Description of an Operating Closed Cycle: Helium Gas Turbine

Author(s):  
James K. La Fleur

In May of 1960 La Fleur Enterprises, later to become The La Fleur Corporation, undertook the design of a closed-cycle gas turbine utilizing helium as a working fluid. The useful output of this machine was to be in the form of a stream of helium bled from the last stage of the compressor. This stream was to be used in a low-temperature refrigeration cycle (not described in this paper) and would be returned to the compressor inlet at approximately ambient temperature and at compressor-inlet pressure. The design of this machine was completed by the end of 1960 and construction was initiated immediately. The unit was completed and initial tests were made in the Spring of 1962. This paper covers the design philosophy as it affected the conceptual and preliminary design phases of the project and describes briefly the design of the various components. Photographs of these components and a flow schematic are included.

1982 ◽  
Vol 104 (1) ◽  
pp. 3-8 ◽  
Author(s):  
T. Kajikawa

An ocean-based, 1-MWe (gross) test plant has been planned to establish the feasibility of OTEC (ocean thermal energy conversion) power generation in the revised Sunshine Project. The preliminary design of the proposed test plant employs a closed-cycle power system using ammonia as the working fluid on a barge-type platform with a rigid-arm-type, detachable, single-buoy mooring system. Two types each of titanium evaporators and condensers are to be included. The steel, cold-water pipe is suspended from the buoy. The design value of the ocean temperature difference is 20 K. The paper presents an overview of the preliminary design of the test plant and the tests to be conducted.


Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Theoklis Nikolaidis ◽  
Pericles Pilidis ◽  
Suresh Sampath

One major challenge to the accurate development of performance simulation tool for component-based nuclear power plant engine models is the difficulty in accessing component performance maps; hence, researchers or engineers often rely on estimation approach using various scaling techniques. This paper describes a multi-fluid scaling approach used to determine the component characteristics of a closed-cycle gas turbine plant from an existing component map with their design data, which can be applied for different working fluids as may be required in closed-cycle gas turbine operations to adapt data from one component map into a new component map. Each component operation is defined by an appropriate change of state equations which describes its thermodynamic behavior, thus, a consideration of the working fluid properties is of high relevance to the scaling approach. The multi-fluid scaling technique described in this paper was used to develop a computer simulation tool called GT-ACYSS, which can be valuable for analyzing the performance of closed-cycle gas turbine operations with different working fluids. This approach makes it easy to theoretically scale existing map using similar or different working fluids without carrying out a full experimental test or repeating the whole design and development process. The results of selected case studies show a reasonable agreement with available data.


Author(s):  
Ali Afrazeh ◽  
Hiwa Khaledi ◽  
Mohammad Bagher Ghofrani

A gas turbine in combination with a nuclear heat source has been subject of study for some years. This paper describes the advantages of a gas turbine combined with an inherently safe and well-proven nuclear heat source. The design of the power conversion system is based on a regenerative, non-intercooled, closed, direct Brayton cycle with high temperature gas-cooled reactor (HTGR), as heat source and helium gas as the working fluid. The plant produces electricity and hot water for district heating (DH). Variation of specific heat, enthalpy and entropy of working fluid with pressure and temperature are included in this model. Advanced blade cooling technology is used in order to allow for a high turbine inlet temperature. The paper starts with an overview of the main characteristics of the nuclear heat source, Then presents a study to determine the specifications of a closed-cycle gas turbine for the HTGR installation. Attention is given to the way such a closed-cycle gas turbine can be modeled. Subsequently the sensitivity of the efficiency to several design choices is investigated. This model is developed in Fortran.


Author(s):  
C. Rodgers

A small semi-closed gas turbine was designed, fabricated, and tested to demonstrate the cycle the cycle feasibility with exhaust gas recirculation. The demonstrator unit comprised a low pressure spool compressor and turbine supercharging a high pressure spool compressor and turbine, whose exhaust passed through a recuperator, and was subsequently split, one half being recirculated to the high pressure spool compressor inlet via an intercooler, and the remaining half expanded across the low pressure spool turbine. The design and fabrication phases proceeded on schedule but commencement of engine development testing encountered mechanical difficulties. These were eventually resolved and shakedown testing of the demonstrator accomplished prior to final contractual delivery. The demonstration program was funded under a NASA LeRc contract NAS3-27396.


