Performance and optimization of a new spray cooling system with PV/T and heat recovery in sow houses: A case study in Nanchang, China

Abstract

The uncertain cooling effect and additional huge primary energy consumption (EC) caused by humidity regulation are currently the main problems of traditional air-conditioning systems in sow houses. In this paper, a new spray cooling system (NSCS) is developed based on PV/T and heat recovery in sow houses. Compared with traditional spray cooling systems, the cooling efficiency of new system can be significantly improved due to solar dehumidification and its EC can be reduced due to PV/T 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. Aiming at the maximum utilization rate of cooling and heating equipment, the annual operation modes are determined for NSCS based on the above models. The results show that cooling season is from May 21st to September 25th, heating season is from January 1st to March 16th and from November 1st to December 31st, and the transitional spring and autumn are from March 17th to May 20th and from September 26th to October 31st, respectively. Meanwhile, the optimal spray cooling power (SCP) and mass flow rate of circulating water (MFCW) are obtained by analyzing the operation characteristics of NSCS in cooling and heating seasons. The results show that in cooling and heating seasons, it is suggested to use the minimum ventilation required by sows (42763.5 kg/h) for the ventilation rate of NSCS. Meanwhile, the optimal SCP and MFCW are recommended as 40 kW and 12245 kg/h, respectively. Finally, the matching between exergy efficiency (EE) and EC is analyzed for NSCS in transition season through simulation. The operational control methods are further proposed for NSCS in transition season through optimization. The results show that in transition season, increasing mass flow rate of supply air (MFSA) and reducing equipment power are the operational control methods to obtain the optimal performance and minimum EC of NSCS. Specifically, in the transitional spring, the optimal MFSA, SCP and MFCW are recommended as 47812.0 kg/h, 30 kW and 10245 kg/h, respectively. In the transitional autumn, they are recommended as 55806.3 kg/h, 25 kW and 7245 kg/h, respectively. The above conclusions can provide new ideas for the development of new energy-saving air-conditioning systems in sow houses, and guide the operation control and performance optimization of NSCS.