Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
THERMODYNAMIC MODELING OF A TWO-STAGE REFRIGERATION SYSTEM FOR A BATTERY ELECTRIC VEHICLE
Submission Author:
George Vegini , SC
Co-Authors:
George Vegini, Guilherme Borges Ribeiro
Presenter: Administrador ABCM
doi://10.26678/ABCM.COBEM2021.COB2021-0030
Abstract
Following the market and environmental concerns, the development and commercialization of hybrid powertrain and battery electric vehicles (BEV) increased in the last years. With the consistent increase of energy storage, an efficient and compact scheme of battery thermal management systems is a crucial aspect that must be taken into account for an adequate BEV operation. The most common technologies used are air cooling, liquid cooling, heat pipes, or direct refrigerant cooling. Focusing on the latter type, a vapor-compression refrigeration system can be used to extract the battery heat and provide cabin temperature comfort through two distinct evaporators connected to the same compressor. The performance of the two-stage refrigeration cycle is a key aspect to ensure a proper vehicle range without overloading the electrical grid. Also, the battery surface temperature must be kept below pre-defined values to avoid battery runaway and reduction of lifespan. Moreover, the use of environmental-friendly refrigerant fluids is also envisaged to reduce the global warming impact and CO2 emissions in future BEV. Considering all these aspects, this paper proposes an endoreversible thermodynamic modeling of a two-stage refrigeration system responsible for the battery and cabin cooling that makes use of R-134a as refrigerant fluid. The battery and cabin heat generation are considered as data input for the proposed modeling. A positive displacement compressor with fixed volumetric and global efficiencies is modeled, and constant global thermal conductances are considered for both evaporators and condenser. The heat exchangers were discretized in zones related to the fluid phase. The final system condition was achieved numerically using the software Engineering Equation Solver (EES). The distribution of the total global thermal conductance between heat exchangers is evaluated as a manner to align good performance and system compactness. The performance comparison with different refrigerants as R-1234ze, R-1234yf, and R-32 is part of the analysis. Results can serve as guidelines for the future design of hybrid powertrains and BEV.
Keywords
Refrigeration, modeling, battery cooling, electric vehicle, Refrigerant fluid
