Investigation on the control strategy of new spray cooling system based on PV/T and heat recovery in sow houses: As a case study in Nanchang, China

The uncertain cooling effect and additional huge primary energy consumption caused by humidity regulation are currently the main problems of traditional air-conditioning systems in sow houses. In order to address the above problems, a new spray cooling system is proposed based on PV/T and heat recovery in sow houses in this paper. Compared with traditional spray cooling systems, the cooling efficiency of new system can be improved and its energy consumption can be reduced due to solar dehumidification and heat recovery. Meanwhile, the mathematical models are established for its key equipment and their reliability is verified according to literature data. The results show that the maximum error is less than 7.2% for the models. The main operating parameters affecting the system characteristics are determined through simulation. The results show that with the changes in the set inlet temperature of second heat exchanger (IHET), the set subcooled temperature (SCT) and the set superheated temperature (SHT) of sensible heat exchanger, the total energy consumption and gain of new system are changed by 2%–11.9%, while they are changed by 54.5%–86% with the changes in the set inlet relative humidity of rotary dehumidifier (IRH) and the set inlet temperature of spray device (ISDT). In other words, the total energy consumption and gain of new system are slightly affected by IHET, SCT and SHT, but significantly affected by IRH and ISDT. The annual control strategy is further proposed for the new system. In cooling season, supply air of sow house will be dehumidified, heat exchanged with exhaust air and cooled, and the optimal setting ranges of operating parameters are IRH = 70%, SCT = 18 °C, SHT = 26 °C and ISDT = 22–24 °C. In heating season, it will be heat exchanged with exhaust air and heated, and the optimal setting ranges of operating parameters are SCT = 19 or 20 °C, SHT = 26–28 °C and IHET = 22–24 °C. The above research will provide guidance for the improvement of traditional spray cooling systems and the operating control of new system.