Pressure control for cleanrooms in the pharmaceutical industry is a necessary means to avoid the cross-contamination. The pressure control of traditional air conditioning can only handle the working stage. In the non-working stage, the system cannot reduce the air change rate per hour (ACH) in order to alleviate the problem of high energy consumption. This paper proposes an improved air conditioning system, which focuses on the ability to control pressure gradient of the system in working and non-working mode. By theoretical derivation of the combined fan frequency conversion, when the impedance and volume of the infiltration air satisfy $\sqrt{S_i}{G}_{Z,i}=\sqrt{S_j}{G}_{Z,j}=\sqrt{S_k}{G}_{Z,k}=constant$, the pressure gradient in multi-zone cleanrooms can remain stable. A mathematical model of the system has been established, which includes five modules: air pipe network, fan characteristic curve, fan operating point solution, variable volume damper characteristic curve and multi-zone network pressure gradient solution. The correctness of the model is verified by field measurements. Taking a clean workshop as case study, the room pressure can be stabilized in the range of ± 3 Pa by switching the working and non-working mode, which can save 39.8% of the energy consumption in non-working mode, while ensuring cleanliness. This paper demonstrates the process of the air pipe network’s influence on cleanrooms pressure and proves the effectiveness of improved purification air conditioning system in pressure gradient control and energy saving potential.

制药行业洁净室的压力控制是避免交叉污染的必要手段。传统空调的压力控制只能处理工作阶段。在非工作阶段，系统不能降低每小时换气率（ACH）以缓解高能耗问题。本文提出了一种改进的空调系统，其重点是控制系统在工作和非工作模式下的压力梯度的能力。通过组合风机变频的理论推导，当渗透空气的阻抗和体积满足$\sqrt{{秒}_{\mathrm{一世}}}{G}_{Z,\mathrm{一世}}=\sqrt{{秒}_j}{G}_{Z,j}=\sqrt{{秒}_{克}}{G}_{Z,克}=C○n秒吨\mathrm{一种}n吨$，多区洁净室的压力梯度可以保持稳定。建立了系统的数学模型，包括空气管网、风机特性曲线、风机工况点求解、变风量阻尼器特性曲线和多区管网压力梯度求解五个模块。通过现场测量验证了模型的正确性。以洁净车间为例，通过切换工作模式和非工作模式，可将室内压力稳定在±3Pa范围内，在保证洁净度的同时，可节省39.8%的非工作模式能耗。本文论证了空气管网对洁净室压力影响的过程，并证明了改进的净化空调系统在压力梯度控制和节能潜力方面的有效性。