EP3457052A1

EP3457052A1 - The atmospheric cold steam engine and operating method thereof

Info

Publication number: EP3457052A1
Application number: EP18174541.5A
Authority: EP
Inventors: Algimantas ROTMANAS
Original assignee: Vilniaus Gedimino Technikos Universitetas
Current assignee: Vilniaus Gedimino Technikos Universitetas
Priority date: 2017-09-06
Filing date: 2018-05-28
Publication date: 2019-03-20
Anticipated expiration: 2038-05-28
Also published as: LT2017522A; LT6635B; EP3457052B1

Abstract

The invention relates to the atmospheric cold steam engine for generating mechanical energy through the use of atmospheric pressure and environmental thermal energy or excess of low temperature thermal energy released during production processes. The operating principle of the atmospheric cold steam engine is based on the characteristic of the materials to absorb or release the thermal energy during their transition from liquid to gaseous phases and vice versa. The purpose of the invention is to expand the possibilities of the heat pump by converting the thermal energy collected from the environment into the mechanical energy. The mechanical energy thus obtained can be used for the compressor of the same heat pump or be transformed into another type of an energy (electricity etc.) to be used by consumers in need.

Description

TECHNICAL FIELD

The invention relates to energy transformation machines. Thermal energy is converted into mechanical energy.

BACKGROUND ART

The heat engines and generators currently available in the industry transform relatively high-temperature thermal energy into mechanical or other energy acceptable for the consumer. Low-temperature (0 °C to 90 °C) thermal energy is usually released into the environment as waste. Almost all modern heat engines operate under the Carnot cycle, i.e., they work within a certain temperature range that is very far from the temperatures of the phase transition of the used material - energy carrier. Higher temperature thermal energy that is easily converted to other types of energy is derived from the chemical energy of a combustible fuel, which is associated with intense environmental pollution. The environment is polluted by combustion waste and heated by excessive heat. These ecological issues are known and have been addressed in various ways, however, not effectively enough.
Heat pumps operate in a different way, the most common being compressor heat pumps. The heat pumps characterize by collecting and concentrating the low-temperature thermal energy, thereby turning it into higher temperature thermal energy. In order to do this, the heat pumps use mechanical energy, which is in turn transformed from electrical energy. Heat pumps as mechanisms are unique by the fact that they consume several times less energy than they collect from the environment and concentrate. This becomes possible because heat pumps use the phase-transition heat of the material: the material is cyclically changed from the liquid phase to gaseous, and back. However, heat pumps have one major disadvantage: they provide thermal energy in the form of a final product that is however of inadequate quality, i.e., the temperature is not high enough to be transformed effectively into other forms of energy that are more in demand, for example, mechanical or electrical. There are multi-stage heat pumps whose final product is relatively high-temperature thermal energy; however, these heat pumps lose their meaning with the diminishing of their main advantage: absorbing from the environment and providing the consumer with significantly more energy than is used to maintain their operating process.
The patented idea is how, by taking advantage of the unique properties of a heat pump, the thermal energy concentrated by a heat pump can be used for changing the states of matter of the material (refrigerant fluid, suitably selected according to the phase transition temperatures, the specific heat and the specific heat of vaporization) by inducing changes in volumes and pressures, and using the latter for generating mechanical energy. In other words, to convert low-temperature environmental or waste heat into useful mechanical energy.
