Discussion: “The Effect of Longitudinal Heat Conduction on Periodic-Flow Heat Exchanger Performance” (Bahnke, G. D., and Howard, C. P., 1964, ASME J. Eng. Power, 86, pp. 105–117)

1964 ◽  
Vol 86 (2) ◽  
pp. 117-119
Author(s):  
J. R. Mondt
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Periodic Flow ◽  
Flow Heat

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

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.

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.

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.

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