Showing papers on "Thermal efficiency published in 1974"

Parallel-compound dual-fluid heat engine

Abstract: A heat engine provides work output from a first working fluid operating in essentially a Brayton-type thermodynamic cycle and from a second working fluid operating essentially in a Rankine-type thermodynamic cycle, the two working fluids interacting with each other so that the work output of the two working fluids, working in parallel during the conversion of heat energy to work, is compounded.

Method and apparatus for storing a medium heated by solar energy

Abstract: A heating system has means for directing heat only to a portion of a medium for storing heat which portion is at a temperature below that to which heating means then heats the medium. The system then functions to store heat in the medium during periods of less-than-maximum heating of the medium without degrading the temperature of a higher-temperature portion of the medium. The system has particular utility with a solar heat collector from which the available heat varies with the intensity of the solar energy. Heat is then collected in the portion of the medium during periods of marginal solar energy intensity without degrading the higher temperature of another portion of the medium heated to a higher temperature during a prior period of greater solar energy intensity. In a specific embodiment the system has three compartments for separating a fluid heat-storing medium into portions, a pump supplying the fluid to a solar heat collector, and a pump supplying the fluid to a heat exchanger for heating a house. The means for directing heat to a portion of the medium then direct fluid heated in the collector to a compartment of fluid at a temperature nearest below that to which the solar heat collector then heats the fluid. The pump supplying fluid to the collector withdraws fluid from a compartment at a lowest temperature to maximize the thermal efficiency of the collector and exchanger.

Internally vaporizing low emission combustor

Abstract: A combustor adapted for use in a gas turbine engine comprising a combustion prechamber zone, a main combustion chamber zone and a dilution air zone including a system for introducing a premixed fuel-air mixture with elevated inlet air temperatures which allows the thermal efficiency of the engine to be increased without a corresponding increase in the percentage of oxides of nitrogen in the combustion products.

Feasibility demonstration of a road vehicle fueled with hydrogen-enriched gasoline

Abstract: Evaluation of the concept of using hydrogen-enriched gasoline in a modified internal combustion engine in order to make possible the burning of ultralean mixtures The use of such an engine in a road vehicle demonstrated that the addition of small quantities of gaseous hydrogen to gasoline resulted in significant reductions in exhaust emissions of carbon monoxide and nitrogen oxides as well as in thermal efficiency improvements of the engine performance

Apparatus for the determination of the thermal efficiency of chemical reactions

Abstract: An apparatus for determining the thermal efficiency of a chemical reaction wherein a reaction vessel is equipped with a double-wall jacket or shell which forms a heat exchanger, a heat transfer fluid medium is circulated so rapidly that the difference of its temperature at the inlet and at the outlet of the shell throughout the entire duration of the reaction, with the exception of possibly occurring momentary irregularities in the reaction kinetics, does not exceed 1° C. A temperature regulator is provided which is constructed as a mixture regulator and encompasses a respective container for heat transfer fluids which are hotter and colder with respect to the temperature of the heat transfer fluid which is circulated in the circulation system and each such container is operatively connected with the circulation system as a function of the reference value deviation of the temperature of the reaction mixture. Further, there is provided an apparatus for the continuous determination of the difference between the temperatures of the reaction mixture and the heat transfer fluid at a randomly selected location of the heat exchanger.

External combustion engine and engine cycle

Abstract: An engine, particularly adapted for use in automobiles, in which ambient air is compressed in a positive displacement compressor and then heated in a heat exchanger. The heat exchanger output drives a rotary turbine which, in turn, drives the positive displacement compressor and produces output power. Any source of heat, such as the combustion products from a fuel burning chamber, may be used to apply heat to the heat exchanger. A heat storage device is also incorporated into the system to provide power during sudden turbine demands.

Method of testing for rating solar collectors based on thermal performance

Abstract: Abstract This paper describes a proposed test method for determining the efficiency of solar collectors under specified outdoor “steady-state conditions. The prescribed series of tests should provide useful data for the rating of solar collectors based on thermal performance. A study was made of existing theory, measurement practices and a number of collector test procedures in use prior to the publication of the proposed method. The test apparatuses and major components have been prescribed so a liquid or air can be used as the transfer fluid. The energy of the fluid entering and leaving the collector is determined by making appropriate measurements and these quantities are than compared to the energy incident upon the collector (also determined by measurement) in order to calculate the collector efficiency. The series of tests to be conducted consists of determining the average efficiency for 15 min periods (integrating the energy quantities) over a range of temperature differences between the average fluid temperature (average of inlet and outlet) and the ambient air. The test apparatuses have been designed so that the temperature of the fluid entering the collector can be controlled to a selected value. This feature is used to obtain the data over the temperature range desired. At least sixteen “data points” are required for a complete test series and they must be taken symmetrical with respect to solar noon (to prevent biased results due to possible transient effects).

