Comparison of the Accuracy and Speed of Transient Mobile A/C System Simulation Models

Abstract

The operation of air conditioning (A/C) systems is a significant contributor to the total amount of fuel used by light-and heavy-duty vehicles. Therefore, continued improvement of the efficiency of these mobile A/C systems is important. Numerical simulation has been used to reduce the system development time and to improve the electronic controls, but numerical models that include highly detailed physics run slower than desired for carrying out vehicle-focused drive cycle-based system optimization. Therefore, faster models are needed even if some accuracy is sacrificed.In this study, a validated model with highly detailed physics, the "Fully-Detailed" model, and two models with different levels of simplification, the "Quasi-Transient" and the "Mapped

Developing a model for analysis of the cooling loads of a hybrid electric vehicle by using co-simulations of verified submodels

“…because of more frequent opening and closing of the shut-off valves. Nevertheless, these simulation times are acceptable as they are considerably shorter than those reported for similar models by Kiss et al 27 and Rasmussen.…”

“…Determining the appropriate model fidelity for this purpose has been studied by various researchers. [24][25][26][27][28] The present work is focused on developing a representative model of a chosen vehicle that can support calculation of hot ambient cooling loads within drive cycle energy efficiency simulations. Such applications allow little compromise on the simulation speed owing to their time length.…”

MATLAB/Simulink Framework for Modeling Complex Coolant Flow Configurations of Advanced Automotive Thermal Management Systems

“…The new single phase solution method integrates the "Quasi-Transient" modeling method for the refrigerant circuit with a similar approach for coolant loops. The details of the two-phase refrigerant loop solution method are discussed in [7]. This paper focuses on details of the single-phase coolant loop modeling.…”

“…This approach ensures that the coolant exit temperature from the segment does not overshoot the wall temperature: (6) where T in is temperature at the inlet boundary, T w is the segment wall temperature, A is the heat transfer area (segment length times inner channel perimeter), α is the heat transfer coefficient, and C p is the constant pressure specific heat. Then, the heat transfer rate from the coolant to the wall can be calculated as follows: (7) Once the heat transfer rate is computed with Eq. (7), the specific enthalpy on the outlet boundary can also be calculated with: (8) where Ḣ in is the enthalpy flow rate through the inlet boundary of the segment.…”

“…The Fully-Detailed model captures the system transient behavior accurately but runs at 0.1 of real-time speed [6]. The Quasi-Transient and Mapped-Component models are progressively more simplified while trying to maintain accuracy and run at real-time speed and faster than 10 times real-time speed, respectively [7]. The goal of these newer model versions was to provide faster simulation tools for less detailed, vehicle-focused drive-cycle-based evaluations of A/C systems.…”