CH-12-C055 -- Multi-Zone Test Facility for Variable Capacity Multi-Split Heat Pump Systems PDF

The latest advances in HVAC technologies focus on delivering the exact cooling or heating required to each individual zone by modulating the system capacity. New technologies like variable speed compressors and inexpensive controls have allowed manufacturers to introduce a new family of direct expansion systems with multiple indoor conditioning coils. The HVAC design and modeling community is interested in analyzing reliable and accurate laboratory data on such systems to further understand the actual benefits. In a typical dual room psychrometric chamber used to test unitary systems, one chamber houses the outdoor unit and the other houses the indoor unit. The multi-split systems provide a unique testing challenge. With multiple indoor coils, a single indoor chamber is unable to simulate individual return air conditions to each indoor coil. This problem is further exacerbated in case of systems which can provide simultaneous heating and cooling. This paper details the design, construction, and commissioning of a novel multi-zone test facility (test stand) for multi-split heat pump systems. A four zone, 10-Ton (35.2kW) ducted test stand is constructed for testing multi-split systems. Each zone has individual temperature, humidity and air flow control which allows indoor coils to be tested at different conditions irrespective of the other coils. The temperature control is achieved by using resistance heaters and cooling coils while the humidity control is achieved by an air /water atomizing system. An axial fan upstream of the indoor units is used to deliver air flow with required static pressure. All three control systems--temperature, humidity and air flow - are controlled through a dedicated data acquisition system. The same system is used to collect data from various sensors. The paper elaborates on the design challenges, construction details andvarious instrumentation aspects of the test stand.