Showing papers on "Thermodynamic cycle published in 1982"

Regenerative gas turbine cycle

Abstract: In a regenerative gas turbine cycle in which heat recovery is carried out by a mixture of air/steam which is obtained by contact between water and a part of or the whole of compressed air, said compressed air being compressed by a compressor for compressing gas using air or air based gas as a combustion supporting/working medium gas; the improvement comprising: the mixture of air/steam and liquid phase cooled water being obtained through the contact between the compressed air and heated water which is used as heat recovering medium; said cooled water being used as heat recovering medium not only for heat recovery of turbine exhaust gas but also, for (a) intercooling of the compressor, and/or (b) precooling of compressed air for the contact operation; supplying water corresponding to the amount of water which contacts the compressed air and is lost by evaporation to the liquid phase water for contact or heat recovery as it is or after using as a heat recovering medium.

Gain and efficiency of a traveling wave heat engine

Abstract: Gain and efficiency equations are derived for a traveling wave heat engine, a device in which acoustic traveling waves force gas within a differentially heated regenerator to undergo a Stirling thermodynamic cycle and transform energy between thermal and acoustic forms. This derivation assumes nonturbulent flow conditions, a linear drag coefficient, a constant heat exchange coefficient, and neglects regenerator end effects. The complex characteristic impedance, gain, and efficiency are calculated for a thin slice of the regenerator in terms of dimensionless variables. With a Prandlt number of 0.7, the equations predict an efficiency of 70% that of an ideal Carnot cycle, and gain of 85% of that of theoretical maximum gain when fN ≡ωτ=0.003 and T′N≡ (dT/dx)T−1CIτ=0.4, where ω is the acoustic angular frequency, τ is the thermal time constant for the heat exchange process, dT/dx is the regenerator temperature gradient, and CI is the isothermal velocity of sound. In general, the equations predict that efficien...

Thermodynamic machine and method

Abstract: In thermodynamic apparatus and methods utilizing constant volume cycling devices, substantial improvements in energy output can be gained by utilization of an integrated thermodynamic process placing regenerator efficiency in a higher regime. Displacer elements operating in phased relation to the thermodynamic cycle provide superheating and supercooling to extended opposite ends of the regenerator, to establish steady state conditions which increase the temperature ratio of the system. In turn, the pressure ratio of the thermodynamic cycle is increased and the specific energy output improved. This expansion of the capability of thermodynamic machines for working in moderate temperature ranges is further utilized with systems for achieving thermal gain for heating or cooling, utilizing ambient energy as a heat source as well. It thus becomes feasible to effect thermal transformation between different temperature levels with high coefficients of performance, vastly increasing the number of alternatives available for practical thermal exchange systems.

Development and test of solar Rankine cycle heating and cooling systems

Abstract: Well-designed solar-powered Rankine-cycle systems can be used to drastically reduce building heating and cooling energy requirements while meeting all comfort operational requirements. A turbocompressor system using a common refrigerant, R11, and advanced aerodynamic and mechanical design features can efficiently provide heating and cooling at efficiency levels equal to or above those of current systems. Equipment costs, i.e., collector, storage, and heat pump, as well as installation costs are currently too high for widespread solar application. However, as energy costs continue to escalate and equipment cost is reduced due to increased production, solar cooling and heating will become competitive and gain acceptance. The Southwest will probably lead the way to solar energy utilization.

Cycle design for the Isabelle helium refrigerator

Abstract: The cycle schematic for the ISABELLE Refrigerator with a simplified load is given. The subcooler section is described with a summary on the performance requirements shown with system parameters itemized. The main refrigerator uses a Claude-type cycle which is described along with detail design. State variables at each process point in the cycle are shown with flow properties and flow rates. The refrigerator is scheduled for completion and testing in 1983.

