energy, efficiency, automotive, air conditioning, tropics
Air conditioning (AC) is an integral component of modern cars in the tropics. However, AC usage in this region consumes a large amount of energy. In conventional internal combustion engine cars, it consumes up to 30% of the fuel, while in battery electric cars, AC may reduce the battery range by up to 40%. Fortunately, there are various ways to improve the efficiency of automotive ACs in the tropics. In this paper, three energy saving measures are discussed. These include a higher indoor temperature setting, a smaller temperature lift and a separate dehumidification system. The study suggests that increasing the indoor temperature setting alone from 20°C to 24°C can save about 22% of the compressor power and increase the COP by up to 13%. Reducing the temperature lift by reducing the temperature difference between the condensing and ambient temperatures can potentially save up to 30% of the compressor power and increase the COP by 45%. An important requirement of this method is the need for a compact and lightweight heat exchanger design. The separation of dehumidification and cooling is very effective as it reduces the thermal load and allows for a higher evaporating temperature. About 50% compressor power saving can be achieved with a dehumidification system. An important requirement is that the energy for regeneration of the dehumidifier must come from waste energy. Finally, combination of all the methods can save compressor power requirement of automotive AC systems in the tropics by up to 70%.