Author(s):  
R. P. op het Veld ◽  
J. P. van Buijtenen

This paper investigates the layout and achievable efficiencies of rotating components of a Helium gas turbine. This is done by making a preliminary design of the compressor and turbine needed for the power conversion in a combined heat and power plant with a 40 MWth nuclear high temperature reactor as a heat source. State of the art efficiency values of air breathing gas turbines are used for the first calculations. The efficiency level is corrected by comparing various dimensionless data of the Helium turbomachine with an air gas turbine of similar dimensions. A single shaft configuration with a high speed axial turbine will give highest performance and simple construction. If a generator has to be driven at a conventional speed, a free power turbine configuration must be chosen. The choice of the configuration depends among others on the cost and availability of the asynchrone generator and frequency convertor.


Author(s):  
L. D. Stoughton ◽  
T. V. Sheehan

A nuclear power plant is proposed which combines the advantages of a liquid metal fueled reactor with those inherent in a closed cycle gas turbine. The reactor fuel is a solution of uranium in molten bismuth which allows for unlimited burn-up with continuous fuel make-up and processing. The fuel can either be contained in a graphite core structure or circulated through an external heat exchanger. The cycle working fluid is an inert gas which is heated by the reactor fuel before entering the turbine. A 15 MW closed cycle gas turbine system is shown to illustrate the application of this reactor.


Author(s):  
A. Montakhab

Because of its relatively high coolant temperature, the closed cycle gas turbine HTGR is well adapted to dry cooling and its waste heat can be rejected with relatively low cost. The preliminary design of natural-draft dry cooling towers for a 1200 MW(e) GT-HTGR is presented. The effects of air approach velocity, capacity rates of air and water mediums, and number of heat exchanger cross flow passes on salient tower and heat exchanger dimensions are studied. Optimum tower designs are achieved with three cross flow passes for the heat exchanger, resulting in a simultaneous minimization of tower height, heat exchanger surface area and circulating water pumping power. Four alternative tower designs are considered and their relative merits are compared. It is concluded that the 1200 MW(e) plant can be cooled by a single tower design which is well within the present state of the natural-draft dry cooling tower technology. In comparison, the fossil-fired or HTGR steam plants of the same output is shown to need three such towers.


Author(s):  
L. H. Russell ◽  
J. Campbell

The U.S. Department of Energy is sponsoring a program of research and development on coal-fired heaters to provide heat input to the working fluid of a closed-cycle gas turbine/cogeneration system. One of the fired heater concepts being researched employs the atmospheric pressure fluidized bed coal combustion concept. This paper describes a research oriented atmospheric fluidized bed of 6- by 6-foot plan dimensions that has been designed and is being constructed for utilization during the R&D program. The design rationale is presented, details of the more significant details are described and discussed, and the planned methods for utilizing the 6- by 6-foot AFB as a research tool are presented.


Author(s):  
L Chen ◽  
W Zhang ◽  
F Sun

A thermodynamic model of an open cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling with pressure drop irreversibilities is established using finite-time thermodynamics in Part 1 of this article. The flow processes of the working fluid with the pressure drops of the working fluid and the size constraints of the real power plant are modelled. There are 12 flow resistances encountered by the working fluid stream for the cycle model. Three of these, the friction through the blades, vanes of the compressor, and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in the flow cross-section at the mixing chamber inlet and outlet, the compressor inlet and outlet, the combustion chamber inlet and outlet, the heat exchanger inlet and outlet, and the turbine inlet and outlet. These resistances associated with the flow through various cross-sectional areas are derived as functions of the mixing chamber inlet relative pressure drop, and they control the air flowrate and the net power output. The analytical formulae about the power output, efficiency, and other coefficients are derived with the 12 pressure drop losses. The numerical examples show that the dimensionless power output reaches its maximum at the optimal value and that the dimensionless power output and the thermal efficiency reach their maximum values at the optimal values of the compressor fore-stages pressure ratio of the inverse Brayton cycle.


Author(s):  
L Chen ◽  
W Zhang ◽  
F Sun

Performance analysis and optimization of an endoreversible Brayton cycle coupled to a Brayton refrigeration cycle has been performed using finite-time thermodynamics. The analy-tical formulae are derived with respect to power, efficiency, optimal extracted pressure ratio of air refrigeration cycle corresponding to optimal power, optimal power and the corresponding efficiency. The influences of various parameters on the cycle performances are analysed by numerical examples. The results show that there exists one optimal pressure ratio of the compressor corresponding to maximum power and another optimal pressure ratio of the compressor corresponding to maximum efficiency; the compressor inlet temperature is reduced by mixing the chilled working fluid from the Brayton refrigeration cycle and the main intake working fluid streams; the intake working fluid temperature could be controlled even below the temperature of the heat sink and the gas turbine performance can be improved.


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