The Nuclear Gas Turbine: A Perspective on a Long-Term Advanced Technology HTGR Plant Option

Abstract: Comprehensive design studies and assessments were carried out in the 1970s on an advanced, direct-cycle high-temperature gas-cooled reactor (HTGR) option. These led to conclusions in 1980 that an extensive development effort was necessary to establish a technically viable gas turbine HTGR (HTGR-GT) plant to satisfy demanding safety and licensing criteria and that further design innovation was necessary to identify plant features for improved economics. Accordingly, the steam cycle HTGR was designated as the lead plant and the HTGR-GT classed as a long-term, advanced technology, second-generation HTGR plant option. With the necessary development, a dry-cooled gas turbine plant with a reactor outlet temperature of approximately 950/sup 0/C, operating in a combined cycle mode (with an efficiency of over 50%) or cogeneration mode (power plus process steam production), could be realized in the early decades of the 21st century. This paper reviews the status of the Brayton cycle plant and gives a perspective on the HTGR-GT plant as a follow-on option to the steam Rankine cycle lead plant.

Helium liquefier cycles with saturated vapor compression

Abstract: This paper is the design study of a saturated-vapor-compression helium liquefier operating at elevated pressure. The study was done to show the potential of the SVC cycle by direct comparison with a conventional cycle using the same precooling expanders and a supercritical wet expander instead of a J-T valve. A description of convential and SVC helium cycles is given with diagrams. Optimization of the SVC cycle is presented with a graph of the expander inlet temperatures. A discussion of the results includes conventional and SVC cycle dates for four states each. The SVC cycle has the potential for significant improvements of helium liquefiers producing atmospheric pressure liquid. This and other results encouraged the construction of apparatus to be used with a conventional helium liquefier to test a wet expander and a cold compressor and to demonstrate the potential of the SVC cycle.

Cogeneration from glass furnace waste heat recovery

Abstract: In glass manufacturing 70% of the total energy utilized is consumed in the melting process. Three basic furnaces are in use: regenerative, recuperative, and direct fired design. The present paper focuses on secondary heat recovery from regenerative furnaces. A diagram of a typical regenerative furnace is given. Three recovery bottoming cycles were evaluated as part of a comparative systems analysis: steam Rankine Cycle (SRC), Organic Rankine Cycle (ORC), and pressurized Brayton cycle. Each cycle is defined and schematicized. The net power capabilities of the three different systems are summarized. Cost comparisons and payback period comparisons are made. Organic Rankine cycle provides the best opportunity for cogeneration for all the flue gas mass flow rates considered. With high temperatures, the Brayton cycle has the shortest payback period potential, but site-specific economics need to be considered.

Gas system external combustion engine

Abstract: PURPOSE:To improve efficiency of a gas system external combustion engine by permitting said engine to repeat heat cycle of adiabatic compression, isobaric heating, adiabatic expansion and isobaric cooling. CONSTITUTION:Tanks 1, 2, 3, and 4 contain each gas under each condition respectively corresponding to points 1, 2, 3 and 4 in p-v diagram. First, valves 6, 9 are closed and valve 5, 7, 8 and 10 opened. When pistons 19, 20 are operated from the lower dead point and pistons 21, 22 from the upper dead point, the gas in the tank 3 depresses the piston 21 and the gas below the piston 22 enters the tank 4. The gas above the piston 19 enters the tank 2 and the gas in the tank 1 enters beneath the piston 20. Next, when the valves 6, 9 are opened and the valves 5, 7, 8 and 10 closed, each piston moves reversely while the gas above and below each piston is replaced by each other through the valves 6, 9. Then, the valves 6, 9 are closed and the valve 5, 7, 8 and 10 are opened so that the condition returns to the initial one thus a gas system external combustion engine operating through a heat cycle consisting of adiabatic compression, isobaric heating, adiabatic expansion and isobaric cooling, may be provided.

Modified Brayton Cycles Utilizing Alcohol Fuels

Abstract: This paper demonstrates that there are significant improvements in thermal efficiency possible by modifying the manner in which alcohols are used in Brayton cycle engines. It is shown that injection of the alcohol during the compression process can materially improve both thermal efficiency and specific work because of the intercooling effect of evaporation. 14 refs.

