Validation of a 5-zone-car-cabin model to predict the energy saving potentials of a battery electric vehicle’s HVAC system

Abstract

Abstract. This paper presents a 5-zone-car-cabin model which is able to simulate the car cabin's thermal condition depending on several influencing parameters. This includes the solar radiation, to which special attention is paid in this paper. In addition, a generic methodology for parameter optimization considering measurements on a reference vehicle is presented. Thus, a very high degree of determination of the model was achieved. This paper is motivated by the impact of auxiliary loads on overall energy consumption in battery electric vehicles. The further use of the model is intended to calculate the energy saving potentials of the heating, ventilation, and air conditioning system by reducing or increasing the target interior temperature. This is necessary for a predictive control of secondary consumers. IntroductionMost of the potential car buyers do not trust in the vehicle range of battery electric vehicles (BEVs), as they are often smaller than the manufacturer indicates. In addition, the so-called range anxiety (The fear that a vehicle cannot reach its destination because of insufficient range.) is still widespread. In order to counteract the range disadvantage, an efficient use of the available energy is necessary. This requires the knowledge of the overall energy requirement to cover the present route. Each route has different energy loads in terms of propulsion and secondary consumers. The heating, ventilation, and air-conditioning (HVAC) system can be the largest auxiliary load. It is shown that the range of electric vehicles significantly reduces when the HVAC system is activated [1], [2]. Depending on the weather conditions, up to 25% of the required energy is used by secondary consumers [3]. Thus, the HVAC system offers a considerable energy saving potential by reducing or increasing the target interior temperature in case of a predictive control. However, possible energy savings quickly lead to the conflict with passenger's comfort. To identify the energy saving potentials of an HVAC system, some preparation steps are necessary, according to figure 1.

Design, Implementation and Validation of a Hardware-in-the-Loop Test Bench for Heating Systems in Conventional Coaches

“…By contrast, there are lumped models that treat the whole cabin as a single homogeneous zone, primarily intended to assess the impact of the different thermal loads [15] or passenger comfort [16]. Finally, between the two previous types of models, there are those that segment the cabin into several zones, which exchange air volumes, defining lumped models for each one as a simplification of CFD models [17][18][19]; therefore, such exchange mechanisms between adjacent zones must also be mathematically defined. These latter models are a well-suited option for bus or coach cabins, which can be easily partitioned into clearly distinguished air zones, with an optimal balance between accuracy and simplicity with a reasonable computational cost when they are used in the design of control strategies and for real-time simulation.…”

Modelo térmico de un sistema de calefacción para vehículos de transporte público

“…Respecto al primero, en la bibliografía se pueden encontrar diferentes enfoques para modelar térmicamente el habitáculo de un vehículo, algunos más detallados y computacionalmente más costosos basados en Dinámica de Fluidos Computacional (CFD, Computational Fluid Dynamics), centrados en el confort de los ocupantes [7,8], en el estudio de la calidad del aire [4,13] o en la influencia de la apertura de puertas y ventanas [6]. Por otro lado, en la literatura relacionada se pueden encontrar también modelos de parámetros concentrados para furgonetas y coches (lumped-parameter models), de menor complejidad y coste computacional, siendo los más recomendables para, por ejemplo, aplicaciones de control; algunos de ellos consideran el habitáculo del vehículo como una única zona térmica [5,9], mientras que otros lo dividen en dos o más zonas [3,11]. Con respecto a los sistemas de calefacción, existe una extensa bibliografía sobre el modelado de sus componentes, entre los que se pueden encontrar los intercambiadores de calor [14], las válvulas de control, con especial énfasis en su comportamiento no lineal [10], o los ventiladores [15].…”