Several attempts to design similar devices are known, but most of them have certain drawbacks, their declared parameters raise doubts, or even their principle of operation is questionable: for example, the device described in patent application CN1180790 cannot function in a continuous mode. The refrigerant fluid cannot cyclically change the states of matter at the same temperature and pressure, i.e., cannot change the heat inflow or outflow without changing the circumstances. This device will work, i.e. will produce mechanical energy, only until all liquefied gases using environmental heat evaporate from the tank and the pressures and temperatures become equal. A similar device is described in patent application CN1181461 : this is also a short-term operating device. The liquid, heated by a heat pump, is diverted "to take" heat from the environment; however, after a while the heating circuit temperature of the heat pump of the device will become higher than the ambient temperature, and the energy exchange will cease. The situation in this device could possibly be improved by partially releasing the heat of the heating circuit into the environment. However, the authors do not propose this, therefore, this device will operate in the short-term and the cycles will not repeat.
The device in patent application CH647590 operates under the direct Carnot cycle: it needs two media, warm and cold, and operates in a conventional manner: a pressure difference is created by alternating media, the direct Carnot cycle is realized, thus obtaining mechanical energy; however, as there are relatively small temperature changes, a relatively small amount of mechanical energy is obtained. Patent application DE3001315 provides the principle and one of the structures that can be realized: the device uses environmental energy that it can partly convert into mechanical energy. It is different from the current device by the fact that it uses only one refrigerant fluid circulating through a compressor and a turbine, which is a completely different way of obtaining mechanical energy than a membrane and atmospheric pressure. In addition, gas condensation in liquid is not used, therefore only a very small part of the thermal energy will be converted into mechanical. In other words, more significant compensation of mechanical energy with thermal energy is impossible.
The device described in patent application DE102010049337 operates not on a reversed, but direct Carnot cycle, using heat of significantly higher temperature that is released as excess by, for example, an internal combustion engine. The main difference is that the device uses the atmospheric environment as a cooler rather than as a heat source.
Patent application FR2547399 describes a device similar to the patented device, i.e. it operates on a reversed Carnot cycle, converts part of the environmental energy into mechanical energy, but differs by the fact that there is one circuit, it circulates gas that remains in the gas phase, i.e. there are no phase changes, and at the same time it does not use the heat of phase transitions and changes in volumes and pressures. In addition, its adaptability raises some doubts as, even in the ideal case, in the absence of losses the amount of energy released to and taken from the environment is equal; the balance is zero.
The operating principle of the device described in another patent application RU2132470 is also substantially similar to the device to be patented: as the refrigerant fluid evaporates, thermal energy is taken from the environment, and as a sufficient amount of energy is absorbed, pressure increases and performs mechanical work. The problem is that it fails to describe the return of the gas (in the patent application, helium, and nitrogen are given as examples) into the liquid state. The claim made by the authors of the patent application, that the gas will condense to a liquid naturally after expansion work is not reasonable, because it should be borne in mind that the liquefying point of nitrogen is lower than minus 195 °C (while in the case of helium it is close to zero Kelvin), therefore, liquefaction at ambient temperatures cannot be realized and the process will not be steady as stated by the authors (the scheme does not show the work on liquefaction and heat transfer from this stage of the process). Since the scheme described is not detailed and no embodiments are presented, it is difficult to judge the nuances of the operation. It is possible, as in patent application CN1180790 , that the device will only operate until all liquefied gases are converted from liquid to gas by taking energy from the environment.
In summary, the above attempts to design devices converting low-temperature thermal energy into mechanical energy can be divided into three groups:

