Abstract: A solar energy powered Stirling duplex cooler is presented which includes a Stirling engine and a Stirling cooler. The Stirling engine drives the Stirling cooler to produce cold temperatures for refrigeration or air conditioning. The Stirling duplex cooler includes a solar concentrator to focus high temperature solar radiation upon the Stirling engine expansion space. The Stirling duplex cooler further includes a thermal storage tank to receive and store heat rejected from the cooler expansion space. This stored heat is used to operate the cooler at night. A flywheel connected operatively to engine and cooler expansion space pistons and a crankshaft connected operatively to engine and cooler compression space pistons actuate the pistons to move a working fluid between the expansion and compression spaces.

Abstract: A solar energy powered Stirling duplex cooler is presented which includes a Stirling engine and a Stirling cooler. The Stirling engine drives the Stirling cooler to produce cold temperatures for refrigeration or air conditioning. The Stirling duplex cooler includes a solar concentrator to focus high temperature solar radiation upon the Stirling engine expansion space. The Stirling duplex cooler further includes a thermal storage tank to receive and store heat rejected from the cooler expansion space. This stored heat is used to operate the cooler at night. A flywheel connected operatively to engine and cooler expansion space pistons and a crankshaft connected operatively to engine and cooler compression space pistons actuate the pistons to move a working fluid between the expansion and compression spaces.

Abstract: A reversible system for dissipating heat power generated in a gas turbine engine, the system including a condenser-forming first heat exchanger, an evaporator-forming second heat exchanger, a scroll compressor suitable for operating as a compressor when the temperature of the cold source is higher than a predefined threshold temperature and as a turbine when the temperature of the cold source is lower than the threshold temperature, an expander and a pump arranged in parallel, and a control valve arranged upstream from the expander and the pump and suitable for directing the refrigerant fluid to the expander when the temperature of the cold source is higher than the threshold temperature and to the pump when the temperature of the cold source is lower than the threshold temperature.

Abstract: An efficient stirling engine comprises an expansion chamber with a heater and a compression chamber with a cooler, wherein the two chambers are connected through a regenerator. A passage between the heater and the expansion chamber is provided with a first valve system, a passage between the cooler and the compression chamber is provided with a second valve system, the first valve system can close or open the passage between the heater and the expansion chamber, and the second valve system can close or open the passage between the cooler and the compression chamber. After adopting the structure above, when a heating end is heated to expand, a cooling end at the other end is closed, and on the contrary, when the cooling end is cooled to shrink, the heating end at the other end is closed, so that the heating energy is fully used, so as to increase the efficiency of the stirling engine.

Abstract: An improvement is provided to a pressurized close-cycle machine that has a cold-end pressure vessel and is of the type having a piston undergoing reciprocating linear motion within a cylinder containing a working fluid heated by conduction through a heater head by heat from an external thermal source. The improvement includes a heat exchanger for cooling the working fluid, where the heat exchanger is disposed within the cold-end pressure vessel. The heater head may be directly coupled to the cold-end pressure vessel by welding or other methods. A coolant tube is used to convey coolant through the heat exchanger.

Abstract: A Vuilleumier heat pump is disclosed in which hot and cold displacers are controlled by first and second electromagnetic actuators, respectively. The first actuator is capable of moving the hot displacer between the first and second ends of travel while the cold displacer remains stationary and the second actuator is capable of moving the cold displacer while the hot displacer remains stationary. Prior art crank arrangements are unable to provide dwell in one displacer while moving the other displacer. Actuation of the displacers according to embodiments of the present disclosure provides a higher coefficient of performance than crank arrangements.

Abstract: A domestic appliance for drying a damp product by means of a process air stream that is conducted in a process air channel. The appliance has a treatment chamber that includes the damp product. A cooling assembly cools and condenses the process air stream after it flows through the treatment chamber. A first heat exchanger supplies heat from the process air stream to a working fluid. A heating assembly heats the process air stream before it flows through the treatment chamber and a second heat exchanger supplies heat from the working fluid to the process air stream. The working fluid is conducted in a heat pump that has at least two mechanically coupled displacement pistons. The heat pump operates according to a regenerative gas cycle process that includes a Vuilleumier gas cycle process.

