This issue of Science and Technology for the Built Environment includes a special section regarding Variable Refrigerant Flow (VRF) technology. VRF systems provide precise cooling and heating to dynamically varying multiple space loads. To do so the system varies the refrigerant flow by means of electronic expansion valves and the variable speed compressor. As a result, it provides an improved occupant's thermal comport and energy savings.
This VRF topical section includes an article about optimization of VRF and VAV combined air conditioning systems, “Coordinated optimization of the variable refrigerant flow and variable air volume combined air-conditioning system in heating conditions,” by Yonghua Zhu et al. The other, “A review of recent development in variable refrigerant flow systems,” by myself and colleagues from the University of Maryland, provides a comprehensive research review on VRF systems. These two articles put forward how to improve VRF systems, and provide future research direction in order to further improve VRF system energy efficiency.
Yunho Hwang, PhD
Member ASHRAE and IIR
Research Professor
University of Maryland
College Park, MD, USA