The lack of controllable ventilation design for acceptable indoor air quality is a major problem facing small-scale direct expansion air conditioning (DXAC) systems for household applications. The DXAC-IEC hybrid cooling system, consisting of DXAC systems and indirect evaporative cooler (IEC) ventilators, can provide an energy-efficient solution to this problem. An adaptive controller is proposed in this study to respond to changeable indoor and outdoor disturbances to provide standard-compliant fresh air demand, guarantee indoor thermal comfort and reduce energy consumption at the same time. In the adaptive control scheme, different operation modes are applied by combining three modes of compressor speed (high-low, low-off, off) and three modes of IEC fan speed (high, middle, low) responding to outdoor and indoor conditions. The dynamic performance of DXAC-IEC system on typical days and annual performance were numerically investigated. The results show that considerable energy saving (22.1% to 34.1% in Xi’an) can be achieved in transition seasons by DXAC-IEC system for providing standard-compliant ventilation rate and guaranteeing indoor thermal comfort simultaneously compared to a standalone DXAC system. However, extra energy (10.0% to 25.4% in Xi’an) will be consumed on summer days. On a typical summer day, the indoor relative humidity will increase by 10% to 15% because of extra latent load brought from IEC ventilator compared to the standalone DXAC system, but indoor temperature can be precisely controlled and CO₂ concentration is mostly below 1500 ppm.

对于可接受的室内空气质量，缺乏可控的通风设计是家庭应用中小型直接膨胀式空调 (DXAC) 系统面临的主要问题。DXAC-IEC 混合冷却系统由 DXAC 系统和间接蒸发冷却器 (IEC) 通风机组成，可为该问题提供节能解决方案。本研究提出了一种自适应控制器，以响应多变的室内外干扰，以提供符合标准的新鲜空气需求，同时保证室内热舒适度并降低能耗。在自适应控制方案中，通过结合三种压缩机转速模式（高低、低关、关）和三种IEC风扇转速模式（高、中、低）来响应室外和室内条件，应用不同的运行模式。对DXAC-IEC系统典型日动态性能和年性能进行了数值研究。结果表明，与独立的 DXAC 系统相比，DXAC-IEC 系统在提供符合标准的通风率和保证室内热舒适度的同时，可以在过渡季节实现可观的节能（西安 22.1% 至 34.1%）。但是，夏季将消耗额外的能量（西安为 10.0% 至 25.4%）。在典型的夏日，由于 IEC 通风机带来的额外潜在负荷，室内相对湿度会比独立的 DXAC 系统增加 10% 到 15%，但室内温度可以精确控制，CO 与独立的 DXAC 系统相比，DXAC-IEC 系统可在过渡季节实现 1% 的换气率，同时提供符合标准的通风率并保证室内热舒适度。但是，夏季将消耗额外的能量（西安为 10.0% 至 25.4%）。在典型的夏日，由于 IEC 通风机带来的额外潜在负荷，室内相对湿度会比独立的 DXAC 系统增加 10% 到 15%，但室内温度可以精确控制，CO 与独立的 DXAC 系统相比，DXAC-IEC 系统可在过渡季节实现 1% 的换气率，同时提供符合标准的通风率并保证室内热舒适度。但是，夏季将消耗额外的能量（西安为 10.0% 至 25.4%）。在典型的夏日，由于 IEC 通风机带来的额外潜在负荷，室内相对湿度会比独立的 DXAC 系统增加 10% 到 15%，但室内温度可以精确控制，CO₂浓度大多低于 1500 ppm。