Closure to “Discussion of ‘Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions’” (1964, ASME J. Eng. Power, 86, p. 126)

1964 ◽  
Vol 86 (2) ◽  
pp. 126-126
Author(s):  
J. R. Mondt
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Periodic Flow ◽  
Fluid Temperature ◽  
Temperature Distributions ◽  
Flow Heat

Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions

1964 ◽  
Vol 86 (2) ◽  
pp. 121-126 ◽  
Author(s):  
J. R. Mondt
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
General Motors ◽  
Periodic Flow ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Temperature Distributions ◽  
Flow Heat

Design, fabrication, and operation experience with periodic-flow heat exchangers used in General Motors regenerative vehicular gas turbines has indicated that analysis techniques available in published reports are too restrictive for accurate performance and thermal distortion calculations. The design usefulness of previously published analyses is somewhat limited because fluid and metal temperature distributions are not part of the calculated results. These distributions are required for primary seal matching and core and structural thermal stress calculations. A nodal analysis has been accomplished at the General Motors Research Laboratories and a type of finite difference solution obtained for the periodic-flow heat exchanger. This solution can be used to study the effects of longitudinal thermal conduction, variable heat-transfer coefficients, finite rotation, and provides temperature distributions as functions of time and space for transient as well as “steady-state.” This has been checked both with available solutions for more simplified cases and some experimental measured results for periodic flow heat exchangers designed and built as part of the General Motors vehicular regenerative gas turbine program. A brief outline of the calculation procedures, program capabilities, and some calculated results is presented. This includes temperature distributions for periodic-flow heat-exchanger parameters encountered in the vehicular regenerator application.

Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions

1963 ◽  
Author(s):  
James R. Mondt
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
General Motors ◽  
Periodic Flow ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Temperature Distributions ◽  
Flow Heat

Design, fabrication and operation experience with periodic-flow heat exchangers used in General Motors regenerative vehicular gas turbines has indicated that analysis techniques available in published reports are too restrictive for accurate performance and thermal-distortion calculations. The design usefulness of previously published anaylses is somewhat limited because fluid and metal-temperature distributions are not part of the calculated results. These distributions are required for primary seal matching and core and structural thermal-stress calculations. A nodal analysis has been accomplished at the General Motors Research Laboratories and a type of finite-difference solution obtained for the periodic-flow heat exchanger. This solution can be used to study the effects of longitudinal thermal conduction, variable heat-transfer coefficients, finite rotation, and provides temperature distributions as functions of time and space for transient as well as “steady state.” This has been checked both with available solutions for more simplified cases and some experimental measured results for periodic-flow heat exchangers designed and built as part of the General Motors vehicular regenerative gas-turbine program. A brief outline of the calculation procedures, program capabilities, and some calculated results are presented. This includes temperature distributions for periodic-flow heat exchanger parameters encountered in the vehicular regenerator application.

The Effect of Longitudinal Heat Conduction on Periodic-Flow Heat Exchanger Performance

1964 ◽  
Vol 86 (2) ◽  
pp. 105-117 ◽  
Author(s):  
G. D. Bahnke ◽  
C. P. Howard
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Zero Element ◽  
General Purpose ◽  
Periodic Flow ◽  
Gas Streams ◽  
Flow Heat ◽  
Area Use ◽  
Significant Figures

A numerical finite-difference method of calculating the effectiveness for the periodic-flow type heat exchanger accounting for the effect of longitudinal heat conduction in the direction of fluid flow is presented. The method considers the metal stream in crossflow with each of the gas streams as two separate but dependent heat exchangers. To accommodate the large number of divisions necessary for accuracy and extrapolation to zero element area, use was made of a general purpose digital computer. The values of the effectiveness thus obtained are good to four significant figures while those values for the conduction effect are good to three significant figures. The exchanger effectiveness and conduction effect have been evaluated over the following range of dimensionless parameters. 1.0⩾Cmin/Cmax⩾0.901.0⩽Cr/Cmin⩽∞1.0⩽NTU0⩽1001.0⩾(hA)*⩾0.251.0⩾As*⩾0.250.01⩽λ⩽0.32

Consideration of Uncertainties in Compact Cross-Flow Heat Exchanger Design for Gas Turbine Engine Application

2013 ◽  
Author(s):  
Randall D. Manteufel ◽  
Daniel G. Vecera
Keyword(s):  
Fluid Flow ◽  
Heat Exchanger ◽  
Gas Turbine ◽  
Flow Rate ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Fluid Flow Rate ◽  
Heat Exchanger Design ◽  
Cold Fluid ◽  
Flow Heat