1) Devices operating according to the direct Carnot cycle, obtaining differences in pressure from low differences of temperature and converting them into mechanical energy;
2) Devices filled with liquefied gases, and generating mechanical energy only until all gases are evaporated by using environmental heat;
3) Devices analogous to heat pumps, concentrating the thermal energy accumulated in the environment and converting it into mechanical energy in one way or another. Therefore, patent application DE3001315 should be considered as the main prototype for the invention. The difference between the device to be patented and the latter is that two refrigerants and a more energy-efficient way of obtaining mechanical energy from heat are used.

SUMMARY OF THE INVENTION

In this invention, the operating principle of the atmospheric cold steam engine is based on materials with the characteristic of absorbing or releasing thermal energy in phase transitions, e.g., from the liquid to gaseous and vice versa. It is also based on their characteristic of significantly changing in volume when changing from one state of matter to another. The essence of the operating principle is that atmospheric pressure is suppressed with the help of heat absorbed from the environment and concentrated through the evaporation of the working material. When this material is condensed, the atmospheric pressure transforms the thermal energy transmitted to the material into mechanical energy. The energy absorption and concentration processes are continuous, and the process of transformation into mechanical energy is cyclic.
The purpose of the invention is to expand the possibilities of a heat pump by converting the thermal energy collected from the environment (air, water, soil, by-products of production processes, etc.) and concentrating it into mechanical energy. The mechanical energy generated can be used for the compressor of the heat pump itself (which would significantly reduce energy consumption and increase efficiency) or transformed into another type of energy (electricity etc.) and used by external consumers as needed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic drawing, illustrating the design and operating principle of the atmospheric cold steam engine;
Fig. 2 is a schematic drawing of the energy balance, illustrating three alternative embodiments of the invention: 1) when the heat absorbed from environment, and the added mechanical energy, are used solely for generating mechanical energy, which is supplied to consumer, and the excess heat is returned to the engine; 2) when part of the mechanical energy is returned to the engine (to the extent required for providing the engine units with mechanical energy), the remaining energy is supplied to consumers, and the excess thermal energy is returned to the engine; 3) when the first or the second option is embodied, but the excess thermal energy is supplied to consumers.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the invention is described with reference to the enclosed drawings, wherein: 1 - a cold circuit of the first refrigerant fluid for absorbing thermal energy from the environment; 2 - a compressor; 3 - a concentrated thermal energy circuit; 4 - an expansion valve; 5 - a heat exchanger between the first and the second refrigerant liquids; 6 - an evaporator for the second refrigerant fluid; 7 - a valve between the second refrigerant fluid tank and the evaporator; 8 - a second refrigerant fluid tank; 9 - a valve; 10 - an expansion - condensation chamber for the second refrigerant fluid; 11 - a crankshaft and a flywheel (mechanical energy output link); 12 - a membrane; 13 - a one-way valve; 14 - a nozzle emulsifier; 15 - a steam valve for the second refrigerant liquid; 16 - a pump.
The operating principle of the atmospheric cold steam engine of this invention is based on overcoming the atmospheric pressure by evaporating the working material, adsorbed from the environment, using the concentrated heat. When this material is condensed, the atmospheric pressure transforms the thermal energy transmitted to the material into mechanical energy. The energy absorption and concentration processes are continuous, and the process of transformation into mechanical energy is cyclic.
The engine operation can be described by distinguishing the four main stages of the process together with the structural units and the two refrigerant fluids circulating in them. At the first stage, in the circuit 1 filled with the first refrigerant fluid, the compressor 2 maintains a low pressure, and, in the same way as the refrigerant liquid in heat pumps, this fluid evaporates using for evaporation its own heat energy and that of the surrounding structures, and absorbs the energy deficiency from the environment. At this stage, conditions for maximum interaction of the fluid with the heat exchange through the circuit 1 with the environment are provided. The properties of the first refrigerant fluid are very close to those of fluids used in conventional heat pumps.
At the second stage in the circuit 3, the compressor 2 and valve 4 maintain a high pressure; the first refrigerant fluid material enters this zone and condenses, thus returning to the liquid state and releasing the energy collected from the environment. The processes of phase transition and thermal energy transfer at the first and the second stages described above are almost the same as in case of a conventional heat pump, and the ratio between the energy consumed by the compressor, and the energy received from the environment, is approximately 1: 4. The second-stage processes are isolated from the environment.
At the third stage in the heat exchanger 6, the thermal energy obtained is used for evaporation of the second refrigerant fluid. This fluid material and its characteristics - boiling point, specific heat, evaporation (condensation) specific heat, evaporation pressure, and other parameters - are selected so that, having consumed the heat energy obtained at the second stage and evaporated, the material in the gaseous phase reaches a pressure close to or higher than atmospheric pressure. At this stage, as at the second, the processes are isolated from the environment.