Abstract: A motor assembly for a motor vehicle includes an internal combustion engine that has an exhaust gas purification device and a heat engine. The heat engine has at least one closed working space that is filled with a gas. The at least one closed working space includes first and second cylinders, which are each movably mounted in the longitudinal direction between initial and expansion positions. The heat engine includes at least one heating unit for heating the gas in at least one heating region of the closed working space and at least one cooling unit for cooling the gas in at least one cooling region of the closed working space. The gas heated in the heating region pushes the first piston from its initial position into its expansion position, and then flows through the overflow line into the cooling region such that the second piston is then pushed into its expansion position. The overflow line leads at least in sections through the exhaust gas purification device.

Abstract: A thermodynamic machine (1) of a Stirling type, the machine comprising an expansion chamber (5), a compression chamber (6), a regenerator (12) disposed between the expansion and compression chambers; a first heat exchanger (13) in communication with the expansion chamber and the regenerator; a second heat exchanger (14) in communication with the compression chamber and the regenerator; a first bypass conduit (15) connecting the expansion chamber with the regenerator bypassing the first heat exchanger; a second bypass conduit (16) connecting the compression chamber with the regenerator bypassing the second heat exchanger; at least a pair valves (18, 20, 22, 24), one valve (18, 20) provided between the expansion chamber and the first heat exchanger and/or between the regenerator and the first heat exchanger and/or in the first bypass conduit between the expansion chamber and the regenerator; and the other valve (22, 24) provided between the compression chamber and the second heat exchanger and/or between the re

Abstract: A novel engine for producing power from a temperature differential with additional benefits of low cost, high efficiency, quiet operation minimal wear of components, and the ability to produce power or cooling from low grade heat sources.

Abstract: Lighting apparatus suitable for use in a gas lantern lighting fixtures and containing a single piece body member with a horizontally oriented gas inlet, a vertically oriented gas outlet, and a fastener along with a valve; an orifice; and a burner tip connected to one another are disclosed. Lighting apparatus which are easy to assemble and capable of efficiently producing an aesthetically pleasing flame along with associated methods are described.

Abstract: A Stirling engine can take advantage of adiabatic compression (which heats working gas leaving the cold cylinder) and adiabatic expansion (which cools working gas leaving the hot cylinder) to increase efficiency. In some implementations, partially-heated gas leaving the cold cylinder and partially-cooled gas leaving the hot cylinder can be routed directly to a regenerator using bypass paths that are opened using one-way valves. The resultant relatively reduced temperature difference across the regenerator, e.g., as compared to a typical Stirling engine, can reduce thermal loss and improve efficiency. In some implementations, the compression ratios of the Stirling engine can be adjusted such that the temperature of the adiabatic heated gas is the same or higher than the temperature of the adiabatic cooled temperatures, thus eliminating the need for a regenerator.

Abstract: An ECU is used for a Stirling engine that is provided with a starter that drives an output shaft of the Stirling engine. The ECU includes a control portion that commences an engine-starting drive of the starter within a phase interval, during which the torque of the Stirling engine that varies according to phase of the output shaft is relatively small. The phase interval is an interval during which the torque of the Stirling engine is less than or equal to the torque obtained when the compression begins. The phase at which the driving of the starter is commenced is set to the phase at which the torque of the Stirling engine becomes smaller than the torque obtained when the compression begins.

Abstract: An external-combustion, closed-cycle thermal engine is provided with: a gas chamber, a heater, and a cooler which are closed; flow paths for connecting the gas chamber and the inlet and outlet sides of the heater; flow paths for connecting the gas chamber and the inlet and outlet sides of the cooler; on-off valves respectively provided to the flow paths on the inlet and outlet sides of the heater and of the cooler; and a means for moving a working gas. The switching of the destination of the working gas between the heater and the cooler is performed by the on-off valves, and an operation body is driven. As a result of the configuration, the volume of the heater or the cooler does not affect the efficiency of the engine, and the engine operates under various conditions.

