Development And Validation Of A Low-Order Thermal Model For Building Behavior

The development and validation of a control-oriented dynamic thermal model for a polymer electrolyte membrane (PEM) fuel cell stack is presented. This model is based on the first law of thermodynamics within four defined control volumes in the fuel cell; the cathode channel, anode channel, coolant channel, and fuel cell stack body. Energy and mass conservation equations are developed for each control volume. Transient dynamics captured by this model include the electrochemical reaction, heat transfer and mass transport. Activation, ohmic, and concentration voltage losses are also modeled to improve the accuracy of the voltage model response. This allows the stack voltage and cell temperature to be modeled based on the inlet temperature, pressure, and species flow rate and the relative humidity level setting. An experiment was conducted to give a baseline with which to tune the model. Tuning of the model parameters was performed and validation of these adjustments was then conducted through comparison to another experiment. The model predicts the dynamic thermal and electrical response of the fuel cell system with a good degree of accuracy in both cases.

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AN EXPERIMENTALLY VALIDATED LOW ORDER MODEL OF THE THERMAL RESPONSE OF DOUBLE-WALL EFFUSION COOLING SYSTEMS FOR HP TURBINE BLADES

Journal of Turbomachinery ◽

10.1115/1.4050976 ◽

2021 ◽

pp. 1-13

Author(s):

Alexander V Murray ◽

Peter Ireland ◽

Eduardo Romero

Keyword(s):

Heat Transfer ◽

Thermal Model ◽

Transpiration Cooling ◽

Transfer Coefficients ◽

Order Model ◽

Cooling Performance ◽

Convective Cooling ◽

Heat Transfer Coefficients ◽

Double Wall ◽

Low Order

Abstract Transpiration cooling represents the pinnacle of turbine cooling and is characterised by an intrinsic porosity achieving high internal convective cooling, and full coverage film cooling. The quasi-transpiration, double-wall effusion system attempts to replicate the cooling effect of transpiration cooling. The system is characterised by a large wetted area providing high internal convective cooling performance, with a highly porous external wall allowing the formation of a protective cooling film. This paper presents a low-order thermal model of a double-wall system designed to rapidly ascertain cooling performance based solely on the geometry, thermal conductivity, and approximate surface heat transfer coefficients. Initially validation uses experimental data with heat transfer coefficients for the low order model obtained from fully conjugate CFD simulations. A more controlled CFD study is then undertaken with both fully conjugate and fluid only simulations performed on several double-wall geometries to ascertain both overall and film effectiveness data. Data from these simulations are used as inputs to the low order thermal model and the results compared. The low order model successfully captures both the trends and absolute cooling effectiveness achieved by the various double-wall geometries. The model therefore provides a powerful tool whereby the cooling performance of double-wall geometries can be near instantaneously predicted during the initial design stage, potentially allowing geometry optimisation to rapidly occur prior to more in-depth, costly and time-consuming analyses. This benefit is demonstrated via the implementation of the model with input boundary conditions obtained using empirical correlations.

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Thermal Model and Experimental Validation of the Re-Design of High Temperature Superconducting Leads for X-Ray Spectrometer Applications

Heat Transfer, Volume 2 ◽

10.1115/imece2004-59361 ◽

2004 ◽

Author(s):

Vi´ctor L. Marrero ◽

John S. Panek ◽

Sandra Couti´n

Keyword(s):

Heat Load ◽

Thermal Model ◽

Model Development ◽

Research Work ◽

Thermal Conductance ◽

Test Results ◽

X Ray ◽

Adiabatic Demagnetization ◽

Development And Validation ◽

Superconducting Current

The thermal modeling for the redesign of an X-Ray Spectrometer (XRS) High Tc Superconducting Current (HTSC) lead assembly was the objective of this research work. In order to achieve a 2.5-year lifetime for the XRS, low thermal conductance leads were redesign to supply electric current to the Adiabatic Demagnetization Refrigerator (ADR) magnet and the cryostat valve motors with a minimal heat load. This research work consisted of the development of a mockup of the HTSC lead assembly and a computer model to simulate the thermal behavior of the system. Experimental data of the mockup was used to validate the thermal model, which was employed in the optimization of the design to minimize the heat load. The thermal model development and validation of the new HTSC lead design is discussed, with emphasis on thermal test results.

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