Impact of the Evaporation Temperature on the Air Drying Rate for a Finned Heat Exchanger

Abstract

This paper presents the thermal calculations of an air-finned heat exchanger working at temperatures above zero degrees and their verification through testing on a real device. Then, on the basis of the calculations, the influence of evaporation temperature on the drying rate of the constant speed of air flowing through the exchanger was analysed. A quantitative analysis of the effect of the temperature difference between the air being dried and the evaporator on the acceleration of the process was performed. For the analysed case, the same water mass (condensate) can be obtained for an evaporation temperature of 0 °C almost four times faster than for 10 °C. To compare temperature cases, the SMER (specific moisture evaporation ratio) was calculated, which allowed the systems to be compared in terms of energy consumption. The theoretical analysis showed that by reducing the boiling point by 10 degrees, we could increase the SMER from 0.51 kgh20/kWh to 2.18 kgh20/kWh. After receiving the experimental results and including the efficiency of the system, these values were, respectively, 0.44 ± 0.01 kgh20/kWh and 1.91 ± 0.06 kgh20/kWh.

Keywords

• heat pump
• heat exchanger
• evaporator
• drying
• <i>SMER</i>
• finned heat exchanger