Shipboard energy savings with the RACER system

Abstract: The current NAVSEA program to design and develop a waste heat recovery gas turbine cruise propulsion plant called RACER is discussed. RACER is an acronym for RAnkine Cycle Energy Recovery which describes the steam bottoming cycle designed to recover waste exhaust heat from LM2500 gas turbines and augment the main propulsion system through a steam turbine. Such waste heat recovery systems, when used in naval applications, have been more commonly called combined gas and steam turbine (COGAS) propulsion plans. The acronym RACER, however, will be used throughout this paper in the place of the historic COGAS term in an attempt to distinguish the proposed system, which incorporates advanced technology and some unique design concepts, from traditional practice. The conceptual design philosophy followed by Solar as it applies to non-nuclear surface combatants is discussed and the major system components described. Installation and operational considerations are presented. Control and monitoring philosophy is discussed briefly as it relates to the system concept. System performance is presented including its relationship to fuel savings and increased military effectiveness.

Process for direct treatment of links for tractors or tracked vehicles

Abstract: The invention refers to a process for direct heat treatment of track links for tracked vehicles, utilizing the residual forging heat of the links themselves so as to reduce production costs. The heat cycle as per the invention calls for careful control of forging times and temperatures, followed by an interrupted cooling sequence, without ever arriving at room temperature except when the part is completely forged and treated. Several particular embodiments of the cycle are indicated, to achieve the final desired metallurgical structure.

Variable pressure supercritical Rankine cycle for integrated natural gas and power production from the geopressured geothermal resource

Abstract: A small-scale power plant cycle that utilizes both a variable pressure vaporizer (heater) and a floating pressure (and temperature) air-cooled condenser is described. Further, it defends this choice on the basis of classical thermodynamics and minimum capital cost by supporting these conclusions with actual comparative examples. The application suggested is for the geopressured geothermal resource. The arguments cited in this application apply to any process (petrochemical, nuclear, etc.) involving waste heat recovery.

Heat exchanger module for Stirling engines

Abstract: The invention relates to Stirling engines and provides a modular assembly composed of a cylinder head, a heater, a regenerator, a cooler and a cold duct, and making it possible by mounting a plurality of identical modules on an engine assembly to construct a multi-cylinder double acting Stirling engine of the indirect heating type.

CAESCAP: a computer code for compressed-air energy-storage-plant cycle analysis

Abstract: The analysis code, CAESCAP, was developed at the Pacific Northwest Laboratory to aid in comparing and evaluating proposed compressed-air energy-storage (CAES) cycles. Input consists of component parameters and working-fluid conditions at points along a cycle. Given these inputs the code calculates thermodynamic properties at each point and then calculates overall cycle performance. Working-fluid capabilities include steam, air, nitrogen, and parahydrogen. The CAESCAP code was used to analyze a variety of CAES cycles. The combination of straightforward input and flexible design make the code easy and inexpensive to use.

Performance predictions for a room temperature, Ericsson cycle, magnetic heat pump

Abstract: : The performance potential of a room temperature magnetic heat pump utilizing Gadolinium and operating on an Ericsson Cycle was investigated at magnetic flux densities of 2 and 7-Tesla which represent the upper limits of conventional and superconducting electromagnetics, respectively. At a coefficient of performance of 5, a 7-Tesla system would provide a cooling capacity of at best 1200 BTU per hour per pound of Gadolinium while a 2-Tesla system would operate at approximately 130 BTU per hour per pound of Gadolinium. Magnetic circuit efficiency was not determined but must be high (95-percent or better) in order for the magnetic heat pump performance to compete with conventional cooling systems. It is unlikely the magnetic heat pump investigated could approach the performance and compactness of the conventional cooling systems unless field strengths much greater than 7-Tesla are possible. (Author)

Method and device for the recovering of efficient energy from environment heat by means of a thermodynamic cycle.

Abstract: not available for EP0055282Abstract of corresponding document: DE3025472According to this method, a gas medium is selected as a working medium for which the isobaric curves represented in a temperature-enthalpy diagram to the right of the junction line joining the summits of successive isenthalpy curves (line VS-I), are substantially directed downwardly to the right hand side. A substantially constant gas quantity is repetitively exposed to a dextrogyre cycle, from a starting state (point 1) at an increased pressure and substantially at room temperature. The working medium is first expanded (point 1 to point 2) to lower its temperature and to obtain a work, and then it is exposed to a pressure increase (point 2 to point 3) and it is finally brought to the starting state (point 1) by an environment heat flow.