Abstract: A method and arrangement are for heat exchanging in and work exchanging with a working fluid in a heat engine, or a heat pump if the method and its sub-processes are substantially reversed.

Abstract: A thermoacoustic engine includes first and second stacks disposed in parallel in a looped tube and a heat storage unit disposed in the looped tube. A circuit length between a center of the first stack and a center of the heat storage unit is equal to a circuit length between a center of the second stack and the center of the heat storage unit. A first acoustic circuit including the first stack and the heat storage unit has a circuit length which is equal to a circuit length of a second acoustic circuit including the second stack and the heat storage unit.

Abstract: A control valve for a double acting type Stirling engine of the type having two or more piston assemblies reciprocating in bores with each of the piston assemblies separating isolated volumes of a working gas. The control valve provides the functions of a check valve which allows an internally defined volume within the engine to be held at a low pressure near the minimum pressure of the cycle volumes. The valve may further be actuated to unload the engine to provide low starting torque and to unload the engine in case of an engine or load malfunction. The control valve further provides a controlled leakage path for working fluid flowing between the cycle volumes and the minimum pressure volume which acts as part of a pressure balancing system for the Stirling engine which maintains the volume or mass of a working fluid in a balanced condition between the cycle volumes.

Abstract: A Stirling engine is provided with a fluid passage that connects a low temperature-side actuating fluid space and a crankcase inner space, and a passage opening/closing valve that is provided in the fluid passage and that opens and closes the fluid passage. Upon stopping of the Stirling engine, the passage opening/closing valve enables communication through the fluid passage, at a region at which the piston floats in the cylinder. This region is determined based on the pressure of an actuating fluid in the actuating fluid space and the rotational speed of a crankshaft of the Stirling engine.

Abstract: A thermoacoustic apparatus capable of reducing the time elapsed until an acoustic wave is generated and improving the energy conversion efficiency significantly is provided. In order to solve the above-described issues, in a thermoacoustic apparatus 1 including a pair of heat exchangers 41 and 43 separately set on the high temperature side and on the low temperature side, a second stack 42 which is sandwiched between the heat exchangers 41 and 43 and which has a plurality of transmission paths in the inside, and a loop tube 2 provided with the heat exchangers 41 and 43 and the stack 42, the thermoacoustic apparatus converting acoustic energy generated in the loop tube 2 with an acoustic wave generator 3 to thermal energy by using the heat exchangers 41 and 43 and the stack 42, a narrow portion 21 in which the inner diameter is relatively reduced is disposed at a position at which the particle velocity of a standing wave generated in the loop tube 2 is in the vicinity of a maximum.

Abstract: A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

Abstract: A novel engine for producing power from a temperature differential with additional benefits of low cost, high efficiency, quiet operation minimal wear of components, and the ability to produce power or cooling from low grade heat sources.

Abstract: In an adiabatic expansion heat engine, adiabatically expanded low pressure fluid is returned to a source of high pressure fluid through a balance of internal pressures or forces that balances out the resistance to the flow of the fluid being pumped from the low pressure to the high pressure with the high pressure fluid metered into the working chamber.

Abstract: A Stirling-like system incorporating a heater, a displacer and a regenerator is intermittently coupled to an external system via valves, providing pneumatic power while ridding waste heat. The external system is commonly a Rankine cycle, sharing the working fluid of the Stirling-like system, and can be used for heat pumping, distillation and drying. The Stirling working fluid and the Rankine working fluid are the same material and are exchanged between the two systems. A dual Stirling-like system mates a heat engine with a heat pump, sharing the same pressure-containment, with the dual system intermittently coupled to external environments for convective exchange of heat and cold.

Abstract: An annular burner assembly having an annular burner mesh. An annular gas/air supply duct supplies a combustible gas/air mixture to the burner mesh in a substantially axial direction. A flow modifier is provided in the vicinity of the burner and has a plurality of fins each extending in a substantially radial plane to define a plurality of passages arranged circumferentially around the supply duct to substantially laminarise the gas/air mixture. The fins provide a thermal link from the burner to a location radially away from the burner. The burner assembly is particularly suited to a Stirling engine.

