Transient Response of the Counterflow Heat Exchanger

1984 ◽  
Vol 106 (3) ◽  
pp. 620-626 ◽  
Author(s):  
F. E. Romie
Keyword(s):  
Steady State ◽  
Heat Exchanger ◽  
Temperature Response ◽  
Empirical Equations ◽  
Fluid Temperature ◽  
Temperature Distributions ◽  
Unit Step ◽  
Steady State Temperature ◽  
Exit Temperature ◽  
Temperature Responses

The exit fluid temperature responses are presented for a unit step increase in the entrance temperature of either of the fluids of a counterflow heat exchanger. The exit temperature response histories are functions of four parameters, three of which are commonly used to define the steady-state temperature distributions in the exchanger. The responses are found using a finite difference method and are represented by simple empirical equations for a range of the four parameters believed appropriate for many technical applications.

Analysis of Cooling Effectiveness for Porous Material in a Coolant Passage

1974 ◽  
Vol 96 (3) ◽  
pp. 324-330 ◽  
Author(s):  
J. C. Y. Koh ◽  
R. Colony
Keyword(s):  
Porous Media ◽  
Approximate Solution ◽  
Steady State ◽  
Heat Exchanger ◽  
Analytical Investigation ◽  
Coolant Fluid ◽  
Governing Equations ◽  
Cooling Effectiveness ◽  
Temperature Distributions ◽  
Steady State Temperature

An analytical investigation of the performance of a heat exchanger containing a conductive porous media was made. The partial differential equations governing the steady-state temperature distributions for both the porous media and the coolant fluid are given. A method for obtaining an approximate solution of the governing equations is shown. A computer program was written in FORTRAN IV and the results are provided for determining the cooling effectiveness.

scholarly journals An Enhanced Vertical Ground Heat Exchanger Model for Whole-Building Energy Simulation

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4058
Author(s):  
Matt S. Mitchell ◽  
Jeffrey D. Spitler
Keyword(s):  
Heat Exchanger ◽  
Temperature Response ◽  
Building Energy ◽  
Energy Simulation ◽  
Building Energy Simulation ◽  
Response Factor ◽  
Fluid Temperature ◽  
Ground Heat Exchanger ◽  
Vertical Ground ◽  
Whole Building Energy Simulation

This paper presents an enhanced vertical ground heat exchanger (GHE) model for whole-building energy simulation (WBES). WBES programs generally have computational constraints that affect the development and implementation of component simulation sub-models. WBES programs require models that execute quickly and efficiently due to how the programs are utilized by design engineers. WBES programs also require models to be formulated so their performance can be determined from boundary conditions set by upstream components and environmental conditions. The GHE model developed during this work utilizes an existing response factor model and extends its capabilities to accurately and robustly simulate at timesteps that are shorter than the GHE transit time. This was accomplished by developing a simplified dynamic borehole model and then exercising that model to generate exiting fluid temperature response factors. This approach blends numerical and analytical modeling methods. The existing response factor models are then extended to incorporate the exiting fluid temperature response factor to provide a better estimate of the GHE exiting fluid temperature at short simulation timesteps.

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.

Thermodynamic Analysis of Thermal Responses in Horizontal Wellbores

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Luis F. Ayala H. ◽  
Ting Dong
Keyword(s):  
Steady State ◽  
Thermodynamic Analysis ◽  
Analytical Models ◽  
Distributed Temperature Sensing ◽  
Enthalpy Changes ◽  
Steady State Temperature ◽  
Horizontal Wellbore ◽  
Horizontal Wellbores ◽  
Physical Changes ◽  
Temperature Responses

Wellbore models are required for integrated reservoir management studies as well as optimization of production operations. Distributed temperature sensing (DTS) is a smart well technology deployed for permanent downhole monitoring. It measures temperature via fiber optic sensors installed along horizontal wellbores. Correct interpretation of DTS surveys has thus become of utmost importance and analytical models for analysis of temperature distribution behavior are critical. In this study, we first show how thermodynamic analysis can describe in detail the physical changes in terms of pressure and temperature behavior from the simplest cases of “leaky tank” to the horizontal wellbore itself. Subsequently, rigorous single-phase thermodynamic models for energy, entropy, and enthalpy changes in horizontal wellbores are derived starting from 1D conservative mass, momentum, and energy balance equations and a generalized thermal models, along with their steady-state temperature profile subsets, are presented. Steady-state applications are presented and discussed. The analysis presents the factors controlling horizontal wellbore steady-state temperature responses and demonstrates that wellbore thermal responses are neither isentropic nor isenthalpic and that the isentropic expansion-driven models and Joule–Thompson-coefficient (JTC) driven may be used interchangeably to analysis horizontal wellbore thermal responses.

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