Improvement of Brayton refrigeration air cycle for electroplating wastewater treatment.

• Two improved Brayton refrigeration air cycles for wastewater treatment are developed. • These two new systems have no air condensation during the expansion process. • The system coupled with a reheater can achieve the exergy efficiency of 70.7%. • The system using a solar collector can acquire the dry air with 163.6 ℃. • System using a solar collector can increase system efficiency ratio to 2.18 kg/(kW h). The Brayton refrigeration air cycle for electroplating wastewater treatment can achieve 100% recovery of water, but there is air condensation during the expansion, which can damage the expander. In order to avoid the harmful air condensation during the expansion, an improved Brayton refrigeration air cycle coupled with a reheater and an improved Brayton refrigeration air cycle using a solar collector for electroplating wastewater treatment are developed in this paper. For these two new systems, as the solar collector or reheater is used to heat the air at the outlet of the chiller, there is no air condensation during the expansion. When the wastewater needs to be treated by the air with low temperature, the reheater can be used at the outlet of the compressor to heat the air after the condensation dehumidification, which can increase the system efficiency ratio and exergy efficiency to 1.21 kg/(kW h) and 70.7%, respectively. When the wastewater needs to be treated by the air with high temperature, the solar collector can be used to heat the air after the condensation dehumidification, which can increase the air temperature at the inlet of the tower and system efficiency ratio to 163.6 °C and 2.18 kg/(kW h), respectively. [ABSTRACT FROM AUTHOR]