At the fourth stage, the process takes place cyclically: through the valve 15, the second refrigerant steam enters chamber 10 separated by a mobile membrane 12 from the environment. The membrane is connected to a flywheel 11 with a crank. When the engine is running and the flywheel returns the membrane to the right-hand side position, and steam fills the entire chamber 10, and the valves 9 and 15 close, steam condensation is initiated by injecting the second refrigerant fluid, cooled in heat exchanger 5, through the valve 13 and nozzle 14 with the help of the pump 16, by absorbing the thermal energy and returning it to the previous stages. As the second refrigerant material, which filled the chamber 10, changes from the gaseous to the liquid state, the pressure in the chamber 10 drops significantly, and becomes considerably lower than atmospheric pressure. Atmospheric pressure starts acting on the membrane 12 from the other side, moving it to the other - left-hand side - position by transferring the force and energy of the atmospheric pressure P to the flywheel 11. For this purpose, alternatives to atmospheric pressure energy might be used: compressed air, a spring or other potential energy, previously generated by the evaporating second refrigerant fluid, therefore the concept of "atmospheric" in the title of the engine is conditional. Atmospheric pressure was selected as the potential energy collector because it is approximately in line with the required pressure value. Furthermore, no additional units are required in the structure. Part of the thermal energy generated during steam condensation at the fourth stage is returned to the third stage through the valve 9, tank 8 and valve 7 together with part of the fluid. The remaining part of the fluid returns to the fourth stage through the heat exchanger 5, and the thermal energy returns to the first stage (when the engine is running on the optimally loaded mode, little thermal energy is left in the chamber 10 and it turns into mechanical energy, however, at the end of the stage the temperature of the condensed fluid is still higher than the ambient temperature). Thus, it becomes possible to reuse the "waste" thermal energy of the fourth stage without letting it go outside the mechanism.
Energy supplementation takes place at the first stage. The energy, absorbed as thermal energy at the first stage and generated as mechanical energy at the fourth stage, can be used for the needs of external consumers, or a part of this energy can be returned through the mechanism to power the service nodes.
The above actualization of the invention is just one possible actualization. Several modifications to the mechanism are possible: for instance, the structure and the work process may be optimized for generating mechanical energy, or only a part of the heat absorbed from the environment may be used for generating mechanical energy (to the extent required for the provision of mechanical energy to the engine units), and, as in case of a conventional heat pump, the remaining energy may be supplied to consumers in the form of heat, as schematically depicted in Figure 2.
In this figure, 100% of the energy is considered to be energy that circulates through the engine in the form of thermal and mechanical energy, i.e., not the absolute energy value, but energy changes and exchanges within the engine and between the engine and the environment, as well as the energy transformations.
Theoretically, the engine can absorb from the environment approximately 25% - 50% of the thermal energy required for operation; calculating from the energy circulating in the engine, it needs another 25% in the form of mechanical energy, and up to 50% of the thermal energy can be recovered from the fourth stage and returned to the first and third stages (through the heat exchanger 5 and evaporator 6). In the ideal case, this optimized engine can supply up to 50% of the energy, transformed into mechanical energy, in the output circuit, i.e. the engine can generate more mechanical energy than it gets by compensating for the deficit present with environmental thermal energy. As a result, up to 25% of the mechanical energy output can be achieved, even if 25% of it is returned to power the mechanical units. Due to mechanical and hydraulic losses, the engine does not automatically deliver 25% of the mechanical energy output; however, its unique operating principle makes it possible to transform all thermal losses into useful work. Considering the fact that mechanical and hydraulic losses are largely converted to heat, and heat is used for purposeful work, the output can be very close to the theoretical one.
The entire mechanism is designed so that those structural elements that have to absorb energy from the environment can achieve maximum interaction with the environment through heat exchange, and those whose temperature must remain constant, are insulated.
While the engine is running, temperatures close to that of the environment, or significantly lower than the environment, dominate at all four stages of engine operation and in the mechanism units. The number of units whose average working temperature is above the ambient temperature is relatively low, their surface area is small, they are thermally isolated, and the heat is purposefully converted into mechanical work, supplied to consumers or returned to the preparatory stages of the engine operation.
The characteristics of the refrigerant liquids are selected taking into account the ambient temperature, in order to maximize the use of thermal energy from the environment and/or optimally transfer it from stage to stage. Therefore, the engine filled with specific refrigerant liquids (analogous to heat pumps) can work efficiently only within a certain temperature range of the heat source. However, unlike heat pumps, not only thermal, but also mechanical energy is produced as a result.
As has already been mentioned, several engine modifications are possible:

