DE4140573A1 - Thermal to mechanical energy conversion process - using e.g. liq. carbon di:oxide with waste heat recycling - Google Patents

Abstract

A process for converting thermal energy into useful mechanical energy employs a liq. work medium, e.g. CO2, in a cyclic process consisting of two polytropes (1-2,3-4) and two isochores (2-3,4-1) as shown on the temp. vs. entropy graph. The cycle pref. consists of a first line (1-2) of adiabatic compression in which the CO2 temp. drops, an isochore (2-3) of heat supply for pressure increase, a line (3-4) of adiabatic expansion under working load in which the CO2 temp. increases and a final isochore (4-1) of waste heat extraction to attain the initial pressure. The extracted waste heat is pref. completely or partially returned to the isochore region (2-3). USE/ADVANTAGE - The process is used in engines, esp. heat engines, and allows return of waste heat to the circuit.

Description

The invention relates to processes for converting heat gie in usable mechanical energy.

Engines for converting energy are already in a big one Number of different configurations, especially as a heat engine known.

Heat engines are devices where in principle that is natural heat gradient is used, comparable to a hydropower plant location where the kinetic energy of water is converted into mechanical energy is changed.

This comparison is only partially correct, because water is a material Medium, the kinetic energy z. B. theoretically in a turbine can be converted 100% into mechanical energy.

Heat, on the other hand, is bound to a material medium (work equipment) energy form that never in one pass through a periodic Heat engine is 100% convertible into mechanical energy.

When the working fluid passes through a periodic thermal force machine can convert only a part of the heat supplied into mechanical Work to be converted, the remaining portion of the heat input must reach the starting position of the periodic thermal power be dissipated as waste heat.

The maximum achievable efficiency depends on the heat gradient and is calculated according to Carnot.

The object of the invention is therefore a method for converting To create thermal energy in usable mechanical energy, in which the natural law with each passage of a work equipment through a periodic engine waste heat returned to the cycle can be led.

All information on this new process for converting thermal energy into usable mechanical energy relates to carbon dioxide CO ₂ , since precise diagrams and data are only available to me via this medium. However, it can be assumed that other liquids also behave in this or a similar manner.

Since these diagrams and documents available to me about CO _{2 are} older, the information about mechanical and thermal quantities is given in old units and not in SI units.

Further details of the process for converting thermal energy into Usable mechanical energy can be found in the drawings.

Fig. 1 Schematic representation of a Mollier ts diagram for CO ₂ with the different physical states.

Fig. 2 section of the ts diagram for CO ₂ in the liquid-gas form, with the Rankine cycle shown.

Fig. 3 section of the ts diagram for CO ₂ in the liquid-high pressure area, with the process cycle shown, for example.

Fig. 4 Schematic representation of an engine and the parameters prevailing at each point in the exemplary CO ₂ cycle process.

The areas hatched differently in the schematic Mollier ts diagram for CO ₂ in FIG. 1 show the area liquid-gaseous (shown in FIG. 2) and the liquid high-pressure area (shown in FIG. 3).

The Rankine cycle shown in FIG. 2 in the ts diagram for CO ₂ is the cycle process most used in the production of usable mechanical energy from thermal energy. It also runs in water, but at higher temperatures.

The working fluid is transferred from (a) to (b) via a feed pump brought to boiler pressure and from (b) to (c) by supplying heat evaporates. In an adiabatic engine from (d) to (e) the steam superheated from (c) to (d) relaxes and does work.

The waste heat released from (e) to (a) during the condensation can since the condensation takes place at a lower temperature than the evaporation, cannot be returned to the cycle.

In the CO ₂ diagram of FIG. 3, when the enthalpy lines (i) are followed from right to left, it can be seen that, with the same enthalpy (i), the pressure (p) increases with increasing temperature (t) up to a peak at approximately 400 at increases to 600 at. After this peak is exceeded, the usual behavior of work equipment is reversed.

With compression, cooling takes place instead of the usual heating.

During relaxation, heating takes place instead of the usual cooling.

The circular process shown in Fig. 3 ( 1/2/3/4 ), consisting of two polytropes ( 1-2 / 3-4 ) and two isochors ( 2-3 / 4-1 ), is shown in Fig. 4 by hand a schematic engine and the parameters readable for each point ( 1/2/3/4 ) of the cycle in the CO ₂ diagram in FIG. 3.

On the route from point ( 1 ), working piston UT, to point ( 2 ), working piston OT, the working fluid is compressed adiabatically, the enthalpy increases by the amount of work done.

On the route from point ( 2 ), working piston OT, to point ( 3 ), working piston OT (isochoric), heat is supplied to the working medium, causing the pressure (p) to rise.

On the route from point ( 3 ), working piston OT, to point ( 4 ) working piston UT, the working fluid is adiabatically relaxed under work performance, the enthalpy drops by the amount of mechanical work gained.

On the route from point ( 4 ), working piston UT, and the starting point ( 1 ) of the cycle, working piston UT (isochore), heat is removed from the working medium, as a result of which the pressure (p) drops to the initial pressure of the cycle process.

The on the route from point ( 4 ) and the starting point ( 1 ) of the cycle process to be dissipated waste heat ( 8 ) occurs at a higher temperature than that of the working fluid on the route from point ( 2 ) to point ( 3 ). Theoretically, the entire waste heat ( 8 ) can be fed to the cycle for reuse.

The amount of heat ( 9 ) to be newly added, which is equivalent to the mechanical work being performed, is supplied at point ( 3 ), working piston OT.

Claims (8)

1. A method for converting thermal energy into usable mechanical energy, characterized in that according to Fig. 3 and Fig. 4, the liquid working medium used, for example, carbon dioxide CO ₂ in one of two polytropics ( 1-2 / 3-4 ) and two isochors ( 2-3 / 4-1 ) existing cycle is carried out. 2. The method according to claim 1, characterized in that the working medium used for example CO _{2 is} adiabatically compressed on the route (1-2) of the cycle, whereby its temperature drops. 3. The method according to claim 1 and 2, characterized in that the working medium used for example CO ₂ on the route ( 2-3 ) of the cycle isochoric to increase the pressure heat ( 7 ) is supplied. 4. The method according to claim 1 to 3, characterized in that the working medium used for example CO ₂ on the route ( 3-4 ) of the cycle is relaxed adiabatically under work, whereby its temperature rises. 5. The method according to claim 1 to 4, characterized in that the working medium used for example CO ₂ on the route ( 4-1 ) to close the cycle process isochorically the waste heat ( 8 ) entzo conditions to achieve the output pressure in the cycle. 6. The method according to claim 1 to 5, characterized in that the waste heat ( 8 ) accumulating on the route ( 4-1 ) of the cycle process ( 8 ) is entirely or partially recycled to the route ( 2-3 ) in the cycle process. 7. The method according to claim 1 to 6, characterized in that the equivalent of the mechanical work submitted to the cycle process to be newly supplied amount of heat ( 9 ) at point ( 3 ) is supplied. 8. The method according to claim 1 to 7, characterized, that the cycle process with liquid or gaseous working fluids is performed in a pressure range in which the temperature at isent halpic pressure increase drops.