WO2015127910A1

WO2015127910A1 - Heat engine with high thermal efficiency

Info

Publication number: WO2015127910A1
Application number: PCT/DE2014/000085
Authority: WO
Inventors: Manfred Carlguth; Volker Carlguth
Original assignee: Manfred Carlguth
Priority date: 2014-02-25
Filing date: 2014-02-25
Publication date: 2015-09-03
Also published as: DE112014006400A5

Abstract

The invention relates to a heat engine with high thermal efficiency, in which water (1) as working fluid flows from the storage vessel (2) via an injection line (3) to the injection pump (4) in which said water is forced, under high pressure, onward to the injection valve (5) of the expansion engine (6). On the path to the injection valve, the water in the injection line has heat (7) supplied to it as far as into the superheated range, without the water being able to evaporate. The externally controlled injection valve opens at the top dead center point of the piston (8), such that the heated water is sprayed into the cylinder chamber (9) that forms. As the upper cylinder chamber increases in size, the injected water is isenthalpically converted to steam and expands adiabatically toward the end of the injection until the outlet valve (10) opens, through which outlet valve said water is discharged. The heat absorption exclusively by the water means that the heat absorption takes place in the small volume, and thus the working fluid has a high heat density w = Q/V (kJ/m³).

Description

Heat engine with high thermal efficiency Description

The heat engine is a modified steam engine that also heats water as a working fluid via external heat exchangers and has features of a diesel engine.

The difference to the steam engine is that the heat absorption of the

Working fluid in the heat engine in a smaller volume than in the

Steam engine takes place and thus allows a higher efficiency.

This type of heat absorption is achieved in that the water despite high

Temperatures has no possibility for evaporation and sprayed in liquid form into the cylinder and turned into steam, which then performs mechanical work.

The feature of injecting hot water into the cylinder of a reciprocating engine also includes the following references, but not of the type as in this invention, that the water is brought to high pressure by an injection pump and conveyed to the injector, on the way it is heated and is injected into the forming cylinder space.

1.) US 2 429 035 A

The spent exhaust steam still has so much pressure and temperature that it transforms the steam needed for the power stroke into hot water for injection.

2.) DE 2 440 659 AI

Steam generation in a cylinder head with a heating element.

3.) DE 825 690 B

Steam generation in a heated cylinder head.

4.) DE 2 158 618 A

Steam is generated in an aggregate connected to the engine. 5.) DE 689 961 A

In a Verclampfungskammer heated with the cylinder chamber open connection is sprayed Verdamprungsflüssigkeit.

6.) US 8 061 133 B2

The space between piston and cylinder forms a working chamber, which with a

Prechamber is connected, in which the liquid working medium is introduced and in which the liquid and the vapor tail are separated from each other.

The heat absorption of the working fluid relative to the volume available to it is referred to in this patent specification as a heat density and treated in more detail as a result of this description.

The type of injection is similar to a common-rail diesel engine, ie with a high-pressure accumulator whose heat transfer medium is oil.

According to Fig.l flows in the heat engine, the water (1) from the reservoir (2) via an injection line (3) to the injection pump (4), where it continues under pending high pressure up to the injection valve (5) of the expansion machine (6) is pressed. On the way to the injection valve is the water in the injection line to the

Overheating area added heat (7), without the water can evaporate. The externally controlled injection valve opens in o.T. Point of the piston (8), so that the heated water injected into the forming cylinder chamber (9).

As the upper cylinder space is enlarged, the injected water transforms isenthalp to steam and expands adiabatically after the end of injection until the exhaust valve (10) opens, through which it is expelled.

Although the injection time is shorter depending on the piston stroke and the injection mass is larger than that of the diesel engine, this is not problematic because the working fluid does not have to be finely atomized and does not require time to burn. An amount of heat in a liquid in the superheated area generates a water

Steam quantity with a specific enthalpy, which is larger with the same amount of heat and enthalpy than with conventional generation of steam. This means a higher efficiency.

The idea that injecting the water into the cylinder chamber filled with compressed air just like the oil in a diesel engine does not make sense thermodynamically since the water would turn into steam when injected and this would take up the space available to it, which would be throttling would come soon and reduce the conversion into mechanical energy. The term of the heat density listed in this invention application as a prerequisite for high efficiency would thus not be met.

Another advantage over the steam engine is the operation of the

Heat engine low amount of water to be heated.