Stirling cycle engine with catalytic regenerator

Abstract: A modified Stirling engine has a regenerator with catalytic surfaces for inducing reversible chemical reaction in the working fluid. The basic Stirling engine has an expansion space and compression space with one or more pistons for periodically transferring the working fluid therebetween. Heat is added to the working fluid in the expansion space to maintain temperature during expansion and heat is extracted from the compression space to counteract compression heating. A regenerator, which is a temporary heat reservoir, is provided in the fluid flow path between the expansion and compression spaces. In this improvement, the working fluid is subject to a reversible chemical reaction which is endothermic in one direction and exothermic in the other direction, and has less specific volume when driven in the exothermic direction. The volume difference arises since there are more moles of gas in the higher temperature regime than in the lower. Particularly suitable is the endothermic dehydrogenation and exothermic hydrogenation of hydrocarbons. In such a system the quantity of working fluid being compressed is minimized so that there is less cooling required. The volume of working fluid being expanded is maximized thereby enhancing power output. Thermodynamic efficiency is significantly enhanced by such a working fluid and catalytic regenerator.

Method and apparatus for fractionating multi-component feeds

Abstract: A three tower pressure-vacuum distillation arrangement for separating crude oil into desired components and the inter-related heat recovery by the crude oil charged to the combination is described. The arrangement of the fractionation sequence along with the use of a reboiler heat in the pressured distillation tower increases the thermal efficiency of the overall process thereby reducing the heat requirement of the process.

Internal combustion and steam powered engine

Abstract: A combination internal combustion and steam powered engine having a reciprocating piston and two separate chambers which increase and decrease in volume with movement of the piston. The piston is driven in one direction by the combustion of fuel in one chamber, and it is driven in the other direction by the evaporation of water and expansion of steam in the other chamber. The steam is generated by heating water with the heat produced by the combustion of the fuel in the first chamber and introducing measured amounts of the heated water into the second chamber where it evaporates and expands.

Conservation in industry.

Abstract: The power of fuel price to promote efficient utilization is illustrated by some fuel conservation measures in industrial plants. Fixing broken windows and closing doors during loading are simple examples. Some technical measures cited are insulating watercooled skid rails used to convey material through a heat-treating furnance, recapturing stack gas heat from a radiant fired tube and using it to preheat combustion air as a heat recuperator, installing heat pipe vacuum furnaces, and combining industrial production of process steam with electric power generation. Awareness of the conservation measure, loans for new equipment, and the risks in installing new equipment are discussed. The use of computer controls in the operation of processing plants is beneficial. (MCW)

Unitary auxiliary electric power, steam supply and heating plant for building construction

Abstract: A rectangular housing is provided with a plurality of vertically spaced, horizontal partitions defining separate sealed chambers in vertical ascending order for fuel storage, fuel and air combustion, steam boiler, combustion air preheating, steam condensation, turbine drive and electrical generation. Ducts connecting chambers effect forced and thermal syphonic movement of combustion air and combustion gases. Conduits fluid connect the turbine to the condenser and boiler heat exchange units. A powered fan introduces fresh air to the condenser chambers for condensing steam with the air being preheated prior to delivery to the combustion chamber.

Method of increasing the output of hydrogen combustion type internal combustion engine by recovery of generated heat and apparatus therefor

Abstract: This invention relates to a new method of increasing the output of a hydrogen combustion type internal combustion engine by recovery of generated heat and to an apparatus therefor. It is the main object of the invention to raise engine output by producing steam by having generated heat absorbed in water obtained from combustion of hydrogen, obtaining high-pressure generated steam by having said heat re-absorbed in newly introduced water and combining said high-pressure steam with said produced steam.

