Comparative investigation of performance of gas dryer and two other types of domestic clothes dryers

The moisture extraction rate (MER) and energy efficiency of domestic gas clothes dryers, heat-pump clothes dryers and electric clothes dryers were assessed. The assessment was performed with regard to five indices: the MER, specific MER, specific thermal energy consumption for dehumidification (m(SPC)), energy efficiency (eta(t)) and primary energy efficiency (eta(1)). The effects of the dry mass of clothes (m(BD)) and the ambient temperature on the performance of the clothes dryers were evaluated. The experiments were divided into two parts. In the first part, the ambient temperature was 20 degrees C, and m(BD) was set as 1.5, 2.5, 3.5, 4.5 and 6 kg. In the second part, m(BD) was 3.5 kg, and the performance of the dryers was tested at ambient temperatures of 5, 7.5, 10, 12.5, 15 and 20 degrees C. The experimental results indicated that the gas dryer had the highest MER the heat-pump dryer had the best performance with regard to energy conservation and all three types of dryers had a higher MER and energy efficiency when the ambient temperature increased. The performance of the gas dryer was lower than that of heat-pump dryer when the temperature was 20 degrees C. But when the temperature was < 9.5 degrees C, the primary energy efficiency of the gas dryer was higher than that of the heat-pump dryer.