Thermal Power Conversion Research Articles

Data assimilation and uncertainty analysis of environmental assessment problems — an application of stochastic Transfer Function and Generalised Likelihood uncertainty Estimation techniques : Romanowicz, R. and Young, P. C . Reliability Engineering & System Safety, 2003, 79, (2), 161–174

Hydrocarbon production fields are energy-intensive, with significant demands for on-site power, process heat and fresh water, particularly in arid climates. A poly-generation scheme based on the conversion of gas turbine exhaust thermal power into mechanical work to drive a seawater reverse osmosis unit and generate process heat in an off-shore oil field in the Arabian Gulf is evaluated thermodynamically and economically. The prime mover exhaust thermal power is recovered using a bottoming organic Rankine cycle (ORC), with four working fluids used in commercial ORC systems evaluated. The performance of the poly-generation system is assessed both on a yearly and a seasonal basis. The octamethyltrisiloxane (MDM) cycle yields 6 MW of net power output at ideal and overall exhaust gas heat recovery efficiencies of 14% and 10%, respectively, 37 MW of process heat, and 1380 m3/hour of permeate. The reverse osmosis unit operates at a specific energy consumption and exergy efficiency of 4.1 kWh/m3 and 29%, respectively. The exergetic efficiency of the poly-generation system is estimated at 32%, thereby enhancing the efficiency of the original gas turbine power generation system by 6%. The system becomes profitable after approximately three years for subsidized local water and natural gas prices.

Microrockets for Smart Dust

This paper details the design and fabrication ofmillimeter-scale solid propellant rockets for one-timedeployment of wireless sensor platforms, known as Smart Dust.Each microrocket assembly is an integrated system, incorporatinga combustion chamber, composite propellant grain, nozzle,igniter, and thermoelectric power converter. Solid propellant isadvantageous for a millimeter-scale single-use device because ofits simple implementation, unlike liquid propellants, whichrequire a more elaborate system of pumps and valves. Thereforethe total system volume and complexity are minimized.One type of combustion chamber was fabricated in silicon;however, thermal losses to the silicon sidewalls during combustionthrough a 1.5 mm2 cross section of fuel were too high toreliably maintain a burn. Successful combustion was demonstratedin cylindrical alumina ceramic combustion chambers with thermalconductivities five times lower than silicon and cross sectionsof 1-8 mm2. Thrusts of 10-15 mN were measured forceramic rockets weighing under l g, with specific impulses up to15 s.Silicon nozzles integrated with polysilicon microheaters andthermopiles for thermal power conversion were microfabricated ina single process. Fuel ignition by polysilicon microheaterssuspended on a low-stress nitride (LSN) membrane wasdemonstrated. Microheaters require less than 0.5 W of power toignite a propellant composed primarily of hydroxyl-terminatedpolybutadiene (HTPB) with ammonium perchlorate (AP) oxidizer.They are suspended for thermal isolation through bulkpost-processing by a backside deep reactive ion etch (DRIE). Theetched hole beneath the igniter area also serves as a nozzlethrough which high-velocity combustion gases exit the rocket.Thermopiles, which generate voltages proportional to hot andcold junction temperature differentials, have been fabricated inthe same process as igniters, and span backside DRIE thermalisolation cavities. Ten-junction thermopiles produced a maximumpower of 20 µW. With potential temperature differences ofhundreds of degrees and a total of 120 thermocouple junctionsfabricated on the silicon nozzle chip, hundreds of milliwatts ofpower could feasibly be produced during the microrocket's flight andused to augment the Smart Dust power supply.

Parametric study of the electrical to thermal power conversion in an inductively coupledrf plasma torch

An inductively coupled (ic) radio-frequency (rf) stabilized argon plasma was generated in a quartz tube using a 7 MHzrf generator. The electrical and thermal powers were measured and the efficiency of energy conversion was computed. The results indicate that for a constant power input, there is an optimum argon flow rate for which maximum energy conversion efficiency occurs.

Alkali Metal/Halide Thermal Energy Storage Systems Performance Evaluation

Materials compatibility and durability of advanced salt/alkali metal slurry thermal energy storage systems has been demonstrated [1]. Applications are being evaluated for both space and terrestrial solar thermal power conversion [2]. High energy density of these thermal storage systems is achieved by colocation of heat input and extraction within the slurry mixture which is overwhelmingly phase-change salt. This paper addresses performance testing of these systems. Understanding of mechanisms of both micro and macro stratification of the slurry is necessary to fully predict system performance as a function of gravity and system geometry. If it can be shown the gravity stratification effects are secondary to a combination of: (1) liquid metal film adhesion (wetting) to the heat exchange surfaces and solidified salt particles, (2) solubility of alkali metal in the salt-rich phase, and (3) stirring produced by liquid to vapor conversion of the alkali metal, then system geometry limitations are greatly relaxed for space application. Performance testing was accomplished using a sodium heat pipe to transfer heat from the slurry canister to a gas gap calorimeter. Testing was accomplished with the heat pipe installed only in the vapor space above the alkali metal/salt slurry and with an increase heat pipe and minimum vapor space. This testing conclusively demonstrated the effectiveness of the pseudo-heat-pipe type heat transfer mechanism operating in the slurry system under terrestrial conditions.

Turbostar: An ICF Reactor using Both Direct and Thermal Power Conversion

Combining direct and thermal power conversion results in a 52% gross plant efficiency with DT fuel and 68% with advanced DD fuel. We maximize the fraction of fusion-yield energy converted to kineti...

Fusion Breeder Blanket Design Considerations

The Fusion Breeder Program is a DOE funded program directed by Lawrence Livermore National Laboratory; the other participants in this hybrid fusion reactor design are TRW Company, GA Technologies Inc., Westinghouse Corporation, and Oak Ridge National Laboratory. GA is responsible for the following areas of reactor design: blanket thermal hydraulics, blanket thermal power conversion, fuel handling, blanket and reactor safety, and reprocessing of the bred fuel. The design of the first four areas is reported in this paper.