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ACRC Technical Report 37PDF


Title:Semi-Theoretical Steady State and Transient Modeling of an Automotive Air Conditioning Evaporator
Author(s):Smith, S.A.
Contributor(s):Pederson, C.O.
Subject(s):mobile air conditioning systems
Abstract:The objectives of this study were to develop semi-theoretical steady state and transient models of a mobile air conditioning evaporator for use in a complete system simulation. The steady state evaporator heat transfer model chosen in this project is a simplification of the enthalpy potential model presented in the ASHRAE Equipment Handbook and correlates the measured data within 5%. The pressure drop model is an empirical model and correlates the data within 10%. The mass transfer model is an empirical model that uses a mass transfer potential of the difference between the humidity ratio's evaluated at the air inlet and the metal surface conditions. This model correlates the data within' 10%. Coefficients for these models were obtained from experimental data using parameter search routines. The three models for heat and mass transfer and pressure drop were placed into a complete evaporator simulation model and continued to correlate the data well. For this study an empirical model was developed for the transient evaporator model. A quasi steady state model was used to determine the transient pressure drop. The transient heat transfer model uses an exponential approach to the steady state predictions of the heat transfer response to the transient inputs. This model is similar to approximating a complicated system response with a series of first order responses to the evaporator inputs. The experimental procedure and the techniques used to develop the evaporator models are discussed in de~ail to aid in future model development The programs that are discussed in detail in chapter 6 and given in the appendix are a Newton Raphson Equation Solver, and linear least squares, nonlinear least squares and Marquardt parameter search routines.
Issue Date:1993-05
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-37
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Center Project 09
Date Available in IDEALS:2009-03-13
Identifier in Online Catalog:3546280

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