The operation of the thermal engine is shown in FIG. 4:

Point 1: start of injection of water into the cylinder

Point 1 to 2: Isothermal injection (Isenthalpe)

Point 2: Injection end

Point 2 to 3: Adiabatic Expansion (Isentrope

Point 3: Opening of outlet valve

Point 3 to 4: expulsion of the steam

Item 4: Close the exhaust valve

To assess thermodynamic processes of Wämekrafmiaschinen the term of the heat density to serve, which is used in this patent application.

The object of all heat engines is that heat is converted into mechanical energy by supplying a quantity of heat to a working medium so that its pressure energy is increased in order to obtain mechanical energy therefrom.

The conversion of the pressure energy into mechanical energy via their degradation by a pressure gradient, which has an increase in volume of the working medium result. On the way of increasing the volume, there is a work service. This can be taken in the form of displacement work or kinetic gas energy of the heat engine.

In order to obtain the largest possible increase in volume, it is essential that the heat volume in the working volume is small and the pressure is large and after the

Volume increase the volume is large and the pressure is small.

Thus, it is essential for the efficiency and efficiency of a heat engine that the highest possible amount of heat in the smallest possible volume

Working medium is supplied, which is also the reason for the compression of the working fluid in the internal combustion engines.

The distribution of the heat quantity to a certain size is called energy density.

During the working process, high energy density is converted into lower energy density, so that the difference between them is the working output of the thermal-energy machine.

To record the thermal quantities in formulas, these are assigned to the physical quantities.

The supply of the heat "Q" takes place on the working medium in the combustion chamber "V", which remains constant during the heat supply, so that the energy density of the heat is expressed by the following formula:

Q kJ

w =

V m ³

To convert heat into mechanical energy, the energy density of the heat must be converted to an energy density of the pressure energy.

The pressure energy is the product of pressure times volume. Pressure energy W = p · V kJ Energy density of the pressure energy is the pressure

V

Thus, the heat density as the pressure is a state variable and the way the

Change of status independently.

If a quantity of heat "Q" is supplied to the working medium with the mass "m", its temperature "T" rises by the temperature increase "ΔΤ".

Equivalently, at the initial pressure "po", the total pressure "p" increases by the heat input due to the pressure increase "pw". p = po + pw

m · cv

According to the general gas equation, p «V

(Τ + ΔΤ) = K

m · Rs

The equation for the temperature increase is used in the general gas equation

Q P · ν

T + = K

m · cv m · Rs

After dissolution after printing results: Rs · T · m Q · Rs

p = + kN / m ²

V V · cv

The first summand gives the pressure before the beginning of the heat supply, while the second summand is divided into two factors after the heat supply.

First factor:

Q 3

kJ / m = w Energy density of heat

V

On the mass of a kg is related with

q kJ / kg

vm ³ / kg

q

w = kJ / m

v

Second factor: Rs kJ kg · k

= A dimensionless conversion factor of the heat density in pressure cv kJ kg · K p = po + w · A

The conversion factor is thus: pw kN / m ^'

A =

w kJ / m ³

In thermodynamics, the mixture heating value "HG" is given for the heat supply in the calculation and design of thermal power machines.

This is an energy density of heat that is based on a standard cubic meter of

Obtains working medium at stoichiometric combustion. If the physical data of the standard cubic meter and the mixture heating value are entered into the formula for the pressure calculation, w = HG kJ / m ³

Rs = 0.287 kJ / kg * K

cv = 0.912 kJ / kg »K

Rs 0.287

= = 0.3146

cv 0.912

Rs · T · m

2

p = + w · A kN / m

V p = 101 + HG x 0.3146 kN / m ²

Only 31, 46% of the mixture's calorific value are converted into pressure.

Otto engine

The Otto engine has a mixture calorific value of the gasoline-air mixture of

HG = 3655.07 kJ / m ³

This results in the following pressure for the uncompressed standard cubic meter of the gasoline-air mixture during combustion: p = 101 + 3655.07 × 0.3146 kN / m ²

p = 1.01 + 11.49 bar p = 12.5 bar

To increase the pressure to a maximum pressure "pmax" in the system, the working medium with its Gemischheizwert before combustion with a compression ratio γ

ε = - compressed so that its heat density is increased, and then during combustion

^ 2

to achieve a higher pressure at the same temperature beginning as with the standard cubic meter.

