Methods for increasing the efficiency of climate control systems for electric buses

KNRTU–KAI, Department of Heat Engineering and Power Engineering, 420111, Kazan, Russia

^* Corresponding author: amermakov@kai.ru

Abstract

Increasing the range of an electric bus on a single battery charge is an important task facing electric bus developers. The auxiliary system that consumes the largest amount of electricity is the air conditioning system. This paper examines the main methods for increasing the efficiency of a climate control system and evaluates them using numerical methods using a verified one-dimensional mathematical model. The following methods were chosen to improve efficiency: the most suitable refrigerants, the use of an internal heat exchanger of a vapor compression unit, the recovery of heat from the air removed from the interior electric bus in the evaporator of a vapor compression unit, and the use of heat from electrical equipment in the climate control system. The greatest efficiency in cooling and heating modes is shown by the use of refrigerants R404a, R410a and R507a in the vapor compression unit. The use of an internal heat exchanger in a vapor compression unit allows an increase in coefficient of performance by 11%. The combined use of cabin heat in the evaporator of the vapor compression unit and the internal heat exchanger allows the coefficient of performance to be increased by 27%. Using the heat of electrical equipment allows you to increase the coefficient of performance in heat pump mode by 20%. The most promising is the combined use of the above methods to reduce the cost of air conditioning in the cold season.