Temperature and humidity control inside an automobile during heating period

Abstract

This article investigates a control strategy for the automobile climate control problem; in particular, the heating mode in winter is considered when the initial car compartment temperature and outside temperature are colder than comfortable. By analyzing the air-conditioning processes involving the automobile air-handling unit operating in various weather conditions on a psychrometric chart, a control strategy is developed based upon the concept of conservation of sensible heat and latent heat. Irrespective of the car compartment's initial condition, the control strategy is to control air flow and mixed air temperature such that the compartment conditions in terms of temperature and humidity reach a set condition. The proposed strategy is composed of two parts. The first is to adjust air mass flow rate by balancing the latent heat transfer between ventilation and automobile compartment. Meanwhile, the second part is to control the percentage of heating air flow rate such that a precise temperature can be maintained. In short, balancing the sensible heat transfer among the air condition processes is essential to achieving temperature control, as variation in the net sensible heat will lead to changes in temperature. The proposed control strategy is evaluated in a Matlab/Simulink simulation environment. The results suggest that the proposed control strategy results in an improved indoor humidity level when compared to traditional fuzzy control.