Dynamic simulation study on regulation characteristics of transcritical CO2 multi-ejector refrigeration system
Dynamic simulation study on regulation characteristics of transcritical CO2 multi-ejector refrigeration system
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DOI：
10.1016/j.ijrefrig.2023.03.002
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发表时间：
2023-03
影响因子：
3.9
通讯作者：
Zhikang Xiong;Yang He;Hongxia Zhao;Jianqiang Deng
中科院分区：
文献类型：
--
作者：
Zhikang Xiong;Yang He;Hongxia Zhao;Jianqiang Deng
基于真实的CO2物性，考虑了跨音速流动、相变和阻塞等因素，建立了多喷射器CO2跨临界制冷系统的动态模型，模型预测值与文献中的实验值吻合较好。通过调节压缩机转速、换热器水流量、膨胀阀开度和引射器组合作为扰动条件，研究了系统的瞬态响应。结果表明，所建立的动力学模型与同类系统具有相似的响应规律。气体冷却器冷却水流量和满液式蒸发器冷冻水流量的变化会引起系统中除低温蒸发器外的其他压力的显着响应，并可以在一定程度上调节冷热负荷。中、低温膨胀阀的开度分别对系统的中、低温制冷量起着决定性的作用，低温膨胀阀是低温制冷量的唯一调节手段。多引射器的最佳操作组合使系统性能和引射器压力提升比最大化。在此基础上，研究并比较了制冷量为75 ~ 115 kW时系统的最优喷射器组合，提出了以“喷嘴质量流量”调节喷射器组合的控制策略，以适应系统在不同负荷下的高性能运行。在研究条件下，最优引射器组合满足喷嘴质量流量稳定在0.066 ~ 0.070 kg·s-1。
This paper presents a dynamic model of transcritical CO2refrigeration system with multi-ejector which is developed based on the real CO2properties and considering the internal transonic flow, phase change and choking, and its predictions are in good agreement with experimental data from the literature. The transient response of the system is studied by adjusting the speed of compressor, water flow of heat exchanger, opening of expansion valve and combination of ejector as disturbance conditions. The presented results show that the developed dynamic model has similar response rules with the same type of system. Changes of cooling water flow of gas cooler and chilled water flow of flooded evaporator can cause significant response of other pressures in the system except low-temperature evaporator, and can regulate the cooling and heating load to some extent. Opening of medium and low temperature expansion valve plays a decisive role in the system's medium and low temperature refrigeration capacity respectively, and the low-temperature expansion valve is the only regulation means of the low-temperature cooling capacity. Optimal operating combination of multi-ejector maximizes the system performance and ejector pressure lift ratio. Furthermore, the optimal ejector combination of the system under the refrigeration capacity of 75∼115 kW is studied and compared, a control strategy of adjusting ejector combination by "nozzle mass flow rate" is put forward to adapt to the high-performance operation of the system under different loads. Under the research conditions, the optimal ejector combination satisfies that the nozzle mass flow rate is stable in 0.066∼0.070 kg·s-1.