Apparatus to improve combustion of fuel

Abstract: Preheated secondary combustion air is delivered across the axis of the burner flame in an oil-fired boiler. By virtue of a secondary combustion air delivery apparatus, the secondary air is heated in three stages before delivery into the flame and is then delivered in a multiplicity of evenly pressurized air jets to control the size of the flame while increasing the heat thereof. A substantial savings of fuel is obtained and boiler efficiency is increased.

The Influence of He-Ne, He-N2, and He-CO2 Gas Mixtures on Closed-Cycle Gas Turbines

Abstract: With reference to a proposal made by Prof. Ackeret studies have been made on the composition of an optimal working medium for closed-cycle gas turbines. These studies are based on the assumption that this aim could be achieved by mixing helium with a gas of higher molecular weight, using neon, nitrogen, and carbon dioxide here. The influence of these gas mixtures on the circuit parameters and on the layout of the turbomachines and heat exchanging apparatus is shown. The calculations have been carried out giving consideration to the real gas behavior of the mentioned gas mixtures. In addition to this, the relationship of the costs of the turbomachinery and apparatus are shown in relation to a reference plant with pure helium as working agent. The basis for these studies is a process with the thermal efficiency, the upper and lower process temperatures and the turbine inlet pressure being the same for all gas mixtures. The results of the calculations are that, for certain gas compositions, cost advantages can be gained relative to the layout with pure helium. These advantages and the mixture compositions, for which they appear, are dependent on the admixed gases. For these calculations the cost relationship of turbomachines and heat exchangers to the total cost have been considered.Copyright © 1974 by ASME

Effect of sulfur compounds in fuel combustion products on efficiency of marine gas turbine engine blades under cyclic thermal loading

Abstract: Tests were ca r r i ed out on ro tor blades (Fig. 1) and guide vanes using fuel mixtures with various sulfur compound contents, to investigate the effect of sulfur compounds in fuel combustion products on the thermal fatigue strength of turbine blades and vanes, using the method previously descr ibed and a specially built gas dynamics test bench [1]. The investigation p rog ram provided for tests at fuel sulfur concentrat ions of 0.05, 0.4, 1.3, and 5 wt. %. The basic fuel used was lighting kerosene of grade KO-25 by GOST 4753-68 with 0.05 wt. % sulfur. The sulfur content was al tered by addition to the fuel of t e r t ia ry dodecyimercaptan (C12H25SH). The method chosen made it possible to evaluate the effect of sulfur compounds on gas turbine engine s t ructural elements in simulated operation on pract ica l ly all grades of fuel, because the sulfur content is of the f i rs t importance f rom the point of view of effect on metal proper t ies . The object of the present work is to investigate blade life, to study the kinetics of c rack origination and development, and to examine the nature of surface layer damage from the combined action of thermal

Method of working a combined nuclear-fossil fuel cycle and device for using same

Abstract: A method of working a combined nuclear-fossil fuel cycle consisting in generating steam in a nuclear reactor, admitting fossil fuel into a regenerator operating with oxygen and effecting the gasification of the fuel therein and raising the heat potential of the steam supplied by the reactor; feeding the steam into a burner and reacting the gaseous fuel with oxygen therein and then causing the mixture of combustion products and steam to work in a turbine driving an alternator.

Rankine-cycle systems for waste-heat recovery

Abstract: Waste heat can be utilized by an organic Rankine-cycle system to produce useful electrical or shaft power without any fuel expense. Such a system starts with a heat recovery boiler, which provides saturated or superheated vapor to an expander by transferring heat from the waste-heat fluid to the Rankine-cycle working fluid. Power is extracted in the expander, and the fluid passes on to a condenser, which provides liquid to a feed pump. The feed pump raises the pressure and resupplies fluid to a boiler, thereby completing the cycle. The working-fluid condenser heat is rejected to a cooling fluid in the condenser. Depending on the particular application and working fluid selected, it may be economical to add a regenerator to improve cycle efficiency.