Recent experimental work characterized the performance of a unique cross-flow heat exchanger design for application of cooling compressor bleed air using liquid jet fuel before it is consumed in the gas turbine combustor. The proposed design has micro-channels for liquid fuel and cools air flowing in passages created using rows of intermittent fins. The design appears well suited for aircraft applications because it is compact and light-weight. A theoretical model is reported to be in good agreement with experimental measurements using air and water, thus providing a design tool to evaluate variations in the heat exchanger dimensions. This paper presents an evaluation of the heat exchanger performance with consideration of uncertainties in both model parameters and predicted results. The evaluation of the design is proposed to be reproduced by students in a thermal-fluids design class. The heat exchanger performance is reevaluated using the effectiveness–NTU approach and shown to be consistent with the method reported in the original papers. Results show that the effectiveness is low and in the range of 20 to 30% as well as the NTU which ranges from 0.25 to 0.50 when the heat capacity ratio is near unity. The thermal resistance is dominated by the hot gas convective resistance. The uncertainties attributed to fluid properties, physical dimensions, gas pressure, and cold fluid flow rate are less significant when compared to uncertainties associated with hot fluid flow rate, hot fluid inlet temperature, cold fluid inlet temperature, and convective correlation for gas over a finned surface. The model shows which heat transfer mechanisms are most important in the performance of the heat exchanger.

Computer simulation of thermoeconomic optimization of periodic-flow heat exchangers

2003 ◽  
Vol 217 (5) ◽  
pp. 559-570 ◽  
Author(s):  
R. K. Jassim ◽  
A. A K. Mohammed Ali
Keyword(s):  
Computer Simulation ◽  
Heat Exchanger ◽  
Finite Difference ◽  
Unit Cost ◽  
Mesh Size ◽  
Computational Time ◽  
Design Parameters ◽  
Periodic Flow ◽  
Unit Costs ◽  
Flow Heat

A computer simulation of heat transfer by the finite difference technique is presented for calculating the fluid and matrix temperature distributions and their effect on periodic-flow heat exchanger performance. The governing differential equations have been formulated in terms of characteristic dimensionless groups. In order both to secure a high degree of accuracy of the results and to save computational time, three modifications have been made to evaluate the finite difference mesh size for regenerator length, hot period and cold period. The geometry of the matrix of a periodic-flow heat exchanger is optimized using the unit cost of the exergy of the warm delivered air as the objective function. The running cost is determined using unit costs for the pressure component of exergy and for the thermal component of exergy. The ratio of the two unit costs is obtained from an air conditioning plant and a power station in which the regenerator is used. The effect of variation in the principle design parameters on the unit cost of the warm air and on the heat exchange effectiveness are examined, and recommendations are made for the selection of the most appropriate parameters for a regenerator of a given capacity.

Prediction of the Transient Thermodynamic Response of a Closed-Cycle Regenerative Gas Turbine

2005 ◽  
Vol 127 (1) ◽  
pp. 57-64 ◽  
Author(s):  
T. Korakianitis ◽  
J. I. Hochstein ◽  
D. Zou
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Mass Flow Rate ◽  
Transient Response ◽  
Mass Flow ◽  
Flow Rate ◽  
Transient Flow ◽  
Closed Cycle ◽  
Flow Heat ◽  
Component Models

Instantaneous-response and transient-flow component models for the prediction of the transient response of gas turbine cycles are presented. The component models are based on applications of the principles of conservation of mass, energy, and momentum. The models are coupled to simulate the system transient thermodynamic behavior, and used to predict the transient response of a closed-cycle regenerative Brayton cycle. Various system transients are simulated using: the instantaneous-response turbomachinery models coupled with transient-flow heat-exchanger models; and transient-flow turbomachinery models coupled with transient-flow heat-exchanger models. The component sizes are comparable to those for a solar-powered Space Station (radial turbomachinery), but the models can easily be expanded to other applications with axial turbomachinery. An iterative scheme based on the principle of conservation of working-fluid mass in the system is used to compute the mass-flow rate at the solar-receiver inlet during the transients. In the process the mass-flow rate of every component at every time step is also computed. Representative results of different system models are compared and discussed.

Calculation of Transients in a Cross-Flow Heat Exchanger

1959 ◽  
Vol 81 (1) ◽  
pp. 61-67 ◽  
Author(s):  
G. M. Dusinberre
Keyword(s):  
Heat Exchanger ◽  
Numerical Methods ◽  
Gas Turbine ◽  
Digital Computer ◽  
Computer Programming ◽  
Cross Flow ◽  
Flow Rates ◽  
Flow Heat

This paper shows how transient temperatures in a cross-flow heat exchanger may be calculated by numerical methods. Digital computer programming is considered. A gas-turbine regenerator is used as an example. In particular, methods are developed which are useful when the flow rates vary, as in the starting transient.

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