Rs

pmax = po · ε + ε · HG · kN / m

cv

With unchanged conversion factor and a compression ratio ε = 10 becomes: pmax = 101 · 10 + 10 · 3655.07 · 0.3146 kN / m ² pmax = 1010 + 11498.9 kN / m2 ^A 125.08 bar

diesel engine

In order to make a comparison of the energy conversion between the heat engine and the diesel engine, both machines are charged with the same amount of heat and the resulting pressure energy determined, which then each measure the

Efficiency represents.

The supply of an amount of heat of Q = 1000 kJ in a standard cubic meter of air corresponds to the usual conditions of running diesel engines with constant pressure combustion.

Because with the diesel engine the injection ratio

y

φ = - determines the efficiency is, as an optimal compromise φ = 1.77 at a sealing ratio of

£ ^■ = 18 selected.

The p-v diagram according to FIG. 2 shows the respective state variables and their course in points PI-P4.

State point PI (state of the standard cubic meter)

T _{ = 273 K ρ _χ ^~ 1.01 bar

, = lm ³

m = 1.2928 kg

v, = 0.7735 m ³ / kg

State point P2

X

Ρ2 = Ρι. _ε = 18 = 57.9 bar

T ₂ = Τ · ε ^χ_1 = 273 · 18 ^0.4 = 867 K

V ₂ = - = 0.0555 m ³

2 ε 18

Compaction work from PI to P2 Li-2 = - ~ (pi ·! - p2 · V ₂ ) -2 = - (lOl · 1 - 5790 · 0.0555)

1.4 to 1 ^J

Ι _2 = 550 kJ state point P3

Q = 1000 kJ Supply of heat from P2 to P3 P3 = 57.9 bar

V ₃ = V ₂ · φ = 0.055 · 1.77 = 0.0983 m ³

T ₃ = T ₂ + ΔΤ

ΔΤ = - = - = 661 K c = 1, 17kJ / kgK m * cp 1.2928 · 1.17 "

T ₃ = 1528K

Volume work from P2 to P3

L ₂ -3 = P ₃ * (v ₃ -V ₂ ) = 5790 (θ, 093-0.0555) L2.3 = 247 kJ

State point P4

V = lm ³

V3 \ X (0.0983 \ 1.4

Ρ4 = Ρ3 · ^ τ Ρ4 = 57.2 · ^ - ^ -) p = 2.22 bar

4

= ₄ = Τ ₃ . ^χ · ¹ Τ ₄ . ₁₅ 2 ₈ . (Η) ° · ⁴

T4 = 604 K.

Volume work = expansion work from P3 to P4

L34 = - · (p3 · ν ₃ - P4 · ν ₄₎ L ₃ _4 = - ^ - · (5790 · 0.0983 to 222 · ΐ)

χ - 1 ι, 4 -ι

L ₃ = 867 kJ

Useful work = energy energy usable for mechanical energy LN ^{= L} 3-4 + L2-3 "Ll-2 L _N = 867 + 247 - 550 LN = 564 kJ

This means that 564 kJ of 1000 kJ heat input have been converted into pressure energy, ie a thermal efficiency of η = 56.4%.

It is the respective useful work of the absorbed heat quantity of Q = 1000 kJ are examined both in the steam engine and in the heat engine, ie without consideration of the efficiency of heat transfer to the working fluid.

The comparison between the steam engine and the heat engine with their same working fluids is based on the heat density, which is set the same for both machines.

For generating superheated water steam for a steam engine is a

Amount of heat needed, which heats the water to the boiling point, then with the

Evaporate evaporation heat and then heat the steam. The sum of these amounts of heat is given as the enthalpy of the vapor. If the steam has the superheating temperature "T" and the vapor pressure "p", then its enthalpy "h" and its specific volume "v" and thus also its heat density w = h / v kJ / m3 are fixed.

In the heat engine, a smaller amount of heat is needed to produce the same high temperature, since it is supplied directly to the working fluid in the smaller volume without conversion into steam and its heating.

In the conversion of the injected water into steam at constant temperature energy is removed from the working fluid in the form of heat of evaporation, so that this reduces the amount of heat absorbed for conversion into useful energy as in conventional steam production.

The heat absorption in the thermal power machine is done on the specific

Heat capacity "Cp" and is: q = Cp »AT kJ / kg

Although the specific amount of heat "q" has the same dimension as the specific one

Enthalpy "h", the heat quantity "q" is higher.

Only when the amount of heat

"q" is converted over the heat density "w" into enthalpy, both can be compared with each other.

