in the figure, the necessary isothermal expansion has been completed (2 in the diagram), but once to the bottom dead center for reciprocation (2 'in the diagram), (c) diagram Return to Diagram 2 again. All you have to do is return to the road you came from (dotted line in the diagram)
Does not affect work.

The valves on both sides of the ventilation pipe (a) are opened in the state of FIG. Since the fluid in the ventilation pipe is also in the state of 2 in the diagram as described above, even if the valve is opened, there is no movement of the fluid and no change in temperature. Next, the fluid moves from A to B as the piston of cylinder A rises and the piston of cylinder B descends. (D) In the figure, after A is completely emptied, the valves on both sides of the ventilation pipe A are closed. Since the volumes before and after the movement are equal, the fluid is still in the state 2 on the diagram. Accordingly, the fluid in the state shown in FIG. 2 is sealed in the vent pipe a in the same manner as before, and is used for the next fluid.

On the other hand, the cylinder B is insulated from the surroundings, and the fluid in B is adiabatically expanded by rotation of the crank, and reaches the diagram (f) through the diagram (e). At this time, state 3 is reached in the diagram. Here, the valves on both sides of the ventilation pipe a are opened. As in the case of the vent pipe a, the fluid of state 3 remains in the a.

Next, the rotation of the crank causes the fluid to move from cylinder B to C
Moved to (G) The figure shows a state in which the valves at both ends of the vent pipe a are closed after the fluid has completely moved to C. In (a), the fluid in the state 3 is also sealed.

The fluid in the state 3 in the cylinder C is cooled by a cooling source that has a large heat capacity and can be regarded as substantially isothermal, and is isothermally compressed while releasing heat. After (h), (i) is reached (state 4 in the diagram), and the valves on both sides of the ventilation pipe c are opened. The fluid of state 4 still remains in c.

(J) In the figure, the fluid moves to the cylinder D, and the valves on both sides of the c are closed. The fluid in state 4 in D under adiabatic conditions
Once the piston descends and reaches bottom dead center (state 4 'in the diagram), it is compressed again (l) and reaches state 1 in the figure. Here, the valves on both sides of the ventilation pipe d open. In d, still state 1
Fluid remains.

Finally, the rotation of the crank causes the fluid to be fed into the cylinder A, and the valve of the ventilation pipe d is closed in FIG. This is the initial state.

The above focuses on one fluid, but the other two fluids have undergone the same process as above, starting from the diagram (e) or (i) instead of the diagram (a).

Correspondence to change in heat source temperature The crank relative angle in the above example is set corresponding to a certain heat source temperature. In the case of different heat source temperature ratios (for example, when the high-temperature heat source temperature changes), a corresponding Carnot cycle can be achieved by only slightly changing the relative angle of the crank and the opening / closing timing of the valve linked thereto.
As for the timing of the valve, when the cam mechanism is operated, the cam is replaced with one corresponding to the temperature ratio, and when the valve is of an electrically controlled type, the timing is controlled in accordance with the temperature ratio.

In addition, if the relationship between the crank angles can be controlled during operation, in conjunction with an electrically controlled valve, even if the heat source temperature changes over time, it can follow in real time and always operate in a Carnot cycle. It is possible.

[Effect of the Invention] As a high-efficiency engine, it contributes to more efficient use of energy. In addition, energy can be extracted from a heat source existing in the environment and having a relatively small temperature difference that has not been conventionally used.

In particular, this engine has a feature that it can be operated as a Carnot cycle at an arbitrary heat source temperature by slightly changing the settings of the crank angle and the cam mechanism after production. Further, if the relative angle of each crank can be automatically controlled, it is possible to perform an optimal operation in real time even when the heat source temperature changes with time.

A disadvantage of the shape of the Carnot diagram is that the device volume per generated energy is larger than that of a conventional engine. According to trial calculations, this is particularly noticeable when the heat source temperature difference is large. Therefore, this engine is most effective when there is no severe restriction on the device size and a heat source having a relatively small temperature difference is used.

On the other hand, when this engine is rotated in the reverse direction and used as a heat pump of a reverse Carnot cycle, a very large operating coefficient can be obtained. This is particularly effective when the temperature difference is small, such as in cooling and heating, hot water supply, and the like. For example, considering a case where the temperature difference is about 30 ° C. near normal temperature, about 10 heat can theoretically be supplied (or removed) to the input work 1.

[Brief description of the drawings]

1 (a) to 1 (l) show various aspects during one cycle of the engine. The rectangle in each figure indicates the cylinder, and the horizontal line inside indicates the upper end of the piston. Further, there are valves at both ends of the ventilation pipe connecting the cylinders, and the closed state is indicated by a thick line. The middle diagram is the correlation of the engine's pv diagram, TS diagram and crank angle.

Claims (2)

(57) [Claims] 1. An external combustion type heat engine, wherein a cylinder A is heated in contact with a heat source which has a large heat capacity and can be regarded as substantially isothermal.
Cylinder B covered with a heat-insulating wall, cylinder C cooled in contact with the same cooling source as described above, cylinder D covered with a heat-insulating wall, a vent pipe connecting them in order in a ring, and a valve mechanism provided in each vent pipe The fluid sealed inside moves sequentially through each cylinder by the interlocking of the piston of each cylinder and the operation of the valve mechanism, isothermal expansion in cylinder A, cylinder B
An engine that operates as a Carnot cycle by performing adiabatic expansion in the cylinder, isothermal compression in the cylinder C, and adiabatic compression in the cylinder D. 2. A heat pump that operates in a reverse Carnot cycle by rotating the engine of claim 1 in reverse.