Alternate fuels for transportation

Abstract: Studies with an ammonia-fueled urban vehicle are reported which indicate that ammonia is attractive as a spark-ignition engine fuel because of its potential availability, adaptability, to existing engine designs, cost, emissions safety and easy storage. The thermal efficiency of spark-ignition engines increases with the engines compression ratio. Ammonia has an extremely high octane rating (130 plus, R.O.N.) and achieves this without use of lead or any other additives. This means that high compression ratios can be used with ammonia to achieve high engine-cycle efficiencies without associated emission penalties. Ammonia does not require cryogenic storage, and can be stored in propane tanks. The heating value of ammonia is low when compared with gasoline and liquid hydrogen. However, on a volumetric basis, liquid ammonia is more attractive than liquid hydrogen. Ammonia is toxic and caution must be exercised in handling it. However, ammonia is readily detectable by its smell at concentration levels (5-50 ppm) well below those considered dangerous for long term exposure. Also, ammonia vapor is lighter than air, and escaping vapor will rise rather than collect near the ground. The results are presented of tests which illustrate the low emmssion capabilities of the fuel. Good fuel distribution is essential for optimium operation of spark-ignition engines and gaseous fuels are therefore superior to liquid fuels. Ammonia is readily vaporized and the latent heat of vaporization is high enough to warrant its consideration as a means for air conditioning the vehicle without the use of a compressor or condenser. Materials compatibility, adaptability to existing engine designs and costs are also discussed.

The generation of hydrogen by the thermal decomposition of water

Abstract: Development of an approach to the evaluation of the thermal efficiency of the process of water splitting to produce hydrogen. A way of viewing thermochemical processes - both overall and step-by-step is suggested, and some recent work on a process evaluation technique is described which provides internal checks on the thermodynamic data and calculates, in addition to the efficiency, many important process parameters.

Parametric thermodynamic analysis of closed-cycle gas-laser operation in space

Abstract: Cycle efficiency and radiator area required were calculated for thermally and electrically pumped lasers operating in closed cycles with a compressor and the required heat exchangers. A thermally pumped laser included within a Brayton cycle was also analyzed. Performance of all components, including the laser, was parametrically varied. For the thermally pumped laser the cycle efficiencies range below 10 percent and are very sensitive to the high-pressure losses associated with the supersonic diffuser required at the laser cavity exit. The efficiencies predicted for the electrically pumped laser cycles range slightly higher, but radiator area also tends to be larger.

Thermal efficiency of the uniflow steam expander at 800 to 1400 deg f inlet temperature

Abstract: A design concept is presented for a single acting uniflow expander with poppet valving, water cooled cylinder walls, and unlubricated piston rings. The calculated thermal efficiency of this expander is shown to be relatively insensitive to inlet pressure. Efficiency increases with inlet temperature, typically from 28% at 800 degrees F to 36% at 1400 degrees F. This improvement is efficiency makes the 1400 degree F uniflow competitive in fuel mileage with present automobiles. /GMRL/

The Constant Volume Gas Turbine: A Thermodynamic Assessment

Abstract: A quasi-steady-state analysis is made of the performance of a gas-turbine working with intermittent, constant volume combustion. Variables considered include inlet temperature, compressor pressure ratio, scavenge ratio, combustion time, heat exchanger thermal ratio. Characteristics are computed over a full loading range. Computations are based on turbines having the following behavior: (a) constant turbine efficiency, (b) characteristics of a multistage axial turbine, and (c) characteristics of a single-stage radial turbine. The analysis indicates that the constant volume gas turbine has advantages in thermal efficiency, specific power and part load performance over constant pressure gas turbines operating at the same compressor pressure ratio and turbine inlet temperature. However, the addition of a heat exchanger shows less advantage when applied to a constant volume than to a constant pressure engine.Copyright © 1974 by ASME

Low BTU Fuels for Gas Turbines

Abstract: The current shortage of conventional gas turbine fuels has created the need for new sources of clean fuel. One of the most promising new fuels is low Btu gaseous fuel, such as that produced by air-injected coal or oil gasifiers or other chemical processes. The various sources of low Btu fuels and their combustion characteristics are discussed. To burn many of the low Btu fuels in the 100 to 300 Btu/scf range necessitates certain design modifications to the gas turbine originally optimized for high energy fuels. The extent of the modification depends greatly on the low Btu fuel. The impact of low Btu fuels on the gas turbine thermodynamic cycle performance and environmental performance is very encouraging. From the environmental viewpoint, low Btu fuels promise to be clean fuels, while providing increased output at higher thermal cycle efficiencies than achieved with conventional fuels. The advantages of low Btu gaseous fuels are that they broaden basic energy sources, have higher shaft output, give low nitrogen oxide emissions, have low flame radiation, and have wide limits of flammability. Disadvantages are the large fuel volume flows, the slow carbon monoxide reaction rate, and compressor-turbine matching problems.