Steam engine according to p-v diagram in Figure 3

For comparison with the diesel engine, a steam is selected with approximately the same pressure:

3

Condition point PI (inflowing steam at Vi = 0.0 m)

pi = 60 bar

T, = 623 K (350 ° C)

3

υι = 0.04225 m / kg

h _! = 3043 kJ / kg k 3043

Wi = - =

v, 0.04225

wi = 72000 kJ / m ³ heat density

Q = 1000 kJ absorbed heat

1000

m = - m =

3043

m = 0.33 kg mass of the steam

State point P2 (steam inflow end) State data of P2 corresponds to PI

P2 = P1

T ₂ = T! υ2 = υι

W2 = wi h2 = hi

V ₂ = υ ₂ × m V ₂ = 0.04225 × 0.33

3

V ₂ = 0.0139 m steam volume

State point P3 (after steam expansion) p ₃ = 1 bar

υ ₃ = 1.43 m3 / kg h ₃ = 2294 kJ / kg

V ₃ = m << ₃ V ₃ = 0.33 · 1.43 V ₃ = 0.472 m ³

Labor gain through steam expansion Δ b.2-3 = h ₂ - h ₃ Δ h2-3 = 3043 - 2294

Ah2-3 ⁼ 749kJ / kg L ₂ _3 = Δ I 12-3 · m L ₂ _ ₃ = 749 x 0.33

L2-3 = 247 kJ

volume work

Ll-2 = P2 * ^v 2 Li.2 = 6000 x 0.0139 Li_2 = 83 kJ

Useful work = energy usable for mechanical energy LN = L2-3 + Li -2 L _N = 247 + 83

L _N = 330 kJ

This means that 330 kJ of 1000 kJ of heat supplied have been converted into useful work, ie a thermal efficiency of η = 33%.

Heat engine according to p-v diagram in Figure 4

State point PI

Start of injection of 623 warm water in a volume starting from zero, in which the state variables are also zero.

State point P2

The following data are identical to the steam of the steam engine in point 2: T2 = 623 K

W2 = 72000 kJ / m ³

Thus, the specific volume and the specific enthalpy are the same as in point 2 of the steam engine. υ ₂ = 0.04225 m ³ / kg h ₂ = 3043 kJ / kg

The mass of injection water: m = - s - Cp = 4.2 kJ / kg K

1000

m =

4.2x350

m = 0.68 kg

This gives a vapor volume during injection:

V2 = m · υ2 V2 = 0.68 · 0.04225

V2 = 0.0289 m ³

Thus, the vapor volume at a pressure of p = 60 bar and a temperature of T = 350 ° C with the same heat absorption twice as large as in a conventional steam generation.

State point P3

Condition data correspond to those in P3 of the steam engine

Specific work profit by steam expansion is equal to that with the steam engine Ah2-3 = 749 kJ / kg.

The volume work is eliminated in the heat engine, because the steam only in

Cylinder space is formed.

Useful work = energy usable for mechanical energy LN = L2-3

LN = Δ h2-3 · m LN = 749 · 0.68 L _N = 509 kJ

This means that 509 kJ of 1000 kJ heat input have been converted into useful work, ie a thermal efficiency of η = 50.9%. With equal absorbed amounts of heat with Q = 1000 kJ, 54% more energy is converted into useful work with the heat engine than with the steam engine with conventional steam generation.

Value determination with changed volume V2 during injection

γ

- - Halved volume V2 during injection gives: w = 100 400 kJ / m ³ L _N = 523 kJ

V2 · 2 = double volume V2 during injection results in: w = 36 580 kJ / m ³ LN = 407 kJ

Comparison of thermal efficiencies of machine types.

The total thermal efficiency results from the product of the thermal

Efficiency of the machine type with the efficiency of the boiler ηκ = 0.85, which characterizes the heat transfer to the working fluid and omitted in the diesel engine.

Diesel engine r | th ⁼ 56.4% Steam engine = 33% · ηκ η _1η = 26.4% Heat engine = 50.9% · r | th = 40.7%

Claims

claims

1. Heat engine with high thermal efficiency, characterized in that water at an ambient temperature from a reservoir to a

Injection pump flows, in which it is transported under high pressure via an injection pipe to the externally controlled injection nozzle, on the way it by external

Heat is heated above its critical temperature and then in one

Piston expansion machine injected from the top dead center of the piston in the forming cylinder space and is converted to steam, and then adiabatically expand and be ejected after expansion by a controlled exhaust valve.

2. Heat engine with high efficiency according to claim 1, characterized

characterized in that the supply of heat to the working fluid for the

Piston expansion machine in its supply line, which serves as an absorber tube of a parabolic trough.