1) When the structure and the work process are optimized for generating mechanical energy;
2) When part of the energy absorbed from the environment is converted into mechanical energy for providing mechanical energy to the engine units, while the remaining energy is supplied to consumers as heat.

In the first case, the transformation of mechanical energy into a more universal (electrical) form of energy and supplying it to consumers is possible. In the second case, it becomes possible to use this engine as a heat pump whose efficiency would be incomparably higher than that of current heat pumps, because not only would low temperature thermal energy be converted into higher temperature thermal energy, but also the mechanism itself would use the low temperature thermal energy to power its units.
The thermal energy source of these devices may be air, water bodies, groundwater, soil or waste heat from technical and household processes: heat from ventilation or wastewater systems, low temperature waste heat from production processes, etc., i.e. all heat sources used by conventional heat pumps or recuperators are suitable.

Claims

An atmospheric cold steam engine, comprising an environmental heat source, a first heat exchanger filled with refrigerant fluid for absorbing environmental heat, refrigerant fluid circulation circuits, a means for feeding refrigerant fluid, an evaporator, a capacitor and a means for conversion of thermal energy into mechanical or other consumer-acceptable energy, characterized by comprising:
- two closed non-connecting refrigerant fluid circuits, where the first refrigerant fluid circuit (3) is placed inside the evaporator (6) of the second refrigerant fluid circuit, and where the first refrigerant fluid circuit (3) is designed for the transfer of the environmental thermal energy collected through a circuit (1) and concentrated by a pump (2), to the second refrigerant fluid in the evaporator (6), thereby evaporating it;

- a device for transforming the second refrigerant fluid thermal energy into mechanical energy, comprising the working chamber (10) separated from the environment by a mobile membrane (12), where the membrane (12) is connected to the mechanical energy output unit (11);

- a tank (8) for collecting the second refrigerant fluid condensed in the working chamber (10), having a valve (7) for returning a part of the condensed fluid and "waste" thermal energy to an evaporator (6), and a pump (16) for injecting the another part of the condensed fluid into the working chamber (10) through the one-way valve (13) and a nozzle (14) to condense the second refrigerant fluid steam;

- an additional heat exchanger (5) between the first and second refrigerant fluids, designed for returning the "waste" heat remaining after its use for transforming heat into mechanical work in the mechanical energy output unit (11) back to the environmental heat absorption circuit (1).
The engine according to claim 1, characterized in that the characteristics of the first refrigerant fluid are such that, through the phase transitions caused by the pressure changes induced by compressor (2), the fluid maximally absorbs and concentrates the thermal energy not only from the temperature media containing the absorption circuit (1), but also from the "waste" thermal energy recovered through the heat exchanger (5).
The engine according to claim 1, characterized in that the characteristics of the second refrigerant fluid, i.e. boiling temperature, specific heat, specific evaporation/condensation heat and evaporation pressure are selected so that upon consuming the concentrated thermal energy of the first refrigerant fluid obtained through circuit (3) and upon evaporating, said fluid in the gaseous phase reaches a pressure close to or higher than atmospheric pressure.
The engine according to claim 1, characterized in that the mechanical energy output unit (11) is the crankshaft and the flywheel.
The engine according to claim 1, characterized in that the first refrigerant fluid circuit (3) and the second refrigerant fluid circuit evaporator (6) are thermally isolated from the environment.
The operating method of the atmospheric cold steam engine, including absorption of the environmental thermal energy and its conversion into mechanical or other consumer-acceptable energy, characterized by:
a) using two non-connecting refrigerant fluid circuits, where the first refrigerant fluid transfers the environmental heat, absorbed in a circuit (1) and compressed in a circuit (3) by a pump (2), to the second refrigerant fluid in an evaporator (6), thereby converting the second refrigerant fluid into steam;

b) delivering the second refrigerant fluid steam into a chamber (10), connected by the mobile membrane (12) with a mechanical unit (11), under pressure close to or higher than atmospheric pressure;

c) when the flywheel of a mechanical unit (11) moves inertially the membrane (12) to the right side position and the steam fills the entire volume of the chamber (10), initiating the condensation of the second refrigerant fluid steam in a chamber (10) by injecting the second refrigerant fluid, collected in a tank (8) and cooled in a heat exchanger (5), through the valve (13) and nozzle (14) with the help of the pump (16), thereby absorbing the thermal energy of the second refrigerant fluid steam transferred from an evaporator (6) to a chamber (10) and condensing the second refrigerant fluid steam;

d) when the pressure in a chamber (10) drops below atmospheric, using the atmospheric pressure to initiate the movement of the membrane (12) to the inside of the chamber (10) by transferring the force and energy of the atmospheric pressure P_atm to the flywheel of the mechanical unit (11);

e) collecting the condensed second refrigerant fluid in a tank (8) and returning the "waste" heat back to the previous stages: a part to an evaporator (6), and a part to the first refrigerant fluid circuit (1) through the heat exchanger (5).
The method according to claim 6, characterized in that the energy absorption and concentration processes are continuous, whereas the process of transformation into mechanical energy is cyclic.