The Constant Volume Gas Turbine Cycle According to Karavodine

Abstract: The basic distinction between the constant volume cycle and the well known constant pressure cycle for gas turbines is the method of heat supply, which necessitates a system of combustion chamber valves to contain the fluid. The object of the proposed cycle analysis, which is mainly based on the fundamental laws of mass and energy, will consider a solution for the discrepancies between the former theory and practice of constant volume gas turbines. The overall performance characteristics which emerge from this analysis show the distinct superiority of the one-valve Karavodine cycle. Evaluation by experiment for this cycle variant shows, however, besides a refinement of the model, a marginal superiority in performance for the Brayton gas turbine at low pressure ratios. Any application could probably be justified by incorporating it in Brayton turbines to diminish starting power and to improve part load performance.Copyright © 1982 by ASME

Improved Stirling engine performance using jet impingement

Abstract: Of the many factors influencing the performance of a Stirling engine, that of transferring the combustion gas heat into the working fluid is crucial. By utilizing the high heat transfer rates obtainable with a jet impingement heat transfer system, it is possible to reduce the flame temperature required for engine operation. Also, the required amount of heater tube surface area may be reduced, resulting in a decrease in the engine nonswept volume and a related increase in engine efficiency. A jet impingement heat transfer system was designed by Rasor Associates, Inc., and tested in the GPU-3 Stirling engine at the NASA Lewis Research Center. For a small penalty in pumping power (less than 0.5% of engine output) the jet impingement heat transfer system provided a higher combustion-gas-side heat transfer coefficient and a smoothing of heater temperature profiles resulting in lower combustion system temperatures and a 5 to 8% increase in engine power output and efficiency.

Development and demonstration of a Stirling/Rankine heat activated heat pump

Abstract: The HAHP concept is schematically illustrated in this paper. The combustor/linear Stirling engine/linear compressor assembly replaces the conventional motor/compressor unit. Performance projections for the HAHP are considered. The penetration of the HAHP into the HVAC market is forecast. In the hardware development program an engineering prototype and a field test model prototype were built. Porous transpiration burner elements, free piston linear inertia compressor, unit free piston assembly all are illustrated. Prototypes 1 and 2 were tested, and the results correlated in graphs. As Phase II drew to a close, diagnostics resulted in these findings: several changes were required in engine components. Better engine/compressor dynamic matching is required, and improved analytic tools are necessary. The prototypes demonstrated the feasibility of the Stirling/Rankine HAHP system.

Overview of international R and D programs on ORC systems

Abstract: The use of organic fluids in Rankine cycles has the potential for economically generating electric power from waste heat sources at lower temperatures than would be practical using steam systems This paper reviews the current status of organic Rankine cycle (ORC) research and development in the United States, Europe, and Japan Some of the problems being addressed are optimal working fluid selection, design of the nozzle/turbine assembly, and design of the vaporizer Commercially available ORC engines range in size from 300 kW to 1,500 kW, while demonstration units start in the 30-40 kW range Most applications to date have utilized the waste heat available in the exhaust gas of diesel engines and oil refinery furnaces Although the focus of R and D work to date has been the technological aspects of ORCs, the economics must also be proven attractive if the systems are to penetrate the market

A concept of heat pipe engine

Abstract: A concept of a new type of thermal cycle system of ''heat pipe engine'' is proposed, principle of which is originated from the extending application of heat pipes. The essence of the idea is to generate a large periodical vapor pressure variation in the completely sealed container, letting the vapor expose to and shut off from the cooled condenser wall alternately with certain mechanical means called ''thermal shutter''. The generated pressure variation will move the loaded piston, and exert work to the externals. To demonstrate the feasibility of this idea, the preliminary experiment was conducted by using the conceptual model of the heat pipe engine. The results revealed a creation of appreciable pressure variation in the cylinder room of the model synchronized with the motion o /SUP i/ the thermal shutter. This implies a possibility of the future use of this engine as an effective thermal system in the medium temperature range of around 300/sup 0/C. This type of engine would be contributive to the wise use of low temperature energy source which should otherwise be wasted as useless.

External-combustion reciprocating engine with ''Isobaric-Diagonal'' thermodynamic cycle

Abstract: A new external-combustion reciprocating engine is presented, whose thermodynamic cycle is characterized by an isobaric diagonal. The parametric analysis and the discussion have shown that performances of such an engine are more than comparable with those of conventional engines of the same class.