Abstract: The invention relates to fluidic oscillators including compressed gas driven pumps and liquid piston and thermoacoustic heat engines and heat pumps in which the intention is to generate large amplitude oscillations by eliminating the dependence of the oscillations on inertia. According to the principle embodiment represented by circuit 200 pressure or temperature variations 27? drive pressure variations in vessel 11? causing a flow of further working fluid between vessel 11? and load 12? wherein useful work is consumed. Said flow varies out of phase with said pressure variations in vessel 11? by a first phase angle determined by inter alia the dissipative load 12? and the capacity of vessel 11?.

Abstract: An energy recovery system permits recovering energy from fumes. The system employs a heat engine such as a Stirling engine, and a supplemental combustible fuel. A combustor receives the paint fumes as well as the supplemental fuel from a fuel supply. The fuel supply includes a fuel throttle regulating the fuel mass flow rate. An air blower provides air to the combustor. The heat engine includes a heater receiving heat from the combustor. A temperature sensor detects the temperature of the heater, while a controller operatively controls the fuel throttle to vary the fuel mass flow rate based on the temperature of the heater.

Abstract: In a Stirling engine, a casing houses therein component elements of the Stirling engine, including a high-temperature-side cylinder, a high-temperature-side piston, a connecting rod, a crankshaft, etc. A pressure control device determines whether the pressure of the gas charged in the casing has declined. If the pressure of the gas has declined, the pressure control device drives a pump to pressurize the gas charged in the casing.

Abstract: A method for improving performance of a free-piston engine, also comprising various other engines such as Stirling Engines, Ericsson engines, Stirling cryocoolers and other external combustion or hot air engines. The improvement is the inclusion of a means, such as a valve or set of valves interposed in a passageway, to contain the working fluid (gas) in the hot or expansion work area so that increased work can occur; or the improvement is by means of piston blocking a port to the working gas passageway such that working gas is contained in the work space such that increased work can occur. The improvement reduces or ideally eliminates free flow of fluid until such time in the cycle where valve or port opens and allows the fluid to flow to the passageway from one space to the other.

Abstract: An external combustion engine having an exhaust flow diverter for directing the flow of an exhaust gas. The external combustion engine has a heater head having a plurality of heater tubes through which a working fluid is heated by conduction. The exhaust flow diverter is a cylinder disposed around the outside of the plurality of heater tubes and includes a plurality of openings through which the flow of exhaust gas may pas. The exhaust flow diverter directs the exhaust gas past the plurality of heater tubes. The external combustion engine may also include a plurality of flow diverter fins coupled to the plurality of heater tubes to direct the flow of the exhaust gas. The heater tubes may be U-shaped or helical coupled shaped.

Abstract: A stirling engine includes a flow path which communicates a working space of the stirling engine and a crankcase of the stirling engine. An output of the stirling engine is controlled so that the output lowers when a pressure inside the working space is higher than a pressure in the crankcase, with a transfer of a fluid in the working space to the crankcase via the flow path thereby causing a decrease in the pressure of the working space.

Abstract: A Stirling engine mounted on a vehicle to efficiently absorb and accumulate the kinetic energy of the vehicle at the time of braking, to improve fuel economy during traveling of the vehicle and to increase the braking effect of an engine brake. The Stirling engine for driving the vehicle is provided with an operating condition-changing device which, at the time of braking the vehicle, changes the operating condition of the Stirling engine over to the heat pump operation. The Stirling engine having, for example, two pistons is provided with the phase difference-changing mechanism 6 for changing a relative phase of the piston 1 and the piston 2. When the brake is applied, the phases of the two pistons are changed to effect the heat pump operation using the power from drive wheels of the vehicle. Heat accumulators 5H and 5C are installed in a heating portion 12 and a cooling portion 22 of the Stirling engine.

Abstract: A stirling engine includes a flow path that communicates a working space of the stirling engine and outside of the stirling engine. A working gas is supplied from the outside of the stirling engine to the working space via the flow path based on a differential pressure of the working space and the outside of the stirling engine.

Abstract: A device and method for equalizing the pressure between work-space and crankcase in a pressurized engine, such as a Stirling engine. The device consists of a two-way valve connected between the work-space and the crankcase. The valve is connected to the work-space with a passageway including a constriction to provide an mean pressure for monitoring purposes. The valve connects the work-space and crankcase allowing the pressure to equalize when the mean pressure of the work-space exceeds the crankcase pressure by a predetermined amount.

Abstract: The heart of a heat engine is a reciprocating expansion chamber, which converts heat from a hot fluid into mechanical work. The expansion chamber utilizes a refrigerant in a liquid state as an input, and heats and expands the refrigerant to move pistons and generate work. A high pressure injector injects the liquid refrigerant into the chamber under enough pressure to keep it in a liquid state until it is desirable to have it expand into a gas. A hot fluid is the heat source for the expansion chamber and cold fluid is an output. Another output is the refrigerant, now a hot, low pressure gas. A compressor pressurizes the refrigerant, forming a hot, high pressure gas, and a condenser generates liquid refrigerant and provides it to the pressure injector.

Abstract: A channelized stratified regenerator with integrated heat exchangers are disclosed using micromachining to precisely construct structural geometries, such as fins and axial stratification of material to be used in a Stirling cycle based system. In operation, a working fluid passes through the regenerator when traveling between two heat exchangers. In some implementations, the regenerator and the heat exchangers are formed as a single construction. In other implementations, the regenerator and heat exchangers are formed separately, but are constructed to integrate efficiently with one another.

Abstract: A channelized stratified regenerator with integrated heat exchangers are disclosed using micromachining to precisely construct structural geometries, such as fins and axial stratification of material to be used in a Stirling cycle based system. In operation, a working fluid passes through the regenerator when traveling between two heat exchangers. In some implementations, the regenerator and the heat exchangers are formed as a single construction. In other implementations, the regenerator and heat exchangers are formed separately, but are constructed to integrate efficiently with one another.

Abstract: A DCHP unit with a Stirling engine (1), a burner (3) and a supplementary burner (11). Water is heated by exhaust gas from the Stirling engine and from the supplementary burner. If a sensor (18) detects that the water temperature has risen indicating that there is insufficient demand for the heat in the exhaust gas, a fan (15), (20) which normally provides the flow of air to the supplementary burner is operated without firing the burner to generate a flow of cool air to cool the water.

Abstract: A Stirling engine comprises a first porous body having a large hole diameter, a second porous body having a small hole diameter and a ring for fixing the first porous body and the second porous body in a pressurization chamber inside a gas outlet closer to the pressurization chamber.

Abstract: A system and method for controlling a thermal dynamic cycle engine, such as a Stirling engine. The system includes a controller able to execute a program to alter certain aspects of the system to provide for a maximum power transfer and substantially stall free start up of the thermal dynamic cycle engine. Generally the controller is able to alter the current load to achieve a selected stroke length, pattern or temperature of a heater head of the engine. The system allows for generally stall free start-up and continuous control for maximum power (with maximum power factor) transfer from the thermal cycle engine or the associated alternator.

Abstract: An external combustion engine having an exhaust flow diverter for directing the flow of an exhaust gas. The external combustion engine has a heater head having a plurality of heater tubes through which a working fluid is heated by conduction. The exhaust flow diverter is a cylinder disposed around the outside of the plurality of heater tubes and includes a plurality of openings through which the flow of exhaust gas may pas. The exhaust flow diverter directs the exhaust gas past the plurality of heater tubes. The external combustion engine may also include a plurality of flow diverter fins coupled to the plurality of heater tubes to direct the flow of the exhaust gas. The heater tubes may be U-shaped or helical coiled shaped.

Abstract: A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed.

Abstract: A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed.

Abstract: A method for controlling the fuel-air ratio of a burner having a blower responsive to a blower drive signal for injecting air into the burner. The method is based at least on the concentration of a gas in an exhaust gas product of a combustion chamber of the burner and includes measuring the gas concentration in the exhaust gas product, deriving a gas concentration signal from the measured gas concentration, determining the fuel-air ratio from the gas concentration signal and the sign of the derivative of the gas concentration signal with respect to the blower drive signal, and controlling the fuel-air ratio by adjusting the air flow rate into the burner. The burner may be, for example, in a Stirling cycle engine.

Abstract: A regenerator for a thermal cycle engine and methods for its manufacture. The regenerator has a random network of fibers formed to fill a specified volume and a material for cross-linking the fibers at points of close contact between fibers of the network. A method for manufacturing a regenerator has steps of providing a length of knitted metal tape and wrapping a plurality of layers of the tape in an annular spiral.

Abstract: An external combustion engine having an exhaust flow diverter for directing the flow of an exhaust gas. The external combustion engine has a heater head having a plurality of heater tubes through which a working fluid is heated by conduction. The exhaust flow diverter is a cylinder disposed around the outside of the plurality of heater tubes and includes a plurality of openings through which the flow of exhaust gas may pas. The exhaust flow diverter directs the exhaust gas past the plurality of heater tubes. The external combustion engine may also include a plurality of flow diverter fins coupled to the plurality of heater tubes to direct the flow of the exhaust gas. The heater tubes may be U-shaped or helical coiled shaped.

Abstract: A Thermo-Acoustic Resonator (TAR) is a miniature thermoacoustic heat pump and thermal-electric generator that is typically imbedded in a thermoplastic or metal package. The TAR converts a thermal gradient into electrical energy. It can range in size from that of a microchip, upward. The operable principle is that sensible and latent heat in a material can be pumped most efficiently when pumped at intervals that are resonant with the natural period of the material at a given temperature, thereby increasing the energy density of the thermoacoustic engine. The normal period of the device is tailored to produce thermodynamic oscillation in the heat exchangers and working fluid, and thereby to cause a miniature armature to reciprocate within a magnetic field and generate alternating current. Power output depends on the amplitude and frequency of the thermal gradient, and the tailored energy flow rate through the device.

Abstract: A heating and refrigerating machine, especially a Vuilleumier heat pump or Stirling engine, in which a gas-air mixture is combusted in a combustion chamber and the exhaust gas radiates thermal energy to a heater head, which functions as a housing for the hot piston of the machine, part of the outer surface of the heater head forming a portion of the combustion chamber. By using a porous-medium burner and by virtue of its adaptation to the heater head, the transmission of heat by convection and radiation is improved and a compact machine design is attained which transmits heat in a highly efficient manner with low emissions over a broad output modulation range.

Abstract: A heat engine is constructed from sheet metal and the like. The heat engine has an outer container and inner container which contains a displacer and a power piston. A plurality of positioning members are provided to dimensionally stabilize the inner and outer containers. By providing positioning members that extend between the inner and the outer containers, a sandwiched construction is obtained which allows the inner and outer containers to reinforce each other thus permitting the use of thin walled containers and improving the thermal efficiency of the heat engine and decreasing the weight of the heat engine.

Abstract: A heat engine is constructed from sheet metal and the like. The heat engine has an outer container and inner container which contains a displacer and a power piston. A plurality of positioning members are provided to dimensionally stabilize the inner and outer containers. By providing positioning members that extend between the inner and the outer containers, a sandwiched construction is obtained which allows the inner and outer containers to reinforce each other thus permitting the use of thin walled containers and improving the thermal efficiency of the heat engine and decreasing the weight of the heat engine.

Abstract: A heat engine is constructed from sheet metal and the like. The heat engine has an outer container and inner container which contains a displacer and a power piston. A plurality of positioning members are provided to dimensionally stabilize the inner and outer containers. By providing positioning members that extend between the inner and the outer containers, a sandwiched construction is obtained which allows the inner and outer containers to reinforce each other thus permitting the use of thin walled containers and improving the thermal efficiency of the heat engine and decreasing the weight of the heat engine.